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INDUSTRIAL RESOURCE RECOVERY PRACTICES

>LINING INDUSTRIES (SIC Divis ion B)

Preparzd t o r U.S . Environmental P r J t Z c t l o n Agency under EPA Contract No.68-01-6000

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FI3AL REP0P.T

INDUSTRIAL RESOURCE RECOVERY PRACTICES: M I N I N G INDUSTRIES (SIC DIVISION B)

EPA C o n t r a c t No. 68-01-6000

P r e p a r e d f o r

U.S. ENVIRONMENTAL PROTECTION AGENCY O f f i c e of S o l i d Waste (W-565)

Washington , D.C. 20460 A t t e n t i o n : M r . Michael J. P e t r u s k a

FRANKLIN ASSOCIATES, LTD. L a r r y E. S e i t t e r

R o b e r t G. H u n t

December 1982

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I

PREFACE

This report is one of a series being prepared by Franklin Associates, Ltd., and JRB Associates under EPA Contract No. 68-01-6000. JRB is the prime coctractor. ject officer for the study is Mr. Michael J. Petruska..

The EPA project officer for che prime coatractor is Doug Ruby. Pro-

This study addresses resource recovery practices in the Mining Industry (SIC Division 13). produce a report which summarizes the current state-of-the-art of resource recovery and evaluates the potential for advancement of such activities; and produce a comprehensive industrial waste resource recovery library.

The specific objective of this study is to

The completion of this study involved collecting available information concerning resource recovery through extensive literature searches and contact with government agencies, knowledgeable industry professionals, trade associations, university research departments, and individual companies and refineries. This information was reviewed and assimilated to identify the current resource recovery practices used within the mining industry.

In addition, valuable information regarding current status of many of the resource recovery technologies was ?repared for Frankliil Associates, Ltd. by researchers at the Mineral Resources Institute, University of Alabama.

The project team greatly appreciates the assistance received from Mr. Michael J. Petruska in performing this work, and also the general guide- ance and encouragement received from Ms. Penelope Hansen.

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 IhTRODTJCTIC:?

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1

2.0 MINING INDUSTRY OVERVIEW 2.1 ASBESTOS M W W G INDUSTRY

2.1.1 Industry Characterization 2.1.1.1 Industry Structure 2.1.1.2 Production Statistics 2.1.1.3 Industry Trends Asbestos Mining and Beneficiation Operations 2.1.2

2.1.3 Waste Stream Characteristics and Quantification 2.1.4 Potential Hazardous Waste Streams 2.1.5 Resource Recovery Technology Descriptions

2.1.5.1 Asbestos Recovery from Tailings 2.1.5.2 Mineral Wool Insulation from Tailings 2.1.5.3 Construction Bricks from Tailings 2.1.5.4 Asphalt Surface Mix Aggregate

2.2 BARITE MINING INDUSTRY 2.2.1 Industry Characterization

2.2.1.1 Industry Structure 2.2.1.2 Production Statistics 2.2.1.3 Industry Trends Barite Mining and Beneficiation Operations 2.2.2

2.2.3 Waste Stream Characteristics and Quantification 2.2.4 Potential Hazardous Waste Streams 2.2.5 Resource Recovery Technology Descriptions

2.2.5.1 Barite Recovery from Tailings 2.2.5.2 Tailings Used as Road Construction

Aggregate

2.3 COAL MINING INDUSTRY 2.3.1 Industry Characterization

2.3.1.1 Industry Structure 2.3.1.2 Production Statistics 2.3.1.3 Industry Trends Coal Mining and Beneficiation Operations Waste Stream Characterization and Quantification

2.3.2 2.3.3 2.3.4 Potential Hazardous Waste Streams 2.3.5 Resource Recovery Technology Descriptions

2.3.5.1 Secondary Fuel Recovery Coal refuse/waste oil fuel

Wash water sludge from fuel

Fluidized bed combustion

pellets

briquettes

3 5 5 5 6 6 7 7 8 8 8 9 9 10

11 11 11 11 11 12 12 13

' 13 13

14

14 15 15 15 16 16 17 19 20 22

22.

22 23

F

i

2 . 3 . 5 . 2 Secondary Mineral Recovery Zinc ani w&l r ich conce2trate Alumina extraction Clean coal recovery

Aggregate in low quality cancrete,

Plastic resin manufacture Mineral wool production Floor and chimney flue tiles Production of portland cement

h-ti-skid road material Embankment material Aggregate Mine and construction fill

Soil conditioner synthetic humus

2 . 3 . 5 . 3 Construction Materials Manufacture

bricks an1 blocks

2 . 3 . 5 . 4 Construction and Highway Uses

2 . 3 . 5 . 5 Horticultural Uses

2 . 4 COPPER MINING INDUSTRY 2 . 4 . 1 Industry Characterization

2 . 4 . 1 . 1 Industry Structure 2 . 4 . 1 . 2 Production Statistics 2 . 4 . 1 . 3 Industry Trends Copper Mining and Beneficiation Operations 2 . 4 . 2

2 . 4 . 3 Waste Stream Characteristics and Quantification 2 . 4 . 4 Potential Hazardous Waste Streams 2 . 4 . 5 Resource Recovery Technology Descriptions

Copper Recovery from Mining and Tailings

2 . 4 . 5 . 1

2 . 4 . 5 . 2 Tailings Used in Construction 2 . 4 . 5 . 3 Anorthosite Concentrate from

Tailings

2 . 5 FELDSPAR MINING INDUSTRY 2 . 5 . 1 Industry Characterization

2.5.1.1 Industry Structure 2 . 5 . 1 . 2 Production Statistics 2 . 5 . 1 . 3 Industry Trends Feldspar Mining and Beneficiation Operations Waste Stream Characteristics and Quantification

2 . 5 . 2 2 . 5 . 3 2 . 5 . 4 Potential Hazardous Waste Streams 2 . 5 . 5 Resource Recovery Technology Descriptions

Materials 2 . 5 . 5 . 1 Use in Building and Construction

Page 24 24 25 26 27

27 30 31 32 3 2 3 3 33 34 36 38 39 3 9

4 1 4 1 4 1 41 4 2 42 46 49 5 0

5 0 53

56 56 56 56 57 57 5 8 5 9 5 9

5 9

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Page

2.6 GOLD MINING INTUSTRY 2.6.1 Industry Characterization

2.6.1.1 Industry Structure 2.6.1.2 Production Statistics 2.6.1.3 Industry Trends

2.6.2 Gold Mining and Beneficiation-Operations 2.6.3 Waste Stream Characteristics and Quantification 2.6.4 Potential Hazardous Waste Streams 2.6.5 Resource Recovery Technology Descriptions

2.6.5.1 Retreatment of Tailings 2.6.5.2 Use of Tailings in Construction

2 . 7 GRA'i'iITE MINING INDUSTRY 2.7.1 Industry Characterization

2.7.1.1 Industry Structure 2.7.1.2 Production Statistics 2.7.1.3 Industry Trends Granite Mining and Beneficiation Operations 2.7.2.1 Crushed Stone 2.7.2.2 Dimension Stone Waste Stream Characteristics and Quantification 2.7.3.1 Crushed Stone 2.7.3.2 Dimension Stone

2.7.4 Potential Hazardous Waste Streams 2.7.5 Resource Recovery Technology Descriptions

2.7.2

2.7.3

2.7.5.1 Mineral Recovery from Fines 2.7.5.2 Silicon Carbide Recovery from Sludge

2.8 IRON ORE MINING INDUSTRY 2.8.1 Industry Characterization.

2.8.1.1 Industry Structure 2.8.1.2 Production Statistics

Iron Ore Mining and Beneficiation Operations Waste Stream Characteristics and Quantification

. 2.8.1.3 Industry Trends 2.8.2 2.8.3 2.8.4 Potential Hazardous Waste Streams 2.8.5 Resource Recovery Technology Descriptions

2.8.5.1 Retreatment of Tailings 2.8.5.2 Aggregate Use

2.9 LEAD MINING INDUSTRY 2.9.1 Industry Characterization

2.9.1.1 Industry Structure 2.9.1.2 Production Statistics 2.9.1.3 Industry Trends

6 1 6 1 61 6 1 62 62 63 65 65 65 66

68 68 68 68 68 69 69 70 70 70 71 7 1 71 71 72

73 73 73 73 73 74 74 75 75 75 76

79 79 79 79 79

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9.2 2.9.3 2.9.4 Potential Hazardous Waste Streams 2.9.5 Resource Recovery Technology Descriptions

Lead Mining and Beneficiation Operations Wzste Stream Characteristics and Qiancification

2.9.5.1 Mineral Recovery from Tailings 2.9.5.2 Aggregate and Construction Use

2.10 PHOSPHATE ROCK MINING INDUSTRY 2.10.1 Industry Characterization

2.10.1.1 Industry Structure 2.10.1.2 Production Statistics 2.10.1.3 Industry Trends Phosphate Mining and Beneficiation Operations Waste Stream Characteristics and Quantification

2.10.2 2.10.3 2.10.4 Potential Hazardous Waste Streams 2.10.5 Resource Recovery Technology Descriptions

2.10.5.1 Aggregate Recovery 2.10.5.2 Ceramic Uses 2.10.5.3 Vanadium Recovery 2.10.5.4 Uranium Recovery

2.11 ACID MINE DRAINAGE 2.11.1 Potential Hazardous Waste Streams 2.11.2 Resource Recovery Technology Descriptions

2.11.2.1 2.11.2.2 2.11.2.3 Ceramically Bonded Sludge 2.11.2.4 Chemically Bonded Sludge

AMD Sludge in Strip Mine Revegetation AMD Sludge as Rock Dust

2.12 MISCELLANEOUS MINING INDUSTRIES 2.12.1 Molybdenum Mining

2.12.1.1 Waste Stream Characteristics and Quantification

2.12.1.2 Potential Hazardous Waste Streams 2.12.1.3 Resource Recovery Technology

Descriptions 2.12.2 Uranium Mining



Descriptions 2.12.3 Zinc Mining



Descr ip t ions

80 81 83 83 84 84

86 86 86 86 86 86 88 89 90 90 94 95 95

96 96 97 97 97 98 98

99 99

99 99

100 100

100 101

10 2 104

104 105

105

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3.0 STATE-OF-THE-ART 9F RESOLTCE RECOVERY IN THE MWZNG INDUSTRY

3 . 1 MATRIX DEVELOPMENT AND STRUCTURE 3.1.1 Matrix Waste Streams 3 . 1 . 2 Matrix Resource Recovery Technologies 3.1.3

3.1.4 Identifying Recovery Process Technical

Matrix Technology Development Stages and Waste Material Transfer Codes

Publications 3.2 MATRIX APPLICATION

4 . 0 SELECTED RESO'jRCE RECOVERY PROCESS ANTI WASTE MANAGEMENT APPROACHES

4 . 1 KEY AREAS FOR INCREASED RECOVERY 4 . 1 . 1 Technological Selection Criterion 4 . 1 . 2 Economic Selection Criterion

* 4.1.3 Regulatory Selection Criterion 4.1.4 Institutional Selection Criterion 4 . 1 . 5 Summary of Analysis

4 . 2 . 1 4 . 2 FURTHER RESEARCH AND INCENTIVE DEVELOPMENT

Emerging Technologies with Good Potential 4 . 2 . 1 . 1 Fluidized Bed Combustion of Coal

4 . 2 . 1 . 2 Vanadium Recovery from Phosphate

4 . 2 . 1 . 2

Refuse

Wastes Pelletized Waste Oil-Coal Dust Mixture

REFERENCES

RESOURCE RECOVERY BIBLIOGRAPHY

Page

107

107 107 10 7

110

111 112

117

117 119 121 123 1 2 3 125 129 129

123

129 130

13 1

144

P

Tabid

2-1 2-2 2-3 2-4 2-5

2-6 2-7 2-8 2-9 2-10 2-11

2-12 2-13 . 2-14 2-15

3- 1

LIST OF TABLES

Properties of Bricks Made from Asbestos Tai l ings Analysis of Barite Waste Pond Samples Average Material Characterization of D r y Bulk Raw Refuse Average Elemental Composition of Coal Refuse Properties of Colliery Tailings Digest Polypropylene

Analysis of Tailings from a Copper Concentrator Chemical Analysis of Copper Mill Tailings Chemical Analysis of Two Gold Mine Wastes Chemical Analysis of Granite Fines Chemical Analysis of Iron Ore Tailings Analysis of Tailings fram Zinc-Lead Mines and

Oxide Analysis of Lead-Zinc Tailings Specifications of Phoshate Slime Lightweight Aggregate

Hazardous Material Content of Uranium Tailings Chemical Analysis of Zinc-Lead Tailings

Mixes Compared with Those of PVC

Concentrators

According to ASTM C330

Summary of Mining Waste Recovery Processes

Page

10 13 18 18

31 47 48 64 70 75

82 83

93 102 104

114

LIST OF FIGURES

Figure

2-1 2-2 2-3 2-4

3-1

4-1

4-2

4-3

4-4

Typical open pit copper mine Typical underground copper mine Schematic diagram of fluid-bed dryer Compressive strength of concrete made with phosphate slime coarse aggregate

Status of resource recovery in the mining industry

Technological advantages and disadvantages of selected

Economic advantages and disadvantages of selected

Regulatory advantages and disadvantages of selected

Institutional advantages and disadvantages of selected

resource recovery processes



. resource recovery processes 4-5 Overview of selected resource recovery processes

Page

43 45 92

92

108

120

122

124

126 128

EXECUTIVE SUMMARY

This report, which was prepared for the U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, details the current state- of-the-art of resource recovery practices in the Mining Industry (SIC Division B). It is one of a series of such reports that summarizes information on industrial resource recovery practices currently used or under development in 11 industry categories. This information was obtained through examination of pertinent literature, contacts with knowledgeable industry professionals, government officials, trade associations, research organizations, and engineering firms. A l l of this information i s included in a comprehensive industrial resource recovery library at che EPA as part of this project.

Industry Perspective

The Standard Industrial Classification (SIC) Manual classifies the Mining Industry as Division B. ments primarily engaged in mining.

This classification encompasses all establish-

The S I C Manual divides the mining industry into the following groups:

0 Metal Mining - Major Group 10 0

0 Bituminous Coal and Lignite Mining - Major Group 12 0 Oil and Gas Extraction - Major Group 13 0 Mining and Quarrying of Nonmetallic Minerals, Except Fuels -

Anthracite Mining - MajGr Group 11

Major Group 14

This breakdown of major groups may be summarized into three basic categories under which any given ore could be included. are: metals, nonmetals, and fuels. The minerals sought after are generally contained in ores which may exist in locations ranging from surface deposits to deep underground strata. The wastes generated in the mining and beneficiating of these ores, and the practiced or proposed technologies for the utilization of these wastes, are the subject of this report.

These three categories

The primary wastes generated in this industry are waste rock (tailings) left over after the desired mineral has been removed from the host ore. The other wastes produced consist largely of dusts and sludges generated during the cleaning and beneficiation processes connected with removing the mineral from the ore, and upgrading the minerals t o commercial specifications.

The entire domestic mining industry generates over 2.2 billion tons This amount is being added to the estimated 23 bil- of solid waste annually.

lion tons already accumulated. half of -the mining waste generated annually. large amounts of waste include the mining of coal, iron ore and taconite, uranium, phosphate, gold, gypsum, lead, and zinc.

The copper industry accounts for nearly one- Other operations which produce

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Every state in the United States has some kind of mining activity, although the volume of crude ore produced varies greatly. Areas of the United States in which large quantities of waste rock and mill tailings are produced ir.cl-lAe the large Cmpet-prGdccing states (Arizona, Utah, Montana, Michigm, and Tennessee); the Mesabi Range taconite runes (northeastern LXinnesota); the major iron-ore mining areas (Minnesota, Michigan, Missouri, Pennsylvania, California, and Wyoming) and several lead-zinc regions (Idaho, Tennessee, and Wisconsin). There are also large accumulations of dredge tailings from past gold mining in the Mother Lode district (northern California) and of chat (coarse tailings) from past mining of lead-zinc ores in the Tri-State mining district (Missouri, Kansas, and Oklahoma).

It is anticipated that most types of mining wastes will be generated even more rapidly in the next several decades. Only a small fraction of these wastes is currently being used in any application. Probably their largest use is for self-containment purposes. The most promising prospective use of mining wastes appears to be in large engineering projects such as the construction of highways and earth dams, and in landfills or minefills. Their application as highway materials, especially as aggregates, continues to receive significant attention. However, economics usually restricts the use of these materials-in heavy construction to locations quite close to the point of generation. Transport of the material for distances greater than 25 miles is unusual, with 5 to 10 miles being a frequent maximum. Thus, the economical use of these materials can be quite limited in scope.

Resource Recovery Practices

Eighteen waste streams from 14 separate sub-industries in the mining industry have been identified, to which 61 resource recovery technologies are, or theoretically could be, applied. Some of these technologies are applicable to more than one waste stream. two major categories:

The resource recovery technologies fall into

0

0 Physical utilization of the waste. Retreatment of the waste stream for further mineral recovery

The state-of-the-art of resource recovery in the industry was determined based on evaluation of information from literature and knowledgeable industry professionals. This evaluation involved examination of each of the identified resource recovery processes, the material being recovered, sources of waste material, impediments to current use or further development of the process, and potential for more widespread use.

The evaluation of the state-of-the-art of the 61 resource recovery processes is summarized in a matrix (Figure l), which is defined by the following four study areas:

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P

m VI I

W

I Resou= I Acid I Recovery Mine Asbestos Barite Process Dr a i n n g e Tai 1 in gs Tai lings

Mineral/Metal Recovery Precipitation

* Foreign countries. Key :

Development Stage 1. Proposed research area 2. Bench scale research project 3. Pilot scale research project 4 . Full scale demonstration project 5. Full scale, sporadically practiced 6 . Full scale, commonly practiced 7 . Formerly practiced

Figure 1. Status of Resource Recovery in the ning

Coal Mine Ref use

6a

2c 2c 2c 2c 2c 4c, 6c 2c, 6c 5c 5c

Copper Silver

4a 4 a 6a 3c 2a

2c 2c 2c 2c

2c

5c 5c t

.5a, c Sa

I

Waste Material Transfer a. Within a single facility b. Between facilities, within the industry c. Between facilities, between industries

Industry (SIC D1 Lsion B).

1

I 1

Plastic Resins Fue 1 Ceramic Products Ant i - Skid-Aggre gate Embankment Construction General Annrenate Fill or Pavement Base As pha 1 t Aggregate

I 2c 2c I

5c 5c 2C 5c

5c 5c 2c

Key :

Development Stage 1. Proposed research area 2 . Bench scale research project 3 . Pilot scale research project 4 . Full scale demonstration project 5. Full scale, sporadically practiced 6 . Full scale, commonly practiced 7. Formerly practiced

Waste Material Transfer a. Within a single facility b. Within facilities, within the industry c. Between facilities, between industries

Figure 1 (cont.) Status of Resource Recovery i n the Mining Industry (SIC Division B).

I

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0 Mining industry waste streams (horizontal axis) 8 AFFliczble res0urc.p. rxovery technalogies (vertical axis) 0 State of development of the resaurce recovery techaolcgies

as applied to specific waste streams (numerical matrix code) 0 Transfer and use of recovered materials (alphabetical matrix

code)

The state-of-the-art of the recovery technologies varies in application throughout the industry. used on an industrial scale either commonly or sporadically, while 54 percent are in the demonstration or test stage. materials are transferred f o r recoverylreuse between facilities, between industries. This is due to the fact that the largest use for mining wastes is as an aggregate material.

Forty-three percent of the recovery technologies are

In addition, the majority of the waste

Activities with Potential for Further Implementation

Of the 61 resource recovery processes evaluated, 10 processes appear to have-the most potential for further application within the industry. ever, three of these 10 recovery processes, mining wastes used as aggregate, as embankment fill, and in construction products, are general in nature, and apply to more than one sub-industrial waste stream. For instance, mining waste used as aggregate waste, and nany of the other individual mine wastes. Those selected are:

How-

applies to coal mining waste, copper mining waste, gold mining

0

a 0

0

a 0

0

0

0

0

Mining wastes as aggregate Mining wastes in embankment Mining wastes in construction products Mineral wool from asbestos tailings Retreatment of barite tailings Clean coal recovery from refuse pile Coal waste as an anti-skid material Uranium recovery from phosphate mining wastes Uranium, radium, and vanadium recovery from uranium mine tailings Ion exchange uranium recovery from mine water.

These resource recovery processes were selected based upon favorable combinations of technological, economic, regulatory, and institutional factors. Each of the 61 resource recovery processes reviewed in this report have varying degrees of potential for advancement. However, the 10 selected above have more potential in the form of fewer disadvantages to overcome.

In addition to the selected recovery processes discussed above, there are several others that are felt may prove valuable to the industry in the future. These processes are:

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e Fluidized bed combustion of coal refuse Vanadium recovery from phosphate wastes

e ? e l l e t i z e d vaste oil -eo21 dust aixture

The first has reached a f u l l s ca le demonstration, the second i s s t i l l i n the research lab phase, while the third one has been researched and proposed, but never u t i l i z e d . These three have the potential f o r widespread use providing that the i n i t i a l favorable research resu l t s continue.

i

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1.0' INTRODUCTION i

This study focuses on resource recovery from mining waste streams, wit5 par t i c - i l a r at,eri:Fo;z t o wastes which are 3Jtentfally hazardous. time no mining wastes have been designated as hazarams, peniing a comprz- hensive review by EPA of mining waste streams as required by section 3001(b) of R C M (as anended). This study bas used preliminary information on mining wastes to highlight certain wastes that may be potentially hazardous or may have the potential for significant environmental harm. no implication intended that those wastes so identified will in fact eventually be designated by EPA as being hazardous.

At this

However, there is

For the purpose of this study, resource recovery is defined a s :

Transfer of materials between different facilities (in the same o r different industries) in whicn the waste receiver utilizes the waste in materials or energy recovery operations.

Reuse of waste materials within the same facility f o r materials o r energy recovery operations.

Each resource recovery practice is classified according to the waste streams to which it is applicable, the use of the recovered material, and the current stage of development of the recovery pracrice. s m r i z e d and presented in a matrix which presents the current state-of-the- art of resource recovery within the mining industry.

This information is

The information presented in the matrix is then evaluated with regard to the potential for advancing the state-of-the-art of resource recovery. resource recovery practices with the greatest potential for advancement are identified and evaluated.

Those

In four chapters, this report presents the results of a comprehensive literature search and subsequent analysis of reports found. introduction. Chapter 2 presents an overview of the mining industry in general, including an overview of each industry with regard to structure, production, and trends; a detailed description of the mining and beneficiation process; a description and quantification of the waste stream generated; an evaluation of potentially hazardous characteristics; and finally, a description of each resource recovery technology.

Chapter 1 is the

P

Chapter 3 presents the matrix which summarizes the status of resource recovery in the industry. can be used to analyze b2th the current status of resource recovery and the potential for advancement of the state-of-the-art.

It also includes an explanation of how the matrix

1

Chapter 4 highlights these resource recovery practices ident i f ied i n Chapter 2 that have the greatest potential for increased application with- i n the industry. References c i t e d throughout the study are presented in the bark of the r e p o r t .

2

2.0 M I N I N G INDUSTRY OVERVIEW

The Standard I n d u s t r i a l C l a s s i f i c a t i o n (SIC) Manual c i a s s i f i e s :he Mining Indus t ry as Divis ion B. l ishments p r i m a r i l y engaged i n mining. Mining is used i n t h e broad sense he re t o inc lude t h e e x t r a c t i o n of m i n e r a l s occur r ing n a t u r a l l y such as c o a l and mineral 3rE.s. The term mining i s a l s o used i n t h e broad sense t o in- c lude quarrying, m i l l i n g (crushing , sc reen ing , washing, f l o t a t i o n , etc. ) , and o t h e r p r e p a r a t i o n customari ly done a t t h e mine s i te , o r as p a r t of t h e mining a c t i v i t y . * The mining of culm banks, o r e dumps, and t a i l i n g s p i l e s i s c l a s s i f i e d as mining according t o t h e p r i n c i p a l mining product der ived. E x t r a c t i o n of crude petroleum and n a t u r a l gas are included i n t h e Div i s ion B d e f i n i t i o n of mining, but are n o t included i n t h i s r e p o r t .

Th i s c l a s s i f i c a t i o n encompasses a l l es tab-

The SIC Manual d i v i d e s t h e mining i n d u s t r y i n t o t h e following groups:

0 Metal Mining - Major Group 10 0 A n t h r a c i t e Mining - Major Group 11 0

0

Bituminous Coal and L i g n i t e Kining - Major Group 12

Mining and Quarrying of Nonmetallic Minerals , Except Fuels - Major Group 14

* 0 O i l and Gas E x t r a c t i o n - Major Group 13

This breakdown of major groups may be summarized i n t o t h r e e b a s i c c a t e g o r i e s ucder which any given o r e could be included. g o r i e s a r e : metals, nonmetals, and f u e l s . The mine ra l s sought a f t e r are gene ra l ly contained i n d e p o s i t s which may e x i s t i n l o c a t i o n s ranging from s u r f a c e d e p o s i t s t o deep underground s t r a t a . The o r e may c o n t a i n only one d e s i r a b l e or r ecove rab le mine ra l , which i s common among t h e nonmetal l ic o r e s , o r i t may be composed of a combination of r ecove rab le mine ra l s as i s common wi th t h e m e t a l l i c ores . I n some cases such as i n l ead mining, t h e value of t h e by-product and/or co-product, which may be s i l v e r , copper, z inc o r o t h e r metal, i s of more v a l u e t h a n t h e primary metal contained i n t h e o re .

These t h r e e ca t e -

'

The e x i s t e n c e of a producing mine is brought about i n t h r e e d i s t i n c t phases. Phase I invo lves t h e p r o s p e c t i n g and e x p l o r a t i o n r equ i r ed t o l o c a t e , c h a r a c t e r i z e , and prove a p o t e n t i a l o r e body. Phase I1 i nvo lves e x t r a c t i o n of t h e o re , which may be accomplished by v a r i o u s underground or s u r f a c e mining techniques. Phase I11 i n v o l v e s t h e b e n e f i c i a t i o n or p rocess ing of t h e ore . and producing a f i n a l product s p e c i f i e d by grade, s i z e , and p u r i t y (100).

This i nc ludes removing t h e d e s i r e d mine ra l s from t h e o r e

* Smelting and r e f i n i n g of t h e o r e are included i n ano the r r e p o r t i n t h i s series.

3

Any of t h e s e t h r e e phases may b e more complex than t h e o t h e r depending u7on f a c t o r s such as oTe 3ody l o c a t i o n [ su r face , underground, remote a r e a ) , d i f f i c u l t y of d e t e c t i o n , and re la t ive e f f o r t and expense of mining and b e n e f i c i a t i o n processes .

~

Every s t a t e i n t h e Union has some kind of mining a c t i v i t y , a l though c k volume ox c rude a r e they produce v a r i e s g r e a t l y . Mines s ta t i s t ics (183) shows that i n 1979 t h e two extremes of ore production i n t h e country are between t h e states of Delaware (1.69 m i l l i o n tons ) and F l o r i d a (287.0 m i l l i o n t o n s ) . The t o t a l U.S. product ion of c rude o r e i n 1979 w a s 3.12 b i l l i o n tons,which r e p r e s e n t s t h e ou tpu t of approximately 20,625 metal, nonmetal, and c o a l mines (150, 161) .

The latest Sureau of

Although mine wastes are gene ra l ly r e f e r r e d t o as overbmden a t su r face mining o p e r a t i o n s and waste rock o r development w a s t e rock a t underground o p e r a t i o n s , t hey are a l s o r e f e r r e d t o by such names as "gob," ' l s p o i l , " and "refuse." Overburden a s s o c i a t e d with t h e mining of most nonmetal l ic o r e s gene ra l ly c o n s i s t s of t o p s o i l and o t h e r unconsol idated materials (sand, g rave l , and s i l t ) and o c c a s i o n a l l y weathered bedrock. Overburden a s soc ia t ed wi th th'e mining of most m e t a l l i c o r e s con ta ins va ry ing amounts of bedrock i n add i t ion t o t o p s o i l and o t h e r unconsolidated materials. Waste rock a s soc ia t ed wi th underground mining ope ra t ions c o n s i s t s of both the consol i - dated and unconsol idated materials generated du r ing v a r i o u s s t a g e s of mine development ( e . g . , s h a f t , t u n n e l , and d r i f t development) and those generated d u r i n g ort e x c r a c t i o n (100).

During t h e b e n e f i c i a t i o n of t h e o r e s , large volumes of s o l i d wastes a r e generated. Various t e r m s such as t a i l i n g s , g r i t , slimes, gob, f i n e s , and r e f u s e are used throughout t h e i n d u s t r y i n r e f e r r i n g t o t h e s e wastes. How- eve r , " t a i l i n g s " i s the most common term used by t h e i n d u s t r y .

The e n t i r e domestic mining indus t ry g e n e r a t e s ove r 2.2 b i l l i o n tons of s o l i d waste annua l ly . 23 b i l l i o n t o n s a l r e a d y accumulated (49) . nea r ly one-half of t h e mining w a s t e generated annual ly . Other ope ra t ions which produce l a r g e amounts of waste inc lude t h e mining of c o a l , i r o n o r e and t a c o n i t e , uranium, phosphate, gold, gypsum, l e a d , and zinc.

This amount is be ing added t o t h e est imated The copper i n d u s t r y accounts f o r

Areas of t h e United S t a t e s i n which l a r g e q u a n t i t i e s of waste rock and m i l l t a i l i n g s are produced i n c l u d e t h e l a r g e copper-producing states (Arizona, Utah, Montana, Michigan, and Tennessee); t h e Mesabi Range t a c o n i t e mines ( n o r t h e a s t e r n Minnesota); t h e major iron-ore mining areas (Minnesota, Michigan, Missouri , Pennsylvania , C a l i f o r n i a , and Wyoming) and several lead- z inc regions (Idaho, Tennessee, and Wisconsin). There are also l a r g e accumu- l a t i o n s of dredge t a i l i n g s from p a s t gold mining in t h e Mother Lode d i s t r i c t (northern C a l i f o r n i a ) and of chat (coarse t a i l i n g s ) from p a s t mining of lead- z i n c o r e s i n t h e T r i - S t a t e mining d i s t r i c t (Missouri , Kansas, and Oklahoma) (49). --

I -

4

The l a r g e s t accumulations of c o a l r e f u s e are l o c a t e d i n the eastem Other s i g n i f -

The amount

states of Pennsylvania, West V i r g i n i a , Tennessee, andKentucky. i c a n t accumulations are i n I l l i n o i s , Ohio, and Wyoming. There are more than 3 b i l l i o n tons of c o a l r e f u s e i n Pennsylvania and Kentucky alone. of c o a l r e f u s e produced annua l ly w i l l c e r t a i n l y i n c r e a s e because of t h e g r e a t e r emphasis be ing placed i n t h e United S t a t e s on c o a l u t i l i z a t i o n (49).

I t is a n t i c i p z r e d that most types of mining wastes w i l l . be generated Only a small f r a c t i o n of t h e s e

Probably t h e i r l a r g e s t use even more r a p i d l y i n t h e nex t several decades. wastes i s c u r r e n t l y being used in any app l i ca t ion . i s f o r self-containment purposes. wastes appea r s t o b e i n l a r g e eng inee r ing p r o j e c t s such as t h e c o n s t r u c t i o n of highways and e a r t h dams, and i n l a n d f i l l s O r m i n e f i l l s . Their app l i ca - t i o n as highway materials, e s p e c i a l l y as aggregates, con t inues t o r ece ive s i g n i f i c a n t a t t e n t i o n . However, economics usua l ly r e s t r i c t s t h e use of t h e s e materials i n heavy c o n s t r u c t i o n t o loca t ions q u i t e c l o s e t o t h e po in t of gene ra t ion . Transport of t h e m a t e r i a l f o r d i s t a n c e s g r e a t e r than 25 m i l e s i s unusual , w i t h 5 t o 10 miles being a frequent maximum. Thus, t h e use of t h e s e m a t e r i a l s i s q u i t e l i m i t e d i n scope.

The most promising p r o s p e c t i v e use of mining

Recovery of heavy metals from mine wastes where t h o s e metals are t h e primary product of t h e m i n e h a s been p rac t i ced f o r yea r s . r e source recovery a c t i v i t y f o r materials which are p o t e n t i a l l y hazardous and no t a primary product of t h e mine is quite low. I n fact , t h e only example found was recovery of radium from unranium mine t a i l i n g s . The reason f o r t h e l o w l e v e l of x t i v i t y i s economics. I n the ?ast, d i s p o s a l c o s t s of t h e s e wastes has been less than recovery c o s t s . t h a t recovery a c t i v i t y w i l l be q u i t e low u n t i l economic changes t ake place t h a t w i l l e i t h e r i n c r e a s e t h e v a l u e of t he recovered materials, o r i n c r e a s e t h e c o s t s of d i s p o s a l t o the p o i n t where recovery and r euse i s a v i a b l e op t ion .

However,

It can be expected

._ - - _ - 2 . 1 ASBESTOS M I N I N G INDUSTRY

2.1.1 I n d u s t r y C h a r a c t e r i z a t i o n

2.1.1.1 I n d u s t r y S t r u c t u r e (98)

I n t h e United S t a t e s , five mine and m i l l o p e r a t i o n s were run by as many companies, t o produce a s b e s t o s i n 1979. Three of t h e ope ra t ions were i n C a l i f o r n i a , and one each in Arizona and Vermont. Together, t h e s e f i v e firms produced 93,000 t o n s of a s b e s t o s . This r e p r e s e n t s 17 p e r c e n t of t h e 561,000 tons consumed i n t h e U.S. i n 1979. The remaining 468,000 tons were imported.

Canada is t h e l e a d i n g s u p p l i e r of a s b e s t o s imports into t h e United S t a t e s , about 95 pe rcen t , w i t h t h e Republic of South Africa second. South Africa s-upplies a l l of t h e U.S. demand for c r o c i d o l i t e and amosite.

5

Canada, w i t h major a c t i v i t y i n t h e Province of Quebec, l e a d s t h e West i n both t o t a l q u a n t i t y produced and t h e s i z e of i n d i v i d u a l mines and m i l l s . The U.S.S.R. is t h e l e a d i n g world a s b e s t o s producer. The Republic of South A f r i c a , Mainland China, I t a l y , and t h e United States mine substan- t i a l tonnages and, i n combination w i t h Canada and t h e U.S.S.R., produce over 90 pe rcen t of t h e world 's supply. C h r y s o t i l e i s t h e v a r i e t y most i n demand by over 95 YP-rcmt of the w o r l d ' s consumers, and most of t he d a t a in t h i s report re late t o c h r y s o t i l e .

The United S t a t e s has been supplanted by t h e U.S.S.R. as t h e l a r g e s t consumer of a s b e s t o s f i b e r s . u ses t h e m a j o r i t y of a sbes tos f i b e r s i n such products as a s b e s t o s cement p i p e and s h e e t , r o o f i n g p roduc t s , f l o o r i n g products , p a i n t s , and caulking.

2 . 1 . i . 2 Production S t a t i s t i c s

The c o n s t r u c t i o n i n d u s t r y worldwide p r e s e n t l y

To ta l world product ion i n 1979 w a s 5.3 m i l l i o n tons of a l l grades and v a r i e t i e s . c e n t ; the Republic of South A f r i c a , 5 percen t ; Mainland China, 5 pe rcen t ; I t a l y , 2 percen t ; and t h e United S t a t e s , 2 percent . U . S . product ion w a s 93,000 tons , valued a t $28.9 m i l l i o n . U.S.S.R. product ion wi th t h e lower grades t h a t are n o t used as f i b e r s (98).

Canada's s h a r e w a s 28 pe rcen t ; t h e U.S.S.R. produced 47 per-

These d a t a on world product ion do n o t c r e d i t

2.1.1.3 I n d l s t r y Trends

Canada has been overtaken by t h e U.S.S.R. and is no longer t h e w o r l d ' s l a r g e s t producer of a sbes tos . e v a l u a t i o n , and development of new o r e bodies , however, signals t h a t Canada i s l i k e l y t o con t inue as t h e l e a d i n g world expor t e r . United S t a t e s demand shows clear s i g n s of l e v e l i n g o f f or even l e s s e n i n g somewhat. The q u e s t f o r p a r t of t h e a s b e s t o s market by producers of s u b s t i t u t e s remains s t r o n g , bu t t h e s u b s t i t u t e materials proposed gene ra l ly f a i l t o compete w i t h as- b e s t o s when measured by q u a l i t y and /o r economic ya rds i cks . t u t e s are needed f o r both h e a l t h and economic reasons.

The h igh l e v e l of a c t i v i t y i n e x p l o r a t i o n ,

Viable s u b s t i -

The h e a l t h haza rds a s s o c i a t e d w i t h a s b e s t o s are s t i l l undergoing c l o s e s c r u t i n y by t h e Fede ra l and l o c a l governments, unions, i n d u s t r y organiza- t i o n s , and concerned env i ronmen ta l i s t s . The many areas of controversy g i v e promise of prolonged d i spu te . E f f o r t s t o r e g u l a t e cond i t ions t o m i n i m i z e t h e hazard are given as a reason for t h e p o s s i b l e loss of a v i a b l e a s b e s t o s product ion i n d u s t r y in the United S t a t e s .

6

1 - ?

2.1.2 Asbestos Mining and B e n e f i c i a t i o n Operations

Asbestos d e p o s i t s throughout t h e world d i f f e r widely i n character; and as t h e mining method must b e a d a p t e d t o t h e p r e v a i l i n g cond i t ions , a g r e a t v a r i e t y of methods i s followed. Open p i t quarry methods, gloryhole , undzrgromd r o m - a n d - p i l l x , sSrinicage s top?ing, block caving, and o t h e r methods are employed throughout t h e world.

Regardless of excavat ion technique, t he o r e b e n e f i c i a t i o n is b a s i c a l l y t h e same everywhere. It c o n s i s t s of conveying t h e rock t o l a r g e primary j a w c r u s h e r s and then through secondary c rushe r s reducing t h e rock t o walnut s i z e . From t h e r e t h e material i s s tockp i l ed a t t h e m i l l .

Primary and secondary c rush ing are the f i r s t s t e p s i n mi l l i ng . The crushed mill rock s t o c k p i l e d a t t h e m i l l con ta ins cons ide rab le moisture which m u s t be removed because e f f i c i e n t m i l l operat ion r e q u i r e s dry rock. The rock i s d r i e d i n l a r g e v e r t i c a l o r r o t a r y d r i e r s and then conveyed t o l a r g e dry-s torage b i n s .

From t h e dry s t o r a g e t h e rock i s c a r r i e d through a t h i r d crushing s t a g e and fed t o shaking s c r e e n s equipped wi th s u c t i o n hoods, where t h e f i r s t s t e p in f i b e r removal occur s . t i o n . The o r e con t inues through a f i b e r i z e r stage which breaks t h e rock f u r t h e r by impact. The t h r z e s t e p s - - f i b e r i z i n g , screening, and a i r SUC-

t ion--are t h e major elements i n a s b e s t o s mi l l i ng .

The f r e e f i b e r is l i f t e d b y . a i r suc-

2 . 1 . 3 Waste Stream C h a r a c t e r i s t i c s and Quan t i f i ca t ion

The ch ie f waste stream product i n a sbes tos mining and b e n e f i c i a t i o n o p e r a t i o n s i s overburden and rock. The r a t i o of o r e recovered t o ba r ren material i n some of t h e more p roduc t ive mines o r e and 40 percen t waste (106). The waste overburden is of no p r a c t i c a l va lue except a s . f i l 1 m a t e r i a l . C u r r e n t l y , overburden is placed i n waste dumps.

is approximately 60 percent

Barren sc reen ings , which c o n s t i t u t e about 90 pe rcen t of t h e rock m i l l e d , a r e conveyed t o waste areas. from baghouse c o l l e c t o r s and as aggrega te s from breakage, c u t t i n g s , and d r i l l i n g s c r e a t e d du r ing p rocess ing operat ions. The Bureau of Mines gives a r a t i o of ore t r e a t e d t o marketable product of 18.6:l. Over 2 m i l l i o n t o n s of waste are generated each y e a r i n t h e United S t a t e s (107).

Wastes are a l s o accumulated as d u s t

A p a r t i a l chemical composition of t h e major components i n a sbes tos t a i l i n g s f i n e s i s as fol lows: FeO (8.0 p e r c e n t ) , A1703 (0.5 p e r c e n t ) , L . O . I . * (13 pe rcen t ) (1).

S i 0 2 (38.0 pe rcen t ) MgO (40.0 percent),

* L . O . I . = l o s s on i g n i t i o n .

7

2.1 .4 P o t e n t i a l Hazardous Waste Streams

The h e a l t h hazards a s s o c i a t e d wi th a sbes tos are s t i l l undergoing c l o s e s c r u t i n y by t h e Federa l and l o c a l governments, unions, i ndus t ry or- gan iza t ions , and concerned envi ronmenta l i s t s . However, i t is t h e use of asb2s tss i n a prsl i rc t vh ich r e p r e s e n t s a p o s s i b l e h e a l i h hazard. The waste.-, l e f t from mining and benef i c i a t i o n pose no hazardous environmental problems.

2.1.5 Resource Recovery Technology Desc r ip t ions

The d iscarded a sbes tos t a i l i n g s r e p r e s e n t t h e bulk of t h e i n d u s t r i e s waste stream. t a i i i n g s dump.

Consequently, a l l waste u t i l i z a t i o n techniques focused on t h e

2.1.5.1 Asbestos Recovery from T a i l i n g s

Technological improvements i n m i l l i n g and process ing equipment i n t h e a sbes tos indus t ry through t h e y e a r s have r e s u l t e d i n an apprec i ab le in- c r ease i n the percentage of marke tab le f i b e r t h a t can b e recovered from a given a sbes tos ore . This has reached t h e po in t where very l i t t l e market- ab le f i b e r remains i n t h e t a i l i n g s from a modern a s b e s t o s m i l l . I n earlier yea r s , however, p a r t i c u l a r l y p r i o r t o t h e 1930s, m i l l r e j e c t s were known t o be r i c h i n s h o r t f i b e r . Tests on t h e r e j e c t s i n d i c a t e d t h a t t h e r e w a s a poss ib l e recovery of 4 percent o r more Group 6* f i b e r i n a low q u a l i t y range (89).

Johns-Manville, a Canadian a sbes tos manufacturing f i rm, designed and operated a p i l o t p l a n t f o r t h e purpose of a sbes tos t a i l i n g s re- t reatment . E s s e n t i a l l y t h e recovery process w a s t h e r e s u l t of more e f f i c i e n t f i b e r i z e r s i n t h e process ing system. mary c rushe r s and thus a mixture of "v i rg in" f i b e r s from primary o r e and f i b e r obtained from t h e r e t r ea tmen t of t a i l i n g s was t h e r e s u l t (89).

The t a i l i n g s were blended w i t h o r e from t h e p r i -

P resen t ly , no company i s known t o be r e t r e a t i n g a sbes tos t a i l i n g s . Demand f o r a sbes tos s u b s t i t u t e s for h e a l t h and f o r economic reasons, as w e l l as the i n f e r i o r q u a l i t y of f i b e r s recovered from the t a i l s , has discouraged e f f o r t s t o re t reat t h e t a i l i n g s .

A t one time t h e t a i l i n g s were used by t h e Vermont Asbestos Group t o "sand" i c y roads i n t h e New England area but t h e p r a c t i c e w a s stopped f o r environmental reasons. C u t l e r and Nicholson a t the Unive r s i ty of Utah produced good f o s t e r i t e r e f r a c t o r y materials from the t a i l i n g s but none of t h e s e processes i s p r e s e n t l y known t o be i n use (53, 166) .

1

* Group-.6 - The main consumption for t h i s group is i n asbestos-cement products , gaske t s , b rake l i n i n g s , v i n y l s h e e t backings, and mi l lboard (98).

8

2.1.5.2 Mineral Wool I n s u l a t i o n from Ta i l ings

Laboratory tests conducted by t n e Mineral Processing Divis ion, Mines Branch, Department of Energy, Mines and Resources, O t t a w a , Canada, concluded t h a t a mine ra l wool of good q u a l i t y w a s prepared from a 70:30 mixture of c h r y s o t i l e a s b e s t o s t a i l i n g s and a l o c a l sand from t h e Eastern Township of Quebec. t h e p r o c e s s i n d i c a t e d t h a t a v i a b l e operation w a s f e a s i b l e (1).

A prel iminary market study aaa c a p i t a l cos t ing of

The p rocess e s s e n t i a l l y w a s t o blend t h e sand and t a i l i n g s , p l a c e t h e charge i n a melt ing p o t and heat t o 2800°F. w a s complete, an a i r va lve w a s opened and t h e m e l t poured i n t o t h e a i r stream. The a i r broke t h e m e l t i n t o d r o p l e t s , which f i b e r i z e d t o form mine ra l wool. Not only d id t h e p rocess produce mine ra l wool, bu t a l s o b u t t o n s of n i c k e l i f e r o u s i r o n w e r e found i n t h e cooled m e l t . These were analyzed and found t o c o n t a i n 5 t o 6 percent n i c k e l , a by-product which would be c r e d i t e d t o process c o s t s .

When t h e melting

According t o R. A. C l i f t o n (169), Commodity S p e c i a l i s t f o r t h e U.S. Blreau of Mines, a s b e s t o s t a i l i n g s a r e n o t now being used t o make minera l wool. Although t h e p rocess developed by C o l l i n g s (168) f o r u t i - l i z i n g t h e waste t a i l i n g s produces good i n s u l a t i o n , g l a s s wool manufac- t u red from cheap, abundant raw materials has l a r g e l y s t i f l e d any e f f o r t s t o use t h e t a i l i n g s f o r t h i s purpose.

2 . 1 . 5 . 3 Construct i on Bricks from T a i l i n g s

A l a b o r a t o r y i n v e s t i g a t i o n performed by t h e Bureau of Mines demonstrated t h a t b u i l d i n g b r i c k s can be produced by t h e steam cur ing p rocess from va r ious types of i n d u s t r i a l mineral wastes. Asbestos t a i l - i n g f i n e s were included i n t h e tests.

B a s i c a l l y , t h e f i n e s were d r i ed and screened t o break up lumps. Thenvarying percentages of p o r t l a n d cement type 1 and water were added. These mixtures we-re p re s sed a t e i t h e r 4,000 or 6,000 p s i . they were steam cured i n an a u t o c l a v e a t 194'C and 200 p s i g f o r per iods of 4 or 6 hours. On completion of t h e cu r ing c y c l e , t h e specimens were oven d r i e d u n t i l ready f o r t e s t i n g i n accordance w i t h ASTM designat ions C67-66. R e s u l t s are p resen ted i n Table 2-1.

Following t h i s ,

While t h e l a b o r a t o r y tests showed that t h e t a i l i n g s could be r eused , t h e t a i l i n g s do n o t impart any p a r t i c u l a r q u a l i t i e s t o t h e b r i c k s o r b locks t h a t cannot b e ob ta ined from use of conven t iona l materials. Limited q u a n t i t i e s of t h e t a i l i n g s are being used by the Vermont Asbestos Group i n t h e mznufacture of w a l l board (166).

9

Table 2-1

PROFERTIES OF BRICKS MADE FROM ASBESTOS TAILINGS L/ (Autoclave p r e s s u r e acd temperature he ld

a t 200 p s i g and 194"C, r e s p e c t i v e l y )

Por t l and Cement a d d i t i v e ,

We ight-Percent

8.0 1 2 . 0 20.0

7.0 1Q.O

7.0 7.0

7.0 7.0

Forming Curing Time, Water P res su re , Hours Absorption,

Air Autoclave Percent - psi

6 ,GOO - 6.9 11.8 6,000 - 6.0 10.6 6 , 000 - 6.0 10.2

6,000 2.0 6 .O 10.2 6,000 2.0 6.0 8.9

6,000 2.0 4.0 11.5 6,000 2.0 6.0 10.2

4,000 2.0 4 .O 12.5 6,000 2.0 4.0 11.5

Compressive St rength ,

D S i

2,100 2,800 5 , 800

7 , 800 9,200

5 , 700 7,800

4 , 900 5,700

- From Ruberoid Co., Hyde Park , Vermont.

2 - 1 - 5 . 4 ksphalt Surface Mix Aggregate

been u t i l i z e d i n a s p h a l t wearing s u r f a c e mixtures i n C a l i f o r n i a and Nevada. This material, c a l l e d a s b e s t o s s h o r t s because of the shor tnes s of the re- s i d u a l f i b e r s remaining a f t e r p rocess ing , must be sepa ra t ed from the ser- pen t ine h o s t rock p r i o r t o use . It has been r epor t ed t h a t by-product as- b e s t o s s h o r t s were used i n t h e a s p h a l t mix placed on Interstate Route 15 nea r L a s Vegas, Nevada and are a l s o f r equen t ly used i n the resur fac ing of playgrounds and parking l o t s (46).

The f i n e r . s i z e t a i l i n g p roduc t from the process ing of a sbes tos has

10

i

2.2 BARITE M I N I N G INDUSTRY

Barite, alsc, known 3 s b a r y t e s , %cavy s p a r , t i f r , and raxk, is a heavy, s a f t . and chemically i a e r c mineral t h a t con ta ins 58.8 barium (Ba) and 41.2 per- c e n t s u l f a t e (SO4). U.S. consumption of b a r i t e (BaS04) is a d i r e c t r e s u l t of t h e need f o r weighted muds i n o i l and gas w e l l d r i l l i n g , with over 90 percent of demand stemming from t h o s e ac t iv i t i e s . B a r i t e i s ground f3r use i n w e l l d r i l l i n g muds, as a f i l l e r i n rubbe r , p a i n t , p l a s t i c , paper, and g l a s s , and is crushed f o r manufacture of barium chemicals (98).

2 . 2 . 1 Indus t ry C h a r a c t e r i z a t i o n

2.2.1.1 Indus t ry Structure

B a r i t e production w a s r epor t ed from 32 mines: 16 in Nevada, 7 in Missour i , 2 each i n Georgia, I l l i n o i s , and Tennessee, and 1 each i n Ar- kansas , Montana, and New Mexico. Nevada w a s t h e l e a d i n g producing s ta te w i t h 84 percent of t he r epor t ed ou tpu t . scending o rde r of production were Arkansas, Missouri , Georgia, Montana, I l l i n o i ; , Tennessee, and New Mexico. Smal l q u a n t i t i e s of b a r i t e were produced i n Alaska and Idaho.

The o t h e r producing states i n de-

Domestic and/or imported b a r i t e w a s ground a t 42 p l a n t s i n 11 s ta tes du r ing 1979. h e a v i e s t concentrat ion of g r i n d i n g p l a n t s , because of t h e a v a i l a b i l i t y of p o r t f a c i l i t i e s f o r import ing b a r i t e and t h e proximity t o areas of high d r i l l i n g a c t i v i t y . Other s ta tes w i t h gr inding p l a n t s i n 1979 were Mis- s o u r i w i t h six opera t ions ; Nevada and Utah wi th f i v e each; C a l i f o r n i a wi th t h r e e ; Arkansas, Georgia, and I l l i n o i s , two each; and one each i n Montana and Tennessee (98) .

Texas wi th e i g h t p l a n t s and Louisiana wi th seven had t h e

2.2.1.2 Production S t a t i s t i c s

The United' S t a t e s i s t h e w o r l d ' s l a r g e s t producer and consumer of b a r i t e ; i n 1979, domestic product ion w a s 2.03 m i l l i o n tons o r 27 .6 percent of t h e w o r l d ' s t o t a l output. consumption (sold or used by b a r i t e g r ind ing e s t ab l i shmen t s ) w a s 3.02 m i l l i o n t o n s (98). T o t a l world p roduc t ion of b a r i t e

Imports of b a r i t e w e r e 1.49 m i l l i o n tons and r epor t ed

in 1979 vas 7.35 a l l o n tons.

2.2.1.3 Industry Trends

gas w e l l d r i l l i n g a c t i v i t y . an annual average ra te of about 6 p e r c e n t through 1986 from a 1978 base and then d e c l i n e as U.S. d r i l l i n g a c t i v i t y i s expected t o wane a t t h e end of t h e century-. growth rate of 0.5 pe rcen t f o r t h e pe r iod 1978 t o 2000.

The f u t u r e of t h e b a r i t e market i n t h e United S t a t e s depends on o i l and Domestic b a r i t e demand is expected t o grow a t

Probable demand of 3 m i l l i o n t o n s i n 2000 r e p r e s e n t s an average

11

i : - !

U . S . reserves (32 m i l l i o n t o n s ) are not adequate t o f i l l t h e p r o j e c t e d cumulative demand of about 79 m i l l i o n tons t o t h e year 2000. Imports w i l l b e necessary t o provide t h e a d d i t i o n a l b a r i t e requirements. Source c o u n t r i e s f o r s u b s t a n t i a i tonnage of b a r i t e i n 1979 were Peru, I r e l and , Mainlana China, I n d i a , Mexico, Morocco, and Thai land. Crude b a r i t e w a s imported from 14 c o u n t r i e s i n 1979 (98).

2 . 2 . 2 B a r i t e Mining and B e n e f i c i a t i o n Operations

Residual d e p o s i t s of b a r i t e are gene ra l ly mined by power shove l s i n open p i t s a f t e r removal of overburden. washer p l a n t s equipped wi th r o t a r y b reake r s , l og washers, trommel s c r e e n s , and j i g s t o s e p a r a t e b a r i t e from o t h e r material. Fine b a r i t e i n t h e over- f low from t h e l o g washers i s recovered by t a b l i n g and f l o t a t i o n .

The o r e is then b e n e f i c i a t e d i n

Bedded and v e i n d e p o s i t s may b e mined i n open p i t or underground methods depending on l o c a l c o n d i t i o n s . The bedded d e p o s i t s of Arkansas have been mined by both methods. The o r e , a f t e r e x t r a c t i o n , is crushed and ground f o r b e n e f i c i a t i o n by f l o t a t i o n . mined by open p i t methods u s i n g a combination of bul ldozers w i th r i p p i n g t e e t h - a n d convent ional b l a s t i n g . The o r e is picked up by front-end load- ers and put i n dump t r u c k s f o r haulage t o a processing p l a n t . I n some d e p o s i t s , t he o r e i s of s u f f i c i e n t grade t o be washed, crushed, s c reened , and shipped t o a gr inding p l a n t ; however, much of t h e o r e r e q u i r e s bene- f i c i a t i o n by j i g g i n g or f l o t a t i o n .

Bedded b a r i t e i n Nevada i s

Grinding is accomplished by Raymond mills i n most p l aces ; however, Barite i s b a l l m i l l s a re used when i r o n contaminat ion i s n o t important.

ground e i t h e r w e t or dry. For use i n w e l l d r i l l i n g , b a r i t e i s ground d r y ; i f i t r e q u i r e s upgrading by f l o t a t i o n , i t is ground w e t . Also, b a r i t e t o b e bleached f o r f i l l e r use is ground w e t . The bleached b a r i t e pulp i s then s e t t l e d and sepa ra t ed , washed, d r i e d , s i z e d , and bagged.


I n t h e mining and b e n e f i c i a t i o n of b a r i t e , t h e e n t i r e waste stream is d i sposed of i n t a i l i n g s ponds. recovered i n t h e b e n e f i c i a t i o n p rocess . t o 7 percen t (62). It w a s e s t ima ted in 1972 t h a t 1.9 mil l ion tons of b a r i t e are contained i n t h e t a i l i n g s ponds l o c a t e d i n t h e Washington County, Mis- s o u r i b a r i t e d i s t r i c t alone.

These ponds con ta in b a r i t e which is n o t Barite content can range from 4

Chemical composition of the t a i l i n g s ponds can vary from mine t o mine as shown i n t h e following t a b l e . The f o u r samples were from mines i n t h r e e d i f f e r e n t states.

1 2

Missouri Nevada - c o a r s e Nevada - f i n e Georgia

Table 2-2

ANALYSIS OF BARITE WASTE POND SAMPLES (2) ( I n pe rcen t )

3.1 0.76 0.67 32.0 17.9 11.2 68.7 0.34 0.32 17.4 2.6 4.7 56.4 0.80 0.20 22.0 2 . 5 4.6 12.7 0.10 0.40 51.4 8.4 7.5

2.2.4 P o t e n t i a l Hazardous Waste Streams i

None of t h e waste products generated i n ' t h e ,mining o r processing of b a r i t e o r e are considered p o t e n t i a l l y hazardous.

2.2.5 'Resource Recovery Technology Desc r ip t ions

2.2.5.1 Barite Recovery from T a i l i n g s

The Bureau of Mines has conducted l abora to ry s t u d i e s t o dev i se new methods f o r recovering ba r i t e from o ld t a i l i n g s ponds, t a i l i n g s from cur- r e n t o p e r a t i o n s and m a t e r i a l s being by-passed i n p re sen t mining o p e r a t i o n s (2,3) .

The t a i l i n g s pond samples tested by t h e Bureau of Mines were ob ta ined from t h r e e of t h e h i s t o r i c b a r i t e product ion areas. sen ted material from an o ld t a i l i n g s pond in Missouri . r ep resen ted t h e coa r se f r a c t i o n from a pond being f e d by t h e overflow from t h e primary desl iming c i r c u i t i n a c u r r e n t Nevada ope ra t ion , wh i l e t h e t h i r d sample r ep resen ted t h e f i n e f r a c t i o n from t h e same u n i t ope ra t ion i n t h e p l a n t . The f o u r t h sample w a s from t h e t a i l i n g s of an o l d ope ra t ion i n Geor- g i a . A chemical a n a l y s i s of t h e s e samples can b e found i n Table 2-2.

The f i r s t sample repre- The second sample

Barite concen t r a t ion by f l o t a t i o n received t h e major a t t e n t i o n i n t h e i r s tudy , p r i m a r i l y because of t h e small p a r t i c l e s i z e s involved. c o l l e c t o r used i n t h e f l o t a t i o n tests w a s sodium cetyl s u l f a t e . agent w a s an e x c e l l e n t b a r i t e c o l l e c t o r and w a s ve ry e f f e c t i v e i n r ecove r ing extremely f i n e b a r i t e . s u l f o n a t e c o l l e c t o r s , with r e s u l t s similar t o those obtained wi th sodium c e t y l s u l f a t e (2) .

The This re-

Tests were a l s o made wi th f a t t y ac id and petroleum

R e s u l t s of t h e s e s t u d i e s show that much of t h e b a r i t e l o s t i n p a s t and p r e s e n t m i l l i n g o p e r a t i o n s can b e recovered by a simple f l o t a t i o n technique. f o r u s e as an o i l w e l l d r i l l i n g f l u i d component (2) .

Concentrate grades and s p e c i f i c g r a v i t i e s m e t t h e requirements

13

The Cyprus Thompson Weinman Co. i n C a r t e r s v i l l e , Georgia has been recover ing bar i te from o l d m i l l i n g waste ponds by f l o t a t i o n f o r a number of yea r s . While t h e p l a n t f eed is highly v a r i a b l e , repor ted ly 8 t o 15 p e r c e r t b a r i t e c o n c e n t r a t e s ana lyz ing from 95 t o 38 percent Bas04 are recovered. and t h e r e f o r e b r i n g a premium p r i c e from t h e automotive p a i n t indus t ry .

The c o n c e n t r a t e s con ta in l i t t l e or no f l u o r i n e

Processes have been developed by the U.S. Bureau of Mines for recover ing b a r i t e from both mining and m i l l i n g wastes conta in ing 3 t o 60 percent b a r i t e . However, i t i s n o t known a t t h i s t i m e i f t he methods a r e being u t i l i z e d by t h e i n d u s t r y , o t h e r than Cyprus Thompson Weinman Company (170).

2.2.5.2 T a i l i n g s Used a s Road Cons t ruc t ion Aggregate

In Missour i , t h e t a i l i n g s from b a r i t e mining opera t ions have been used a s aggrega te i n highway cons t ruc t ion . These m a t e r i a l s , l o c a l l y r e f e r r e d t o a s " t i f f c h a t , " are a v a i l a b l e i n t h e e a s t c e n t r a l po r t ion of t h e s t a t e and have been used i n bi tuminous wearing sur faces . Their use is permi t ted i n t h e Missouri Standard Spec i f i ca t io r , s .

B a r i t e t a i l i n g s have a l s o been used as highway cons t ruc t ion m a t e r i a l i n Nevada. The t a i l i n g material, composed mainly of c h e r t wi th a p a r t i c l e s i z e l e s s than 3/4-inch (19.1 mm) d iameter , w a s used by t h e Nevada Department of Highways t o r e s u r f a c e a s e c t i o n of I n t e r s t a t e Route 80 nea r B a t t l e Mountain i n Lander County (46).

Z o 3 COAL MINING INDUSTRY

Coal r e f u s e u t i l i z a t i o n has been d iscussed in academic and engineer ing papers f o r a t least t h e p a s t 50 years . knowledge on t h e p r o p e r t i e s and uses of this material; however, t h e r e is no th ing new o r r evo lu t iona ry t o r e p o r t which d l overn ight change the d i s p o s a l o r u t i l i z a t i o n p i c t u r e f o r this material. What is new, however, i s t h e a c c e l e r a t i n g u s e of c o a l r e f u s e in Europe, e s p e c i a l l y i n the United Kingdom, du r ing the last decade. coupled wi th g r o w h g environmental awareness on the p a r t of the p u b l i c and p r e s s u r e s from S t a t e and Fede ra l governments,have caused a new surge of interest in u t i l i z i n g c o a l r e f u s e . acknowledge the e x i s t e n c e of this material no t only as a problem b u t as a r e source w i t h p o t e n t i a l market v a l u e and devote funds and manpower t o "moving it." r e f u s e product i s u l t i m a t e l y u t i l i z e d by some o t h e r i ndus t ry or f o r some o t h e r purpose as a raw material (31).

There is a cont inuing growth of

This proven u t i l i za t ion in t h e Old World,

The mining i n d u s t r y must, t he re fo re ,

A r e f u s e p i l e should be cons idered as temporary s t o r a g e un t i l t h e c o a l

2 . 3 . 1 Indus t ry Charac t e r i za t ion

2.3.1.1 Industry S t r u c t u r e

The U . S . c o a l i n d u s t r y is divided i n t o a n t h r a c i t e and bituminous/ 11p.iLe z i n i n g . The c n t h r a c i t e s e p e n t is l i m i t e d a l n o s t e n t i r e l y t o north- e a s t e r n Pennsylvania and o p e r a t e s under a state c o n t r o l board that schedules p roduc t ion and a s s igns s h a r e s t o t h e s e p a r a t e ope ra to r s . minous and l i g n i t e segment c o n t a i n s over 6,100 mines o p e r a t i n g i n 26 states i n Appalachia, t he Midwest, and t h e Mountain and P a c i f i c regions. c o a l producing s t a t e s i n o r d e r of output were Kentucky, West Vi rg in i a , Pennsyl- v a n i a , I l l i n o i s , Ohio, and V i r g i n i a . Combined they account f o r over 70 per- ceRt of t c t a l U.S. production (107, 113).

The f a r l a r g e r b i t u -

The l ead ing

During t h e p a s t decade, t h e number of ve ry small mining companies has s t e a d i l y been decreasing, due p r i n c i p a l l y t o t h e c o s t i nc reases incu r red as a r e s u l t of t he Federal Coal Mine Health and S a f e t y A c t of 1969 (114).

* Major owners of c o a l r e s e r v e s include t h e l a r g e o i l companies-- '

p r i n c i p a l l y through t h e i r ho ld ings of Western and Federal. and p r i v a t e leases. Rai l roads own enormous amounts of c o a l which w a s given t o them as g r a n t s nea r ly a century ago t o encourage t h e b u i l d i n g of r a i l r o a d s . Many of these lands a r e "checkerboarded," i .e . , i n t e r s p e r s e d wi th alternate s e c t i o n s of Federally-owned c o a l . The largest of a l l owners of c o a l reserves i s t h e Federal government, which c o n t r o l s v a s t acreages throughout t h e West. I n Appalachia, major r e s e r v e owners are t h e o ld c o a l and steel companies such a s Bethlehem and Consal.

2 . 3 . 1 . 2 Production S t a t i s t i c s

Approxinately 228,500 workers produced 829.7 m i l l i o n s h o r t t ons of bi tuminous, l i g n i t e , and a n t h r a c i t e c o a l from n e a r l y 6,450 mines i n 1980 (107, 115). . I n the United S t a t e s 43 percent or 360.5 m i l l i o n tons of t h e annual c o a l product ion i s taken from underground mines while t h e remaining 57 percent o r 469.2 m i l l i o n tons were produced from s u r f a c e mines (107).

Of t he 829.7 m i l l i o n tons of c o a l produced, 702.7 m i l l i o n tons were consumed domest ical ly , 1 . 2 m i l l i o n tons were imported, 91.7 m i l l i o n t o n s were exported and 34.1 m i l l i o n tons were added t o e x i s t i n g stock- p i l e s a t e l e c t r i c u t i l i t i e s , coke p l a n t s , and o t h e r i n d u s t r i a l u se r s (115).

15

2.3.1.3 Indus t ry Trends

The e n t r y of o i l companies i n t o t h e coa l i ndus t ry is a f a i r l y r ecen t phenomenon, a l though now n e a r l y every major o i l campany has bought or s t a r t e d a c o a l business . Of t h e top 15 coal-producing companies, only t h r e e are independent conpanies (114).

Federa l support of r e s e a r c h d e a l i n g with conversion of c o a l t o o i l o r gas has helped t o encourage t h e mergers of coa l mining companies with dl r e f i n i n g and process ing o r g a n i z a t i o n s . purchase of l a r g e tracts w i t h undeveloped coa l reserves by l ead ing o i l companies. r ep laced by a l l i a n c e s ‘in t h e g e n e r a l energy market.

This has a l s o l e d t o t h e d i r e c t

Thus t h e compet i t ion between d i f f e r e n t fonns of f u e l has been

Coal product ion w i l l i n c r e a s e in t h e f u t u r e i n response t o t h e n a t i o n ’ s Environmental s t anda rds are d e s i r e t o become more s e l f - s u f f i c i e n t i n energy.

demanding h igher q u a l i t y , cleaner burning c o a l s which w i l l r e q u i r e more in- t e n s i v e c leaning , p a r t i c u l a r l y i n areas where lower q u a l i t y seams are now being mined. r e j e c t m a t e r i a l s due t o t h e l a c k of selected mining. In a d d i t i o n , c leaned and processed coa l r e s u l t s in a c o n s t a n t q u a l i t y product , c o s t s less t o t r a n s p o r t , and inc reases i n market p r i c e s e v e r a l d o l l a r s pe r ton over run- of- the mine c o a l (25).

Also, modern automated mines produce l a r g e r percentages of

2 . 3 . 2 Coal ?lining and B e n e f i c i a t i o n Operations

Coal mining ope ra t ions can be considered under t h r e e main headings:

(1)

(2)

Underground or Deep Mining - Coal i s e x t r a c t e d from t h e s e a m wi thou t removal of over ly ing strata. S t r i p o r Opencast Mining - The strata ove r ly ing t h e coa l seam (overburden) are removed and c o a l is ex t r ac t ed from t h e exposed seam. Auger-Mining - Coal is e x t r a c t e d by m e a n s of l a r g e diameter augers b o r i n g h o r i z o n t a l l y i n t o t he out- cropping seam.

(3)

The type of mining employed depends upon the area of c o a l a v a i l a b l e ,

In t h e United States, almost t h e th i ckness and i n c l i n a t i o n of the seam and ove r ly ing strata, t h e va lue of s u r f a c e land , and o t h e r economic f a c t o r s . 65 percent of t h e bituminous coal ou tpu t i s mined by underground methods, j u s t over 32 percent by s t r i p mining, and t h e remaining 3 percent by auger- i n g (117).

i

Coal as brought from t h e mine (run-of-mine)conrains unwanted i m p u r i t i e s ( a l s o te rmed re fuse , gob, t a i l i n g s , slate, waste) i n varying amour ts ; che p r i n c i p a i ones being s h a l e , c! ay , sandstcne, nudstone, l?ae- s t o n e , and p y r i t e . The i m p u r i t i e s , or r e fuse , are mined along wi th the c o a l . Thin bands of shale and c l a y and o the r impur i t i e s and minera ls are found w i t h i n t h e c o a l seam. Occasional ly a c o a l seam w i l l d iv ide , or p a r t , -7ert;cally w F t F 2.n aztendant t h i c k l a y e r of c lay o r s h a l e f i l l i n g t h e p a r t - i ng . of c o a l w i t h unwanted i m p u r i t i e s t h a n t o t r y t o mine only t h e pure coa l . Contamination from overburden p rov ides an a d d i t i o n a l source of i m p u r i t i e s i n s t r i p mining opera t ions . I n underground mining i t is sometimes neces- s a r y t o mine a p o r t i o n of t h e roof o r f l o o r i n order t o provide a satis- f a c t o r y roof f o r c l ea rance suppor t or a hard , s t a b l e f l o o r t o work on. A t s e l e c t e d l o c a t i o n s the roof must be taken f o r overcas t s and o the r v e n t i l a t i o n s t r u c t u r e s . Many t i m e s t h e coal-seam th ickness w i l l decrease , t hus r e q u i r i n g more roof and f l o o r t o be taken i n order t o provide c l e a r - ances f o r mechanized mining and haul ing equipment. Vertical cleates con- t a i n i n g minera ls are sometimes encountered. A l l t hese condi t ions provide sou rces f o r t h e r e f u s e materials.

With mechanized equipment it i s easier and cheaper t o extracr: a seam

The purpose of process ing i s t o remove t h e bulk of t hese i m p u r i t i e s . Th i s w i l l i n t u rn reduce t h e a sh and s u l f u r con ten t s , while i nc reas ing t h e h e a t i n g va lue p e r ton of f i n i s h e d product . The coa r se r f r a c t i o n s are normally separa ted by heavy-media methods s i n c e c o a l has a lower s p e c i f i c g r a v i t y as compared t o the hea~7ier rock and o the r r e fuse . Fine coa l and r e f u s e a r e gene ra l ly separa ted by t h e use of s p e c i a l f r o t h i n g agents which w i l l a t t a c h and f l o a t t h e c o a l , whereas the nonfrothing r e fuse s inks (117).

2 . 3 . 3 Waste Stream Charac te r i za t ion and Quan t i f i ca t ion

Coal r e f u s e i s a mixture of fragmented ma te r i a l s t h a t are removed from run-of-mine c o a l during t h e c l e a n i n g and prepara t ion process so t h a t t h e q u a l i t y of t h e c o a l w i l l be improved. Sources of r e fuse materials are d i scussed i n t h e preceding s e c t i o n . It i s easier and cheaper, w i t h mech- an ized equipment, t o e x t r a c t a seam of c o a l w i th i t s unwanted i m p u r i t i e s than t o t r y t o mine only the pure c o a l . The r e f u s e can genera l ly be p laced i n t o two c a t e g o r i e s accord ing t o s i z e : coa r se (g rea t e r than 1 mm) and f i n e (less than 1 mm). The f i n e r e f u s e may a l s o be r e f e r r e d t o as s l u r r y o r t a i l i n g s . Workers i n Great B r i t a i n have def ined f o u r c l a s s e s of mine r e fuse : mine d i sca rd , c o a r s e d i sca rd , t a i l i n g s , and s l u r r y (23 ) .

i t

17

E

i

The i nc reas ing product ion of c o a l w i l l add s i g n i f i c a n t amounts of mine r e f u s e t o t h e a l r eady enormous accumulated q u a n t i t s w h i c h has been es t imated t o exceed 3,230 m i l l i o n tons.** 13e product ion of c o a l mine r e f u s e i n 1980 was approximately 137* m i l l i o n tons,which r e p r e s e n t s an average of 29 pe rcen t of t h e tonnage of c o a l that was cleaned. i t is expected that t h e annual r a t i o of mine refuse t o marketable c o a l w i l l decrease because of t h e t r end t o burn more uncleaned coa l (23).

Eouever,

In a Unive r s i ty of Kentucky s tudy on c o a l r e f u s e (117) some material and chemical c h a r a c t e r i z a t i o n t e s t s were performed on 61 samples of c o a l r e f u s e from mines throughout t h e S t a t e of Kentucky. A summary of t h e results of t hese tests is presented in t h e fo l lowing t ab le s .

Table 2-3

Number of Samples

61

S i 0 2 T i 0 2 - - 54.20 1.27

AVERAGE MATERIAL CHARACTERIZATION OF DRY BULK R A W REFUSE

Heating Value Percent (B tu / lb ) Ash

4,683 61.09

Table 2-4

AVERAGE FZEMWTAL COMPOSITION OF COAL BEPUSE

Percent Su l fu r

1.37

'2'5 M203 Fe203 &O MgO CaO K 2 0 Na20 - -- --- - - 24.25 9.80 0.04 1.40 1.25 3.65 0.41 0.20

6 6 * Using Reference 119, page 26 [57% of (829.7 x 1 0 ) x 29% = 137 x 10 ]

** Frankl in Assoc ia tes , Ltd. estimate based on earlier estimates (Reference 23) p l u s 25 percent of t h e c o a l produced i n t h e fol lowing years .

18

Wash water s ludge i s ano the r component of t h e c o a l c leaning p l a n t waste stream. used t o c lean tne c o a i . wlen i t i s judged K ~ E t h e m d t e i i 3 1 is no l m g e r capab le of impurity removal from t h e c o a l , i t i s f ed t o ponds, allowed t o s e t t l e , a n d t h e c l e a r e f f l u e n t decanted and e i t h e r reused or drained i n t o t h e water shed.

Sludge i s the material held i n suspension i n t h e wash water

Dens i f i ca t ion of wash water i n an i n v e r t e d cone is accomplished wi th t h e a d d i t i o n of f i n e sand and uses t h e phys ica l d i f f e r e n c e s between t h e impuri ty and the c o a l , p a r t i c u l a r l y t h e d i f f e r e n c e s in t h e i r s p e c i f i c g r a v i t i e s , as the s e p a r a t i o n p r i n c i p l e . t h e water by weight discharged from t h e washing of c o a l .is s o l i d s i n composition,and s i n c e some two t o n s of water are requ i r ed pe r ton of c o a l processed, some 6 t o 16 pe rcen t of t h e t c t d tonnage washed i s deposited i n ponds (11). This amount could r e p r e s e n t from 25 t o 50 m i l l i o n tons of pond s ludge being generated i n 1980.

Approximately 3 t o 6 percent of

2 . 3 . 4 P o t e n t i a l Hazardous Waste Streams

a The problems a s s o c i a t e d w i t h c o a l waste d i s p o s a l ar ise o r i g i n and cha rac t e r of t h e c o a l seam, the mining and processing methods employed, t he t e r r a i n a v a i l a b l e f o r t h e d i s p o s a l s i t e , and t h e construc- t i o n c o n t r o l s app l i ed . These f a c t o r s e x i s t i n a complex i n t e r r e l a t i o n s h i p . Heavy metals and acid c o n s t i t u t e t h e major waste p o l l u t i o n hazards of c o a l r e f u s s (125) .

from t h e

The mining, c rush ing , and washing processes tend t o concen t r a t e many of t h e i m p u r i t i e s i n t h e r e f u s e , which are dumped i n huge p i l e s . I n t h e waste p i l e , t h e f i n e l y broken r e f u s e is exposed t o t h e a i r and ox id ized , often producing l a r g e q u a n t i t i e s of f e r r o u s s u l f a t e . The product ion of f e r r o u s s u l f a t e i s t h e f i r s t s t e p i n gene ra t ing an ac id d ra inage (125). Water moving through t h e r e f u s e p i l e i s f r e e t o p i ck up t h e s u l f u r i c ac id which has been generated by ox ida t ion of p y r i t i c materals. The a c i d , i n t u r n , enab le s t h e water t o d i s s o l v e extremely l a r g e q u a n t i t i e s .of i r o n , aluminum, and 0the.r heavy metals. S tud ie s have shown t h e e f f l u e n t from c o a l r e f u s e areas t o c o n t a i n s i g n i f i c a n t q u a n t i t i e s of z i n c , copper, n i c k e l , i r o n , l e a d , boron, magnesium, and manganese. Streams i n t h e very s t e e p t e r r a i n of e a s t e r n Kentucky and southern West V i r g i n i a , a l though less a f f l i c t e d w i t h a c i d , are more s u b j e c t t o pol- l u t i o n from s i l t and sediments washed from t h e p i l e s (125).

19

2.3.5 Resource Recovery Technology Descriptions

Disposal of an increasing quantity of refuse in an economically and environmentally accsptaSle manner is an issue which the coal industry has constantly faced. Conventional disposal practices invoive either placing the refuse in large waste piles or pumping it behind retaining structures. the higher costs associated with more stringent environmental controls. Obviously, making use of coal refuse would eliminate the need for complex, permanent disposal facilities.

The per-ton disposal costs are increasing yearly due to

Attempts to find productive uses for coal refuse are not a recent phenomenon. coal refuse disposal and utilization stimulated a great deal of study and experimentation. In 1889, the Commonwealth of Pennsylvania appointed a commission to investigate coal refuse production and the potential for its utilization. The Commission's report included 134 references to reports, journals, and books publtshed between 1884 and 1892 discussing the productive use of coal waste, 82 patents f o r utilizing or burning fine coal sizes and coal waste, and 89 patents for manufacturing arti- ficial fuels by combining coal fines and waste with other materials. Much of the early work focused on ways to use fine coal sizes, but other modes of utilization were also being investigated.

Through the latter half of the nineteenth century,

In this study, a review of the literature on coal refuse utilization was performed to identify the full range of utilization techniques that have been employed and/or considered in the United States and else- where. It was found that coal refuse disposal and utilization have been under study for more than 100 years and that a wide variety of uses have been proposed and, in many cases, implemented. A list of these coal refuse utilization techniques is given on the following page.

20

1. Secondary fuel recovery 0 Coal refuse combined with waste oil and pelletized (17).* 0 Wash water sludge dried, mixed with binder and briquetted

0 ill, 19j. Fluidized bed combustion of refuse (12, 26, 29, 33, 111. 118, 137).

2. Secondary mineral recovery 0 Magnetite recovery (110). e Production of zinc and coal rich concentrates (9). 0 Alumina extraction (19, 25, 27, 32, 112, 130, 132). 0 Clean coal recovery (6, 121, 124, 127, 131, 133, 138,9,22,141,142)

3. Construction materials manufacture 0 Aggregate in l o w quality concrete, bricks and blocks

0 Plastic resin manufacture (14). 0 Mineral wool production (14, 26, 27, 124). 0 Floor tiles, chimney flue tiles (8, 80). 0 Production of portland cement (10, 31)

(4, 8, 10, 14, 15, 16, 18, 20, 28, 108, 124, 126, 153).

4. Construction and highway uses 0 Anti-skid road material (7, 14, 26, 31, 124) 0 Embankment material (5, 10, 12, 13, 14, 16, 20, 21, 24, 31,

e Aggregate (8, 10, 15, 16, 20, 26, 27, 28, 29, 46, 86, 108,

0 Mine and construction fill (8, 10, 12, 14, 21, 23, 26, 30,

46,109, 128, 146).

124, 128,144, 147).

31, 122, 124).

5. Horticultural uses 0 Soil conditioner (27). 0 Synthetic humus (27, 124, 134).

Each of the above mentioned technologies will be discussed in the following sections.

* Numbers in parenthesis refer to articles in the Reference section.

21

2;3.5.1 Secondary Fuel Recovery

Coal r e fuse lwas te o i l f u e l p e l l e t s . A s t a b l e p e l l e t i z e d f u e l has been made from a mixture of waste crankcase o i l and c o a l dus t i n a Univers i ty of Alabama r e s e a r c h p r o j e c t (17). Waste crankcase o i l w a s mixed wi th -28 mesh c o a l d u s t a t a ra t i? of 1:5 by weight. The mixture was subjec ted t o a p r e s s u r e of 30,000 t o 35,000 p s i i n a p e l l e t press , which produced a w e l l bonded p e l l e t no t t oo b r i t t l e nor coo d u c t i l e f o r normal handling. The average h e a t i n g va lue of t h e s e p e l l e t s w a s found t o be 13,670 Btu p e r pound. t h e hea t conten t of v i r g i n coa l . t i v e l y high hea t ing va lue of t h e p e l l e t s , coupled wi th a r e l a t i v e l y low s u l f u r con ten t , should make them very a t t r a c t i v e f o r use i n coa l - f i red furnaces .

This is equal t o o r s l i g h t l y higher than The conclusions were t h a t t h e rela-

In a conversa t ion wi th D r . C . D. Haynes, i t was learned t h a t no commercial a p p l i c a t i o n of t h i s process has been at tempted. Dr. Haynes f e l t t h a t t he b i g g e s t hinderance t o commercial use of t h e coa l dus t lwas te o i l p e l l e t s i s t h e problem of a i r p o l l u t a n t emissions from the burning of t h e crankcase o i l . No t e s t s were conducted regard ing t h i s i s s u e . Also most l a r g e gene ra to r s of waste o i l a l r eady have a market f o r t h e i r o i l wi th r e - r e f ine r s (180) .

Wash water s ludge from f u e l b r i q u e t t e s (11). Attempts t o u t i l i z e wash water s ludge employing var ious methods and cont r ivances have had d ive r se r e s u l t s . Thickeners , preceded by w e t c l a s s i f i c a t i o n , have been success fu l . The s ludge is removed from t h e bottom, d r i ed t o about 8 percent mois ture c o n t e n t , then combined wi th coa r se r grades. I f t he m a t e r i a l i s i n i t i a l l y of a c o a r s e grade, it i s o f t e n s tacked, a l lowed t o d r a i n and d r y , then combined. The la t ter course is unpredic tab le as success depends upon the weather. For t h i s reason i t i s seldom p r a c t i c e d i n t h e win ter . The combination of f i n e p a r t i c u l a t e and high ash, however, seems t o have been a d e t e r r e n t as t o any u n i v e r s a l a t t e m p t a t rec lamat ion wi th in t h e indus t ry . Perhaps t h i s a t t i t u d e on t h e p a r t of producers and t h e gene ra l inadequacy of process equipment t o treat t h e material economically could be under ly ing causes f o r t h e v a s t accumulation of t h i s p o t e n t i a l energy source .

Newly genera ted s ludge d i f f e r s from t h e con ten t s of t h e o l d e r ponds i n that t h e material has n o t been p a r t i a l l y or t o t a l l y leached of t h e oxygen contained t h e r e i n . For t h i s reason, i t l ends i t s e l f t o t h e f r o t h f l o t a t i o n p rocess of f i n e p a r t i c u l a t e s epa ra t ion . A f r o t h so lu- t i o n i s crea ted by t h e use of a l c o h o l s , heavy o i l s , and reagents , which f l o a t s t h e c o a l wh i l e t h e i m p u r i t i e s s ink . wash water i s accomplished by b r i q u e t t i n g wi th a s u i t a b l e b inder . des i r ed end product should have a d e n s i t y and compressive s t r e n g t h a t least equal t o t h e o r i g i n a l c o a l as w e l l as being impervious t o mois ture . The l a t t e r i s mandatory f o r t h e purpose of sh ipping and customer s t o r a g e .

The agglomeration of prepared The

- 1

1

t

22

Br ique t t ing of s ludge has never been widely p r a c t i c e d by producers

Binders attempted have been s u l f o n i t e emulsions,

Many have d e l e t e r i o u s e f f e c t s upon combustion due t o impur i t i e s con-

due t o two reasons: (1) economical a v a i l a b i l i t y of l a r g e r s i z e s , and (2) l a c k of a s u i t a b l e b inde r . c o a l tar d e r i v a t i v e s , a s p h a l t i a m a t e r i a l s , and va r ious s t a r c h e s , t o name but a few. t a ined the re in . Another o b j e c t i o n i s so f t en ing of b inding substance dur ing warm weatner and r e s u l t i n g s t o r a g e p i l e set-up.

The b inder used i n t h e b r i q u e t t i n g process is a s a t u r a t e d s o l u t i o n

To form t h e b inder , rock salt i s combined of minera l sodium c h l o r i d e b r i n e ( rock s a l t ) i n t h e amount of e i g h t pounds p e r ton of coa l agglomerated. w i t h water and a s a t u r a t e d b r i n e produced a t ambient temperature. This i s t r e a t e d with calcium oxide and sodium carbonate , allowed t o s e t t l e and t h e b r i n e decanted. It i s then ready f o r use a s a d e n d r i t i c c r y s t a l producing s o l u t i o n .

A 1.5 t o 2 .0 percent s a t u r a t e d b r i n e s o l u t i o n is the recommended a d d i t i v e by weight t o each ton of p a r t i c u l a t e , r e s u l t i n g i n t h e a d d i t i o n of 30 or 40 pounds of b r i n e . Upon c r y s t a l l i z a t i o n , t h e binder w i l l weigh from 6 t o 8 pounds p e r ton of c o a l .

This mixture i s then heated t o 165°F and subjec ted t o 20-24,000 This produces c r y s t a l l i n e l a t t i c e which b inds pounds p e r l i n e a l n i p inch.

t h e p a r t i c u l a t e i n t o a mois ture r e s i s t a n t b r i q u e t t e .

Fluidized bed combustion. It has long been known t h a t materials wi th very l o w hea t ing va lues can be burned. q u a r t e r inch s i z e and w i t h as l i t t l e as 3,000 t o 3,500 Btu per pound hea t - i n g va lue has been burned i n t h e Of f i ce of Coal Research p i l o t scale f l u i d - bed column designed and opera ted by Pope, Evans and Robbins of Alexandria, V i rg in i a . Coal waste w i t h as l i t t l e as 5,000 Btu pe r pound hea t ing va lue can be burned i n s p e c i a l l y designed, convent iona l b o i l e r s provided t h a t t h e wastes are f r i a b l e enough t o permit economical g r ind ing t o a f i n e s i z e . Boilers designed t o burn c o a l waste must be equipped w i t h overs ize ash handl ing c a p a b i l i t y s i n c e approximately one-half o r more of t h e c o a l wastes fed t o t h e b o i l e r would remain as a sh and would t h e r e f o r e have t o be cont inuously removed ( 3 3 ) .

Coal r e f u s e crushed t o one-

The d i r e c t burn ing of l e a n gob p i l e s t o produce power i s w e l l e s t a b l i s h e d from exper ience i n France where a n t h r a c i t e waste banks have been used up as a sou rce of f u e l dur ing the p a s t 25 yea r s . Combustion was achieved us ing t h e I g n a f l u i d b o i l e r which b u m s c o a l r e fuse crushed t o asproximately 1 / 4 inch. Refuse w i t h a dry a s h con ten t as high as 40 p e r c m t and hea t con ten t as low as 7,500 Btu w a s found t o provide a satis- f a c t o r y f u e l . Moreover, it i s p r e f e r a b l e t h a t refuse fed t o an I g n a f l u i d i n s t a l l a t i o n should con ta in between 15 t o 20 percen t v o l a t i l e matter, less than 5 percent s u l f u r and have a sh wi th a fus ion temperature ranging from 2,000 - t o 2,600"F ( 3 3 ) .

23

Most p re sen t c o a l burning power p l a n t s o p e r a t e wi th c o a l having f u e l va lues ranging between 10,000 and 12,000 Btu p e r pound and w i t h a sh c o n t e n t s ranging up t o approximately 30 percent . The r e f u s e from most banks can be mixed d i r e c t l y w i t h c o a l provided t h a t t h e h e a t i n g v a l u e and ash con ten t of t h e mixed product meets t h e Btu design level of t h e b o i l e r f o r which the f u e l i s intended.

The p r i n c i p a l impediment t o blending r e f u s e w i t h c l e a n c o a l is t h a t i t tends t o i n c r e a s e downtime a t t h e p l a n t . Any sav ings r e a l i z e d by us ing a cheaper grade of c o a l can b e quickly o f f s e t by loss of b o i l e r u s e f o r a couple of days (179) .

Using an experimental p l a n t (225 I b s / h r ) t h e CSIRO Div i s ion of P ~ O , - & ~ Technology of North Ryde, N e w South Wales, A u s t r a l i a , has developed a pro- c e s s of t r e a t i n g washery waste, i nc lud ing s l u r r y , w i t h up t o 85 percen t inerts ( i .e . , ash p l u s moi s tu re ) by fluidized-bed combustion. A bed of hot ash p a r t i c l e s i s supported on a steel p l a t e f i t t e d w i t h nozz le s through which combustion a i r blows. When t h e upward flow of air is s u f f i c i e n t l y high, t h e p a r t i c l e s are he ld in suspension and t h e bed resembles a vell- mixed, bcbbl ing f l u i d . Coarse rejects, crushed t o below 0.5 in . , are f e d cont inuously i n t o t h e bed a t 850°C (1,562'F), t h e carbonaceous matter b u m s away t o l i b e r a t e hea t and a r e s i d u e of bu rn t rejects, o r c a l c i n e d s h a l e , is l e f t ( 2 9 ) .

Mezhods of f i r i n g thickened s l u r r i e s t o g ive s e l f - s u s t a h e d combustion, without problems of agglomerat ion of t h e bed, have a l s o been developed (29).

I !

Culm, t h e waste product of a n t h r a c i t e c o a l min ing , i s being used t o f i r e a steam p l a n t i n Shamokin, Pennsylvania. A n t h r a c i t e culm is f e d t o an atmospheric f luidized-bed combustion b o i l e r t h a t d e l i v e r s 23,400 pounds p e r hour of 200 p s i s a t u r a t e d steam. Cellu-Products Corp., a paper company l o c a t e d next t o t h e p l a n t , is u s i n g t h e steam. is 3,000 t o 4,000 Btu p e r pound, about a t h i r d the h a t i n g v a l u e of the c o a l ; a s h content i s 65 t o 75 percen t . Some 900 million y a r d s of a n t h r a c i t e culm has accumulated i n n o r t h e a s t e r n Pennsylvania. Curtiss-Wright Corporat ion 's power systems group, w a s sponsored by t h e Shamokh Area I n d u s t r i a l Corporat ion and t h e U.S. Department of Energy (118).

Heating v a l u e of t h e c u l m

The p r o j e c t , managed by

2.3.5.2 Secondary Mineral Recovery

Zinc and c o a l r i c h concen t r a t e s . Zinc is p r e s e n t i n t h e c o a l as a s u l f i d e mineral , s p h a l e r i t e (ZnS wi th up t o 1 pe rcen t cadmium). Sphale- r i t e occurs as f i l l i n g s in f r a c t u r e s , c l e a t s , and f a u l t s , and as crystal aggregates i n c l a s t i c d i k e s which i n t r u d e the coa l s .

24

?E E

In a study performed by t h e I l l i n o i s S t a t e Geological Survey ( 9 ) , it w a s determined t h a t t h e w e s t c e n t r a l I l l i n o i s mining d i s t r i c t (Ful ton, Knox, Peor i a , and S ta rk Counties) has an est imated c o a l r e source of 7,500 m i l l i o n tons occurr ing i n t h r e e seams: The Colchester (No. 2), Spting- f i e l d (No. 5 ) , and Herrin (No. 6 ) . With a zinc concen t r a t ion from 0.05 t o 0.09 pe rcen t , t he c o a i s i n t h i s area c o n t a i n several m i l l i o n t o n s of z i n c , an amount equal t o that of some zinc mining d i s t r i c t s . This has l e d t o s p e c u l a t i o n s that recove rab le q u a n t i t i e s of s p h a l e r i t e could be p r e s e n t i n some e x i s t i n g c o a l r e f u s e d e p o s i t s .

The fol lowing r e s u l t s were ob ta ined from the survey team's i n v e s t i - g a t i o n (9) .

A c o a l mine s l u r r y r e f u s e d e p o s i t i n w e s t c e n t r a l I l l i n o i s w a s found t o c o n t a i n about 1 m i l l i o n t o n s of c o a l and 1,100 tons of z inc . I n t h e 45 acres covered by t h e fan-shaped s l u r r y d e p o s i t , the c o a l con ten t was found t o i n c r e a s e r a d i a l l y outward from t h e d i scha rge p i p e toward t h e s e t t l i n g pond, w h i l e t h e z inc content decreased. 600 f e k t from t h e d i scha rge pipe. The bu lk of t h e zinc, 95 p e r c e n t , oc- c u r s i n a 450-foot r a d i u s from t h e d i scha rge pipe.

The maximum c o a l con ten t w a s found

The Humphreys s p i r a l c o n c e n t r a t o r produced f i r s t - s t a g e c o a l and heavy mineral concen t r a t e s from t h e r e f u s e fan. There w a s an e f f e c t i v e increase in t h e z inc content of t h e heavy a i n e r a l conceDtrate by an average of 324 p e r c e n t . The h ighes t z inc va lue produced in a heavy concen t r a t e w a s 0.45 p e r c e n t . The t o t a l carbon con ten t of t h e c o a l c o n c e n t r a t e i nc reased an average of 72 percent . and only 3 percent d i s c r e t e mine ra l p a r t i c l e s . Chemical ana lyses showed t h i s c o a l concen t r a t e t o c o n t a i n 2.6 percen t t o t a l sulfur and 9 pe rcen t ash. Secondary and t e r t i a r y b e n e f i c i a t i o n s t a g e s could b e expected t o f u r t h e r improve t h e q u a l i t y of t h e s e c o n c e n t r a t e s .

The b e s t c o a l concen t r a t e contained 97 percen t c o a l

These ba tch tests demonstrate the f e a s i b i l i t y of producing bo th c o a l and zinc-r ich concen t r a t e s u s i n g a s p i r a l concen t r a to r . These tests were a f i r s t - s t a g e concen t r a t ion ; f u r t h e r s e p a r a t i o n s by g r a v i t y or chemical t echn iques could s i g n i f i c a n t l y improve the r e s u l f s .

-

According t o one of t h e a u t h o r s of t h e study (182) t h e technique f o r r ecove r ing t h e zinc concen t r a t e i s n o t being p r a c t i c e d commercially. No economic f e a s i b i l i t y a n a l y s i s w a s performed regarding t h e technique, bu t i t i s be l i eved t h a t t h e zinc recovered would n o t pay f o r i t s recovery.

Alumina e x t r a c t i o n . It i s a wel l -establ ished f a c t t h a t alumina - i s one of t h e more p l e n t i f u l materials found i n c o a l mining r e j e c t s . r e f u s e may con ta in from 20 t o 30 p e r c e n t Al2O3. chemis t s have demonstrated several p rocesses for recovering e i t h e r aluminum o r aluminum c h l o r i d e from o r e s c o n t a i n i n g alumina. a p p l i c a b l e t o c o a l wastes.

Coal Over t h e p a s t cen tu ry

Many of t h e s e would be

!

25

In all of t h e published l i t e r a t u r e and conve r sa t ions wi th represen- t a t i v e s of t h e aluminum and c o a l i n d u s t r i e s , t h e conclusion w a s t h e same. Alumina e x t r a c t i o n from c o a l r e f u s e i s p o s s i b l e t e c h n i c a l l y , b u t n o t economically. rec.)very f r m c c a l r e f u s e (184).

Cur ren t ly t h e r e is no commercial a p p l i c a t i o n of alumina

Clean c o a l recovery. A waste c o a l p i l e or culm bank is heterogeneous r a t h e r than homogeneous in composition and v a r i a t i o n will occur , bo th h o r i z o n t a l l y and v e r t i c a l l y . Culm bank materials w i l l gen- e r a l l y c o n s i s t of c o a l , s h a l e , bone c o a l , s u l f a t e s , carbonates and p y r i t e or marcas i t e . I n a d d i t i o n , s l a g materials may be p re sen t i f combustion of p o r t i o n s of t h e bank has occurreci. The v a r i a b i l i t y of na te r ia l i n a c o a l r e f u s e p i l e depends on many f a c t o r s , such as t h e market f o r c o a l , method of c l ean ing , e f f i c i e n c y of t h e c l ean ing p rocess , mining methods and systems employed,and t h e q u a l i t y of t h e c o a l seam. t a n t conclusion t o be drawn from t h i s i s t h a t ex tens ive sampling, bo th on t h e s u r f a c e and a t depth, h a s t o be performed b e f o r e a c c u r a t e estimates can be-made as t o t h e f u e l v a l u e of a r e f u s e p i l e .

The most impor-

The d i r e c t burning of c o a l w a s t e banks t o produce power has been p r a c t i c e d i n Europe s i n c e World War 11. c i t e banks a s a source o f f u e l and power p l a n t s have been cons t ruc t ed ir? Great B r i t a i n designed t o b u m c o a l waste (137) .

France has used up i t s anthra-

Seve ra l c o a l r e f u s e recovery ope ra t ions i n t h e United States and Europe have been designed t o recover h igh grade and/or low grade f u e l and u s e f u l end products from t h e r e s idue . Several processing p l a n t s i n d i c a t e t h a t i t i s p o s s i b l e t o completely u t i l i z e an abandoned r e f u s e bank.

C e r t a i n o ld d e p o s i t s are s u f f i c i e n t l y high i n carbon con ten t tha t they are being loaded out and s o l d , w i t h only minor sca lp ing , f o r u t i l i t y use. Th i s i s e s p e c i a l l y t r u e w i t h t h e culm banks t h a t have r e s u l t e d from earlier product ion of coking c o a l .

One method of c l ean c o a l recovery from t h e r e f u s e p i l e employs t h e Haldex (Simdex) cyclone u t i l i z i n g r e f u s e as a heavy medium (138). The modified heavy media ope ra t ion u s e s t h e f i n e s izes of r e f u s e as .a low c o s t s p e c i f i c g r a v i t y c o n t r o l l i n g medium. Refuse con ta in ing 10 t o 20 percen t c o a l i s u t i l i z e d as p l a n t f e e d t o produce c l e a n c o a l (maxi” of 1 2 pe rcen t a s h ) , low grade f u e l (20 t o 40 percen t ash) and r a w ma- t e r i a l f o r b r i c k , l i gh twe igh t aggrega te , cement manufacture, and back- f i l l (121) .

26

The Renkol Coal C l a s s i f i e r , operated by Recco Coals, Inc . , u t i l i z e s t h e r eve r se C o r i o l i s e f f e c t (139). is pumped i n t o the cyclone i n t a k e under p re s su re a t an angle that creates a counterclockwise c e n t r i f u g a l s w i r l . c lockwise. The r e f u s e is t h e medium of s epa ra t ion .

Waterborne material from t h e s l u r r y tank

Most cyclone des igns s w i r l t h e material

Some companies process r e f u s e by sc reen ing , c rush ing , g r ind ing , and blendirig w i t h f l o t a t i o n t a i h t o produce c lean c o a l ( 6 , 1401, whi le i n o t h e r cases o l d e r banks are simply being rewashed t o recover the coa l .

I n Pennsylvania , a 50 TPH p i l o t p l a n t p laced i n ope ra t ion i n 1965 w a s designed t o produce a s a l e a b l e grade of bituminous c o a l and r a w material f o r manufacture of c o n s t r u c t i o n products (141) . I n essence , t h e p l a n t f low cons i s t ed of c l o s e d - c i r c u i t c rush ing t o minus one inch , desl iming t h e minus one inch a t 28 mesh, c e n t r i f u g a l heavy media c l ean ing of minus one inch p lus 28 mesh feed followed by c e n t r i f u g a l dewater ing of t he low grade f u e l ( 1 2 1 ) . concen t r a t e con ta in ing 7 percent a sh wi th a c o a l recovery of over 90 per - cen t ( 9 , 1 4 2 ) .

The HuDphreys s p i r a l concen t r a to r w a s t e s t e d and produced a c o a l

2 . 3 . 5 . 3 ' Const ruc t ion Mate r i a l s Manufacture

Aggregate i n l o w q u a l i t y conc re t e , b r i c k s , and b locks . Much r e sea rch has been conducted over t h e years o n . t h e p o s s i b i l i t y of using c o a l r e f u s e as an aggrega te i n conc re t e o r b r i c k products . Resu l t s of most of the s t u d i e s were f avorab le axd showed t h a t t echEica l ly , c o a l r e f u s e could be used as an aggrega te i n thase products . s ea rche r s on t h e s u b j e c t ( 1 4 3 ) , t he only p l aces t h a t t h e s e products are being made a r e i n l a b s conducting work t h a t is s t i l l experimental .

However, according t o one of t he primary re-

Publ ished r e s u l t s of t h e experimental work obtained i n t h e l i t e r a t u r e survey a r e presented i n t h e fo l lowing paragraphs.

I n a r e sea rch p r o j e c t conducted a t t h e Un ive r s i ty of Kentucky ( 4 ) i n which c o a l r e f a s e w a s u t i l i z e d as aggregate f o r producing conc re t e (coa l - Cre te ) mixes, encouraging r e s u l t s were found. The fo l lawing conclus ions were drawn from t h e r e s u l t s of tests on 26 d i f f e r e n t coal-Crete mixes:

1) Raw c o a l r e f u s e can be used as an aggrega te f o r low- q u a l i t y conc re t e (coal-Crete) ; however, i n d i s c r i m i n a t e use of a given r e f u s e source may n o t provide a satis- f a c t o r y mix. C e r t a i n p r i n c i p l e s used i n producing q u a l i t y conc re t e must b e adhered t o as c l o s e l y as pos- s i b l e when producing coal-Crete.

2) Since d u r a b i l i t y of coal-Crete is very poor when exposed t o weather ing elements , i t s a p p l i c a t i o n i s l i m i t e d t o w i t h i n a mine o r o t h e r l o c a t i o n s where normal temperature and h igh humidity remain n e a r l y CORStant.

27

i m

Coal-Crete w i t h a compressive s t r e n g t h of 2,000 p s i can b e produced c o n s i s t e n t l y w i t h proper c o n t r o l s and a l t e r a t i o n s of t he r e f u s e material. A cement f a c t o r of 5.00 t o 5.25 bags p e r cub ic yard is recommended i n o r d e r t o maintain s t r e n g t h s above 2,000 p s i .

Refuse c o n t a i n i n g s u b s t a n t i a l amounts of c l ay and f i n e material should be washed p r i o r t o use i n c o a l - c r e t e . A n e f f e c t i v e way of determining whether a given r e f u s e should b e washed is t o conduct bo th a w e t and dry s i e v e a n a l y s i s on t h e r e f u s e . I f t h e r e s u l t i n g tests show a v a r i a t i o n i n t h e material pas s ing a No. 200 s i e v e of 3 percen t o r g r e a t e r , t he r e f u s e should b e washed.

The a d d i t i m o f 25 percenr: n a t u r a l sand w i l l gene ra l iy s i g n i f i c a n t l y improve the working c h a r a c t e r i s t i c s , s t r e n g t h , and d u r a b i l i t y of coal-Crete mixes.

Poss ib l e a p p l i c a t i o n s of coal-Crete are n o t as general as f o r conven- t i o n a l - c o n c r e t e . ing, a p p l i c a t i o n would be l i m i t e d t o underground mines where approximately 55°F temperature and h igh humidity remain n e a r l y cons t an t a l l y e a r , and i n l o c a t i o n s where h igh r e s i s t a n c e t o abrasion is n o t required. mining-oriented a p p l i c a t i o n of coal-Crete being considered i s as roof- support p i l l a r s i n underground mines. The p i l l a r s would be placed i n mined out areas s o cha t t h e remaining c o a l p i l l a r s , which prsviousiy hac? been used f o r roof s u p p o r t , could a l s o be mined.

S ince it is n o t s u f f i c i e n t l y d u r a b l e t o withstand weather-

The major

I n another s tudy performed he re i n the U.S. ( 18 ) , i t w a s found that c o a l e x h i b i t s hydrophob ic i ty , as shown by producing h igh content ang le s wi th water. This suggested t h a t t h e inco rpora t ion of c o a l washing f i n e s i n t o bu i ld ing materials, e s p e c i a l l y cement block, would impart i nc reased water r e s i s t a n c e t o t h e material.

The use o f 26.6 p e r c e n t of minus 100 mesh c o a l d u s t from mine washing ope ra t ions w a s found t o reduce t h e rate of p e n e t r a t i o n of water by a f a c t o r of 4 . 5 , and t h e rate of t r ansmiss ion of water by a f a c t o r of 7.5. S t r e n g t h s and freeze-thaw resistances are not adversely a f f e c t e d .

An economic a n a l y s i s shows t h a t t h e c o s t of cement blocks c o n t a i n i n g t h e c o a l dust depends t o a g r e a t e x t e n t upon t h e d i s t a n c e from t h e p o i n t of o r i g i n t o the manufacturer ; f o r d i s t a n c e s up t o 45 m i l e s t h e . p r o d u c t con ta in ing c o a l d u s t i s cheaper than the r e g u l a r product . f i gu red f o r t h e P h i l a d e l p h i a a r e a , f o r which l a b o r and overhead rates are h igh compared wi th Appalachia (18).

These c o s t s are

Although t h e u s e of c o a l r e f u s e as an aggrega te i n conc re t e o r b r i c k i s l i m i t e d t o l a b o r a t o r y work h e r e i n t h e United S t a t e s , t h e s i t u a t i o n is q u i t s - + t h e oppos i t e i n Great B r i t a i n and France. The SUREX method developed

28

by t h e Nord and Pas-de-Calais area, France, i n c l o s e c o l l a b o r a t i o n wi th Cerchar is very f l e x i b l e and makes i t p o s s i b l e t o use, as raw material, washery s h a l e s con ta in ing between 4 and 10 percent carbon ( 8 ) . are crushed t o the requi red f i n e n e s s ( l e s s than 0.02 inch ) and t h e powder is mixed wi th 1 2 percent water. The p a s t e is extruded and c u t i n t o small c y l i n d e r s of va r ious d iameters . Af t e r dry ing , t h e nodules undergo hea t t rea tment i n a l i n e of fou r r o t a r y k i l n s i n series, w i t h automatic c o n t r o l , t h e s e being a prehea t ing k i l n , decarbonizat ion k i l n , pre-expansion k i l n , and an expansion k i l n .

The sha le s

The SUREX method makes i t poss ib l e t o o b t a i n , from va r ious s i z e c a t e g o r i e s , aggrega tes of which t h e apparent s p e c i f i c g r a v i t y may vary from 25 t o 44 pounds pe r cub ic f o o t , according t o t h e type of u t i l i z a t i o n . The s p e c i f i c g r a v i t y is ad jus t ed cont inuous ly , r a p i d l y , and accu ra t e ly . The l a t e n t hea t of t h e coo l s h a l e rnakes i t p o s s i b l e t o reduce t h e hea t consuinp- t i o n of t h e method t o less than 7 7 2 thermal units p e r ton , which i s a fac- t o r i n favor of t he development of aggregates of shale. A p i l o t p l a n t wi th a capac i ty of 3,500 cubic f e e t per day has been b u i l t a t Hulluch by the Nord and Pas-de-Calais area, and has been i n o p e r a t i o n s i n c e 1969 (8). From France i t i s repor ted t h a t t h e r e i s product ion of 200,000 s h a l e b r i cks p e r day' (10).

I n the United Kingdom t h e use of c o l l i e r y s p o i l s h a s decl ined because t h e s p o i l i s r e a l l y only s u i t a b l e f o r t h e manufacture of common b r i c k s , t he consunption of which has dec l ined i n t h e f a c e of compet i t ion f r o n conc re t e blocks. Product ion of c o l l i e r y s h a l e b r i c k s i s now mainly i n Scot land where t h e t r a d i t i o n a l wa l l ing u n i t i s common b r i c k or s tone w i t h a rendered o u t e r su r f ace . The b r i c k s are made i n cont inuous k i l n s where t h e f u e l i nhe ren t i n t h e s p o i l can most e f f i c i e n t l y c o n t r i b u t e t o t h e t o t a l energy requirements of f i r i n g t h e b r i c k s (10). I n t h i s count ry , p a r t of t he f u e l requi red f o r f i r i n g i s incorpora ted i n t o t h e mix a t t h e molding s t a g e . Because of t h i s , t he e x t e r n a l energy requirements are very low, 104 ,460 t o 1,150,000 Btu pe r ton of b r i c k s compared wi th about 2,507,160 Btu p e r t on of b r i c k s f o r equiva len t b r i c k s made from a c lay which does not con ta in inhe ren t f u e l (10).

The reasons f o r t h e r e s t r i c t i o n of c o l l i e r y s p o i l s t o rhe manu- f a c t u r e of common b r i c k s i n t h e United Kingdom are:

1) The poor p l a s t i c i t y of t h e s p o i l which necessitates a p res s ing technique r a t h e r than e x t r u s i o n which is usua l ly used i n t h e forming of f a c i n g b r i c k s ;

2) The presence of "black hea r t s " i n t h e f i r e d b r i c k due t o incomplete ox ida t ion of t h e carbonaceous matter i n t h e s p o i l ;

29

3) Imperfect ions i n t h e s u r f a c e of t h e f i r e d b r i c k mainly due t o the presence of par t ic les of l i m e on t h e s u r f a c e ;

4 ) S t a i n i n g due t o s o l u b l e su lpha te or i r o n compounds i n the b r i c k ;

5) D i f f i c u l t y i n c o n t r o l of t h e f i r i n g due t o v a r i a t i o n s i n t h e c a l o r i f i c va lue of t h e s p o i l .

I n genera l t h e s e f a c t o r s r e s u l t i n a b r i c k of poor and v a r i a b l e appearance b u t y e t one which has good d u r a b i l i t y . Attempts t o make b r i c k s of b e t t e r appearance from c o l l i e r y s p o i l s , whether by reducing the temperature of f i r i n g o r by ex t ruding t h e spoi1 ,have tend-ed t o a f f e c t t h e d u r a b i l i t y adversely (10).

I n Germany, t he ex tens ive l abora to ry and p l an t t r ia ls which have been c a r r i e d out r ecen t ly have examined t h e e f f e c t s of adding t h e s p o i l t o a c l ay mainly i n o rde r t o save f u e l . Laboratory examinations of the s p o i l s h o w e d t h a t t h e c o a r s e r washery waste had a lower and more s t a b l e c a l o r i f i c va lue and a lower su lphur conten t and w a s t h e r e f o r e p re fe rab le as a raw materiaf. o r c rush the coa r se r e f u s e , t h e r e f o r e t h e f i n e t a i l i n g s were used.

However, i n t h e p l a n t t r i a l s i t w a s found impossible t o s e p a r a t e

The percentage a d d i t i o n s v a r i e d from works t o works up t o a maximum of 25 percent by volume. A t t h e b e s t works 35 percent of f u e l o i l w a s saved 5y t he use of t h e s p o i l . The p h y s i c a l p r o p e r t i e s cf t he r e s u l t i n g b r i c k s were i n genera l good though some p i t t i n g or s p a l l i n g of t h e s u r f a c e caused problems i n the manufacture of f a c i n g b r i c k s (10 ) .

P l a s t i c r e s i n manufacture ( 1 4 ) . The Coal Research Bureau i n Great B r i t a i n has devised a novel process f o r making cheap p l a s t i c s from t a i l i n g s . The c o a l conten t of t h e t a i l i n g s is converted i n t o a p l a s t i c b inde r by d iges- t i o n wi th a heavy c o a l t a r o i l , and i n t h e course of t h i s t he water is evap- o ra t ed . The minera l matter ac ts as a f i l t e r i n t h e r e s u l t i n g mixture (which i s c a l l e d t a i l i n g s d i g e s t ) , and i t can b e pressed, molded, o r extruded i n t o cheap u s e f u l materials. The t a i l i n g s d i g e s t product i s a bituminous material which has low-grade p r o p e r t i e s compared w i t h s y n t h e t i c r e s i n s ; i t is n o t , however, as b r i t t l e as p i t c h and g e n e r a l l y i s a mechanically more d e s i r a b l e materisl.

A s a p l a s t i c m a t e r i a l , t a i l i n g s d i g e s t needs reinforcement of some kind. One way i n which t h i s can b e achieved is t o use the t a i l i n g s d i g e s t as the inne r co re of a paper c o n t a i n e r . Such f a c t s show some promise of r ep lac ing wood b locks used i n making p a l l e t s f o r f o r k l i f t t rucks . Su rp r i s - i n g l y , t h e d i g e s t is r e s i l i e n t enough f o r n a i l s t o be hammered i n t o i t . Another way of r e i n f o r c i n g t h e d i g e s t is t o compound it phys ica l ly , i n an i n t e r n a l mixer, wi th materials such as PVC and polypropylene, which improves i t s phys ica l p r o p e r t i e s . The p r o p e r t i e s of re inforced t a i l i n g s d i g e s t are compared wi th PVC i n Table 2-5. I t should be poss ib l e t o compensate f o r i t s poor phys i ca l p r o p e r t i e s as a p l a s t i c by i t s cheapness.

30

Table 2-5

PROPERTIES OF COLLIERY TAILINGS DIGEST POLYPROPYLENE MIXES COMPARED WITH --

-THOSE OF -PVC

T e n s i l e Crossbreak Notched Mix Percent S t r eng th Elongat ion S t r e n g t h Impact

PolypropyleneeTailings l b pe r sq i n Percent l b p e r sq I n f t l b l i n notch

100 0 7,200 20 9,500 0 . 3 3 80 20 3,900 60 6,230 0.47 60 40 3,000 56 5,050 0.37 40 60 1,680 35 4,090 0.28 30 70 1,300 25 - -

T a i l i n g s d i g e s t (40 percen t ) w i th polypropylene is s u p e r i o r i n It has been made i n t o ex t ru - impac t s f r e n g t h and much cheaper than PVC.

s i o n s of var ious shapes and forns s u i t a b l e f o r duc t ing , f l a s h i n g s for bui ld- i n g and engineer ing purposes .

One problem i n t h i s a c t i v i t y i s t h a t s u p p l i e s of an thracene o i l , a coa l so lvent used i n t h e p rocess , are l i m i t e d ; perhaps 20,000 t o n s per a n n m could be made a v a i l a b l e . Although t h i s would s u f f i c e f o r a consid- e r a b l e output of d i g e s t , a r e a l l y l a r g e s c a l e use of t a i l i n g s d i g e s t i s precluded.

There are va r ious p o s s i b l e ways out of t h i s d i f f i c u l t y . There is some hope of being a b l e t o produce materials d i r e c t l y from c o a l which could r ep lace the anthracene o i l a s a c o a l so lven t . A l t e r n a t i v e l y , o t h e r b inde r s such a s s i l i c a t e s , bitumen, and s y n t h e t i c latexes, could be used. One in- t e r e s t i n g p o s s i b l e source of b i n d e r i s waste rubber tires; no work has y e t been c a r r i e d out on t h i s sugges t ion .

Current ly , t h e r e i s no commercial u t i l i z a t i o n of c o a l t a i l i n g s d i g e s t mixed wi th polypropylene.

Mineral wool product ion. Mineral wool is an i n s u l a t i n g material made by c r e a t i n g a f i b r o u s matrix from a molten g l a s s y feed . method of producing t h e molten g l a s sy feed is t o charge a cupola w i t h 2 inches by 5 inches coke and b l a s t fu rnace s l a g . has demonstrated t h e f e a s i b i l i t y of producing mineral wool from a n t h r a c i t e c o a l a sh and r e fuse . The procedure employed a s l agg ing p l a c e of t h e cupola (26) . by a mineral wool producer us ing c u r r e n t a n t h r a c i t e r e f u s e as a r a w material. The r e s u l t i n g wool w a s an undes i r ab le brown c o l o r , b u t more impor t an t ly , t he

The c u r r e n t

Research i n t h e l a t e 1930s

gas producer i n I n o t h e r r e sea rch , pre l iminary tests w e r e made

_ _

! -

cupola d i d n ' t ope ra t e i n its normal temperature range without f r eez ing , The need f o r a h igher temperature w a s ass igned t o t h e high alumina con- t e n t of t h e r e fuse . The m a t e r i a l normally used by this manufacturer of minera l wool con ta ins 12 percent t o 13 percent alumina while t h e an thra- c i t e r e f u s e contained 24 percent t o 28 percent . The cupola would e i t h e r have t o be redesigned f o r ope ra t ing a t a h igher temperature t o use t h e h igher alumina m a t e r i a l or o the r m a t e r i a l s would have t o be added (124) .

Other r e p o r t s which were found i n t h e l i t e r a t u r e survey suggested c o a l r e f u s e as a r a w material f o r minera l wool product ion, bu t none had any re- s u l t s more promising than those desc r ibed above. Curren t ly the re i s no commercial u se of c o a l r e fuse i n mineral wool product ion.

F loor and c h i m e y f l u e tiles. I n v e s t i g a t o r s working f o r a Japanese f i rm , Chemical Consul t ing Engineers , Tokyo, have devised a pro- c e s s f o r manufacturing heavy weight f l o o r t i l es from c o a l mine washery waste (80).

A s h a l e o r clay-based c o a l mine washing d e b r i s w a s used as a p l a s t i - c i z e r for hard p o t t e r y s tone waste con ta in ing FeS as an impuri ty . The FeS r eac t ed G i t h carbonaceous matter i n t h e d e b r i s t o prevent foaming of t h e burn t mass. Heavy weight f l o o r t i l es were produced from t h i s mixture and were being t e s t e d i n use s i t u a t i o n s a t t h e t i m e of th i s r epor t .

I n France, i t i s reported t h a t red s h a l e , t h e r e s idue of spontaneous combusrim of b l ack s n a l e , is crushed and graded and used i n the manufacture of chimney f l u e t i l e s . An e s t i n a t e d 440,000 t o 550,000 short- tons are consumed each y e a r f o r t h i s purpose (8).

Commercial u t i l i z a t i o n of t i l e product ion from c o a l wastes i s n o t being p r a c t i c e d i n t h e United S t a t e s . Due t o t h e abundance, cheapness, and c o n s i s t a n t q u a l i t y of convent iona l and t r a d i t i o n a l materials i t i s no t be l ieved t h a t t h i s process w i l l eve r u t i l i z e any s i g n i f i c a n t q u a n t i t i e s of c o a l wastes.

Product ion of po r t l and cement. Coal r e f u s e can be used as a r a w feed i n t h e making of cement. E i t h e r r a w c o a l r e f u s e or preburned r e f u s e i s used as r a w material o r k i l n grog. c l a y f r a c t i o n of t h e usua l cement k i l n feed composition. the s i l i ca and alumina requi red f o r t h e p repa ra t ion of t h e proper por t land cement c l i n k e r . The use of c o a l r e f u s e f o r manufacture of cement o r b r i c k s depends i n l a r g e measure on t h e a v a i l a b i l i t y of competing c l ay (31).

The c o a l r e f u s e i s used t o r ep lace t h e The r e f u s e provides

However, t h e use of c o a l r e f u s e i n the making of por t land cement i s c u r r e n t l y n o t being p rac t i ced ( 1 4 3 ) .

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2.3.5.4 Cons t ruc t ion and Highway Uses

Anti-skid road m a t e r i a l . There are w e l l over 400 coal mine r e f u s e banks i n t h e a n t h r a c i t e reg ion of no r theas t e rn Pennsylvania, con ta in ing over 900 m i l l i o n tons of r e f u s e (7). Because of t h e combustible na tu re of t h e c o a l remaining i n t h e s e banks, many caught f i r e by spontaneous combustion. Some banks burned f o r over 50 yea r s . The r e s u l t w a s no t only land devas ta - t i o n , bu t a l s o a i r p o l l u t i o n due t o t h e noxious su l fu rous gases r e l e a s e d in’io t h e atmasphers.

I n 1964, t h e Pennsylvania Department of Mines and Mineral I n d u s t r i e s s t a r t e d a massive r e sea rch and demonstration program t o ex t inguish t h e s e r e f - use bank f i r e s and thus e l i m i n a t e t h e r e s u l t i n g a i r po l lu t ion . P r i o r t o 1964, very l i t t l e , i f anyth ing , was done t o ex t inguish t h e f i r e s or t o e l i m i n a t e cond i t ions r e s p o n s i b l e f o r spontaneous combustion. Today, i f a f i r e develops i n a bank, t h e owner must immediately ex t ingu i sh i t .

One of t h e most success fu l methods of ex t inguish ing t h e l a r g e banks uses hydrau l i c j e t s t o undercut t h e burning material. The undercut t ing w i t h t h e water j e t s causes t h e burning m a t e r i a l t o r o l l down i n t o a water poo l located-between t h e j e t s and t h e burning bank. of water and coo led , t h e burned ou t ma te r i a l i s r e f e r r e d t o as i n c i n e r a t e d a n t h r a c i t e mine r e f u s e , o r “red dog.”

When ext inguished i n t h e pool

One p o s s i b l e method of u t i l i z i n g r e l a t i v e l y l a r g e tonnages of t h i s m a t e r i a l is as an t i - sk id highway m a t e r i a l . P re sen t ly i t i s on Pennsylvania’s approved i i s t of m a t e r i a l s f o r use as an t i - sk id highway aggregate spread on i n t e r s t a t e , p r imary , and secondary highways. The Pennsylvania Department of T ranspor t a t ion uses approximately 1 . 5 mi l l i on tons of an t i - sk id m a t e r i a l each yea r dur ing t h e course of a win te r season (7), and many tons of crushed and graded r e d dog a r e used each w i n t e r i n t h i s app l i ca t ion . Occasional ly t h e red dog w i l l be mixed wi th sand or sal t be fo re spreading (12). During t h e c rush ing of t h e red dog, i t i s important t h a t the f i n e s be removed t o improve i t s f l o w a b i l i t y from t h e spreader t ruck . Without t he removal of t h e f i n e s , t h e c l a y material i n t h e r e f u s e would prevent i t from f lowing o u t of t h e t r u c k onto t h e spreader (124).

The only impediment t o increased usage of r ed dog is t h a t s u p p l i e s are dwindling and due t o modem c o a l r e fuse handl ing techniques, very l i t t l e a d d i t i o n a l red dog i s generated each year .

Research c a r r i e d out by t h e Road Research Laboratory (RRL), Great B r i t a i n , i n conjunct ion w i t h l o c a l a u t h o r i t i e s , has shown t h a t t h e w e t weather acc iden t rate a t busy i n t e r s e c t i o n s and c ross ings has been very s i g n i f i c a n t l y reduced by apply ing a s k i d - r e s i s t a n t su r f ace d re s s ing t o the road. s t o n e s do n o t have a l a s t i n g sk id r e s i s t a n c e because of ease of p o l i s h i n g . Tests r e s u l t s by RRL have shown t h a t a s a t i s f a c t o r y s t o n e can be produced from a mixture of red dog and baux i t e a t a 4 t o 1 r a t i o (14).

N a t u r a l

33

Embankment material. S ince e a r l y 1973, t h e Pennsylvania Department of Transpor ta t ion (PennDOT) has been a c t i v e l y engaged i n t h e u t i l i z a t i o n of c o a l mine r e fuse i n t h e des ign and c o n s t r u c t i o n of-highway embankments. The S o i l s and Geological Engineer ing Div is ion of t h e Bureau of Materials, T e s t i n g and Research ( t h e Bureau) has t h e t a s k of managing t h e program which inc ludes f i e l d i n v e s t i g a t i o n s , l abo ra to ry t e s t i n g , engineer ing ev;lu?t LDP, :1 x n i i q . c o o r d i n a t i m , I sp l emen tz t lon , co ixc ruc t ion c o n t r o l , and review of c o n s t r u c t i o n performance (146).

H i s t o r i c a l l y , t h e p r i n c i p a l o b j e c t i o n t o t h e use of c o a l mine r e f u s e i n cons t ruc t ion w a s t h e f e a r of spontaneous combustion. Addit ional objec- t i o n s were t h e supposed d i f f i c u l t y of cons t ruc t ion , undes i r ab le engineer ing c h a r a c t e r i s t i c s , and t h e product ion of ac id d ra inage . The problem w a s con- s i d e r e d pr imar i ly a s one of cons t ruc t ion perfcrmance which refers t o che

compaction c h a r a c t e r i s t i c s " of t h e r e f u s e material. The most fundamental cons ide ra t ion i s t h e n e c e s s i t y of oxygen t o promote combustion; i t i s a l s o necessary i n t h e product ion of a c i d dra inage . The re fo re , i t is only neces- s a r y t o exclude oxygen. This i s accomplished by compacting c o l l i e r y r e f u s e t o i t s maximm d e n s i t y where t h e m a t e r i a l h a s t h e minimum void r a t i o or a i r void percentage (146).

II

The now completed embankment of t h e Cross Valley Expressway i n Luzene County, Pennsylvania , w a s t he f i r s t major p r o j e c t i n t h e U.S. where c o a l mine r e f u s e was u t i l i z e d . Therefore , many eng inee r s and t echn ic i ans were involved i n t h e a c t u a l c o n s t r u c t i o n and monitor ing of t h e embankment and much d a t a on i t s performance eva lua t ion w a s genera ted and publ i shed ( 1 4 6 ) .

The embanbent i s 2,344 f e e t i n l e n g t h , w i t h counter berms, reaches a maximum width of about 475 f e e t and a maximum h e i g h t of 57 f e e t . About 1.5 m i l l i o n cubic yards of bo th r e f u s e and burned r e f u s e were u t i l i z e d i n t h e c o n s t r u c t i o n of t he embankment and coun te r berms. The r e f u s e came from t h e Harry E. breaker-bank a t Swopersv i l le , about two m i l e s w e s t of t h e p r o j e c t and t h e burned r e f u s e ( red dog) w a s ob ta ined from s e v e r a l l o c a t i o n s t o t h e n o r t h i n the v i c i n i t y of West P i t t s t o n , Pennsylvania . The i n d i v i d u a l percen tages of burned and unburned r e f u s e are n o t a c c u r a t e l y known, bu t are est imated t o be of about equa l propor t ion . and w a s completed i n June 1974 (146). over t h e e n t i r e a r e a of t h e coun te r berms and on t h e embankment s lopes . t o p of t h e embankment was covered w i t h 2 feet o f s o i l upon which 2 f e e t of burned r e f u s e was placed t o provide an access road for t h e cons t ruc t ion of t h e br idge . The s o i l cover was mulched and seeded. The s o i l cover w a s r e q u i r e d , from an a e s t h e t i c viewpoint , t o p rov ide a medium f o r v e g e t a t i v e growth, and, from an engineer ing viewpoint , t o p rov ide an i n s u l a t i o n a g a i n s t s u r f a c e water i n f i l t r a t i o n and atmospheric exposure, t h u s adding a d d i t i o n a l p r o t e c t i o n a g a i n s t combustion and product ion of a c i d d ra inage (146).

Cons t ruc t ion began i n May 1973, A 4-fOOt t h i c k s o i l cover w a s placed

The

i

The s u c c e s s f u l c o n s t r u c t i o n of t he Cross Valley Expressway embankment, and the experience gained therefrom, i n d i c a t e s t h a t c o a l mine r e f u s e can be used as an a c c e p t a b l e embankment cons t ruc t ion material.

An th rac i t e c o a l r e f u s e was a l s o used t o c o n s t r u c t embankments 40 t o 50

The r e f u s e w a s placed and compacted i n 5-foot l i f t s and t h e o u t s i d e f e e t high f o r two s e c t i o n s of I n t e r s t a t e Route 81 nea r Hazleton in Luzerne County. s l o p e s were covered w i t h 10 f e e t of s o i l (145).

Based on t h e s u c c e s s of t h e s e i n s t a l l a t i o n s , t h e Pennsylvania Depart- ment of T ranspor t a t ion i s planning t o u t i l i z e c o a l r e f u s e i n f u t u r e highway p r o j e c t s . co rpora t e processed bituminous c o a l r e f u s e i n t o c o n s t n c t i o n as embankment material (5) .

Several p r o j e c t s i n t h e western p o r t i o n of t h e s t a t e will in-

I n Illinois c o a l mining was te s have been used t o a l i m i t e d e x t e n t . p o r t i o n of I n t e r s t a t e Route 57 i n F rank l in County w a s cons t ruc t ed on an embankment of c o a l r e f u s e . Seve ra l r e f u s e p i l e s were l o c a t e d w i t h i n t h e c o r r i d o r of t h e I n t e r s t a t e and t h e material w a s used as f i l l r a t h e r than being removed and s t o c k p i l e d a t ano the r s i te . s ec t ion 'o f I n t e r s t a t e Route 57 i n d i c a t e s t h a t t h e r e has been no d i r e c t problems r e s u l t i n g from t h e use of c o a l r e f u s e f o r embankment ( 4 6 ) .

A

Presen t eva lua t ion of t h i s

In e a s t e r n Ohio, c o a l r e f u s e has been accepted f o r use in embankments for y e a r s , provided t h e m a t e r i a l s conform t o weight, compaction, and o t h e r r equ i r enen t s of t h e s p e c i f i c a t i o n s . material in t h e s t a t e s p e c i f i c a t i o n ( 4 6 ) .

Coal r e f u s e i s considered as random

The use of c o l l i e r y s p o i l i n t h e cons t ruc t ion of embankments i s w e l l e s t a b l i s h e d i n Gerinany, France, and t h e United Kingdom. When a v a i l a b l e burnt s p o i l has u s u a l l y been t h e p r e f e r r e d material because of i t s g ranu la r n a t u r e and good grading. of unburnt s h a l e s have been used s u c c e s s f u l l y . embankments t h e r e is no p a r t i c u l a r r e s t r i c t i o n on t h e use of s p o i l and c i v i l engineer ing t e s t s g e n e r a l l y app l i ed t o f i l l materials are used.

However i n recent y e a r s cons ide rab le q u a n t i t i e s I n t h e lower p a r t of t h e

I n t h e United Kingdom t h e r e i s a l i m i t on the s u l p h a t e con ten t (less than 2.5 grams of SO2 p e r l i t e r i n a 1:l s h a l e water extract) i f the s o i l is t o be used w i t h i n 1-1/2 f e e t of t h e road s u r f a c e or of t h e c o n c r e t e s t r u c t u r e s . Fea r s of spontaneous combustion of unburnt s h a l e embankments have been a l l a y e d by l a r g e scale tests which have shown t h a t such combus- t i o n does not occur i f t h e s p o i l i s w e l l compacted s o t h a t a i r cannot p e n e t r a t e (10).

35

I n t h e upper l a y e r s of embankments t h e r e i s need t o e s t a b l i s h t h a t t h e material i s n o t f r o s t s u s c e p t i b l e . T e s t s f o r f r o s t s u s c e p t i b i l i t y are r equ i r ed f o r material i n the top 1-1/2 f e e t i n t h e United Kingdom and i n t h e top 6 f e e t i n Germany. g e n e r a l weather r e s i s t a n c e of s h a l e i n t h i s upper l a y e r and i n p a r t i c u l a r about t h e a d v e r s e e f f e c t s of f i n e p a r t i c l e s . There is a l i m i t of 3 per- c e n t on p a r t i c l e s below 20 microns. I n g e n e r a l i t is considered that i f s p o i l is t o be used i n t h e upper l a y e r t hen some pretreatment is neces- s a ry . Th i s means c o n t r o l of t h e upper and lower limits of grading and a degree of homogenization. The German Fede ra l Roadway I n s t i t u t e has is- sued a s p e c i f i c a t i o n f o r t h e use of c o l l i e r y s p o i l , "Recommendations f o r t h e U t i l i z a t i o n of Mine Stone as a Road Bu i ld ing Material'' (10).

I n Germany t h e r e is a l s o concern about t h e

Aggregate. Consul tants* t o t h e former Pennsylvania Depart-

The c o n s u l t a n t , ment of Mines and Mineral I n d u s t r i e s proposed t h e use of burned o u t an th ra - c i t e mine r e f u s e as an aggregate f o r bituminous concrete . a f t e r e x t e n s i v e l a b o r a t o r y t e s t i n g and a n a l y s i s , concluded t h a t t h i s ma- t e r i a l would perform w e l l under highway t r a f f i c and t h a t i t s use could resul.t i n reduced cons t ruc t ion c o s t s t o t h e Department and a t a x sav ings t o t h e Commonwealth (108). The c o s t r e d u c t i o n would r e s u l t from more coverage p e r t on of bituminous mix due t o t h e l i g h t e r dens i ty of t h e material. A t a x savings could be r e a l i z e d by s e l l i n g t h e processed r e f u s e material and applying t h e money t o t h e extinguishment c o s t s of burning mine bank p r o j e c t s under t h e " S c a r l i f t " r e s t o r a t i o n program ( 1 4 7 ) .

Four experimental p r o j e c t s and one c o n t r o l s e c t i o n were placed du r i zg June and J u l y 1970. The p r o j e c t s , i n Luzerne County, involved approximately 30,000 squa re yards of r e s u r f a c i n g . The material w a s placed i n dep ths r ang ing from 1 t o 2 inches and a t o t a l of 1,382 t ons w a s used. The mix des ign developed by t h e c o n s u l t a n t and t h e Bureau of Materials, Tes t ing and Research, Pennsylvania Department of Highways, u t i l i z e d a n a s p h a l t con ten t of 8.0 percent by weight and 4 2 . 0 percent pas s ing t h e No. 8 s i e v e (147). The i n i t i a l r e p o r t cove r ing t h e s e i n s t a l l a t i o n s w a s i s s u e d by t h i s Bureau i n Ju ly 1970 (108).

The fo l lowing conclusions w e r e drawn from t h e s e experimental p r o j e c t s (147) :

1. A n t h r a c i t e mine waste w i l l produce aggregate s u i t a b l e f o r use i n bituminous conc re t e . Although t h e wear w i l l probably b e more rapid than normal, th i s is c o n s i s t e n t w i t h t h e d e s i r e f o r good s k i d r e s i s t a n c e .

2. The mixing c h a r a c t e r i s t i c s of t h e bituminous mixture u s i n g a n t h r a c i t e r e f u s e aggrega te were very s i m i l a r t o t h e convent ional ID-2A.

i

* McCreath L a b o r a t o r i e s , Inc . , Har r i sbu rg , Pennsylvania.

36

a- $

3 . The l i g h t e r s p e c i f i c g rav i ty of the bituminous m i x (2.008) increased t h e coverage by more than 20 percent .

4 . The Marshall s t a b i l i t y w a s increased i n most cases by 50 pe rcen t .

5 . The use of a n t h r a c i t e r e fuse aggrega te produced sk id r e s i s t a n c e va lues equa l t o and i n most cases s l i g h t l y h igher than t h e c o n t r o l material.

6 . . Var ia t ions i n t h e a s p h a l t c o n t e n t , when allowed t o drop below the s p e c i f i e d minimum, produced a su r face m a t e r i a l t h a t w a s s u s c e p t i b l e t o rap id e r o s i o n by t r a f f i c .

A thorough l abora to ry i n v e s t i g a t i o n i n t o t h e u t i l i z a t i o n of bituminous r e f u s e as an aggrega te w a s conducted a t t h e Un ive r s i ty of Kentucky dur ing t h e l a t e 1970s (86). Bituminous c o a l r e f u s e obta ined from f i v e coal-prepara- t i o n p l a n t s i n Kentucky w a s succ2ss fu l ly s i n t e r e d on a p i lo t - s i zed t r a v e l i n g g r a t e t o produce l igh tweight c o n s t r u c t i o n aggregate .

Tests were conducted us ing t h e aggrega te i n bituminous conc re t e mixes and i n por t land cement concre te mixes. R e s u l t s showed t h a t both dense-graded bituminous conc re t e mixes t h a t contained s i n t e r e d material as t h e coa r se f r a c t i o n and open-graded mixes t h a t contained only s i n t e r e d aggrega te ex- h i b i t e d accep tab le l eve ls of s t a b i l i t y , water s e n s i t i v i t y , and o t h e r desigr! parameters. The mixes performed w e l l i n l a b o r a t o r y po l i sh ing tests, and .

t h e r e s u l t s i n d i c a t e a h i g h - f r i c t i o n , nonpol ishing aggregate . Skid- res i s - t a n t qua l i t i es are p a r t i c u l a r l y important and t imely s i n c e increased enphas is i s expected t o be placed i n t h e f u t u r e on developing and us ing more h ighly s k i d - r e s i s t a n t paving materials.

The s i n t e r e d aggregate performed very w e l l i n t h e por t land cement conc re t e mixes. The tes t va lues i n d i c a t e d good compressive s t r e n g t h , e x c e l l e n t freeze-thaw d u r a b i l i t y , and no au toc lave popouts wi th a unit weight i n t h e range of 113 l b s / f t 3 .

Using l i gh twe igh t aggregate from s i n t e r e d coal-mine r e f u s e i n concre te c o n s t r u c t i o n o f f e r s s i g n i f i c a n t technical and economic i n c e n t i v e s from t h e s t andpo in t s of reduced weight and t h e g r e a t l y reduced thermal conduc t iv i ty of t h e products formed. I n t h e thermal conduc t iv i ty tests performed i n the Univers i ty r e sea rch , s l a b conc re t e wi th l i gh twe igh t aggrega te showed a 55 pe rcen t r educ t ion i n thermal conduc t iv i ty over similar shapes made wi th normal weight aggregate .

As noted i n t h e earlier s e c t i o n s of t h i s r e p o r t , much work and i n v e s t i - g a t i o n is be ing done i n Europe concerning t h e u t i l i z a t i o n of c o a l r e fuse . I n t h e United Kingdom, r e f u s e i s be ing used on an inc reas ing scale t o produce s i n t e r e d c l i n k e r - l i k e aggrega te f o r b lock making (15). of tliis i s r e l a t i v e l y wel l e s t a b l i s h e d and i t s f u r t h e r development w i l l probably come from wi th in t h e i n d u s t r y i t s e l f .

The technology

37

The Building Research Establishment i n Garston, Wetford, England, is i n v e s t i g a t i n g the p o s s i b i l i t y of producing a dense aggregate for general use i n conc re t e , as an a l t e r n a t i v e t o g rave l and crushed rock, i n order t o h e l p meet the inc reas ing demand i n a r e a s wi th l o c a l sho r t ages of n a t u r a l aggrega te s such as t h e London area (15).

In northern France, a p l a n t has been b u i l t t o produce a high-grade l i gh twe igh t aggregate ( 2 5 t o 40 pounds p e r cubic f o o t ) from c o a l r e f u s e by a m u l t i s t a g e r o t a r y k i l n p rocess (16) . The p rocess invo lves t h e s e l e c t i o n from t h e washer). of large blocks of r e f u s e which averaged about 4 percent carbon. These are ground, made i n t o a p a s t e and extruded t o form small c y l i n d e r s , and then h e a t - t r e a t e d i n f o u r stages--each s t a g e employing a r o t a r y k i l n . The product has been used i n the r e c o n s t r u c t i o n of t h e Jargean s u r Lo i re suspension b r idge and t h e Cheneau b r idge (15) .

Lightweight aggregate (25 t o 40 pounds p e r cubic f o o t ) is manufactured i n Belgium (28) from t h e 0.5 t o 3 . 0 i nch s i z e f r a c t i o n of c u r r e n t production from t h e c o a l washery s c r e e n s , a l though i t is a l s o intended t o use material

. o b t a i n e d af ter rewashing of e x i s t i n g r e f u s e banks. The use of t h i s manufac- t u red aggregate i n conc re t e r e s u l t s i n a 30 percen t r educ t ion i n weight r e l a - t i v e t v conventional conc re t e .

Impediments t o inc reased use of c o a l waste a s aggregate are s i m i l a r t o those of o t h e r mining wastes . Qu i t e o f t en t h e c o a l waste i s no t compet i t ive wi th abundant, cheap, and q u a l i t y c o n t r o l l e d quarry aggrega te s . T ranspor t a t ion and handling c o s t s gene ra l ly e l i m i n a t e any m a t e r i a l p r i c e advantage of t h e c o a l waste .

Mine and c o n s t r u c t i o n f i l l . The use of c o a l mine waste f o r s t r a t a c o n t r o l has been demonstrated by t h e Bureau of Mines i n s e l e c t e d urban areas ove r ly ing abandoned a n t h r a c i t e c o a l mines i n n o r t h e a s t e r n Pennsylvania. The main o b j e c t i v e of t hese s t r a t a c o n t r o l p r o j e c t s i s p r o t e c t i o n of t h e s u r f a c e from subsidence damage. mine waste, removal of sou rces of a i r and water p o l l u t i o n and f i r e hazard a s s o c i a t e d with s u r f a c e p i l e s of c o a l waste, and r e s t o r a t i o n of needed urban land (122).

Coro l l a ry b e n e f i t s i nc lude underground d i s p o s a l of

The method used f o r s t ra ta c o n t r o l i n t h e a n t h r a c i t e region is hy- d r a u l i c b a c k f i l l i n g of mine vo ids . p r o j e c t s t o develop a pumped-slurry p rocess whereby l a r g e q u a n t i t i e s of f i l l material can be placed i n i n a c c e s s i b l e mine voids from a s i n g l e i n j e c t i o n borehole . mixing tank, through a pumping u n i t and large-diameter d i s t r i b u t i o n p i p e l i n e and i n j e c t i o n boreholes , t o t h e mine workings (122).

The Bureau has undertaken demonstration

Di lu t e s l u r r y i s pumped through a c losed i n j e c t i o n system from a

There are s e v e r a l methods of hydrau l i c b a c k f i l l i n g which can be used, depending on e x i s t i n g c o n d i t i o n s a t t h e mine t o be f i l l e d . c o n t r o l l e d f l u s h i n g and t h e pumped-slurry method. Con t ro l l ed f l u s h i n g is a method-in which crushed mine r e f u s e i s s l u i c e d through c a s i n g s i n i n j e c t i o n bo reho les by g r a v i t y . A t t h e l e v e l s of t h e v a r i o u s coalbeds t o be b a c k f i l l e d , connect ions t o p l a s t i c p i p e l i n e s a r e made through 90 degree elbow tu rns . The s l u r r y i s d i r ec t ed by hand t o f i l l t h e spaces des igna ted f o r b a c k f i l l i n g . The c o n t r o l l e d f lu sh ing method can be used only i n mine workings t h a t are a c c e s s i b l e f o r workers t o e n t e r s a f e l y ( 1 2 2 ) .

Two of t hese are:

In t h e pumped-slurry method, t h e s o l i d s are p l a c e d i n suspension i n a mixing tank and maintained i n suspension throughout a closed d i s t r i b u - t i o n system. The process is designed f o r inundated mine washings; i ts u s e has shown that wide l a t e r a l d i s t r i b u t i o n from a s i n g l e borehole i n j e c t i o n i s p o s s i b l e . I n t h e early 1970s, t h e Bureau of Mines completed a s u c c e s s f u l f u l l - s c a l e demonstration of t h i s method of subs f s t ance c o n t r o l i n Scranton, Pennsylvania, using crushed c o a l mine r e f u s e f o r f i l l material (122, 148).

Raw c o a l r e f u s e has been used i n t h e United Kingdom as l a n d f i l l f o r a v a r i e t y of cons t ruc t ion purposes. The Nat ional Coal Board (NCB) h a s developed t h e art and s c i e n c e of c o a l r e f u s e u t i l i z a t i o n as f i l l material t o a f i n e degree. Adequate compaction has assured t h e c r i t i c s of c o a l r e f u s e t h a t t h i s material w i l l n e i t h e r burn, s l i d e nor leak a c i d i n t o nearby streanns. Compacted c o a l r e f u s e has beon used s u c c e s s f u l l y f o r development of a i r c r a f t hoverport pads, a i r p o r t s , i n d u s t r i a l s i te f i l l and f i l l f o r housing developments (31).

Coal r e f u s e i n gene ra l has been found t o b e extremely s a t i s f a c t o r y as an earthwork m a t e r i a l and can be used wi th l i t t l e o r no r e s e r v a t i o n s in a wide v a r i e t y of l a n d f i l l o p e r a t i o n s . The Minis t ry of Transport* i s cur- r e n t l y bu i ld ing extensive road f i l l s using c o a l r e f u s e as t h e f i l l ma- t e r i a l . A i r p o r t s , a t h l e t i c t r a c k s , i n d u s t r i a l s i tes ( t o raise low l y i n g land above t h e f lood p l a i n ) , p rope r ly constructed e a r t h f i l l dams, cover f o r s a n i t a r y l a n d f i l l s and o t h e r s imi la r l a n d f i l l u s e s have been developed and demonstrated f o r t h e u s e of c o a l r e fuse .

The key t o u t i l i z a t i o n of c o a l r e f u s e i n t h e above a p p l i c a t i o n s l i e s This compaction reduces a i r vo ids

This i s s u f f i c i e n t l y t i g h t t o e s s e n t i a l l y preclude a i r

i n t h e proper compaction of t h e r e f u s e . t o less than 10 percent and the reby a t t a i n s a pe rmeab i l i t y of less than 0.4 x 10-6 i n / sec . and water permeation of t h e p i l e , thereby a t t a i n i n g a s a t i s f a c t o r y f i l l . I n c a s e s where c o a l r e f u s e i s brought i n t o c o n t a c t w i t h conc re t e s t r u c t u r e s a c o a t i n g of b i t u m e n i s t i c p i t c h i s sometimes uniformly app l i ed t o p r o t e c t t h e conc re t e s t r u c t u r e a g a i n s t s u l f a t e a t t ack . In t h e case of a d ra inage p i p e through c o a l r e fuse , c o r r o s i o n r e s i s t a n t p i p e such as dense conc re t e , super-sulfated conc re t e or terra c o t t a is used. The NCB has concluded t h a t almost without regard t o chemical and p h y s i c a l p r o p e r t i e s , c o a l r e f u s e , when properly placed, can b e a u s e f u l and v a l u a b l e s u r f a c e f i l l material (31).

2 . 3 . 5 . 5 H o r t i c u l t u r a l Uses

S o i l - l e s s medium, s o i l condi t ioner . Experiments have been conducted by the F l o r i c u l t u r e Department a t Penn S t a t e (124) and t h e Department of E o r t i c u l t u r e a t the Unive r s i ty of Kentucky (134) t o determine t h e f e a s i b i l i t y of using i n c i n e r a t e d c o a l r e f u s e as a growing medium f o r container-grown p lan t s .

* England,

39

It w a s found by both groups t h a t inc inera ted coa l r e f u s e , where proper ly prepared by crushing and s i z i n g and mixed with pea t moss and es- s e n t i a l f e r t i l i z e r s , can b e used s a t i s f a c t o r i l y as a s o i l - l e s s medium f o r use by greenhouse ope ra to r s and p o t t e d p l a n t growers. Azaleas, Af r i can v i o l e t s , begonias , chrysanthemums, geraniums, philodendrons, p o i n s e t t i a s , and t ana toes have been grown s u c c e s s f u l l y i n inc inera ted c o a l r e f u s e and

pea t mcssmixtures . crop and season, b u t i n gene ra l , a 50:50 mixture produced good c rops f o r a l l s p e c i e s t e s t e d (124).

The b e s t p ropor t ions of r e f u s e t o pea t va r i ed w i t h t h e

As of t h e time of t h i s r e p o r t , no commercial opera t ions are us ing t h e i n c i n e r a t e d c o a l r e f u s e as a growing medium (143). It i s f e l t that even t h e maximum p o t e n t i a l f o r t h i s use of c o a l waste would be i n s i g n i f i c a n t compared t o t h e amounts of waste genera ted . As wi th o the r a p p l i c a t i o n s of c o a l waste, convent iona l materials are abundant and Cheap, and t h e r e f o r e no i n c e n t i v e e x i s t s t o use t h e waste product .

40

2.4 COPPER MINING INDUSTRY

; -

Used f o r a t least 6,000 y e a r s , copper has been one of t h e important materials in t h e advance of i n d u s t r y , technology, and the arts. I n i t i a l use of copper w a s probably i n unal loyed form f o r tools, weapons, and or- naments. By adding t i n , bronze w a s produced, g iv ing a name t o an e n t i r e age of c i v i l i z a t i o n . t e n s i v e l y employed f o r about 2,000 years . The age of e l e c t r i c i t y , which d a t e s from about 1840, has been i n t i m a t e l y l i nked with copper, and elec- t r ica l a p p l i c a t i o n s cont inue t o be t h e metal's p r i n c i p a l u s e (98).

Brass, an a l l o y of copper and z inc , has been ex-

2.4.1 Indus t ry C h a r a c t e r i z a t i o n

2.4.1.1 Indus t ry S t r u c t u r e

The primary copper i n d u s t r y is one of t h e most energy-intensive i n d u s t r i e s i n t h e United S t a t e s , r ank ing t w e l f t h i n terms of energy purchased i n t h e i n d u s t r i a l s e c t o r (149). f o u r segments: mining, b e n e f i c i a t i o n , smelt ing, and r e f i n i n g .

The i n d u s t r y is divided i n t o

The United S t a t e s i s t h e l e a d i n g copper producing country i n t h e world, followed i n o r d e r by Chi l e , t h e U . S . S .R., Canada, Zambia, and Zaire. P r in - c i p a l copper-producing s t a t e s are Arizona (66 percent of t h e t o t a l U.S. produc t ion ) , Utah (13 p e r c e n t ) , New Mexico (12 percent) and Montana (5 per- c e n t ) . These s ta tes account f o r 96 percent of t o t a l production wi th t h e remainder obtained most ly irom Missour i , Michigan, Nevada, and Tennessee (98). I n 1979 , 25 mines accounted for 94 percent of t he U.S. ou tpu t ; t h e f i v e l a r g e s t produced 45 percen t ; and four companies accounted for 63 pe r - c e n t of t he domestic mine product ion.

2.4.1.2 Product ion S t a t i s t i c s (98)

I n 1979 , world mine product ion of copper w a s 8 . 2 m i l l i o n s h o r t t o n s , w i t h 1 4 c o u n t r i e s each producing o v e r 100,000 tons. The United S t a t e s w a s t h e l ead ing producer and consumer of copper with 1.59 m i l l i o n tons of mine product ion and 2.66 m i l l i o n t o n s of primary p l u s o ld scrap consumption. Components of supply e n t e r i n g domest ic consumption f o r 1969 t o 1978, ex- c l u d i n g s tock changes, average 66 p e r c e n t from domestic mines, 21 percen t from o l d sc rap , and 13 percen t from n e t imports,

Copper sme l t ing c a p a c i t y i n t h e United S t a t e s i n 1979 t o t a l e d approximately 9.0 m i l l i o n tons of cha rge , es t imated t o r ep resen t 2.1 m i l l i o n t o n s of smelter product. Refinery c a p a c i t y t o t a l e d 2.9 m i l l i o n tons, of which approximately 88 percent was e l e c t r o l y t i c r e f i n i n g and e l e c t r o - winning c a p a c i t y , and 12 pe rcen t was f i r e - r e f i n i n g capacity.

4 1

Domestic mine product ion i s approximately f o u r - f i f t h s from open p i t mining and o n e - f i f t h from underground mining. domestic consumption of copper w a s r equ i r ed for electrical a p p l i c a t i o n s such as i n motors, g e n e r a t o r s , power d i s t r i b u t i o n , i n d u s t r i a l c o n t r o l s , communications equipment, and house wir ing.

More than one-half of t h e

2.4.1.3 Industry Trends ( 9 8 )

Based on a methodology of r e l a t i n g t h e v a r i o u s end-use s e c t o r s t o a p p r o p r i a t e economic i n d i c a t o r s , U.S. demand for copper (primary plus o l d sc rap ) i n 2000 w a s f o r e c a s t t o be between 3.5 and 6.1 m i l l i o n tons. The most probable demand w i t h i n t h e range w a s e s t a b l i s h e d a t 4.6 mi l l i on tons , r ep resen t ing an average annua l growth ra te of 3.0 percent during t h e per iod 1978 t o 2000. Most of t h e growth w a s f o r e c a s t t o occur i n t h e e l e c t r i c a l end-use s e c t o r . Consumption i n e l e c t r i c a l u ses w a s fo re - cast t o i nc rease from 58 pe rcen t of t h e t o t a l consumption i n 1978 t o 69 pe rcen t i n 2000. For t h e rest of t h e world, demand i n 2000 w a s f o r e c a s t t o be from 1 4 . 6 t o 24.5 m i l l i o n t o n s , w i th a p robab le demand of 19.0 m i l l i o n tons , a 4 . 2 percen t annua l growth rate.

Demand f o r copper beyond 2000 i s a n t i c i p a t e d t o s t r a i n i d e n t i f i e d supply sources. However, g r e a t e r recovery of o l d s c r a p and poss ib l e s i g n i f i c a n t e x p l o i t a t i o n of sea nodules can augment onshore mining. Also, micro-miniatur izat ion, copper c l add ing , and o t h e r conservation methods w i l l be more e x t e n s i v e l y used t o extend t h e supply of copper.

I n t h e process of copper p roduc t ion , s u b s t a n t i a l q u a n t i t i e s of s o l i d wastes a r e generated i n t h e form of waste s t r i p p i n g a t t h e mine, t a i l i n g s a t t h e concen t r a to r , and s l a g a t t h e smelter. However, t h e most p r e s s i n g problem fac ing t h e copper i n d u s t r y i s concern ove r ' emis s ion of s u l f u r compounds, t r a c e elements, and p a r t i c u l a t e s t o t h e atmosphere during smelt ing. New technology and l a r g e c a p i t a l investments w i l l be r equ i r ed t o e i t h e r modify e x i s t i n g p y r o m e t a l l u r g i c a l p r a c t i c e s or t o adopt new chemical-processing techniques as a s o l u t i o n t o t h e problem. The domestic e x t r a c t i o n indus t ry a l s o f a c e s problems of c r i t i c a l land use c o n f l i c t s , opposing views on s u r f a c e r e s t o r a t i o n s t anda rds , water r i g h t s , and new r e g u l a t i o n s f o r emission of hazardous materials.

2 . 4 . 2 Copper Mining and B e n e f i c i a t i o n Operat ions

The copper mining i n d u s t r y uses a v a r i e t y of mining and b e n e f i c i a t i o n methods. ground, and i n s i t u .

There are t h r e e g e n e r a l t ypes of copper mines: open p i t , under-

Open P i t Mining' (151)

There are s e v e r a l d i f f e r e n t mining methods used i n open p i t mining of copper o re s . d r i l l i n g and b l a s t i n g are c a r r i e d ou t on one level or bench, and t h e

The most common method is t h e bench method, i n which

, I

d r i l l i n g equipment i s moved t o a lower bench f o r d r i l l i n g and b l a s t i n g . Af te r t h e o r e i s loosened, i t is loaded by shovels i n t o t r u c k s or railcars f o r de- l i v e r y t o t h e concent ra tor . A t least one mine uses r i p p e r s t o remove the o r e from t h e ground and loads i t i n t o s c r a p e r s f o r de l ive ry t o t h e concentrator . Some of t h e small open p i t mines d r i l l and b l a s t t h e o r e loose from t h e sur- roundings. I t does not use benches b u t takes every th ing t o t h e same level.

The flow diagram f o r a t y p i c a l open-pit mining ope ra t ion i s shown i n F igure 2-1. Typica l ly , open-pit mining involves fou r b a s i c s t e p s : d r i l l i n g , b l a s t i n g , loading , and haul ing . The convent ional mining ope ra t ions inc lude d r i l l i n g , b l a s t i n g , power shovel l oad ing , and t ruck and r a i l haul ing . a d d i t i o n , about 55 percent of t h e mines inc lude c rushing and g r ind ing i n t h e mine. t o t h e concen t r a to r where c rush ing and gr inding are c a r r i e d out .

I n

Ten pe rcen t do n o t c r u s h o r g r ind . The o the r 35 percen t s h i p d i r e c t l y

Trucks a r e u t i l i z e d f o r t r a n s p o r t a t t h e mine s i t e (e .g . , t o a primary c rushing p l a n t and c o n c e n t r a t o r ) , and ra i l haulage is used t o move t h e o r e t o o f f - s i t e concen t r a to r p l a n t s . Open p i t copper mines account f o r 88 percent of t h e copper o r e mined.

Underground Mining (98 , 151)

.- Underground copper mines account f o r 12 percent of t h e copper o r e mined. A t y p i c a l example of underground mining i s presented i n Figure 2-2.

Most of t h e nodem underground mining of copper i s done by two methods: caving and supported scopes. Caving methods a r e of t w o d i s t l n c t types : block caving and s u b l e v e l caving. A r t i f i c i a l l y supported s topes a r e those i n which i n s t a l l a t i o n of sys temat ic temporary o r permanent sup- p o r t of ground i s p a r t of t h e mining cyc le .

The broken o r e produced i n underground mining i s r a i s e d by a h o i s t and t r anspor t ed t o a nearby concen t r a to r . Waste rock from t h e mine has been used f r equen t ly f o r c o n s t r u c t i n g t a i l i n g s pond dams, as i n d i c a t e d in Figure 2-2.

I n S i t u Mining

f

i

There are t h r e e methods f o r i n s i t u mining. One method is t o remove overburden and s t o c k p i l e i t ; t h e o r e body is then d r i l l e d and b l a s t e d i n p l ace . A second method i s t o d r i l l and b l a s t t h e o r e body on t h e s i d e of a h i l l and use t h e b l a s t t o move t h e o r e i n t o an ad jacen t v a l l e y . method i s t o d r i l l and b l a s t underground t o s h a t t e r t h e o r e body. i s then leached by s u l f u r i c a c i d and pumped t o a concen t r a t ing p l a n t f o r recovery of copper.

The t h i r d The o r e

43

-

g] Blast to

Concentrotor n Source: Reference 150 and 151.

Figure 2-1. Typical open p i t copper mine.

' Load

-~

Source: Reference 150 and 151.

Dam Construction

Figure 2-2. fypical underground copper mine.

Waste Rock

I - -. .)

* Ta i l iw pod

b a d Ore L t f

+ Smelter b

f

Co M e n t ra tor - Sand Plant * Backfi I I StopesinMiw

There are two primary concent ra tor processes f o r recovery of copper from o re : f l o t a t i o n and leaching . Leaching is accomplished i n f o u r d i f f e r e n t m o d e s : heap l e a c h , dump l each , v a t l each , and $n s i t u leach . I n add i t ion t o t h e above leaching p rocesses , t h e r e are t h r e e secondary copper recovery pro- ces ses : i r o n p r e c i p i t a t i o n , so lven t ex t r ac t ion , and electrowfnning. The copper-rich l e a c h s o l u t i o n must be f u r t h e r processed a t t h e mine. Two methods are used t o F r e c i 7 i t s t e t h e copper from t h e leact. E o l u t i m . P r e c i p i t a t i c n over i r o n , or cementa t ion , is t h e most widely used process , and t h e product , conta in ing 80 pe rcen t copper , is shipped t o a smelter. The use of e l ec t ro - winning t o recover a 99 percent copper product i s growing, however; t h i s material i s then s o l d t o a r e f i n e r y or copper product manufacturer. The f l o t a t i o n product is shipped t o a smelter. Smelting is t h e secondary recovery process f o r f l o t a t i o n concent ra te . (Because smel t ing is n o t a mining o r concen t r a t ing p rocess , i t i s not discussed here . )

The p r i n c i p a l leaching methods (98) are dump leaching , heap leach- i n g , i n - p h c e l e a c h i n g , and v a t leaching. copper from low-grade waste material r e s u l t i n g from open p i t mining of copper o r e depos i t s ; t h e l each ing c y c l e i s measured i n years . Heap leaching is employed-to d i s s o l v e copper from oxide ore t h a t has been placed on a prepared s u r f a c e : t h e l each ing cyc le i s measured i n months. In-place leaching techniques a r e a p p l i c a b l e t o s h a t t e r e d , broken, or otherwise porous ore bodies f o r leaching oxide o re s of copper; t he leaching c y c l e r e q u i r e s yea r s . Vat leaching i s employed t o e x t r a c t copper from crushed and s i zed oxide o r e ; t h e leaching c y c l e can vary from days f o r simple placement of t h e ore i n v a t s , t o only hours f o r a g i t a t i o n leaching of f i n e l y ground ore .

Dump leaching i s used t o e x t r a c t

The t r ea tmen t of mixed o r e , conta in ing both s u l f i d e and oxide mine ra l s , depends on t h e r e l a t i v e propor t ions of t h e two types of minera ls . I f s u l f i d e s predominate , f l o t a t i o n i s used, employing r eagen t s t h a t p r in- c i p a l l y recover t h e s u l f i d e mine ra l s , bu t b y a l s o recover a small p a r t of t h e oxide minera ls . When t h e o r e con ta ins almosf equal amounts of s u l f i d e and oxide mine ra l s , combinations of leaching and f l o t a t i o n are used. u a l l y t h e o r e i s . f i r s t vat-leached t o recover copper from t h e oxidized minera ls and then t r e a t e d i n a concen t r a to r where t h e s u l f i d e minera ls are recovered by f l o t a t i o n .

Us-

2 . 4 . 3 Waste Stream C h a r a c t e r i s t i c s and Q u a n t i f i c a t i o n

Mining Wastes

Waste rock and overburden r e s u l t i n g from copper o r e mining ope ra t ions amounted t o approximately 400 m i l l i o n tons i n the U.S. i n 1979 (150). The waste rock c o n s i s t s p r i n c i p a l l y of g r a n i t e , s c h i s t , and l imestone contain- i n g quartz a2d hemat i t e and con ta ins less than 0.05 pe rcen t copper. waste rock and overburden materials are genera l ly hauled t o a waste dump.

The

46

B e n e f i c i a t i o n Wastes

The two primary b e n e f i c i a t i o n o r concen t r a to r processes f o r recovery of copper from o r e are f l o t a t i o n and leaching. The annual t o t a l of copper o r e treated i n concen t r a to r p l a n t s i n t h e U.S. i n 1979 w a s 274 m i l l i o n s h o r t tons. Of t h i s amount, 1.33 m i l l i o n tons of copper were produced l eav ing over 272 m i l l i o n tons of t a i l i n g s (150). The wastes from t h e copper f l o t a t i o n process are L m s i d e i e d z a i l i n g s , which is a f i n e sand-like material. P rac t i ca l> ] a l l copper f l o t a t i o n p l a n t s d i spose of t h e i r t a i l i n g s i n a t a i l i n g s pond. every ton of copper produced by f l o t a t i o n concen t r a t ion , 206 t o n s of t a i l i n g s must be disposed of .

For

An a n a l y s i s of the t a i l i n g s w a s t e from a copper c o n c e n t r a t o r ope ra t ion i n t h e Coeur d'Alene Region i n Idaho is shown i n Table 2-6. These d a t a show t h a t t h e concen t r a t ion of cadmium, copper, l e a d , and z inc ( a l l of which are p o t e n t i a l l y hazardous metals) i n t h e t a i l i n g s stream discharged t o a t a i l i n g s pond a r e w e l l above the background concen t r a t ions of t h e s e metals. The background d a t a were compiled by ana lyz ing s o i l samples taken i n t h e area around t h e mine, c o n c e n t r a t o r , and t a i l i n g s pond.

Table 2-6

ANALYSIS OF TAILINGS FROM A COPPER CONCENTRATOR

E l emen t

Calcium Cadmium Copper Iron Pot as sium Magnesium Manganese Sodium Lead Antimony Zinc

Concentrat ion, ppm Concentrator Background

1 , 1 7 2

2,179 264,667

115 6,051

19,129 75

1,349 462 86 8

1 .4 1 , 500

21 11 , 800 1,800 3,700

4 90 151 51

150

-

-

Source: Reference 151.

Table 2-7 shows t h e chemical a n a l y s i s of typical copper m i l l t a i l i n g s .

4 7

Composition

S i l i c a (Si02)

Alumina (A1203)

Iron (Fe)

Magnesium (MgO)

Calcium (CaO)

Sodium (Na20)

Potassium (K 0 ) 2 Loss on I g n i t i o n

Nitrogen ( S i )

Titanium (Ti )

Ccpper (Cu)

Table 2-7

CHEXICAL ANALYSIS OF COPPER MILL TAILINGS

Percentage

71.1

1 3 . 2

3.4

2 . 1

1.1

0.3

3 . 3

2.6

0.005

0.4

0.005


The commercially used l e a c h i n g methods as desc r ibed i n an earlier

I n 1979, 17.5 mi l l i on t o n s of copper o r e w e r e t r e a t e d by l e a c h methods, s e c t i o n are heap leaching, dump l e a c h i n g , i n - p l a c e l e a c h i n g , and vat leaching. producing over 97,500 tons of copper (150). mately 17.4 m i l l i o n tons of t a i l i n g s were l e f t t o be disposed of .

From t h e s e o p e r a t i o n s approxi-

I n heap and dump l each ing , u n t i l t h e s i te is abandoned, t h e r e is no waste from t h e l each ing o p e r a t i o n (see Sec t ion 2.4.4).The l e a c h l i q u o r p e r c o l a t e s through t h e heap, where i t i s c o l l e c t e d and t h e copper contained i n t h e s o l u t i o n i s ex t r ac t ed w i t h o r g a n i c so lven t s . l each s o l u t i o n i s once again a p p l i e d t o t h e heap.

From h e r e t h e spen t

48

There are no wastes a t an o p e r a t i n g i n s i t u s i t e and p r e c i p i t a t i o n p l a n t . When a l l t h e leaching o p e r a t i o n s are f i n a l l y terminated, t h e i n s i t u leached o r e becomes a waste. I n s i t u l each ing of a given s i te lasts f o r many yea r s . A thorough water r i n s i n g of t h e l e a c h area t o remove t h e a c i d and recover t h e copper i n t h e a c i d s o l u t i o n i s performed by t h e oper- acin;: C'YF2rtniea.

I n vat l each ing , crushed oxide o r e i s leached i n a series of open- top conc re t e v a t s w i th an aqueous s o l u t i o n of s u l f u r i c acid. The l e a c h s o l u t i o n i s used a t ambient temperature , and t h e pH is maintained a t 1 t o 1.5. A f t e r t h e leaching p e r i o d , t h e slimes are separated and dewatered by a th i cken ing operat ion and pumped t o t h e t a i l i n g s pond. waste rock i s a l s o disposed of i n t h e ponds (151).

The

According t o the Bureau of Mines (150), a t o t a l of 139,400 tons of copper w a s recovered from l each ing t h e t a i l i n g s p i l e s , dumps, and in s i t u m a t e r i a l s n o t c l a s s i f i e d as copper o r e . Another 97,500 tons of copper w e r e leached from copper o re . This b r i n g s t h e t o t a l amount of copper produced by leaohing methods i n 1979 t o 236,900 tons.

2 . 4 . A P o t e n t i a l Hazardous Waste - Streams

The t a i l i n g s m a t e r i a l f r o n t h e f l o t a t i o n of copper s u l f i d e o r e s is a p o t e n t i a l l y hazardous waste. t a i l i n g s inc lude cadmim, copper, lead, and zinc. There a r e no r a d i o a c t i v e maLerials i n the copper waste (151).

The p o t e n t i a l l y hazardous m a t e r i a l s i n t h e

The m a t e r i a l i n a t y p i c a l pond i s about 60 t o 80 percent -60 mesh and has t h e phys ica l appearance of sand. of more than 2 pe rcen t i n the o r e and i s no t n e u t r a l i z e d by lime a d d i t i o n , s u l f u r i c ac id could form by water and a i r c o n t a c t w i t h theFeS2 ( p y r i t e ) and t h e s u l f u r i c a c i d would l each some metals from t h e t a i l i n g s . To counter- a c t t h i s , l i m e o r o t h e r c a u s t i c material i s added i n t h e f l o t a t i o n p rocess .

I f p y r i t e i s p resen t a t concen t r a t ions

Chemical a n a l y s i s tests of t a i l i n g s ponds r epor t ed by t h e U.S. Environmental P r o t e c t i o n Agency O f f i c e of So l id Waste (152) found t o x i c i t y concen t r a t ions of one o r more metals i n l i q u i d s or a c i d e x t r a c t s of s o l i d materials w i t h i n t h e t a i l i n g s are more than 10 times t h e concen t r a t ion s p e c i f i e d i n "primary dr inking water s tandards" (PDWS) but less than 100 times t h e PDWS. The EP t o x i c i t y tests are based on 100 times t h e PDWS. I f an e x t r a c t c o n t a i n s a c o n s t i t u e n t i n a concen t r a t ion g r e a t e r than 100 t i m e s t h e PDWS, then t h e waste i s hazardous due t o EP t o x i c i t y .

49

E

In tests of c o r r o s i v i t y , l i q u i d s were found w i t h a ' p H between 2 and 3 . A l i q u i d w i t h a pH af less than 2 would b e a hazardous waste. S o l i d s have a p o t e n t i a l a c i d i t y of greater than 5,000 but less than 50,000 ug carbonate /g of material (152).

T h ;ea,:h lic,u=rs from l e a c h dumps exhibi ted c o r r o s i v i t y c h a r a c t e r i s - t i c s t h a t could be d e t r i m e n t a l t o t n e environment (pE < 2 ) . A l s o , cmcerA- t r a t i o n s of cadmium and selenium of more than 100 t imes t h e PDWS were found, c o n s t i t u t i n g t h e p o t e n t i a l f o r n e g a t i v e impact from t o x i c i t y ( 1 5 2 ) .

U n t i l a dump l e a c h i s abandoned, t h e r e is no waste from the l each ing ope ra t ion . r e s i d u e is a p o t e n t i a l l y hazardous waste ma te r i a l t h a t could cause environmental p o l l u t i o n due t o n a t u r a l l each ing by r a i n f a l l and runof f . This w i l l happen un le s s t h e a c i d i s washed out by water f looding of t h e heap by t h e mining company. c o n t a i n s the p rov i s ion t h a t heaps must be water flooded b e f o r e abandonment.

A f t e r t h e l each ing of t h e o r e i s terminated, t h e spent rock

Some s t a t e s r e q u i r e t h e f i l i n g of an a c t i o n p l an t h a t

2.4.5 .Resource Recovery Technology Desc r ip t ions

The amounts of waste rock , overburden, and t a i l i n g s generated i n t h e mining and m i l l i n g of copper are tremendous and must be expressed i n t h e m i l l i o n s of t ons a t each s i t e . Because of t h e extremely low percentages of copper i n low-grade copper-bearing o r e s (0.3 t o 0.6 p e r c e n t ) , n e a r l y a l l of t he o r e processed i s e v e n t u a i l y disposed of as t a i l i n g . t i o n of copper i n t h e Cnited States w a s responsible for t h e gene ra t ion of approximately 272 m i l l i o n tons of by-product t a i l i n g s i n 1979. copper t a i l i n g s t h e f o u r t h most abundantly produced material i n t h e U.S., exceeded only by crushed s tone , sand and g rave l , and c o a l ( 4 6 ) . f u l l y comprehend t h e enormity of t h e s e f i g u r e s , consider t h a t t h e l a r g e s t dam i n t h e e n t i r e world, i n terms of t o t a l volume of material, i s t h e New Cornelia t a i l i n g dam l o c a t e d n e a r A j o , Arizona. an est imated 275 m i l l i o n cubic ya rds (46).

The ixoduc-

This makes

To more

This dam c o n t a i n s

The tremendous volumes of copper waste rock and m i l l t a i l i n g s make i t v i r t u a l l y impossible t o cons ide r t o t a l u t i l i z a t i o n of t h e s e wastes f o r any purpose. Nonetheless, t h e r e source recovery t echno log ie s c u r r e n t l y p r a c t i c e d or proposed are summarized and presented in t h e fol lowing s e c t i o n s .

2 . 4 . 5 . 1 Copper Recovery from Mining and Mi l l i ng Wates

Copper l each ing of mine wastes has become an important ad junc t of n e a r l y a l l copper miniag ope ra t ions . Leaching of copper, whether from copper bear ing o r e o r waste, fo l lows w e l l e s t ab l i shed chemical r e a c t i o n s commonly i n an a c i d c i r c u i t , b u t where leaching of copper i s t o b e made

50

i n rock t h a t i s a h igh a c i d consumer, ammonia and ammonia carbonate , as w e l l as cyanide leach s o l u t i o n s , can be used e f f e c t i v e l y ( 4 1 ) .

I n 1979, 139,400 tons of copper were recovered from the leach ing of mine waste and t a i l i n g s (150). J u s t t en years ago, i n t h e e a r l y 1970s, FrpGzc:L:>n of c s p e r from t h i s method was over 300,000 tons pe r year . Where copper occurs as an oxide i n s u f i i c i e n t l y high concen t r a t ions EO be c l a s s i f e d as an o r e r a t h e r than waste, then hydrometa l lurg ica l p rocesses such as pe rco la t ion o r a g i t a t i o n leaching i n v a t s , pachuca tanks o r prepared heaps are app l i ed . Th i s approach g ives b e t t e r c o n t r o l over t he recovery of t h e l each s o l u t i o n s .

Nearly a l l of t h e va r ious copper companies have some form of leaching opera t ion a s soc ia t ed wi th t h e l each ing of the t r a c e amounts of copper from t h e mine overburden o r waste. The mine waste dumps are made up of mine run material wi th no a t tempt made a t t h e prepara t ion of t h e material as t o s i z e , type o r e l imina t ion of d e l e t e r i o u s gangue ma te r i a l s . mining ope ra t ions , t h e w a s t e i s moved as rap id ly and e f f i c i e n t l y as p o s s i b l e wi th n o cons ide ra t ion f o r subsequent leaching of the copper. The p resen t method of e s t a b l i s h i n g l each dumps by t ruck haulage does n o t p e r m i t uniform wet t ing of t h e m a t e r i a l f o r proper leaching; material s p i l l e d over t he dump c r e s t s eg rega te s a s i t r o l l s down t h e dump s lope , and t h e h igher t he dump, rhe g r e a t e r t h e degree of s eg rega t ion (41).

I n t h e major i ty of

One common technique of c o n s t r u c t i n g leach dumps i s t o bu i ld f i n g e r duxcps which are long, narrow berms of mine waste s e v e r a i hundreds of f e e t long and approximately 30 t o 50 f e e t deep. The width of t hese f inger- type dumps i s s u f f i c i e n t t o permit t h e l a r g e haulage t rucks t o make an easy tu rn . Af t e r a series of p a r a l l e l f i n g e r dumps have been b u i l t , t h e su r face i s d r i l l e d on 25-foot c e n t e r s t o a depth of 15 f e e t and exp los ive charges are used t o e l i m i n a t e t h e compacted a rea due t o t ruck haulage. Subsequent over lays of f inger - type dumps are then made on top of t h e o r i g i n a l base of f i n g e r dumps u n t i l a depth of 150 f e e t i s a t t a i n e d . These f inger- type dumps give a l t e rn . a t e l a y e r s of c o a r s e and f i n e material, b u t of g r e a t e r s i g n i f i c a n c e is t h e exposure of long , narrow dumps t o t h e oxygen i n a i r , thereby making oxygen a v a i l a b l e f o r t h e oxida t ion of t h e copper s u l f i d e s (41).

At one mine, a p l u s 0.5 p e r c e n t oxide o re is obtained by r ipp ing t h e o r e i n t h e mine and t r a n s p o r t i n g t h i s t o t h e leach heaps. Each success ive l i f t i s only 20 f e e t deep. After 120 days of leaching of t h e 20-foot deep l i f t , t h e s u r f a c e is r ipped and a n a d d i t i o n a l 20 f e e t is placed on t h e pre- v ious ly leached l i f t . Some l e a c h heaps conta in as many as n i n e l i f t s .

Current dump leaching p rocesses do no t recover any of t h e p o t e n t i a l by-product go ld , s i l v e r , and molybdenum that may occur i n the waste materials. I n a Bureau of Mines p r o j e c t (61) i t w a s shown t h a t metal va lue r ecove r i e s from open p i t s t r i p waste can b e improved by crushing t o minus 6 inches p r i o r t o s i z i n g , f l o a t i n g t h e enr iched f i n e s and leaching t h e remaining coarse rock. Copper, molybdenum, and s i l v e r r ecove r i e s were 73.5, 36.7, and 20.8 pe rcen t , r e s p e c t i v e l y .

51

Solu t ion d i s t r i b u t i o n i n dump leaching fol lows a v a r i e t y of approaches invo lv ing s p r a y s , ponds, i n j e c t i o n ho le s , and i r r i g a t i o n d i t c h e s . Some com- pan ie s c o n t r o l t he pH of t h e i r l e a c h s o l u t i o n s while o t h e r s mere ly r ecyc le t h e s o l u t i o n on an as i s b a s i s from t h e i r cementation process . A l l s t r i p p e d l each s o l u t i o n s a r e recycled because of t h e need t o avoid stream p o l l u t i o n and a d e a r t h of water .

Of t h e d i f f e r i n g methods, the t r i c k l e and s o l u t i o n i n j e c t i o n systems appear t o be t h e p re fe r r ed methods t o leach an area e f f i c i e n t l y . T r i c k l e systems involve the d i s t r i b u t i o n of t h e leach s o l u t i o n s through a network of p l a s t i c p i p e such t h a t t h e s u r f a c e rece ives between 0.1 t o 0.25 ga l lons p e r hour p e r square f o o t of area. Leaching of su l f ide-conta in ing material i s c a r r i e d ou t i n :his manner f o r one t o two w e e k s . The s o l u t i o n s are moved z o another a rea thereby p e r m i t t i n g t h e a rea t h a t had been leached t o rest.

So lu t ion i n j e c t i o n s y s t e m s , t h e l e a s t expensive bu t least e f f i c i e n t method of leaching , involves t h e technique of bu i ld ing diked a r e a s and flood- i n g t h s e a r e a s maintaining a pond of leach so lu t ions . Inva r i ab ly t h e uneven subsidekce of t h e dump su r face causes cracks or c r e v i c e s t o occur through which t h e l each s o l u t i o n s tend t o s h o r t - c i r c u i t .

The capper i s recovered from t h e leach s o l u t i o n s by chemical p r e c i p i t a - t i o n on sc rap i r o n (cementat ion) , by electrowinning, or by so lvent e x t r a c t i o n and e iec t rowinning .

Recovery of copper concen t r a t e from copper m i l l t a i l i n g s i s s t i l l being p r a c t i c e d a t some opera t ions bu t n o t by o the r s . A t Kennecott Copper Corpora- t i o n ' s Magna, Utah opera t ion , over 40,000 tons a day of t a i l i n g s a r e t r e a t e d producing over 100 tons of copper concen t r a t e (90, 181). It should be noted t h a t even though t h i s i s a technique f o r recovering va luab le materials from t h e waste stream, i t s t i l l l e a v e s behind 39,900 tons of t a i l i n g s pe r day which must be disposed of by convent iona l methods. The company's Arthur opera t ion a t one time retreated copper m i l l t a i l i n g s but has been c losed d m due t o t h e use of a new, more e f f i c i e n t primary copper o re t rea tment process . This new method recovers a higher pe rcen tage of copper from the o re , t h u s leav ing behind a t a i l i n g uneconomical t o retreat (181).

I n 1 9 7 4 , t h e Phelps Dodge Corporat ion s u l f i d e o r e m i l l i n g and smel t ing ope ra t ion a t Morence, Arizona, cons t ruc t ed a p l a n t designed t o t rea t 60,000 t o n s p e r day of f l o t a t i o n t a i l i n g s t o recover .about two pounds of oxide copper which is being l o s t i n each ton of t h e t a i l i n g . The f i n e t a i l i n g s were t r e a t e d by a g i t a t i o n l each ing w i t h s u l f u r i c ac id . The process was adopted because of an a n t i c i p a t e d product ion of a l a r g e excess of s u l f u r i c

52

a c i d from p o l l u t i o n c o n t r o l equipment i n s t a l l e d a t t h e Morence S m e l t e r i n compliance w i t h Federa l air p o l l u t i o n r egu la t ions d i r e c t e d toward abate- ment of s u l f u r oxide emissions. The p lan t operated success fu l ly from t h e beginning bu t w a s shut down on December 13, 1980 due t o pe r iod ic sho r t ages of a c i d . and i t s s a l e w a s more p r o f i t a b l e than the va lue of t h e copper recovered from t h e t a i l i n g s (166) .

By t h a t t i m e new u r k e t s for the s u l f u r i c a c i d had been developed

2.4.5.2 T a i l i n g s Used i n Cons t ruc t i o n

The Department of C i v i l Engineer ing, Univers i ty of Arizona, r e c e n t l y conducted i n v e s t i g a t i o n s t o determine the f e a s i b i l i t y of us ing s t a b i l i z e d copper m i l l t a i l i n g s i n road c o n s t r u c t i o n ( 8 7 ) . un t rea t ed t a i l i n g s , inc luding phys ica l and mechanical proper t ies ,were determined. i nc lud ing compaction c h a r a c t e r i s t i c s ; compressive, t e n s i l e and shea r s t r e n g t h ; c o m p r e s s i b i l i t y ; permeabi l i ty ; and e r o d i b i l i t y by r a i n f a l l .

Index p r o p e r t i e s of t h e

Engineering parameters of un t rea ted t a i l i n g s were a l s o determined,

The r e s u l t s of these i n v e s t i g a t i o n s demonstrate that copper m i l l t a i l - i ngs have e x c e l l e n t engineer ing p r o p e r t i e s and can be success fu l ly used i n road cons t ruc t ion . I n p a r t i c u l a r , t h e r e s u l t s i n d i c a t e t h a t t he re i s ex- c e l l e n t p o t e n t i a l f o r using t a i l i n g s as compacted f i l l i n embanbents , compacted foundat ion and subgrade m a t e r i a l , cement-treated base, emulsion- t r e a t e d base , and s t a b i l i z e d m a t e r i a l f o r l i n i n g cana l s , ponds, and r e s e r v o i r s .

I n t h e copper mining d i s t r i c t of Houghton and Xeweenaw Counties i n the Upper Peninsula of Hichigan, a cons ide rab le amount of material has been used from t h e "poor rock" p i l e s l oca t ed i n t h i s d i s t r i c t . because i t has l i t t l e or no copper con ten t , i s composed of t r a p , amygdaloid, and conglomerate, t o chunks 4 inches i n diameter or smaller. The Keweenaw County Road Com- miss ion has used these materials throughout t h e county i n var ious s t a g e s of cons t ruc t ion and found them t o b e extremely adequate f o r base and sub-base materials, depending upon the p a r t i c l e s i z e ( 4 6 ) .

This rock, so-cal led

varying i n s i z e from boulders of about one-foot in diameter

One of t h e most no tab le a p p l i c a t i o n s of t a i l i n g s f o r highway cons t ruc- t i o n i s i n Utah where, i n 1972, t h e Kennecott Copper Corporat ion cons t ruc t ed a s e p a r a t i o n f a c i l i t y t o produce a t a i l i n g product s u i t a b l e f o r use as an embankment m a t e r i a l i n highway cons t ruc t ion . F i f t y pe rcen t of t h e t a i l i n g s from one of Rennecot t ' s concen t r a to r plants is d ive r t ed through t h i s f a c i l i t y , which c l a s s i f i e s and depos i t s up t o 20,000 tons pe r day of t h e c o a r s e r t a i l - i n g par t ic les wi th a m a x i m u m of 20 percent minus 200 mesh ( 4 6 ) . Since 1972, more than 5.5 m i l l i o n tons of t h i s c l a s s i f i e d t a i l i n g have been used t o c o n s t r u c t highway embankments in Utah wi th very s a t i s f a c t o r y r e s u l t s . most ou t s t and ing s i n g l e example of t h e use of c l a s s i f i e d t a i l i n g w a s the c o n s t r u c t i o n of s i x mi les of embankment f o r I n t e r s t a t e Route 215 w e s t of Salt- ,Lake C i t y , using a t o t a l of 3.3 mi l l i on tons of t h e t a i l i ng .

The

53

The Utah Department of Highways has been very pleased wi th t h e compac- cons ide r ing making t i o n c h a r a c t e r i s t i c s of c l a s s i f i e d copper t a i l i n g and is

t h e material an a l t e r n a t e f o r f i l l on primary and secondary state roads. The only problem experienced t o d a t e i n i t s u s e as an embankment material h a s been a tendency t o erode e a s i l y . I n o rde r to combat t h i s problem, t h e fin- i s h e d embankment must be covered w i t h t o p s o i l t o provide t h e necessary e ros ion c o n t r o l ( 4 6 ) .

C l a s s i f i e d copper m i l l t a i l i n g has a l s o been used as a mineral f i l l e r i n bituminous mixtures i n Utah. However, i t s use f o r this purpose h a s n o t been q u i t e a s s u c c e s s f u l as f o r embankment c o n s t r u c t i o n . t h a t t h e use of c l a s s i f i e d t a i l i n g as a mineral f i l l e r seems t o cause aging and hardening of t h e a s p h a l t , more so than for o t h e r mineral f i l l e r s that have been used. To d a t e , t h e r e h a s n o t been any good explanat ion f o r t h i s phenomenon, but chemists f o r t h e Utah Department of Highways are p r e s e n t l y a t t empt ing t o determine t h e cause of t h i s problem ( 4 6 ) .

The problem i s

I n a Bureau of Mines l a b o r a t o r y r e sea rch p r o j e c t (72) , i t w a s shown t h a t b u i l d i n g b r i c k s meeting ASTM s p e c i f i c a t i o n C62-66 f o r grades SW and MW of FBS-iype b r i c k s can be produced from waste copper m i l l t a i l i n g s . T a i l - i n g s from v a r i o u s l o c a t i o n s were dry-pressed i n t o b r i c k s , and t h e p roduc t s were t e s t e d i n accordance wi th ASTM Designation C62-66 on sampling and t e s t i n g of b r i c k .

The b r i c k s were of e x c e l l e n t q u a l i t y but t o c o n t r o l c o l o r tne p y r i t e had t o be removed from t h e t a i l i n g s p r i o r t o b r i c k manufacture. A b r i c k manufacturer i n S a l t Lake C i t y , Utah nego t i a t ed wi th t h e Kennecott Copper Company t o u s e t h e t a i l i n g s from Kennecot t ' s Bingham Canyon Mine f o r produc- t i o n of t h e b r i c k s . Although Kennecott w a s w i l l i n g t o supply the t a i l i n g s t o t h e b r i c k company f r e e of cha rge , i t (Kennecott) w a s unwil l ing t o i n s t a l l t h e f l o t a t i o n c i r c u i t needed t o remove the undesired p y r i t e . Thus, t h e d e a l f e l l through. Obviously, because of t h e massive tonnages of t a i l s generated by Kennecott and a somewhat l i m i t e d market f o r b r i c k i n t h e S a l t Lake C i t y area, only a small p o r t i o n of t h e t a i l i n g s would have been u t i l i z e d had t h e d e a l been consumated (171).

Although t h e m i l l t a i l i n g s r e p r e s e n t an abundant and cheap r a w material, t h i s r e source is l o c a t e d in t h e intermountain states, whereas t h e p r i n c i p a l market f o r b r i c k s is i n t h e l a r g e populat ion c e n t e r s a t cons ide rab le d i s t a n c e from t h e resource. A t p r e s e n t , t h e manufacture and sale of b u i l d i n g b r i c k s depends on t h e supply of l o c a l r a w materials, u s u a l l y s i l i c e o u s c l a y o r intermixed s h a l e s and sandstone, and on nearby markets. Hence a l a rge - sca l e brick-making ope ra t ion using prophyr copper m i l l t a i l i n g s would have t o produce a q u a l i t y b r i c k a t a low enough c o s t t o cover t h e c o s t of sh ipp ing t o popu la t ion c e n t e r s such as Denver, Phoenix, Los Angeles, San Francisco, P o r t l a n d , and S e a t t l e , which are 100 t o 750 miles from t h e t a i l i n g material sou rces (72).

_,

54

!

i

2.4.5.3 Anor thes i t e Concentrate from Ta i l ings

Work performed by t h e U.S. Bureau of Mines, t he Un ive r s i ty of Minne- s o t a and S a l a Magnetics of Cambridge, Massachusetts, has shown that by applying high g r a d i e n t magnetic s e p a r a t i o n techniques t o p o t e n t i a l low c o s t copper-nickel f l o t a t i o n t a i l i n g s , i t is p o s s i b l e t o produce an an- o r t h o s i t e concen t r a t e a s s a y i n g more than 28 percent A1203 t o serve as a p o s s i b l e domestic source f o r producing alumina (37 ) .

This process is n o t p r a c t i c e d and i s considered an u n l i k e l y cand ida te f o r commercialization. Product ion of alumina from a n o r t h o s i t e by t h e l i m e - soda ash s i n t e r p rocess has been c a r r i e d out i n t h e l a b o r a t o r y and on a l a r g e demonstration scale. The p r o c e s s i s t e c h n i c a l l y f e a s i b l e b u t o t h e r p rocesses such as alumina from c l a y by the hydrochlor ic a c i d p rocess , f o r example, are less c o s t l y and less energy in t ens ive . Furthermore, anortho- s i t e i s abundant and could b e mined a t minimal c o s t in a r e l a t i v e l y pu re form and-wi th much less e f f o r t t han recovering i t from t a i l i n g s .

However, t h e recovery of alumina from copper l each s o l u t i o n s h a s been s t u d i e d ( 1 7 2 ) . p r e s e n t l y predominantly i n f e l d s p a r and c l a y minerals. of t h e o r e s , and p a r t i c u l a r l y , t h e waste overburden t o recover t h e copper , some alumina r e p o r t s i n t h e l e a c h s o l u t i o n s , and a f t e r removal of t h e cop- p e r , t h e s o l u t i o n s c o n t a i n 300 t o 600 ppm Al2O3 . are a p o t e n t i a l source of as much as 500,000 tons of alumina pe r yea r . Laboratory and small scale cont inuous p l an t r e sea rch conducted by t h e Bureau o f f i n e s and t h e Kennecott Copper Company has demonstrated that t h e contained alumina can b e recovered from t h e l each s o l u t i o n s by u s e of i on exchange. Although t e c h n i c a l l y f e a s i b l e , t h e recovery of alumina from t h e l e a c h s o l u t i o n s i s n o t economically competi t ive wi th alumina produced from imported b a u x i t e by t h e Bayer process , o r even by emerging t echno log ie s such’ as n i t r i c o r hydrochlor ic l each ings of domestic c l a y s . Also, alumina from l e a c h s o l u t i o n s i s more promising than producing alumina from a n o r t h o s i t e from t a i l i n g s (166).

Copper o r e s c o n t a i n 10 t o 15 percent alumina,which i s During l each ing

These l each s o l u t i o n s

55

t -

2.5 PELDSPAR M I N I N G INDUSTRY

Feldspar i s t h e gene ra l name given t o t h e m e m b e r s of a group of c l o s e l y r e l a t e d mine ra l s t h a t are e s s e n t i a l l y anhydrous aluminum s i l icates i n combi- n a t i o n wi th varying p ropor t ions of one or more bases, one of which u s u a l l y predominates and c h a r a c t e r i z e s t h e p a r t i c u l a r type of material. Potash f e l d - s p a r , soda f e l d s p a r , and lime f e l d s p a r are t h e varieties most commonly d i s - t i ngu i shed . Feldspars are major components i n most igneous rocks and c o n s t i - t u t e a l a r g e p a r t of a t least t h e o u t e r l a y e r s of o u r p l a n e t and i t s n e a r e s t neighbor , t h e moon. Feldspar i s t h u s one of t h e most abundant materials i n t h e world, and a v i r t u a l l y i n e x h a u s t i b l e supply i s a v a i l a b l e (98).


2-5.1.1 Indus t ry S t r u c t u r e

Crude f e l d s p a r i s produced i n t h e United S t a t e s as a primary product by l a r g e d i v e r s i f i e d f i r m s , by major f i r m s t h a t are p r i m a r i l y f e l d s p a r producers , and by a number of i n d i v i d u a l s or groups t h a t m i n e small q u a n t i t i e s f o r sale t o f i r m s t h a t o p e r a t e f e ldspa r -g r ind ing p l a n t s . The mine ra l is a l s o produced as a by-product by s e v e r a l f i r m s t h a t mine and process g r a n i t e , spodumene, o r mica as t h e i r p r i n c i p a l products .

Eleven domestic companies o p e r a t i n g 13 p l a n t s i n seven states produced b e n e f i c i a t e d f e l d s p a r i n 1979 ( i n c l u d i n g fine-ground m a t e r i a l ) f o r shipment t o d e s t i n a t i o n s i n a t least 31 states, Canada, and Mexico. L i s t e d i n descend- i n g o r d e r of output tonnages, North Carol ina had f i v e p l a n t s , wh i l e Con- n e c t i c u t , South Carol ina, and Georgia had one each. Oklahoma had one p l a n t , C a l i f o r n i a had two, and South Dakota and Wyoming had one each.

Major producers and p r o c e s s o r s of f e l d s p a r i n t h e United S t a t e s Fnclude t h e Feldspar Corporation, w i t h o p e r a t i o n s in Connect icut , Georgia, and North Caro l ina ; Lason-United Fe ldspa r and Mineral Company in North Carol ina; and I n t e r n a t i o n a l Minerals & Chemical Corporat ion, a l s o in North Carol ina.

2.5.1.2 Production S t a t i s t i c s (98)

U.S. production of f e l d s p a r in 1979 w a s 740,000 t o n s and i n 1978 w a s 735,000 tons. I n 1979, f l e d s p a r w a s mined in seven states, two less than i n 1978. by Connect icut , Georgia, Oklahoma, C a l i f o r n i a ( e s t i m a t e d ) , South Dakota, and Wyoming. The combined ou tpu t s of the f i r s t f o u r states l i s t e d amounted t o 94 pe rcen t of t h e U.S. t o t a l .

North Carol ina l e d i n p roduc t ion tonnage, followed i n descending o rde r

T o t a l world f e l d s p a r o u t p u t i n 1979 was es t ima ted t o be 3,410,000 tons , In 1979, output came from a t least 40 f o r e i g n or s l i g h t l y more than i n 1978.

c o u n t r i e s , among which the F e d e r a l Repubic of Germany, t h e U.S.S.R., I t a l y , France, and Mexico j o i n t l y c o n t r i b u t e d 40 percen t of t h e world t o t a l .

2.5.1.3 I n d u s t r y Trends

The U.S. Bureau of Mines (98) has f o r e c a s t a range of 1 .16mi l l i on t o 1.66 m i l l i o n s h o r t tons f o r t o t a l U.S. f e l d s p a r demand i n 2000. A f i g u r e of 1 .45 m i l l i o n t o n s , s l i g h t l y above t h e midpoint of t h e f o r e c a s t range, w a s s e l e c t e d as t h e probable level of f e l d s p a r demand in 2000, correspond- i n g t o a growth ra te of 3 . 2 p e r c e n t pe r yea r du r ing 1978 t o 2000. probable U.S. demand i n 1990 i s f o r e c a s t a t 1.06 m i l l i o n tons.

The

With regard t o t h e rest of t h e world, o v e r a l l growth i n f e l d s p a r demand i n t h e major i n d u s t r i a l i z e d n a t i o n s seems l i k e l y t o gain over t h a t i n t h e United S t a t e s . The c u r r e n t u s e of a p l i t e i n Japan and that of nephe l ine s y e n i t e i n Canada axd p a r t s of Europe as s u b s t i t u t e s f o r f e l d - spar can b e expected t o con t inue and perhaps extend t o o t h e r c o u n t r i e s .

I n t h e developing c o u n t r i e s , u s e of f e l d s p a r w i l l probably i n c r e a s e slowly and remain minor u n t i l product ion of g l a s s and ceramic products becomes s u b s t a n t i a l . world should, t h e r e f o r e , be c o n t r o l l e d p r imar i ly by demand i n the more advanced n a t i o n s and r e f l e c t a pace somewhat beyond t h a t i n t h e United States . On t h e b a s i s of t h e s e assumptions, t h e f o r e c a s t range of t h e rest of t h e world i n 2000, namely 5.16 m i l l i o n t o 6.34 m i l l i o n t o n s , w a s obtained by us ing low and h igh growth rates g r e a t e r than those i n d i c a t e d by contingency f o r e c a s t i n g of demand i n t h e United States. The probable o r expected l e v e l of rest-of-world demand i n 2000 was set a t 5.7 m i l l i o n t o n s , corresponding t o a growth rate of 3.5 pe rcen t pe r yea r , and a t 4.04 m i l l i o n t o n s i n 1990.

The p a t t e r n of demand growth i n t h e rest of t h e

2 . 5 . 2 Fe ldspa r Mining and B e n e f i c i a t i o n Operations

Fe ldspa r and f e l d s p a t h i c materials are mined by va r ious methods, depending upon t h e n a t u r e of t h e d e p o s i t s . As long as overburden r a t i o s do n o t become excess ive and land-use c o n f l i c t s can be r e so lved , most f e l d s p a t h i c rocks can be q u a r r i e d by open p i t procedures. sometimes be recovered j u s t by b a r r i n g down massive material from d i s - t i n c t l y zoned and coarse-grained pegmat i t i c d i k e s , b u t t h e ma jo r i ty of d e p o s i t s r e q u i r e t h e use of d r i l l s and explosives . Fe ldspa th i c sand d e p o s i t s are mined by d r a g l i n e excavators .

Feldspar can

High-grade, s e l e c t i v e l y mined f e l d s p a r from coarse-s t ructured peg- matites may be dry-processed, p a s s i n g consecu t ive ly through j a w c r u s h e r s , r o l l s , and s i l e x - l i n e d pebble m i l l s be fo re being sub jec t ed t o h igh - in t ens i ty magnetic o r e l e c t r o s t a t i c t r ea tmen t t o b r i n g t h e i r o n con ten t down t o an a c c e p t a b l e level.

..-

Feldspar o r e s of t h e a l a s k i t e o r beach-sand types are usua l ly b e n e f i c i a t e d by f r o t h f l o t a t i o n . The customary procedure appl ied t o massive materials begins wi th d r i l l i n g , b l a s t i n g , and drop-bal l break- i n g a t t h e qua r ry , followed by primary and secondary c o m i n u t i o n and f i n e g r ind ing i n j a w c rushe r s , cone c rushe r s , and rod mills, respec- t i v e l y . i n t h r e e s t a g e s , each stage preceded by des l iming and condi t ion ing . The f i r s t f l o t a t i o n s t e p depends on an amine c o l l e c t o r t o f l o a t o f f and remove mica, and t h e second uses su l fona ted o i l s t o sepa ra t e i ron - bea r ing mine ra l s , most no tab ly ga rne t . The t h i r d s t e p , by f l o a t i n g the now i ron- and mica-free f e l d s p a r w i th another amine c o l l e c t o r , l e a v e s behind a r e s idue t h a t c o n s i s t s c h i e f l y of q u a r t z .

The sequence t y p i c a l l y cont inues w i t h a c i d - c i r c u i t f l o t a t i o n

P repa ra t ion of f e l d s p a t h i c sands f o r f l o t a t i o n may r e q u i r e no a d d i t i o n a l r educ t ion i n p a r t i c l e s i z e and, i f l i t t l e or no mica i s p r e s e n t , t h e f i r s t f l o t a t i o n s t e p may be by-passed so t h a t t h e m i l l f eed may go d i r e c t l y t o t h e cond i t ion ing s t e p b e f o r e t h e s t a g e of ga rne t removal. It may sometimes a l s o be d e s i r a b l e t o omit t h e f i n a l f l o t a t i o n s t a g e , .the s e p a r a t i o n of f e l d s p a r from q u a r t z ; i n t h i s c a s e the product may be marketed as a f e l d s p a r - s i l i c a mixture , u s u a l l y f o r consumption i n glassmaking.

The f lo t a t ion -cake f e l d s p a r or f e l d s p a r - s i l i c a mixture , whether from s’ands o r from hard-rock sources , i s dewatered i n vacuum o r p re s su re f i l t e r s and then d r i e d and ground f o r market. p l i s h e d s imul taneous lyby pass ing the dewatered cake through a r o t a t i n g gas- f i red c y l i n d e r l i n e d wi th ceramic b locks and charged wi th ceramic g r ind ing b a l l s . used t o a s s u r e compliance wi th p a r t i c l e - s i z e s p e c i f i c a t i o n s .

These f i n a l s t e p s a r e o f t e n accom-

Screening o r a i r c l a s s i f i c a t i o n w i t h ove r s i ze r e t u r n i s

2.5.3 Waste Stream C h a r a c t e r i s t i c s and Q u a n t i f i c a t i o n

Depending upon t h e operat ion,waste streams genera ted from t h e p rocess ing of f e l d s p a r o r e s w i l l c o n s i s t of a coa r se t a i l i n g s stream, or a c o a r s e t a i l - i n g s stream p l u s a f i l t e r cake waste product. The c o a r s e t a i l i n g s r e s u l t i n g from t h e process ing are composed of n e a r l y 65 pe rcen t f e l d s p a r and 20 pe rcen t q u a r t z . The o t h e r 15 percent are c h i e f l y mica, c l a y s , and i ron-bearing mine ra l s such as garne t . The f i l t e r cake material produced i s similar i n g rada t ion t o f i n e sand. It i s es t imated that 1,850,000 tons of t a i l i n g s w e r e generated i n t h e U.S. i n 1979 by f e l d s p a r p rocesso r s (150).

I

i

I

I

Because of t h e h igh percentage of f e l d s p a r conta ined i n the t a i l i n g s , p rocess ing changes are being implemented a t t h e p l a n t s i n order t o recover a h ighe r percentage of f e l d s p a r and qua r t z i n primary processing. do ing , t h e amount of t a i l i n g s produced i n t h e f u t u r e should be reduced by approximately 60 percent (73).

By so

- *

58

2.5.4 P o t e n t i a l Hazardous Waste Streams

NDne of the waste materials generated i n t h e mining and process ing of f e l d s p a r o r e s are considered p o t e n t i a l l y hazardous.

2 . 5 . 5 Resource Recoverv Technoloev DescriDtions

2.5.5.1 Use i n Bui ld ing and Cons t ruc t ion Materials

A n eva lua t ion of t h e p o t e n t i a l f o r use of the sands and f i l t e r cake as c o n s t r u c t i o n materlals was cmducted in t h e Civ i l Engineering Department of North Caro l ina S t a t e Cn ive r i s ty (73 ) . Emphasis w a s p laced on use of t h e materials a s f i n e aggrega tes f o r po r t l and cement mortars and bituminous conc re t e mixtures and f o r s t a b i l i z a t i o n of base-course founda- t i o n materials. The r e s u l t s of t h i s i n v e s t i g a t i o n may b e summarized as fo l lows : The coa r se t a i l i n g s can be used t o make mortars of accep tab le s t r e n g t h and workab i l i t y . However, t h e water and cement requirements are such t h a t they are marginal compet i tors wi th n a t u r a l sands. 2 ) The coa r se t a i l i n g s can be used t o make a s p h a l t s of accep tab le s t r e n g t h and s t a b i l i t y . A s p h a l t cement requirements are near normal, and this p o t e n t i a l use should be developed f u r t h e r . be s t a b i l i z e d w i t h po r t l and cement, l i m e , and f l y ash. The f i n e t a i l i n g s s o s t a b i l i z e d could be used as foundat ion l a y e r s f o r s t r u c t u r e s and low c o s t roads. The u s e i n combination wi th f l y ash, another waste product of i n d u s t r y , i s of s p e c i a l i n t e r e s t ; and comprehensive s t u d i e s t o develop s p e c i f i c g u i d e l i n e s f o r t h i s a p p l i c a t i o n are warranted.

1)

3) The f i n e t a i l i n g s ( f i l t e r cake ma te r i a l s ) can

The U n i v e r s i t y ' s Minerals Research Laboratory demonstrated t h a t sand- l i m e b r i c k s meeting ASTM SW (severe weathering) s t r e n g t h s p e c i f i c a t i o n s could be made by us ing va r ious combinations of t h e materials from t h e f i v e t a i l i n g streams. Promising samples of l i gh twe igh t , foamed ca l c ium-s i l i ca t e b u i l d i n g m a t e r i a l s were produced i n t h e labora tory a l s o .

I n o t h e r a s p e c t s of t h e Un ive r s i ty ' s i n v e s t i g a t i o n , i t w a s found that t h e f i l t e r cake materials probably could b e used as b r i c k raw materials i f a p l a s t i c i z e r such as 2 o r 3 percent of b a l l c l a y were added. However, t h e p re l imina ry work i n d i c a t e d t h a t process v a r i a b l e s such as k i l n atmosphere and k i l n temperature g r a d i e n t s would have t o be c o n t r o l l e d very c a r e f u l l y . Because t h e percentage of c l a y w i l l probably be apprec iab ly h igher i n t h e new t a i l i n g s , they are even more l i k e l y t o be u s e f u l f o r b r i c k product ion.

f

5 9

The results of t h i s i n v e s t i g a t i o n i n d i c a t e that a g l a s s of commercial va lue cannot be produced from any of the t a i l i n g s without a d d i t i o n a l pro- c e s s i n g . Bene f i c i a t ion t o remove such th ings as mica and i r o n m i n e r a l s and t h e add i t ion of a lka l i metal ox ide f l u x e s t o t h e t a i l i n g s might pe rmi t product ion of low grade g l a s s e s . f e a s i b l e .

Th i s does not appear t o be economically

The only l a r g e amounts of f e l d s p a r t a i l i n g s found i n t h e U.S. a r e i n a small s e c t i o n of North Caro l ina . Not only do t h e t r a n s p o r t a t i o n c o s t s h inde r t h e use of t hose t a i l i n g s f o r aggregate , b u t processing of t h e t a i l s would be required f o r t h e i r use i n paving, which f b r t h e r i n c r e a s e s c o s t s . A t t h i s t i m e t he t a i l i n g s are be ing used f o r subsidence c o n t r o l in t h e mines.

Mr. Dewey Hal l , P l a n t Manager of IMC I n d u s t r i a l Mineral D iv i s ion of Spruce Pine, North Caro l ina states t h a t a house had been b u i l t i n F l o r i d a from b r i c k s made from t a i l i n g s w i t h good r e s u l t s b u t t h e p r i c e of t r a n s - p o r t a t i o n of t hese m a t e r i a l s w a s p r o h i b i t i v e (173) .

60

2.6 GOLD M I N I N G INDUSTRY



I n t h e United S t a t e s , about 60 percent of domestic product ion comes from gold o r e s , and t h e remainder i s a by-product of copper and o t h e r base metal product ion. P l ace r gold product ion has dec l ined t o about 1 or 2 percent of t h e t o t a l i n r ecen t yea r s . The t o t a l domestic ou tput comes from approximately 200 mines. Three mines accounted f o r 64 percen t , and 25 mines accounted f o r about 97 percent of domestic output i n 1979. Eighty-eight percent came from South Dakota, Nevada, Utah, and Arizona. The l ead ing producer i n most y e a r s , Homestake Mining Co., p rovides more than one-quarter of domestic output from a deep underground mine i n South Dakota. The Kenne- c o t t Copper Corp., a major copper producer, i s second i n gold output i n most years., bu t w a s f i r s t i n 1979, followed by Homestake. a by-product of i t s ex tens ive copper mining opera t ions . The t h i r d l a r g e s t producer , t he C a r l i n Gold Mining C o . , has an open p i t mine i n no r th -cen t r a l Nevada. Other mines t h a t had opera ted i n ear l ie r y e a r s w e r e under renewed development i n 1980 i n Nevada and o t h e r s ta tes , because of increased gold p r i c e s (98) .

Kennecott 's gold i s

2 . 6 . 1 . 2 Product ion S t a t i s t i c s (98)

I n 1979 t h e United States mine production of gold w a s 970,000 t roy ounces, down from 1,743,000 ounces i n 1970. U.S. gold product ion t o d a t e t o t a l s 319 m i l l i o n ounces, d i s t r i b u t e d as fol lows ( i n m i l l i o n ounces) : C a l i f o r n i a 106, Colorado 4 1 , South Dakota 37, Nevada 32, Alaska 30, Utah 2 1 , and Montana 18; t h e ba lance came from 11 o the r s ta tes . Lode gold mining has suppl ied about 56 p e r c e n t of U.S. product ion, p l a c e r mining 1 p e r c e n t , and base metal mining 43 percent . The Homestake Mine a t Lead, South Dakota, has accounted f o r 10 percent of a l l U.S. gold product ion. Other major sources of p a s t p roduct ion inc lude t h e Mother Lode and Grass Val ley areas of C a l i f o r n i a , t h e Comstock Lode i n Nevada, Cr ipp le Creek i n Colorado, Go ld f i e ld , Nevada, and t h e Fairbanks and Nome, Alaska areas (98, 150) .

T o t a l world product ion t o d a t e i s est imated a t 2 . 9 b i l l i o n ounces, about two-thirds of i t mined i n t h e p a s t 50 yea r s . The t o t a l is equ iva len t t o a cube about 55 f e e t on a s i d e . South Afr ica has been t h e source of 40 percen t of t h a t go ld , bu t n e a r l y a l l coun t r i e s have r epor t ed a t least some product ion of gold.

61

2.6.1.3 Indus t ry Trends (98)

The United S t a t e s produces between 2 and 3 m i l l i o n ounces annua l ly from mining and t h e reclamation of o l d s c r a p , about one-half t h e amount r equ i r ed by domest ic f a b r i c a t o r s . f o r investment has grown u n t i l i n 1979 it w a s nea r ly one-half aga in as l a r g e as t h e demand f o r gold f o r f a b r i c a t i o n . This cons iderable demand, t o g e t h e r w i t h e x p o r t s and t h e r ap id growth of commercial s tocks , r e q u i r e s a l a r g e f low of gold t o t h e U.S. market; i n 1979 t h e market supply of r e f i n e d gold amounted t o n e a r l y 26 m i l l i o n ounces. I n a d d i t i o n , gold i s conta ined i n imported f a b r i c a t e d items such as j ewe l ry and e l e c t r o n i c p a r t s . S t a t e s h a s s i z a b l e resources of go ld , and t h e p r i c e i s now high enough t o encourage expansion of product ion . But given t h e environmental restraints faced by p l a c e r m i n e r s a n d t h e h i g h COSC of developing lode mines, t h e United S t a t e s w i l l cont inue t o import some of i t s market supply of gold.

S ince 1974-75, t h e demand f o r b u l l i o n and c o i n s

The United

The use p a t t e r n f o r gold w i l l probably n o t change much i n t h e remaining y e a r s of t h i s cen tu ry , e i t h e r i n t h e United S t a t e s o r i n t h e rest of t h e world. Jewelry w i l l remain t h e dominant u se f o r f a b r i c a t e d gold. U.S. demand f o r f a b r i c a t e d gold i s f o r e c a s t t o grow a t a n annual ra te of 2.2 pe rcen t t o about 7.6 mi l l i on ounces i n t h e year 2000. The U.S. demand f o r investment b u l l i o n and gold c o i n s i s very d i f f i c u l t t o f o r e c a s t . A t p r e s e n t , t h e s e two demand s e c t o r s are t o g e t h e r more important than t h e demand f o r f a b r i c a t e d gold. Demand f o r f a b r i c a t e d gold i n t h e rest of t h e world i s f o r e c a s t t o grow a t 1 . 4 pe rcen t annua l ly t o 2000. World r e sources are ade- qua te t o meet t h e f o r e c a s t demand.

2.6.2 Gold Mining and Bene f i c i a t ion Operat ions

The technology of gold mining i s w e l l e s t a b l i s h e d , having evolved and Much of t h e wor ld ' s go ld produc- developed l a r g e l y over t h e p a s t cen tu ry .

t i o n has come from deep narrow v e i n s o r from thin-bedded l a y e r s c a l l e d r e e f s ; t h e s e have been d i f f i c u l t t o mine because of h igh temperature , humidi ty , and extreme rock p r e s s u r e , which o f t e n causes dangerous rock b u r s t s . Mine, a long-act ive and deep underground opera t ion . comes from open p i t mining.

About one-fourth of domest ic product ion comes from t h e H o m e s t a k e Most of t h e remainder

P l a c e r mining w a s once an impor tan t source of gold and could become so aga in . d e p o s i t s ; d r a g l i n e o r hydrau l i c methods are commonly used i n smaller, bouldery depos i t s . b u t d ry ope ra t ion i s also p o s s i b l e , u s ing be l lows o r other air-blowing equipment f o r s epa ra t ion . However, recovery e f f i c i e n c y i s lower i n d r y process ing . For la rge-sca le , open p i t l o d e gold mining, computer models have been developed t o ana lyze v a r i o u s product ion f a c t o r s and e s t a b l i s h optimum e x t r a c t i o n e f f i c i e n c i e s .

Dredging o f f e r s t h e maximum e f f i c i e n c y i n l a r g e a l l u v i a l o r marine

Most p l a c e r mining r e q u i r e s l a r g e q u a n t i t i e s of water,

The South African mining industry is a leader in deep-mining techology and has evolved new methods of controlling rock stress, dust, and stope temperature. machine that may allow selective mining at greater depths. Also, the South Africans have developed new techniques of shaft sinking and extraction that are critical to the success of deep mining. of the gold ore is transported to the surface from a depth of 7,200 feet by hydraulic pumps. Generally, ore handling and transportation constitute an Fmportant part of gold mining costs.

Prototypes have been developed of a new mechanical rock-cutting

At the Vaal Reefs Mine, part

Milling technology f o r gold is highly developed, and normal mill recovery rates may range from 92 to 96 percent. amalgamaticn, flotation, gravity Concentration, and smelting or by a combination of these processes. When gold is associated with copper ores, it travels with the base metal through concentration and smelting to the refining stage. It is eventually separated from the anode slimes that accumulate in electro- lytic refining cells and is recovered as gold bullion in the precious metals refinery. Gold losses in concentrating are about the same as for copper, but are negligible in smelting and refining.

Gold is recovered by cyanidation,

Gold is refined by chlorination in the molten state (Miller process) and by electrolysis (Wohlwill process). Generally, gold bullion made by the Miller process is 996 to 997 fine, and bullion made by the Wohlwill process is 999.5 to 999.8 fine.

2.6.3 Waste Stream Characterization and Quantification

Methods of mining vary considerably, based on depth of ore deposit, size and shape of deposit, and the physical and mineralogical character of the ore and the surrounding rock. Regardless though of method of mining, the two chief waste products generated in the mining and beneficiation of gold are overburden waste According to the Bureau of Mines (150) 11,846,000 tons of mine waste were generared in producing 5,640,000 tons of gold-bearing ore in 1978 in the U.S. From these 5 . 6 4 million tons of ore, 559,000 troy ounces, less than 20 tons, of gold were obtained, leav- ing behind 5 .64 million tons of tailings.

and tailings.

The g r e a t e s t amounts of s o l i d waste from gold mining are loca ted i n t h e western S i e r r a Nevada r eg ion of northern Ca l i fo rn ia . These s i l i c e o u s materials were i n i t i a l l y depos i t ed over one hundred years ago as t h e r e s u l t of hydrau l i c mining ope ra t ions . and g rave l depos i t s i n Nevada and S i e r r a Counties r e s u l t i n g from t h i s ac- t i v i t y and l a r g e amounts of these materials have been used f o r cons t ruc t ion purposes over t h e years .

There are an es t imated 26,000 acres of sand

Besides t h e e a r l y h y d r a u l i c mining opera t ions , gold-bearing grave l d e p o s i t s i n the f l a t t e r areas of Bu t t e , Yuba. Sacramento, and ad jacen t c o u n t i e s were worked by bucke t - l i ne dredges. Washings and screening o p e r a t i o n s t o s e p a r a t e t h e gold minera ls have l e f t t a i l i n g s d e p o s i t s of c l ean sand and g r a v e l strewn over 50,000 t o 60,000 acres i n t h e s e coun t i e s . of pebbles and cobbles from r e l a t i v e l y good rock, and have been used i n a number of ca ses as commercial sand and grave l . approximately 2 b i l l i o n tons of t h e s e t a i l i n g s are a v a i l a b l e (46).

Most of t h e s e m a t e r i a l s a r e of good q u a l i t y , being composed

It is estimated that

A chemical composition comparison of two gold mine t a i l i n g s , one from C a l i f o r n i a the o the r from South Dakota, i s shown i n Table 2-8.

Table 2-8

CHEMICAL ANALYSIS OF TWO GOLD MINE XASTES

Const i tuent

S i l i c a (Si02)

F e r r i c Oxide (Fe203)

Alumina (A1203)

Calcium Oxide (CaO)

Magnesium Oxide (MgO)

Sodium (N a203)

Potassium (K203)

Loss on I g n i t i o n

Percentage Ca l i fo rn ia South Dakota

93.0 52.8

2.0 34.0

3.5 1.6

1.0 1.0

0.41 8 . 2

0.07

0.33

0.5

NA*

0.23 NA

* NA - Not Avai lable .

Source: References 144 and 46.

64

i


I n a prel iminary d r a f t r e p o r t on hazardous wastes (152), t h e U.S. Environmental P r o t e c t i o n Agency r evea led that g o l d / s i l v e r t a i l i n g s ponds con ta ined e l eva ted l e v e l s of l e a d , cadmium, selenium, mercury, silver, chromium, and cyanide. The fo l lowing concen t r a t ions by waste c h a r a c t e r i s t i c d e s i g n a t i o n were given i n t h e r e p o r t :

E P Toxici ty: Concen t r a t ions of one o r more metals in l i q u i d s or ac id e x t r a c t s of s o l i d materials w i t h i n t h e t a i l i n g s pond are more than 100 times t h e "primary d r ink ing water s t anda rds" (PDWS).

Cor ros iv i ty : L i q u i d s w i t h i n t h e ponds have a pH between 3 and 4 ; s o l i d s have a p o t e n t i a l a c i d i t y of g r e a t e r than 500 b u t less than 5,000 1.18 carbonate/g o f material.

Because of t h e g r e a t p o t e n t i a l f o r migrat ion of t h e heavy metals and cyanide from t h e t a i l i n g s , t h i s management p r a c t i c e i s receiving compre- hens ive monitoring.

2 0 6 . 5 Resource Recovery Technology Desc r ip t ions

There a r e b a s i c a l l y two methods of u t i l i z i n g gold mine wastes. They

The f ind ings i n each of are: o r u se of t h e t a i l i n g s i n c o n s t r u c t i o n products . t h e s e uses w i l l be d i scussed i n t h e fol lowing s e c t i o n s .

re t reatment of t a i l i n g s by l each ing f o r a d d i t i o n a l gold recovery,

2.6.5.1 Retreatment of T a i l i n g s

I n tests conducted by t h e Bureau of Mines (154) t o determine f e a s i b i l i t y of f u r t h e r g o l d . e x t r a c t i o n from gold mine t a i l i n g s , t h e following r e s u l t s w e r e found.

1. 2.

3.

4.

5.

-6.

7 .

Water l each ing e x t r a c t e d 10 percent of t h e gold. A 24-hour, 70°C cyanide l e a c h e x t r a c t e d 42 percent of t h e gold i n c l u d i n g t h e water-soluble gold. Treatment w i t h h o t s u l f u r i c a c i d followed by a cyanide l each r e s u l t e d i n e x t r a c t i o n of 49 pe rcen t of t h e gold. Addition of 120 pounds of sodium hydroxide p e r ton of o r e t o a 24-hour, 7OoC cyanide l each r e s u l t e d in extrac- t i o n of 60 p e r c e n t of t h e gold. F l o t a t i o n p l u s c y a n i d a t i o n y i e lded a combined e x t r a c t i o n of 47 p e r c e n t of t h e gold. A r o a s t f o r 4 hours a t 530"C, followed by cyanidat ion of t h e c a l c i n e , r e s u l t e d i n e x t r a c t i o n of 65 percent of t h e gold. Leaching of a similar c a l c i n e f o r 6 hours i n ho t (90°C) s u l f u r i c a c i d , followed by n e u t r a l i z a t i o n wi th lime and cyan ida t ion , r e s u l t e d i n e x t r a c t i o n of 79 percent of t h e g o l d .

I n another Bureau of Mines r e sea rch p r o j e c t (157) r e s u l t s showed that an i n j e c t i o n system f o r dump l each ing of gold mine waste and submarginai ox ide o r e s i s p o t e n t i a l l y f e a s i b l e f o r la rge-sca le use. The e f f i c i e n c y of t h e method was demonstrated by t h e 80 percent gold recovery i n 10 days and a total gold recovery of 90 percent i n t h e 21-day test per iod. consumption w a s 0.4 pound of NaCN p e r ton of mine waste t r e a t e d . f e a s i b i l i t y of t h i s approach w a s demonstrated by the Bureau of Mines and qu ick ly adopted by indus t ry . were by t h e C a r l i n and Cortez Mining Companies i n Nevada t o recover t h e gold from s t r i p p i n g wastes con ta in ing 0.04 t o 0.06 ounces per ton of gold These ope ra t ions cont inue t o d a t e . t h i s type i n Nevada, Arizona, Utah, Montana, and New Mexico which are leach- i n g low grade gold and s i l v e r s t r i p p i n g wastes, or they are t r e a t i n g low- grade o r e s which i n t h e p a s t could not be processed by convent ional a g i t a - t i o n cyanide leaching . A r e c e n t l y i n i t i a t e d opera t ion of ch i s k ind is a t the Candelar ia Mine i n Mineral County, Nevada. Not only has the development of t h e heap l each ing technique made p o s s i b l e recovery of gold and s i l v e r from mining wastes a t t h a t opera t ion ,but is now making p o s s i b l e recovery of t h e prec ious metals from low-grade o r e s t h a t were cons idered waste QT submarginal materials i n t h e p a s t (166).

Reagent The

Some of t h e f i r s t a p p l i c a t i o n s of the process

Curren t ly t h e r e are 42 opera t ions of

I n t h e Republic of South A f r i c a , t he East Rand Gold and Uranium Company (Ergo) ope ra t e s a p l a n t which r ecove r s gold, uranium, and s u l f u r from t h e i r slime dams (155). The s l imes are f i r s t pumped t o a f l o t a t i o n p l a n t where a p y r i t e concen t r a t e i s separa ted a s a f r o t h . t i o n p l a n t i s thickened and t r a n s f e r r e d t o a series of a i r - a g i t a t e d v e s s e l s f o r convent iona l ac id leaching . The leached pulp i s fed t o f i l t e r s t o sep- a ra te t h e uranium-bearing s o l u t i o n from which uranium i s recovered by so lven t e x t r a c t i o n . Af t e r uranium l each ing , t h e gold-bearing p y r i t e concen t r a t e i s re-pulped t o 20 percent s o l i d s and passed i n t o t h r e e 50-foot diameter f l u i d bed r o a s t e r s . S u l f u r i c a c i d i s produced i n t h i s s t e p . F i n a l l y , t h e c a l c i n e from t h e r o a s t e r s i s quenched w i t h water, thickened and t r a n s f e r r e d t o a s tandard cyanida t ion c i r c u i t f o r t h e e x t r a c t i o n of gold.

The concent ra te from t h e f l o t a -

2 . 6 . 5 . 2 Use of T a i l i n g s i n Cons t ruc t ion

S i l i c e o u s mine waste from v a r i o u s types of gold mines w a s s t u d i e d i n o r d e r t o determine t h e use fu lness for product ion of b u i l d i n g materials ( 8 5 ) . It w a s found t h a t autoclaved calcium s i l i ca t e products , such as sand-lime b r i c k s and ae ra t ed l i gh twe igh t conc re t e , could be success fu l ly produced from gold mine waste. sh r inkage , d u r a b i l i t y , and e f f lo re scence . The b r i c k s showed a compressive s t r e n g t h g r e a t e r than 8,000 p s i a t a dens i ty of 127 pcf . The a e r a t e d concrete showed a compressive s t r e n g t h of more than 1,000 p s i a t a d e n s i t y of

These b r i c k s were t e s t e d for compressive s t r e n g t h ,

37 p c f .

I

66

[

i While t h e process f o r b r i c k production has been known f o r y e a r s , i n d u s t r y

i s no t a t t h i s t i m e u t i l i z i n g t a i l i n g s f o r t h i s purpose (166). Generally, nore ccnven t iona l , q u a l i t y c o n t r o l l e d materials are a v a i l a b l e f o r b r i c k manufacture and are t h u s p r e f e r r e d over waste materials. Also due t o t h e t y p i c a l l y remote l o c a t i o n s of gold mines, t r a n s p o r t a t i o n c o s t s can be p r o h i b i t i v e .

One of t he o r i g i n a l a t t empt s t o use mining waste i n road c o n s t r u c t i o n occurred during t h e 1930s i n t h e S t a t e of Colorado and involved t h e use of crushed waste rock and t a i l i n g s from gold mining operat ions. These mater- i a l s were used t o b u i l d t h e so-cal led "Million Do l l a r Highway" from Durango t o S i l v e r t o n . This road i s known as U.S. Route 550 o r Colorado Route 789. I n a d d i t i o n , gold dredge t a i l i n g s are a l s o being crushed and used f o r highway c o n s t r u c t i o n aroundBreckenridgeand F a i r p l a y i n Clear Creek County ( 4 6 ) .

There have been numerous i n s t a n c e s i n which t h e sand and g r a v e l t a i l i n g s from p a s t gold mining ope ra t ions i n C a l i f o r n i a have been s u c c e s s f u l l y used i n highway and o t h e r c o n s t r u c t i o n p r o j e c t s . being processed as commercial aggrega te by two producers i n a ten-square mile area qast of Marysvi l le and n o r t h of Sacramento and in t h e Rancho Cordor- Folsom area east of Sacramento ( 4 6 ) .

Large amounts of t h i s material are

Among t h e s p e c i f i c highway p r o j e c t s i n which gold mine t a i l i n g s have been used f o r c o n s t r u c t i o n i n C a l i f o r n i a are U.S. Route 40 freeway i n P l a c e r County, U.S. Route 50 freeway n e a r P l a c e r v i l l e in E l Dorado County, a p o r t i o n of I n t e r s t a t e Route 80 i n t h e v i c i n i t y of Gold Run and Dutch F l a t i n P lace r County, and t h e r e l o c a t i o n of t h e Fea the r River Highway i n Butte County. has a l s o been r epor t ed that gold t a i l i n g s were used i n the c o n s t r u c t i o n of t h e O r o v i l l e D a m , an e a r t h - f i l l e d dam a mile wide and 770 f e e t h i g h , loca t ed i n Bu t t e County.

I t

A spokesman f o r the C a l i f o r n i a Department of Transportat ion n o t e s t h a t some of t h e raw materials f o r base cour ses , port land cement c o n c r e t e , and a s p h a l t i c conc re t e mixtures used i n t h e cons t ruc t ion of freeways i n t h e me t ropo l i t an Sacramento a r e a have come from t h e t a i l i n g s of p a s t gold mining opera t ions . H e a l s o s ta tes t h a t t h e C a l i f o r n i a Department of T ranspor t a t ion i s concerned pr imarly with s p e c i f i c a t i o n s f o r t h e material f o r highway c o n s t r u c t i o n and no t with t h e s o u r c e of t h e material p e r se ( 4 6 ) .

Gold dredge t a i l i n g s from Cus te r County, Idaho, were used as road base f i l l f o r a f o r e s t s e r v i c e road up t h e Yankee Fork of t h e Salmon Rive r ( 4 6 ) .

For many y e a r s the. South Dakota Highway Department, t h e Lawrence County Highway Department, and t h e C i t y of Lead have a l l made u s e of t h e waste rock produced a t t h e Homestake Mining Company from t h e mining of gold o re . Th i s material has been used mainly as a b a c k f i l l , embankment o r f i l l material, and sub-base, a l though waste rock h a s a l s o been crushed and used i n a paver l a i d Seal c o a t r e s u r f acing p r o j e c t n e a r Lead.

\

67

2 . 7 GRANITE M I N I N G INDUSTRY

2 . 7 . 1 Indus t ry C h a r a c t e r i z a t i o n


The U.S. dimension s t o n e i n d u s t r y c o n s i s t s of approximately 280 companies ope ra t ing about 420 q u a r r i e s i n 42 states, major type of s t o n e produced and accounts for, 4 1 pe rcen t of productioq. Leading a r e a s f o r g r a n i t e product ion are New England aad Georgia (98).

G r a n i t e is t'he

Major c u r r e n t u ses f o r dimension s tone are i n d i r e c t bu i ld ing con- s t r u c t i o n (one - th i rd ) , and monuments (one-half); t h e remainder i s used p r imar i ly i n product ion of rough b locks , and used p a r t l y i n bu i ld ing c o n s t r u c t i o n , rubble,curbing, and f l agg ing . Almost a l l curbing and monuments are made of g r a n i t e (150).

Crushed s t o n e w a s produced by 1,876 companies a t about 4,200 q u a r r i e s i n e v e n s t a t e except Delaware and North Dakota. t i o n , 11 p e r c e n t , or 1 2 2 m i l l i o n tons was g r a n i t e , which w a s qua r r i ed c h i e f l y i n Appalachia (150). Its p r i n c i p a l uses are as an aggregate 784 p e r c e n t ) ; r a i l r o a d b a l l a s t (9 pe rcen t ) ; t e r r a z o and roo f ing granules 33 p e r c e n t ) ; and o t h e r ( 4 p e r c e n t ) ,

Of t h e t o t a l U.S produc-


In 1979, 637,000 tons of g r a n i t e were qua r r i ed i n t h e U.S. Dimension g r a n i t e w a s produced i n 1979 by 85 companies a t 150 q u a r r i e s i n 20 states. Georgia continued t o be t h e l e a d i n g s t a t e , producing 31 percent o r 194,000 tons . Vermont, New Hampshire, 'and Massachusetts combined produced 40 per- c e n t or 251,000 t o n s (150).

Crushed g r a n i t e product ion i n 1979 w a s 122 m i l l i o n tons. It was produced by 140 companies a t 425 q u a r r i e s i n 33 states. crushed g r a n i t e were Georgia, North Carol ina, V i r g i n i a , and South Caro l ina ; t h e s e f o u r s ta tes accounted f o r 75 pe rcen t of U.S. ou tpu t (150). mately 99,000 t o n s of g r a n i t e w e r e e x p o r t e d , p r i n c i p a l l y t o Japan and Canada.

Leading states i n

Approxi-

2.7.1.3 I n d u s t r y Trends

Demand f o r crushed and broken s t o n e is expected t o con t inue i ts slow growth between 1978 and 2000; p r e d i c t e d average annual growth through 2000 i s 2 . 2 percen t compared wi th 2.6 percen t over t h e p rev ious 10 years . A requirement f o r roads i s expected t o con t inue on t h e b a s i s t h a t t h e family automobile and t r u c k hau l ing w i l l con t inue as major elements of s o c i e t y and i n d u s t r y and i n e x p e c t a t i o n of a n inc reased popu la t ion growth caused i n p a r t by immigration. However, road b u i l d i n g i s expected t o cont inue a t a somewhat slower growth r a t e because t h e Fede ra l i n t e r s t a t e highway

system is now n e a r l y complete, and growth i n a l l road r e p a i r I s expected t o be impeded by l i m i t e d f i n a n c i n g a t both Federal and l o c a l l e v e l s (98).

Demand f o r dimension s t o n e i s expected t o i n c r e a s e a t an average rate of 1 . 4 percent pe r y e a r from 1978 t o 2000; t h i s would r e v e r s e t h e average 2.5 percent p e r y e a r d e c r e a s e in demand during t h e previous 20 years . The t rend r e v e r s a l i s based p r i m a r i l y on t h e f a c t s t h a t many alternate b u i l d i n g materials, i nc lud ing c o n c r e t e , aluminum, and steel, are very energy-inten- s i v e , and that p las t ics , a n o t h e r s u b s t i t u t e , are based on petroleum. Current and expected f u t u r e i n c r e a s e s i n t h e cos t of energy may inc rease t h e p r i c e s of t h e s e a l t e r n a t e materials more than that of dimension s tone (98).

2.7.2 Grani te Mining and B e n e f i c i a t i o n Operations

2 . 7 . 2 . 1 Crushed Stone

Most crushed and broken s t o n e i s mined from open q u a r r i e s ; however, l a rge - sca l e product ion by underground mining methods are becoming more frequcnt and more prominent. O r d i n a r i l y in s u r f a c e mining, d r i l l i n g and b l a s t i n g methods are employed for loosening t h e rock body and primary breakage. Secondary breakage inc reas ing ly i s done wi th mechanical equipment such as drop hammers t o minimize b l a s t i n g i n urban and r e s i d e n t i a l a r e a s .

Loading and h a u l i n g equipment has grown larger a s increased demand f o r s tone has made h i g h e r p roduc t ion c a p a c i t i e s necessary.

Crushing and s c r e e n i n g p l a n t s have become l a r g e r and more e f f i c i e n t , and ex tens ive use i s made of b e l t conveyors t o t r a n s f e r material from t h e p i t s t o t h e loading-out areas. Bucket e l e v a t o r s are used f o r l i f t i n g ma- t e r i a l up s t e e p i n c l i n e s . Primary crushing i s o f t e n done a t or nea r t h e p i t , u sua l ly by j a w c r u s h e r s or g y r a t o r i e s , but impact and o the r s p e c i a l types of c rushe r s are becoming more popular f o r nonabrasive s tone, and for s t o n e t h a t t e n d s t o c l o g convent ional c rushe r s . i n g , a v a r i e t y of equipment is used, depending on p l a n t s i z e , rock type , and o t h e r f a c t o r s . t ypes used. Impact types, i n c l u d i n g hammer mills, are o f t e n used where s t o n e i s no t too a b r a s i v e .

For secondary crush-

Cone c r u s h e r s and g y r a t o r i e s are t h e most common

For sc reen ing , i n c l i n e d v i b r a t i n g types are commonly used in permanent i n s t a l l a t i o n s , w h i l e h o r i z o n t a l s c reens are used ex tens ive ly i n p o r t a b l e p l a n t s . For sc reen ing l a r g e s i z e s of crushed s t o n e , heavy punched steel or p l a s t i c p l a t e i s used; woven w i r e screens are used for smaller material.

? i

Storage of f i n i s h e d crushed s tone is u s u a l l y done i n open areas excep t for t h e small q u a n t i t i e s t h a t go t o t h e load-out bins . In t h e l a r g e r and more e f f i c i e n t p l a n t s , t h e s t o n e is d r a m ou t , t h rough tunne l s under t h e s t o r a g e p i l e s , and t h e equipment i s designed t o blend any des i r ed mix tu re of s i z e s t h a t may be needed.

63

2.7.2.2 Dimension Stone I I

Present mining methods range from an t iqua ted and very i n e f f i c i e n t t o modern and t e c h n i c a l l y s u p e r i o r . Quarrying methods inc lude use of v a r i o u s combinations of diamond saws, w i r e s a w s , channeling machines, d r i l l i n g machines, wedges, and broaching t o o l s . The choice of equipment depends on t h e type of dimension s t o n e , s i z e and shape of d e p o s i t , product ion c a p a c i t y , l a b o r c o s t s , economics, and management a t t i t u d e s .

L i t t l e b l a s t i n g is done i n t h e mining of dimension stone. Blocks c u t from t h e f a c e are sawed o r s p l i t i n t o smaller blocks f o r ease i n t r a n s p o r t a t i o n and handl ing and taken t o processing p l a n t s , o f t e n l o c a t e d a t t h e quarry s i t e , f o r f i n a l c u t t i n g and f i n i s h i n g operat ions.

Stone-f inishing equipment inc ludes l a r g e c i r c u l a r s a w s 10 f e e t o r more i n diameter , some wi th diamond i n s e r t s and some us ing steel s h o t , o r o t h e r a b r a s i v e s ; diamond c i r c u l a r s a w s of smaller s i z e ; r e c i p r o c a t i n g diamond- bladed or loose-abrasive gang s a w s f o r m u l t i p l e c u t s ; and va r ious types of diamond and o t h e r equipment f o r smoothing, po l i sh ing , edging, and decora t ing t h e f b i s h e d s tone products . s k i l l e d craftsmen us ing a v a r i e t y of methods inc lud ing pneumatic c u t t i n g t o o l s and s p e c i a l s a n d b l a s t i n g techniques.

The f i n a l deco ra t ing is o f t e n done by hand by

2.7.3 Waste Stream C h a r a c t e r i z a t i o n and Quan t i f i ca t ion

2 . 7 . 3 . 1 Crushed Stone

Gran i t e f i n e s are a waste product from quarrying and c rush ing o p e r a t i o n s . Exact f i g u r e s f o r t h e amounts of g r a n i t e f i n e s generated yea r ly are unavai l - a b l e , bu t t h e estimates are measured i n the m i l l i o n s of tons.

Chemical a n a l y s i s of a t y p i c a l waste g r a n i t e fine i s presented i n Table 2-9.

Table 2-9

CHEMICAL ANALYSIS OF GRANITE FINES

C o n s t i t u t e n t

N a Z O

K2°

sio2

CaO

A1203

Fe203 _.

MgO Loss on I g n i t i o n Other

Percent age

3.3 4.8

1.0 14.1

73.9 2.3 0.2 0.2 0.2

70

2.7.3.2 Dimension Stone

The most voluminous waste strearn generated i n t h e production of g r a n i t e dimension s tone i s t h e s ludge produced i n t h e c u t t i n g and p o l i s h - i n g of t h e s tone. The s ludges are gene ra l ly s to red i n ponds.

Chemical a n a l y s i s of a t y p i c a l sludge showed 77.1 percent silicon The s i l i c o n c a r b i d e i s used as a p o l i s h i n g agent and as g r a i n ca rb ide .

i n w i r e sawing. The S i c p a r t i c l e s , suspended i n water , are dragged between t h e w i r e and s tone t o do t h e a c t u a l c u t t i n g .

Amounts of t h i s waste product generated annually are no t a v a i l a b l e .


None of t h e waste materials generated i n t h e production of g r a n i t e s t o n e i s p o t e n t i a l l y hazardous.

2 . 7 . 5 Resource Recovery Technology Descr ipt ions

2 . 7 . 5 . 1 Mineral Recovery from F ines

continuous f l o t a t i o n processing tes ts on waste g r a n i t e f i n e s from Georgia t o determine t h e f e a s i b i l i t y of recovering usab le f e l d s p a r and q u a r t z products by f l o t a t i o n (59).

The Bureau of Mines conducted l abora to ry batch- and small-scale

Two f l o t a t i o n methods w e r e u t i l i z e d f o r t h e removal of b i o t i e and o t h e r i ron-bearing minerals : One w a s i n an ac id -ca t ion ic c i r c u i t , and t h e o t h e r i n an a lka l ine -an ion ic -ca t ion ic c i r c u i t . u s i n g an ac id -ca t ion ic method. q u a r t z products i t w a s necessa ry t o employ e i t h e r two s e q u e n t i a l f r o t h f l o t a t i o n c i r c u i t s o r one f r o t h f l o t a t i o n c i r c u i t supplemented by w e t - magnetic s e p a r a t i o n techniques t o remove i r o n contaminants.

Feldspar w a s recovered To produce commercial-grade f e l d s p a r and

I

Continuous f l o t a t i o n p rocess ing yielded a commercial-grade f e l d s p a r c o n c e n t r a t e con ta in ing , i n p e r c e n t , 3 . 8 Na20, 5.4 K20, and 1.10 CaO, w i t h r e c o v e r i e s of 77.8, 70.3, and 6 4 . 4 , r e spec t ive ly . The f e l d s p a r t a i l i n g w a s high-qual i ty g l a s s sand c o n t a i n i n g 98.2 percent Si02 and 0.024 per- c e n t Fe203. About 42 percen t of t h e qua r t z w a s recovered a t g l a s s sand s p e c i f i c a t i o n s . An e f f e c t i v e s e p a r a t i o n of potash f e l d s p a r from t h e b u l k f e l d s p a r c o n c e n t r a t e w a s achieved by batch f l o t a t i o n i n a mineral separa- t i o n cel l .

Cur ren t ly one crushed s t o n e o p e r a t i o n near A t l a n t a , Georgia i s recovering f e l d s p a r from t h e i r crushed s t o n e f i n e s (174).

2 . 7 . 5 . 2 S i l i c o n Carbide Recovery from Sludge

The Bureau of Mines conducted l a b o r a t o r y b a t c h b e n e f i c i a t i o n tests on a waste g r a n i t e s ludge from New Hampshire t o determine t h e f e a s i b i l i t y o f recovering a r e u s a b l e s i l i c o n c a r b i d e product (60). The g r a n i t e s ludge responded t o a t t r i t i o n scrubbing, desl iming, and f l o t a t i o n i n e i t h e r alka- l i n e or ac id c i r c u i t s u s ing f a t t y a c i d as a c o l l e c t o r . Recovery of over 80 percent of t h e contained s i l i c o n c a r b i d e a t grades of up t o 96 p e r c e n t S I C w a s obtained.

Thomas Llewellyn of t h e USBM, t h e au tho r r e p o r t i n g these f i n d i n g s , does not know of any company p r a c t i c i n g t h i s t ype of recovery a t p r e s e n t due t o t h e i n c o n s i s t e n t composition of t h e s ludge. The process has been used commercially, according t o W. E. Lamont, by S i l i c o n Corporation in E lbe r tdn , Georgia, but i s not be l i eved t o be o p e r a t i n g a t p re sen t (170, 175) .

7 2

2.8 IRON ORE M I N I N G

2.8.1 Industry C h a r a c t e r i z a t i o n

2.8.1.1 Indus t ry S t r u c t u r e (98)

In 1979, i r o n o r e w a s produced in t h e United S t a t e s by 30 companies ope ra t ing 49 mines, 38 c o n c e n t r a t i o n p l a n t s , and 20 p e l l e t i z i n g p l a n t s . I n a d d i t i o n , t h r e e companies produced by-product ore . The mines included 45 open p i t s and 4 underground mines, w i th t h e open p i t s account ing f o r more than 98 pe rcen t of t o t a l o u t p u t of u sab le ore. c e n t of t o t a l output w a s produced from 18 mines operated by 8 companies. About 80 percent of t h e ou tpu t of u sab le o r e w a s produced bv o r f o r t h e account of U.S. companies engaged i n product ion of i r o n or steel .

Approximately 88 per-

In 1979 domestic shipments of u sab le o r e were valued a t $2.8 b i l l i e n (f .0.b. mine), and t h e i n d u s t r y employed about 21,000 workers i n mines and a t

o r by i n

concen t r a t ing p l a n t s .

U.S. imports of i r o n o r e i n 1979 were mostly from mines owned, ope ra t ed , p a r t i a l l y owned by domestic companies. t h e United S t a t e s w a s d e s t i n e d for Canadian s teel companies p a r t i c i p a t i n g U.S. mining p r o j e c t s .

V i r t u a l l y a l l i r o n o r e exported

U.S. companies own about 70 pe rcen t of Canadian production capac i ty f o r i r o n o r e . U.S. companies a l s o had s i g n i f i c a n t minori ty ownership of i r o n o r e mining ope ra t ions i n A u s t r a l i a , New Zealand, L i b e r i a , and B r a z i l .


Iron o r e i s t h e primary source of i r o n , t h e metal most widely used by man. World i r o n ore product ion i n 1979 w a s es t imated a t 887 m i l l i o n t o n s , and an est imated 370 m i l l i o n t o n s w a s shipped in i n t e r n a t i o n a l t r a d e .

The United S t a t e s i s a major consumer of i r o n ore . It i s the w o r l d ' s f o u r t h l a r g e s t producer and a major importer. t h i r d of t h e primary i r o n needed by t h e U.S. steel indus t ry . 85,716,000 t o n s of i r o n o r e w a s produced i n t h e United S t a t e s . sumption, i nc lud ing imports and agglomerates,was 125.4 m i l l i o n tons (98, 150) .

Imports supply about one- In 1979,

T o t a l con-


increase a t a ra te of 1 .4 p e r c e n t p e r y e a r , and a t 2.8 pe rcen t p e r y e a r i n t h e rest of t h e world. U.S. and world o r e reserves are ample t o supply t h i s demand. U.S. product ion of i r o n i n o r e is expected to i n c r e a s e t o 85 m i l l i o n s h o r t t o n s i n 1990, a 42 pe rcen t i n c r e a s e compared w i t h p roduc t ion i n 1979 (98).

Demand f o r primary i r o n i n t h e United S t a t e s t o 2000 i s f o r e c a s t t o

2 . 8 . 2 I ron Ore Mining and Bene f i c i a t ion Operations

The choice of mining method depends on t h e s i z e , s t r u c t u r e , and a c c e s s i b i l i t y of an o r e body. Most i r o n ore i s mined i n open p i t s because most commercial o r e bodies l i e c l o s e t o t h e s u r f a c e and t h e i r l a t e r a l dimensions a r e l a r g e . R e l a t i v e l y narrow, s t e e p l y dipping, or deeply buried o re bodies are mined by underground methods, bu t t h e rela- t i v e l y high c o s t and l i m i t e d product ion capac i ty of underground mines has s t e a d i l y reduced t h e i r a b i l i t y t o compete wi th open p i t opera t ions . Mining i n most open p i t s is done by b l a s t i n g the o re body and haul ing and digging w i t h l a r g e power shovels and t r u c k s w i t h c a p a c i t i e s of 35 tons t o 150 tons.

The o b j e c t i v e of b e n e f i c i a t i n g high-grade i r o n o res is pr imar i ly t o o b t a i n close>] s i zed p roduc t s , a l though some processes are designed t o improve t h e i r o n con ten t as w e l l . grade ores i s p r imar i ly t o raise t h e i r o n conten t by concent ra t ion of i r o n mine ra l s and e l imina t ion of gangue. Benef ic ia t ion is accomplished by c rush ing , sc reening , washing, and t h e use of g r a v i t y , magnetic, f l o t a t i o n , o r o the r methods; t h e process used depends on t h e phys ica l and minera logica l cha rac t - e r i s t i c s of t h e o re . f o r success ive s t a g e s of concen t r a t ion of one mineral or t o concent ra te s e v e r a l minera ls .

The ob jec t ive of b e n e f i c i a t i n g lower

S e v e r a l processes may be used i n t h e same p l a n t ,


The mining of i r o n ore produces an amount of waste rock and overburden almost equal t o t h e amount of o r e obtained. According t o t h e Bureau of Mines (150) i n 1978, 2 6 2 m i I l i o n t o n s of i r o n o re were produced, genera t ing 277 m i l - l i o n tons of mine waste. Over 180 m i l l i o n tons of waste were produced i n 1978 a t processing si tes a r i s i n g from t h e processing of t h e 262 m i l l i o n tons of i r o n ore (150). Overa l l accumulations are est imated a t approxi- m a t e l y 4 b i l l i o n tons over t h e p a s t t h i r t y yea r s (144).

Processing of t h e o r e produces both coarse and f i n e t a i l i n g s comprising about 60 t o 70 percent of t h e t o t a l output . Coarse t a i l i n g s are material mostly i n t h e 4 t o 100 mesh sieve s i z e range, which i s composed predaninant ly of s i l i c a and i r o n oxides . The f i n e t a i l i n g s are discharged as a s l u r r y of 45 percent solids con ten t w i t h 85 t o 90 percent of t h e p a r t i c l e s smaller than a 325 mesh s ieve . The chemical a n a l y s i s of a t y p i c a l t a i l i n g is shown i n Table 2-10 (144) .

7 4

Table 2-10

Compos i t ion

S i l i c a ( S i 0 2 )

Alumina (d2O3)

I r o n (Fe)

Magnesium (MgO)

Calcium (CaO)

Loss on I g n i t i o n

CHEMICAL ANALYSIS OF TRON ORE TAILINGS

Other


Percentage

59.0

2.7

15.0

3.7

2 . 7

7.4

9.5

2.8.4 P o t e n t i a l Hazardous Waste S t r e a s

None of t h e waste m a t e r i a l s generated i n t h e mining and processing of i r o n o r e i s considered p o t e n t i a l l y hazardous.


2 .8 .5 .1 Retreatment of T a i l i n g s

I n 1966, t he I ron Ore Company of Canada commissioned a w e t magnetic scavenging p l a n t 'for t h e recovery of f i n e magnet i te values p re sen t in i r o n o r e s p i r a l t a i l i n g s discharged from a s p i r a l g r a v i t y sepa ra t ion p rocess . The p l a n t i nc ludes dewatering, g r ind ing , c l a s s i f i c a t i o n , thickening, mini - wedge sc reen ing , and primary, secondary, and t e r t i a r y w e t magnetic separa- t i o n s t a g e s . o r i g i n a l design included v a r i a b l e o p e r a t i o n a l procedures t o dea l w i t h t h e s e c o n d i t i o n s ( 9 2 ) . The p l a n t has performed very s a t i s f a c t o r i l y , r ecove r ing 85 t o 90 pe rcen t of t h e magnet i te i n t h e t a i l i n g s .

The sources of f eed varies i n q u a n t i t y and q u a l i t y , so t h e

I n another r e t r ea tmen t method, a l a r g e pneumatic c l a s s i f i e r o p e r a t i n g i n t h e Sahara d e s e r t on t h e w e s t c o a s t of A f r i c a processes some 1,200 tons p e r hour of i r o n o r e t a i l i n g s (56). The g r a v i t a t i o n a l - i n e r t i a l c l a s s i f i e r s e p a r a t e s undesirable minus 100 mesh f i n e s from t h e minus one-half i n c h o r e t h a t remains a f t e r t h r e e c rush ing and screening operat ions. O f t h e minus one-half i nch t a i l i n g s , approximately 72 percen t are p lus 100 mesh, f o r which t h e r e i s a market i f t h e f i n e s are removed. This c l a s s i f i e r , suppl ied by Combustion Equipment Assoc ia t e s , I n c . of New York, makes i t economically f e a s i b l e t o salvage this s i z e a b l e p l u s 100 mesh f r a c t i o n of r i c h i r o n o re .

75

I n a U.S. p a t e n t , No. 4,192,738, a p rocess for scavenging i r o n from t a i l i n g s produced by f l o t a t i o n b e n e f i c i a t i o n i s descr ibed. Basc ia l ly t h e i r o n i s scavenged from t h e t a i l i n g s by m e a n s of a w e t h igh - in t ens i ty mag- n e t i c s e p a r a t o r , whereby a magnetic c o n c e n t r a t e of increased i r o n con ten t and a magnetic t a i l i n g s of reduced i r o n con ten t are obtained (51).

I 2.8.5.2 Aggregate Use

Coarse t a i l i n g s from i r o n ore mining a t Eagle Mountain i n R ive r s ide County, C a l i f o r n i a were used as aggrega te for t h e bituminous paving mix placed on a new county road i n t h e v i c i n i t y of Eagle Mountain during 1974. These t a i l i n g s have a l s o been used as aggregate f o r conc re t e s t r u c t u r e s b u i l t during t h e c o n s t r u c t i o n of I n t e r s t a t e Route 1 0 and as concrete ag- g r e g a t e f o r i n d u s t r i a l c o n s t r u c t i o n p r o j e c t s ( 4 6 ) .

I ron o r e t a i l i n g s from t h e M t . Hope area i n Morris County, New J e r s e y have been used i n t h e p a s t as a dense aggrega te i n conc re t e and a s p h a l t paving mixtures. The t a i l i n g material used w a s a g r a n i t i c gneiss . No information i s a v a i l a b l e on t h e performance of pavements containing t h i s t a i l i n g m a t e r i a l . The mine which provided t h e m a t e r i a l i s not i n o p e r a t i o n a t t h e present t i m e ( 4 6 ) .

Coarse i r o n ore mine t a i l i n g s from Jackson County, Wisconsin w e r e crushed and shipped t o an a s p h a l t producer f o r u se as aggregate i n a b i t - uminous paving mixture on U.S. Route 141 i n t h e metropol i tan Milwaukee area ( 4 6 ) .

The coarse f r a c t i o n or i r o n o r e t a i l i n g s from United S t a t e s S t e e l Company's A t l a n t i c C i ty mine i n Fremont County, Wyoming have been sepa ra t ed and used by t h e Wyoming Highway Department f o r sanding i c y roads and a l s o as a patching material f o r nearby s ta te highway maintenance e f f o r t s . m a t e r i a l has also been used on mine h a u l roads (46).

This

The term t a c o n i t e was o r i g i n a l l y app l i ed to the hard, f ine-grained, The term is now o f t e n banded iron-bearing formation of t h e Mesabi range.

used t o d e s c r i b e similar rocks i n o t h e r areas, such as "low grade d e p o s i t s of t h e t a c o n i t e type." f a i r l y widespread, and i t i s f o r t h i s reason that t a c o n i t e t a i l i n g s use i s included here.

The use of t a c o n i t e t a i l i n g s f o r aggregate h a s been

76

The primary use of t a c o n i t e t a i l i n g s is f o r t h i n s u r f a c e over lays of one inch or less i n th i ckness . The s e r v i c e a b i l i t y of t h e s e t a c o n i t e over- l a y s has been excep t iona l . It has been found that t h e use of coarse taco- n i t e t a i l i n g s d e f i n i t e l y improves t h e sk id r e s i s t a n c e of pavements in which i t i s used. I n t h e f u t u r e , t a c o n i t e t a i l i n g s may be s p e c i f i e d as t h e s o l e m a t e r i a l used f o r s u r f a c e ove r l ays because of t h e i r sk id r e s i s t a n c e qual i t ies ( 4 6 , 4 9 ) .

During 1975, approximately 60,000 tons of t a c o n i t e t a i l i n g s w e r e u t i l i z e d i n va r ious s t a t e highway and br idge deck r e su r fac ing p r o j e c t s throughout Minnesota, i nc lud ing s e v e r a l i n t h e Minneapolis and Duluth met ropol i tan areas. An a d d i t i o n a l 23,000 tons w e r e used i n 1975 on Inter- s t a t e Routes 35-E and 35-W i n t h e Minneapolis-St. Paul area ( 4 6 ) . Coarse t a c o n i t e t a i l i n g s have been used i n Minnesota as embanhnent f i l l , base and sub-base m a t e r i a l , and i n bituminous mixtures . The Department of Eiighvays has allowed t h e use of t h e s e t a i l i n g s a s an a l ternate t o sand and g rave l a t t h e c o n t r a c t o r ' s op t ion . The main d i f f i c u l t y i n using t a c o n i t e t a i l i n g s as a base or sub-base material is t h e l a c k of cohesiveness of t he material. The so lu t ion has been t o keep t h e t a i l i n g s i n a moist cond i t ion and t o s ta - b i l i z e ' t h e top t h r e e inches of t h e material wi th an a spha l t emulsion (46) .

Taconite t a i l i n g s have been developed i n t o f i r e d l igh tweight b locks us ing foarcing techniques . f o o t , depending on t h e amount of foaming agent introduced i n t o t h e mix (158).

D e n s i t i e s ranged from 25 t o 95 pounds per c u b i c

Use of carbonate bonding procedures have been appl ied t o t a c o n i t e t a i l i n g s i n the same way as t h e a p p l i c a t i o n s t o c o a l re fuse . High com- p r e s s i v e s t r e n g t h s on the o r d e r of 4,400 p s i have been recorded on sta- b i l i z e d mixtures. The u s e of t h e s e bonded t a i l i n g s i s suggested f o r road bu i ld ing m a t e r i a l , road aggrega te and/or i n t h e p repa ra t ion of b r i c k s (144, 159).

For many y e a r s , Lou i s i ana had used a very low-grade i r o n o re as a f l e x i b l e base cour se l a y e r f o r secondary roads. a v a i l a b l e sources , i t s u s e w a s d i scont inued over t e n yea r s ago. are large resenres of t h i s material i n northwest Louis iana, bu t i t i s n o t considered economical t o develop ( 4 6 ) .

Due t o dep le t ion of There

The waste rock from i r o n mining ope ra t ions in the western p o r t i o n of t h e Upper Peninsula of Michigan have been used i n highway cons t ruc t ion . During 1962 and 1963 several hundred thousand tons of t h i s material w e r e used f o r swamp b a c k f i l l , embankment, and sub-base in t h e cons t ruc t ion of U.S. Route 2 from Ironwood t o Bessemer in Gogebic County.

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I n Missouri , coa r se w a s t e rock from the now closed I r o n Mountain underground i r o n mine w a s s o l d t o an aggregate producer, who crushes and sel ls approximately 125,000 tons pe r year of this material f o r u se as s k i d - r e s i s t a n t aggrega te f o r bituminous paving i n Missouri and I l l i n o i s . The waste rock i s t r a p rock, crushed t o meet s tandard s p e c i f i c a t i o n s i z e requirements f o r aggregate . Trap rock sand is a l s o produced from t h i s rock f o r u se i n conc re t e mixtures ( 4 6 ) .

Waste rock from i r o n mining has been used in a number of highway con- s t r u c t i o n p r o j e c t s i n Pennsylvania. k'aste rock from Bethlehem S t e e l Company's Cornwall i r o n o r e m i n e i n Lebanon County was processed and used as commercial aggrega te f o r t h e cons t ruc t ion of t h e Pennsylvania Turnpike eastward from Carlisle t o King of P russ i a during 1950. The material used w a s a l imes tone intermixed wTth some magnetite. The mine has been c losed s i n c e 1972 , but some waste rock i s s t i l l a v a i l a b l e ( 4 6 ) .

Waste rock from Bethlehem S t e e l Company's Grace i r o n o r e mine i n Berks County i s p r e s e n t l y being processed by a c o m e r c i a l aggregate producer as a h igh ly s k i d - r e s i s t a n t aggrega te . This aggregate w a s used i n t h e bituminous r e s u r f a c i n g of t h e Pennsylvania Turnpike from Morgantown t o Val ley Forge i n 1974.

The New York S t a t e Department of Transpor ta t ion r e p o r t s that w a s t e rock from t h e mining of i r o n o r e and t i t an ium have been used since 1930 f o r b i - tuminous and po r t l and cement conc re t e pavements. i n Essex and S t . Lawrence Counties and have been used i n a r e a s t h a t are loca t ed c lose t o t h e mining o p e r a t i o n s ( 4 6 ) .

These m a t e r i a l s occur l a r g e l y

78

?

2.9 LEAD M I N I N G INDUSTRY

Lead i s one of t h e most u s e f u l of t h e nonferrous metals. I n terms of tonnage used, i t ranks a f t e r aluminum, steel , copper, and z inc . Its major u s e s are s to rage b a t t e r i e s , as an ant iknock a d d i t i v e i n gaso l ine , and i n m a t e r i a l s for t h e cons t ruc t ion and metalworking i n d u s t r i e s . Other uses inc lude ammunition, p a i n t s , and e lec t r ica l cab le shea th ing .

2 .9 .1 Indus t ry Charac t e r i za t ion


The domestic n in ing i n d u s t r y i s composed of about 25 i n d i v i d u a l mines i n seven s t a t e s , Lead output from t h e s e mines ranges from l e s s than 1 ton to over 100,000 tons annual ly . E igh t mines i n Missouri produced 90 percent of t h e t o t a l domestic lead mine ou tpu t i n 1979. Idaho con t r ibu ted 8 percent t o t h e t o t a l and t h e remaining 2 p e r c e n t w a s d iv ided among small opera t ions i n Colorado, V i rg in i a , New York, Montana, and Arizona ( 9 8 ) .

2.9.1.2 Product ion S t a t i s t i c s

Lead resources are widely scattered throughout t h e world. The United S t a t e s has t h e l a r g e s t r e s e r v e s of l e a d and accounted f o r 15 percent of t h e

l ead i s recovered from complex o r e s conta in ing z inc , s i l v e r , and o f t e n copper. Except f o r t h e depos i t s i n s o u t h e a s t Missouri , t h e va lue of a s soc ia t ed metals o f t e n exceeds t h e va lue of t h e l ead .

. world t o t a l mine product ion i n 1979. Most of t h e wor ld ' s mine product ion of

The L h i t e d S t a t e s i s t h e wor ld ' s l ead ing producer of l ead and a l s o t h e l ead ing consumer. The U.S.S.R. i s ranked second, followed by Canada, Japan, Mexico, and Aus t r a l i a . U.S. mine o u t p u t of recoverable l e a d was 579,300 s h o r t tons i n 1979. This p roduc t ion f i g u r e r e p r e s e n t s t h e f i f t h consecut ive annual d e c l i n e from t h e record h igh level of 663,900 tons achieved i n 1974. I n r e c e n t yea r s , domestic p roduc t ion from lead and lead-zinc mines has m e t ove r 70 percent of t o t a l U.S. pr imary demand f o r l e a d ; the remainder came from imported materials. T o t a l p roduct ion , inc luding b o t h primary and secondary metal from domestic sources , w a s about 84 percent of t o t a l i n d u s t r i a l demand.

Because of t h e re la t ive ease of reclamation, a l a r g e p a r t of t h e l ead consumed i n f a b r i c a t e d metal p roduc t s i s recovered by secondary smelters from recyc led scrap . I n r ecen t y e a r s , l e a d reclaimed from o ld s c r a p materials h a s averaged about 55 pe rcen t of t o t a l l ead consumption.


Based on contingency assumptions of t he growth f o r major end uses t o 2000, a range of p o s s i b l e domestic demand f o r primary l ead i n 2000 i s f o r e c a s t as 948,000 t o 1 .4 mi l l i on s h o r t tons , compared w i t h 805,000 tons i n 1979. A f o r e c a s t of probable primary demand of 1.1 m i l l i o n tons i n d i c a t e s an average

79

annual growth of 1 . 2 pe rcen t from 1978 t o 2000. of demand i s expected t o be con t ingen t p r imar i ly on t h e f u r t h e r expansion of l ead used in s t o r a g e b a t t e r i e s . Fac to r s f avor ing the low l e v e l of demand are t h e continued d e c l i n e i n t h e use of l ead i n gaso l ine and s u b s t i t u t i o n of o t h e r metals o r p l a s t i c s f o r l ead i n c o n s t r u c t i o n materials and e l e c t r i c a l c a b l e . Current domestic r e s e r v e s con ta in ing about 30 m i l l i o n tons are ade- qua te t o support t h e probable cumulat ive domestic primary demand during 1978 t o 2000 of 21.5 m i l l i o n tons. Rest-of-world demand f o r primary lead in 2000 i s f o r e c a s t t o range from 4.6 m i l l i o n t o n s t o 6 .1 m i l l i o n t o n s , compared w i t h 2 . 6 m i l l i o n tons i n 1978. Rest-of-world r e s e r v e s , estimated a t 110 m i l l i o n t o n s , are more than adequate t o m e e t t h e probable cumulative f o r e c a s t demand t o 2000 (98).

The cont inuing high l e v e l

2 . 9 . 2 Lead Mining and B e n e f i c i a t i o n Operations

I n most lead mines, t h e o r e is composed of a combination of l e a d and z inc s u l f i d e s and t h e c o n c e n t r a t o r s recover both l ead and z inc concen t r a t e s . Lead is der ived from o res varying widely i n l ead con ten t , from v i r t u a l l y z inc-free l e a d o r e s i n Missouri , through t h e lead-zinc o r e s of t h e western s t a t e s ; t o nea r ly l ead - f r ee z i n c o r e s of t h e eastern U.S.

Except f o r a few mining o p e r a t i o n s s c a t t e r e d throughout t he world, almost a l l of t h e l ead and lead-zinc o r e s are produced from underground mines. I n t he sou theas t Missouri l e a d d i s t r i c t , t h e common mining method i s a room-and-pillar s y s t e m w i t h a c c e s s by v e r t i c a l s h a f t s . D r i l l i n g f o r breaking the o r e i s done by s e l f - p r o p e l l e d rubber- t i red v e h i c l e s c a l l e d jumbos ca r ry ing two o r t h r e e pe rcuss ion d r i l l s . Haulage from f a c e t o s h a f t i s by load-haul-dump (LHD) rubbe r - t i r ed u n i t s or by a combination of LHD equipment and s u b l e v e l t r a c k haulage t o s h a f t pockets. Most of t h e mines i n western s t a t e s use sh r inkage , c u t - a n d - f i l l , and timbered s top ing methods. However, those i n n o r t h e a s t e r n Washington, where t h e ore bodies are s t ra t i - form, are amenable t o t h e same methods used i n Missouri .

Crushing invo lves a combination of j a w and gyratory c r u s h e r s w i t h g r i z z l y b a r s , s c r e e n s , and conveyors f eed ing i n t o f ine-ore s t o r a g e b i n s . Some mines wi th c e n t r a l l y l o c a t e d v e r t i c a l s h a f t s employ underground c r u s h e r s t o make t h e f i r s t s i z e r e d u c t i o n . Rodmills are commonly used as a f i r s t s t e p i n g r ind ing because they have less tendency t o overgrind t h e r e l a t i v e l y s o f t and f r i a b l e galena. m i l l s i n c losed c i r c u i t w i t h hydrocyclones t o p repa re a feed f o r f l o t a t i o n . Reagents are added a t v a r i o u s p o i n t s i n t h e g r ind ing and cond i t ion ing system.

Fine g r ind ing i s performed by b a l l

I

!

80

F l o t a t i o n i s t h e major concen t r a t ion method used t o recover l ead and z i n c concen t r a t e s . Most l e a d , lead-zinc o r copper-lead-zinc m i l l s have two o r more s t a g e s of f l o t a t i o n cel ls . The number and v a r i e t y of t h e cel ls are determined by t h e design c a p a c i t y of t h e m i l l and t h e mineralogy of t h e o r e . Some m i l l s a re arranged s o t h a t t he c i r c u i t s can be changed t o accommodate. changes i n t h e c h a r a c t e r of t h e feed.

P reconcen t r a t ion by g r a v i t y methods has been used on some o r e s that c o n t a i n r e l a t i v e l y c o a r s e minerals e a s i l y broken f r e e a t an e a r l y s t a g e i n t h e crushing-grinding ope ra t ions . This s t e p c o n s i s t s of j i g s o r heavy- media ( s i n k - f l o a t systems placed ahead of t h e f ine-gr inding p a r t of t h e c i r c u i t . The purpose i s t o remove a p a r t of t h e w a s t e rock from t h e c i r - c u i t ahead of g r ind ing and f l o t a t i o n and, i n e f f e c t , t o i nc rease t h e ca- p a c i t y of t h e system and reduce t h e c o s t of g r ind ing and f l a t a t i o n p e r t o n of m i l l heads.

2.9.3 Waste Stream C h a r a c t e r i s t i c s and Quan t i f i ca t ion

Approximately 11.1 m i l l i o n s h o r t tons of wastesweregenerated by t h e l e a d mining i n d u s t r y i n 1978. waste rock and 8.8 m i l l i o n tons of t a i l i n g s (150).

These wastes included 2 . 3 m i l l i o n t o n s of

The n a t i o n a l r a t i o of waste rock t o o r e shows that 0.24 tons of waste rock w a s mined f o r every ton of o r e (150). T h i s r a t i o can vary from mine t o mine. One reason f o r t h i s v a r i a t i o n i s t h e age of t he mine. The mines w i t h t h e h i g h e s t r a t i o of waste rock t o o r e are gene ra l ly the newer mines. Very l i t t l e waste rock i s brought t c t h e s u r f a c e i n the o l d e r mines because t h e rock i s used underground f o r mine roads (151).

The r a t i o of o re t r e a t e d t o l ead produced is 17,9 t o 1 3150). This means t h a t 17 .9 t ons of t a i l i n g s a r e generated for each marketable ton of l ead produced. Analyses of some t y p i c a l lead-zinc concentrator t a i l i n g s are shown i n Table 2-11 and Table 2-12. Var i a t ions i n this r a t i s between c o n c e n t r a t o r p l a n t s a l s o e x i s t . The v a r i a t i o n s are r e l a t e d t o o r e grade, p e r c e n t of l e a d and z i n c , and o t h e r metals p r e s e n t i n t h e ore , r a t h e r t han t o d i f f e r e n c e s i n recovery methods and d i s p o s a l of by-product materials by t h e mine. t h e d i f f e r e n c e i n t h e mines, w e t ve r sus dry mines. t i n u a l l y pump water out of t h e mine t o be a b l e t o operate, while o t h e r mines are r e l a t i v e l y dry. A l l of t h e water i s pumped t o t h e t a i l i n g s pond w i t h t h e c o n c e n t r a t o r wastes.

V a r i a t i o n s between w e t and d r y concen t r a to r wastes r e g l e c t Some m i n e s must con-

Pumping of a c i d mine water t o t h e t a i l i n g s pond is considered t o be a poor p r a c t i c e , t h u s many companies use a treatment p l a n t t o treat t h e mine water b e f o r e i t i s pumped i n t o t h e pond. N e u t r a l i z a t i m of the mine water - .

b e f o r e adding i t t o t h e t a i l i n g s pond w i l l h e l p t o prevent hazardous materials from l each ing out of t h e pond. d r a s t i c a l l y

The s o l u b i l i t y of t h e metals reduced by r a i s i n g t h e pH of t h e t a i l i n g s s l u r r y t o above -_

is 8 .

Table 2-11

!

ANALYSIS OF TAILINGS FROM LEAD-ZINC MINES AND CONCENTRATORS (CONCENTRATION 'IN PPM)

Concentrator Concentrator Concentrator Concentrator 1 2 3 4 Background El emen t

Calcium 1,549 3 ,279 2,524 1 , 598 1 , 500

19.2 20.9 - Cadmium 8.5 6 .3

Copper 71.6 72.5 1 3 6 1 1 7 . 8 21

Iron 76,708 59,813 88,917 1 1 3 , 667 11,800

Pot ass ium 335 406 4 22 28 7 1,800

Magnesium 2,460 2 ,482 3 , 7 8 1 2,680 3 ,700

Manganese 5,527 5 , 9 3 2 9 ,123 10 , 154 4 90

Sodim 92 69 75 6 9 1 5 1

Lead 2,302 2,624 4 , 380 4,462 51

Antimony 365 360 3 90 1 , 4 6 3 - Zinc 2,057 1 , 3 1 6 3 , 547 3,366 1 5 0


82

i

Cons t i tuen t

S io2

Fe203

A12°3

M@

CaO

Na 2O

K2°

L o s s on I g n i t i o n

Table 2-12

OXIDE ANALYSIS OF LEAD-ZINC TAILING

Percentage

9.8

1.1

0.3

17.8

29.4

42.0



T a i l i n g s from a l l lead-zinc concen t r a to r p l a n t s are c l a s s i f i e d as p o t e n t i a l l y hazardous wastes which r e q u i r e d i s p o s a l safeguards t o prevent environmental contamination. The concen t r a t e s from ores c o n t a i n i n g p y r i t e are gene ra l ly considered t o be more hazardous, so s p e c i a l care must be taken i n t h e i r d i s p o s a l (151). A pre l imina ry d r a f t r e p o r t by t h e U.S. Environmental P r o t e c t i o n Agency on hazardous waste (152) i n d i c a t e d elevated l e v e l s of l e a d , z i n c , mercury, cadmium, chromium, selenium, and s i l v e r i n l e a d / z i n c t a i l i n g s . Concentrat ions of waste c h a r a c t e r i s t i c des igna t ions were given as fo l lows ,

'- I i I

EP Tox ic i ty . Concentrat ions of one o r more metals in l i q u i d s or acid e x t r a c t s of s o l i d materials w i t h i n t h e t a i l i n g s ponds and waste rock dumps are more than 10 times s p e c i f i e d i n "primary drinking water standards" (PDWS) .

83

C o r r o s i t i v i t y . Liquids wi th in t h e t a i l i n g s ponds have a pH between 3 and 4; s o l i d s h a v e a p o t e n t i a l a c i d i t y of g r e a t e r than 500 b u t less than 5,000 pg ca rbona te /g of materials.

Because of t h e great p o t e n t i a l f o r migrat ion of t h e heavy metals from t h e s e t a i l i n g s , t h i s d i sposa l p r a c t i c e is rece iv ing comprehensive s tudy from t h e Environmental P r o t e c t i o n Agency.


2.9.5.1 Mineral Recovery from T a i l i n g s

I n a s tudy performed a t t h e Un ive r s i ty of Wisconsin ( 5 8 ) , a t t e m p t s were made t o s e p a r a t e the s u l f i d e m a t e r i a l s from the l ead /z inc mine and m i l l waste t a i l i n g s accumulating i n southwest Wisconsin. Two c o n c e n t r a t i n g techniques were t r i e d , namely, a high t ens ion e l e c t r o s t a t i c method and a f l o t a t i o n method. A l l of t he mineral processing s t u d i e s were c a r r i e d ou t using l a b o r a t o r y s i z e equipment. Based on t h e r e s u l t s , f l o t a t i o n appeared t o be t h e b e s t technique f o r large-scale o r commercial ope ra t ion . It w a s a l s o found t h a t pu re MgO could be de r ived from t h e t a i l i n g s . b e used i n producing r e f r a c t o r y b r i c k s .

This could

Since t h e 1930s, r e j e c t s from j i g and t a b l i n g concen t r a t ion o p e r a t i o n s i n t h e Missouri l ead b e l t have been reworked s e v e r a l times t o recover t h e contained l ead s u l f i d e . I n i t i a l l y , t h e coarse r e j e c t s were crushed f i n e r and again t a b l e d a n d j igged t o recover a d d i t i o n a l l ead s u l f i d e (ga l ena ) . U l t ima te ly , t h e t a i l i n g s were reworked again by f i n e gr inding and f l o t a - t i o n t o recover t h e remaining galena. E s s e n t i a l l y a l l of t h e old c h a t d w q s ( coa r se m a t e r i a l ) have been reworked and with t h e advent of e f f i c i e n t f l o - t a t i o n p rocesses , t h e t a i l i n g s are no longer being reworked (166).

2.9.5.2 Aggregate and Construct ion U s e .

I n 1963, over one m i l l i o n cubic yards of t a i l i n g s from s i l v e r - l e a d - z i n c mining i n t h e Coeur d'Alene mining d i s t r i c t of no r the rn Idaho w e r e used t o c o n s t r u c t embankments for a four-mile s e c t i o n of I n t e r s t a t e Route 90 nea r Kellogg, Idaho. handl ing and compacted w e l l on t h e job .

The material presented no unusual problems in

The Bunker H i l l Company i n Metal ine F a l l s , Washington produces a waste rock from i t s lead-zinc mine which has been used by c i t y , county, and s t a t e agenc ie s f o r base and sub-base cons t ruc t ion , bituminous r e s u r - f a c i n g , and seal c o a t work. The waste rock i t s e l f is a carbonate rock, which i s p r i m a r i l y 4-inches or less i n s i z e . Cave S t a t e Park used both coa r se and f i n e materials i n t h e bituminous mixtures . P r i v a t e i n t e r e s t s have a l s o purchased t h e material f o r t h e r e s u r f a c i n g of driveways (46).

A parking l o t a t Gardner

84

Waste rock from abandoned Missour i l ead miniqg ope ra t ions in S t . F ranco i s County have been used f o r many y e a r s as aggrega te f o r bituminous paving. This m a t e r i a l is a l s o sold t o t h e C i t y of S t , Louis f o r u se i n s t reet paving work ( 4 6 ) .

Over 100,000 tons of coa r se t a i l i n g s from lead-zinc mining opera- t i o n s have been used as aggrega te i n hot-mix a p p l i c a t i o n s on state highways i n northwest I l l i n o i s and southwest Wisconsin. The i r u s e , h a s been mainly i n t h e shoulders and s u r f a c e cour ses of f o c a l roads.

Chat, t h e coa r se t a i l i n g product from t h e b e n e f i c i a t i o n of lead- z i n c 01-2s i n t h e Tri-State mining d i s t r i c t , h a s been used as aggregate m a t e r i a l i n var ious phases of highway cons t ruc t ion f o r y e a r s i n Kansas, Missour i , and Oklahoma. This m a t e r i a l has been used i n po r t l and cement c o n c r e t e , but i t s major a p p l i c a t i o n i s i n bituminous base courses and wearing su r faces . A cons ide rab le amount of chat i s s t i l l a v a i l a b l e in t h e Tr i -S ta t e a rea . However, an a s p h a l t m a t e r i a l s u p p l i e r in Kansas has indfca ted t h a t t h e h i g h e s t q u a l i t y c h a t material has a l r eady been used and t h a t some of t h e remaining f l i n t cha t has a sh iny s u r f a c e , i n d i c a t i v e of a s p h a l t s t r i p p i n g problems and t h e d i s lodg ing of aggregate p a r t i c l e s from t h e paving s u r f a c e ( 4 6 ) . This opinion i s r e in fo rced by a spokesman f o r t h e Missouri S t a t e Highway Commission, who i n d i c a t e s t h a t , a l though a l o t of c h a t has been used i n t h e p a s t , t h e Highway Commission i s now more s e l e c t i v e i n t h e use of the remaining m a t e r i a l i n t h e waste p i l e s because t h e s l i c k s u r f a c e of t h e s e p a r t i c u l a t e s has been somewhat of a problem. The eastern cha t from t h e Old Lead Belt n e a r Bonne Terre has proven t o be a b e t t e r material than t h e western c h a t from t h e Tr i -S ta t e d i s t r i c t . Th i s eastern c h a t has been used i n a s p h a l t i c concre te , aggrega te i n bituminous bases , and maintenance work ( 4 6 ) .

85

2.10 PHOSPHATE ROCK MINING INDUSTRY

As early as 1653, English farmers started using bones as fertilizer, and in the 1 7 8 0 s the farmers around Sheffield. England, used ground clippings of bones and ivory from button and knife factories i n the area to fertilize the land. The real cause of the stimulating effect on plant growth, due to the phosphate, was unknown. However, today there are no known substitutes for phosphate rock from which phosphate fertilizers can be produced in the quantities required to sustain world agriculture production (98).

2.10.1 Industry Characterization

2.10.1.1 Industry Structure

In 1978, marketable phosphate rock was produced by 23 companies in the United States. was 47.7 million short tons, which is approximately 86 percent of the U.S. production. The remaining 3 . 4 million tons were produced in Tennessee and the western states. total phosphate rock consumption ( 9 8 ) .

2.10.1.2 Production Statistics

The combined production from Florida and North Carolina

The United States produced 40 percent of the world’s

More than 55 million short tons of marketable phosphate rock are produced in the United States each year. The production pattern by state is 86 percent from Florida and North Carolina; 10 percent from the states of Idaho, Alabama, Montana, and Utah; and 4 percent from Tennessee. About 87 percent of the domestic phosphate rock consumption is used for fertilizer and animal feed supplements. The balance is used for detergents, feed phos- phates, and insecticides. About 26 percent of production is exported ( 9 8 ) .

2.10.1.3 Industry Trends

In the United States, the history of the industry has been characterized by adequate supplies and the fact that additional supplies can be quickly developed to satisfy new demands. Since the United States is self- sufficient in phosphate rock, it is forecast to continue to export rock through the mid-1990sY and phosphate fertilizers to the end of the century ( 9 8 ) .

2 . 1 0 . 2 Phosphate Mining and Beneficiation Operations (98)

Phosphate rock mining procedures are somewhat different in each of the major producing areas of Florida, North Carolina, Tennessee, and the western states. Highlights for each area are discussed in the following paragraphs.

86

F l o r i d a land-pebble phosphate d e p o s i t s range from 1 to 50 f e e t i n The overburden covering t h e matrix i s th i ckness bu t average about 16 f e e t .

a q u a r t z sand and c l a y t h a t averages about 20 f e e t i n thickness . P r i o r t o mining, t h e land i s drained if swampy, and v e g e t a t i o n i s removed. Elec- .

t r i c a l l y powered d r a g l i n e s s t r i p overburden and mine matrix. i s s tacked on n a t u r a l ground leve l ad jacen t t o t h e c u t . The d r a g l i n e s d e p o s i t t h e ma t r ix i n prev ious ly prepared s l u i c e p i t s . Hydraulic guns s l u r r y t h e matrix, and i t i s pumped t o t h e washing p l a n t . Mining procedure i n North Caro l ina is similar t o that i n F lo r ida .

Overburden

I n t h e western s ta tes , a l l phosphate o r e i s s t r i p mined except t h a t In Montana, t h e ore i s broken obta ined from one underground mine i n Montana.

i n t h e s t o p e s and removed through chu te s i n t o several a d i t s . i n sou theas t e rn Idaho, main-bed o r e s u i t a b l e f o r consumption i n wet-process phosphoric a c i d p l a n t s and fu rnace s h a l e f o r use i n e lec t r ic furnaces are s e l e c t i v e l y mined. I n Utah, t h e phosphate rock is quar r i ed af ter an ove r ly ing l imes tone cap i s d r i l l e d , b l a s t e d , and removed. The th ickness of t h e o r e bed i s about 20 f e e t , and t h e t o t a l overburden and o r e s e c t i o n th ickness ranges from 50. to 100 f e e t . Ore mined i n t h e western s ta tes is e i t h e r truck-hauled o r moved by r a i l t o process ing p l a n t s .

From t h e mines

Ore i n Tennessee i s s t r i p p e d and mined w i t h 2 o r 3 cubic yard drag- l i n e s . Ore i s t rucked d i r e c t l y t o t h e p l a n t s o r t r a n s f e r r e d t o r a i l r o a d cars f o r d a i l y movement i n t o t h e p l a n t s . i n t h i ckness bu t may b e 20 f e e t . up t o 25 f e e t .

Loose c l ay overburden averages 8 f e e t O r e th ickness averages 6 f e e t bu t may b e

B e n e f i c i a t i o n of F l o r i d a and North Caro l ina phosphate c rude ore v a r i e s somewhat from p l a n t t o p l a n t as grade, s c reen a n a l y s i s , and r a t i o of pebble t o concen t r a t e i n t h e f eed change. p i p e l i n e s a t 20 t o 50 percent s o l i d s t o t h e washing p l an t . of s c reens i n c losed c i r c u i t w i t h hammer mills and l o g washers, the matrix is broken down t o permit s e p a r a t i o n of t h e sand and c l ay from phosphate- bea r ing pebbles and sands. The p roduc t s are a f l o t a t i o n concen t r a t e and a waste sand.

The matrix is pumped through Through a series

Western states phosphate o r e is c l a s s i f i e d as main bed i f t h e grade i s 31 t o 32 percen t P2O5, and as f u r n a c e shale i f t h e grade is 24 t o 26 per- c e n t P2O5. The furnace s h a l e i s nodul ized t o p repa re a f ine - f r ee charge f o r elemental-phosphorus producing e l ec t r i c furnaces . b e n e f i c i a t e d by c rushing , g r ind ing , c l a s s i f i c a t i o n , f i l t e r i n g , and d r y i n g t o produce a 30 t o 32 percent P205 product f o r wet-process phosphoric a c i d manufacture. i t is used i n w e t a c i d p l an t s .

Furnace s h a l e is also

Main bed o r e is c a l c i n e d t o reduce hydrocarbon levels b e f o r e

!

87

2.10.3 Waste Stream Characteristics and Quantifications

The beneficiation of land-pebble phosphatic deposits by washing and flotation results in the generation of two by-products: sand tailings and phosphate slimes. Sand tailings, the coarse reject from the flotation process of phosphate rock, are being generated at an estimated rate of ten to fifteen million tons per year and are frequently disposed of with the finer slimes or used to construct impoundment dikes (46). The size of the particles ranges 16 to 150 mesh (1.0 to 0.1 ram), which is in the size range of a fine to medium sand. These sand tailings are composed of 90 percent quartz sand, 8 percent carbonate fluorapatite, with the remaining 2 percent being feldspar and heavy minerals. dustry are used fDr land reclamation or to help dewater slimes.

Most of the sand tailings in the in-

Slimes are essentially colloidal materials which vary somewhat in grain size distribution from one plant to another due to slight dif- ferences in the nature of the matrix being mined and variations in beneficiation methods. A typical phosphate slime is minus 0.1 millimeter in particle diameter with over 70 percent of the particles being less than one micron in diameter. The slimes are usually deposited at from '2 to 6 percent solids. Due to their colloidal particle size, settlement rates are extremely slow. Even after years of settlement, solids contents do not often exceed 20 percent.

Mineralogically, these slimes have been analyzed and found to be composed mainly of carbonate fluorapatite, montmorillonite, and quartz with lesser amounts of kaolinite, attapulgite, and feldspar. The analyses con- firm that these slimes are essentially clay-like and contain a substantial amount of phosphate mineral value.

Phosphate slimes are generated in approximately a 1:l correspondence by weight to the amount of phosphate rock produced. slimes are generated as a by-product of phosphate production in central Florida. Lesser quantities of phosphate slimes are also produced in Tennes- see and North Carolina. It is estimated that a total of approximately 40 million tons of these colloidal clay-bearing slimes must be disposed of each year by the phosphate industry. years in large storage ponds. It is almost impossible to precisely estimate the amount of slimes impounded at the present time, but there are probably more than a billion tons of solids in these holding ponds. Vasan (99) has estimated that from 1.5 to 2 billion tons of slimes are currently being stored in impoundments in the Florida phosphate-producing area.

Huge volumes of these

These wastes have accumulated over the

88

!

Disposal of these materials has caused several environmental problems. Estimates are that as much as 4,000 acres of new ponds are being added each year in Florida. A great deal of water is impounded with the slimes and, due to the slow settling rate of the slimes, this water is entrapped and becomes unavailable for other uses for many years. Approxinately 7 tons of makeup water are required for every ton of phosphate rock that is produced.

In order to consider utilizing these materials, it is necessary to recover the slimes from the holding ponds and to reduce the moisture content to a more manageable range. After thickening, the slimes could probably be retrieved by pumping. The problem of dewatering is the biggest deterrent to possible utilization of these slimes. Conventional settling practices have proven to be ineffective. Although various other techniques for dewatering, such as centrifuging .and freezing, have been investigated; to date there has been no technically and economically feasible method for reducing the moisture content of these slimes to workable levels.

2.10.4 Potential Hazardous Waste Streams

Radioactive constituents in fugitive dust that escapes before the burial of phosphate mine wastes are not believed to constitute a significant hazard because the dust receives limited atmospheric distribution. In addition, recent monitoring studies have shown that measured radioactivity from groundwaters adjacent to tailings pond areas is less than the background radiation in groundwaters of this area. This condition is thought to result from the fact that the radium is tied up chemically with the phosphate that is removed as product (100).

Ponding slimes poses several environmental hazards. In the early '70s two towering dams broke inundating surrounding areas and deluging streams and flat terrains with phosphate slimes, resulting in multi-million dollar suits being filed against the companies concerned. Heavy water demands from these operations drop the water table and pull water from the surrounding areas, at the same time that the housing boom in these areas increases the demand for fresh water. Salt water encroachment fromcoastalareas about 30 miles away could develop as this demand for fresh water expands. The drainage or seepage of water from the slime pounds into the water table could ultimately lead to the pollution of ground waters with colloidal slime particles and chemicals, rendering them unfit for human consumption and recreation. These elevated slime ponds are also a blot on the landscape and tie up large areas of expensive land that could be more productive, especially when the demand for housing in Florida is so pressing.

2.10.5 Resource Recovery Technology Description

The principal waste products associated with the mining and processing of phosphate rock are the overburden, sand tailings, and slimes. The utilization practice and potential of these wastes is discussed in the following pages.

2.10.5.1 Aggregate Recovery

Overburden

The overburden has little practical value. The biggest percentage of it is simply left in large piles while small amounts are used on site for fill, embankment or dike building. Although the results of one laboratory study ( 9 4 ) concluded that a skid-resistant highway aggregate may be fabri- cated from phosphate mine overburden tailings using Na2C03 to produce a water insoluble glass bond between tailings particles, no actual application has been attempted.

Sand Tailines

Sand tailings, the coarse reject from the flotation processing of phosphate rock, are generally disposed of with the finer slimes or used for land reclamation o r to construct impoundment dikes. Since the land tailings are virtually all consumed, very little is left for further utilization.

PhosDhate Slines

There are two key hurdles to the commercial utilization of the phos- phaste slimes: 1) the lack of a technique for retrieving slimes from the pond, and 2 ) the need for an efficient and economical method for drying the slimes.

Slimes Retrieval

Test work conducted by the Ceramic Division of IIT Research Insti- tute (78), demonstrated that two types of pumps could easily handle the continuous pumping of slimes. Since it would be uneconomical to move slimes containing up to 75 percent water any distance, all preliminary processing would have to be done at a site adjacent to the slime ponds.

Drying of Slimes

Additional test work reconfirmed earlier findings that conventional rotary dryers were not efficient o r economical for the hard-to-handle phosphate slimes. Engineering cost estimates also ruled out the use of spray dryers ( 7 8 ) .

90

A cross-flow fluid dryer was selected as the most promising route, which is shown schematically in Figure 2-3. tions were made to meet the special needs of phosphate slimes. corporating these changes, phosphate slimes with 30 percent solids-content were continuously dried to a powder with a 95 to 99 percent solids-content. The dryer worked in the range of 75 percent fuel efficiency. Knowledge and experience were gained in processing the phosphate slimes in the course of about 20 separate pilot plant test runs under a wide range of temperature and processing conditions. the drying of phosphate slimes commercially feasible (78).

Design changes and modifica- After in-

The high efficiency of this type of dryer makes

Dried slimes thus become a potentially useful raw material for conversion into ceramic products like brick, tile, and aggregate. Phos- phate slimes with 30 percent solids-content were continuously dried in a pilot unit, and the product from these pilot plant runs were used by IITRI's Ceramic Laboratories in their ceramic development and material testing pro gram .'

Lightweight Aggregate

The most promising ceramic material developed from the phosphate slimes was lightweight aggregate. The market potential for lightweight aggregate (used as lightweight concrete) in Florida is roughly 3 million tons per year with only a small part supplied from local resources.

Lightweight aggregate was made by agglomerating the dried phosphate slimes in a pangranulator in a pilot unit (78). kilned in a rotary kiln in the temperature range of 1,050 to 1,lOO"C to obtain the desired properties. density in the range of 20 to 30 pounds per cubic foot. These aggregates were of good quality as can be seen in Table 2-13,which shows the results of ASTM Specification Tests on these aggregate-from-slimes. The high crush-strength of these lightweight aggregates indicated that they could yield good high-strength lightweight concrete.

These pellets were next

The kilning produced aggregate with a bulk

Because there are no large competitive producers of lightweight aggregate for structural concrete in the area, lightweight aggregate from slimes has a good potential market within easy access of Tampa and the Ocala, Florida areas.

91

i

Figure 2-3.

7 Schematic diagram of fluid-bed dryer (of Taylor & Co., Bettendorf, Iowa).

Figure 2-4. Compressive strength of concrete made with phosphace slime coarse aggregate.

Symbol: . h e Aggregate Cement Factor V Smd 3!!

A A Sand 5 6 0 0 Mat er i dit e

I

t

Source: Reference 78. 92

Table 3-13

SPECIFICATIONS OF PHOSPHATE SLIME LIGHTWEIGHT AGGREGATE ACCORDING TO ASTM C330

(Lightweight aggrega tes f o r s t r u c t u r a l conc re t e )

T e s t

S t a i n i n g

- Method

ASTM C330

Results

S t a i n i n t e n s i t y is l i g h t t o very l i g h t ; S t a i n Index = 40 t o 20

Loss on I g n i t i o n ASTM C114 Chemical a n a l y s i s ( s e e 3rd Q u a r t e r l y Report , 8-3-70) i n d i c a t e s < 0.6% v o l a t i les

Organic I m p u r i t i e s

Grading

ASTM C40 No apparent o rgan ic materials

ASTM C136 & AST, C330

Not graded accord ing t o s p e c i f i c a t i o n s 11 -

F r i a b l e P a r t i c l e s in Aggregates

ASTM C142 0% f r i a b l e

Clay Lumps ASTM C330

ASTM C142

ASTM C29

ASTM C127

None d i s c e r n i b l e

5.62 ( coa r se aggrega te) - 2/

27.92 l b l f t

0.845

3 (average) - 31

Fineness

Unit Weight

Bulk S p e c i f i c Gravi ty

Bulk S p e c i f i c Gravi ty ( s a t u r a t e d s u r f a c e dry b a s i s )

ASTM C127 1.12

Apparent S p e c i f i c Grav i ty

ASTM C127 1.16

Water Absorpt ion ASTM C127

ASTM C88

32.2%

- 4.8% s i z e r educ t ion Soundness (sodium s u l f a t e )

- I/

- 21 - 31 Conforms t o s p e c i f i c a t i o n s (dry- loose b a s i s ) . Maximum al lowable u n i t

Q u a n t i t i e s produced requi r ingeconomica l use of a l l a v a i l a b l e aggrega te s , t h u g provid ing a somewhat non-specif ic material. For informat ion only , more a p p l i c a b l e to f i n e aggregate .

weights range from 55 t o 70 l b / f t 3 , depending on s i z e of aggrega te .

Source: Reference 78. 93

Lightweight Concrete Aggregate

The aggregates produced from phosphate slimes were used and tested in a number of concrete formulations. In all cases the resultant lightweight concrete showed a bulk density much lower than the ASTM maximum of 115 pounds per cubic foot.

The line in the graph in Figure 2-4 is drawn through three ASTM reference points defined by ASTM (on the basis of 28-day compression tests) in terms of compressive strength and density. Any test data falling to the left of the reference line are within the ASTM specifications. All of the IITRI test samples of concrete using aggregate-from-slimes are well within the standards, as can be seen in Figure 2-4.

Most lightweight aggregates, such as perlite and vermiculite, have

The aggregates based on slime- very low compressive strengths. for decorative and insulation purposes only. solids are not only decorative, but also they seem to have excellent load- bearing characteristics.

When used in concrete mixes, they are used

In conclusion, it was found that these uses of phosphate slimes discussed in the past few pages, have been demonstrated as feasible, but none of the uses have reached commercializatiob as yet. The high cost of dewatering the slime and the remoteness of the phosphate operations from potential major markets probably has deterred use of the slime f o r rhese purposes.

2.10.5.2 Ceramic Uses (78)

Brick

Early lab tests at IITRI showed that bricks made from phosphate Even though these problems slimes have problems of bloating and warping.

were overcome by further development, the reproducibility of the brick quality was less than desirable.

Pipe

The Ceramic Laboratory at IITRI was successful in making a sewer pipe from phosphate slimes with low shrinkage. However, its higher porosity and low strength were definite drawbacks. only 100,000 tons per year, which could not be considered a major outlet for the waste slimes.

And the market was assumed to be

94

c

2.10.5.3 Vanadium Recovery

Western phosphate o r e d e p o s i t s are one of t h e l a r g e s t p o t e n t i a l sou rces of domestic vanadium i n t h e U.S. today. Within t h e phosphate o r e , the vanadium is a s s o c i a t e d wi th t h e f i n e s t p a r t i c l e s of t h e matrix, which r e p o r t t o t h e slime t a i l i n g s during b e n e f i c i a t i o n . These t a i l i n g s thus have an upgraded c o n c e n t r a t i o n of approximately a q u a r t e r of a percent vanadium, by we igh t , and a t a mining rate of 9.5 m i l l i o n t o n s of phosphate o r e p e r y e a r , t h i s amounts t o 7,150 t o n s of vanadium, more than t h e t o t a l U.S. consumption f o r 1980. of o r e per day w i t h 30 pe rcen t of t h e feed r e j e c t e d as s l ime t a i l i n g s . These t a i l i n g s , i f processed, could r ep resen t 5 t o n s of vanadium product per day wi th a v a l u e of $35,400.

A t y p i c a l phosphate b e n e f i c i a t i o n p l a n t w i l l p rocess 7,200 t o n s

The Bureau of Mines Albany Research Center (136) has conducted labora- t o r y r e sea rch on vanadium recovery. l each ing of unroasted t a i l i n g s w i l l y i e l d approximately 40 pe rcen t d i s s o l u t i o n of t h e vanadium p r e s e n t . When r o a s t e d , i t w a s found t h a t t h e a d d i t i o n of N a C l t o t h e t a i l i n g s b e f o r e r o a s t i n g w i l l raise vanadium d i s s o l u t i o n from approximately 60 pe rcen t t o g r e a t e r t han 95 percent . t o l i b e r a t e more of t h e vanadium t o an a c i d s o l u b l e form. e ra l is too f i n e l y d i spe r sed f o r accurate i d e n t i f i c a t i o n of changes i n t h e mineral du r ing r o a s t i n g . But, i t has been determined t h a t t h e vanadium i s as soc ia t ed w i t h a mica s t r u c t u r e , most probably r o s c o e l i t e . f i t of r o a s t i n g is t h e ox ida t ion of organic materials which would consume ac id and cause e x c e s s i v e f r o t h i n g du r ing leaching.

Their r e s u l t s have shown that d i r e c t

The presence of salt appears The vanadium min-

An added bene-

It w a s found t h a t a s u l f u r i c a c i d l each can d i s s o l v e v i r t u a l l y a l l of t h e vanadium, uranium, and P2O5 p r e s e n t in t h e t a i l i n g s . After f i l t r a - t i o n and washing of t h e r e s i d u e , t h e ac id f i l t r a t e is s t r i p p e d of vanadium i n a l i q u i d - l i q u i d e x t r a c t i o n c i r c u i t and recycled back t o t h e l e a c h i n g s t e p . The f ina1,vanadium product i s recovered from t h e loaded organic .

2.10.5.4 Uranium Recovery

from phosphate rock. of uranium from phosphate wastes, b u t was not p u t i n t o commercial u s e un t i l a few y e a r s ago. A t that t ime, t h e p r i c e of uranium w a s s u f f i c i e n t t o make recovery p r o f i t a b l e . b u t only a few, such as Gard in i e r , are s t i l l producing uranium. The drop i n p r i c e has d i scon t inued most o p e r a t i o n s except t hose wi th long-term c o n t r a c t s w i t h power companies. The presence of r a d i o a c t i v e materials i n phosphate waste m a k e s i t even more of a problem. exists -_ i n an i n s o l u b l e form (166).

Becker I n d u s t r i e s Conda o p e r a t i o n s i n Idaho are recovering uranium The p rocess w a s developed in t h e 1950s f o r remval

Seve ra l companies went i n t o p roduc t ion t h e n ,

Fo r tuna te ly t h e uranium

9 5

2.11 ACID MINE DRAINAGE

Many U.S. mines are cut into rock strata that have been penetrated by natural water channels, which often release large volumes of water into the mine workings. In some cases, the water leaves the mine by gravity flow to a surface opening o r through outflowing seepage channels. More frequently, it is collected in water sump areas in the mine and pumped to surface discharge locations. In many mineralized areas, such as the Appalachian coal fields, the copper mines near Butte, Montana, the lead-zinc mines of Idaho, gold and silver mines of Nevada, and many other areas, the inflming water reacts with various exposed pyritic and other constituents of the mineral beds and/or the overburden. Eventually it becomes polluted with sulfuric acid and dissolved or suspended solids. water," which is characterized by a low pH and relatively high concentrations of metallic salts, primarily iron and lesser amounts of metals such as aluminum, magnesium, and calcium (101). Current best available estimates indicate that 25 percent of the hard rock or metallic mineral mining and benefic'iating industries generate solid waste with sufficient pyrite to produce acid water (100).

Pioper treatment of acid mine water requires oxidation of the soluble

It is then known as "acid mine

ferrous iron to insoluble ferric iron, which will settle out with other suspended solids. The sulfuric acid must be neutralized with lime, lime- stone or some other chemically basic material such as industrial fly ash (101).

2.11.1 Potential Hazardous Waste

Acid water and acid slurries from acid-producing solids constitute a major source of groundwater and surface water contamination. Mine water and tailings-pond water with a pH of 5 or less can be expected to have deleterious effects on surface water and groundwater in most hydrogeologic environments. This is a significant source of contamination.

The impact of acid water, which is almost always combined with solid waste in the form'of a low-viscosity slurry, is compounded by the fact that low-pH waste slurries increase the solubility of heavy metals. water not only increases the rate of the dissolution of soluble compounds that are ubiquitous in beneficiation processes, it also displaces heavy metal cations that may be absorbed on the particulate matter in the solid waste. The acid contributes protons to ion exchange sites, and the heavy metal cations replace the protons in solution. This not only results in acid water, but in acid water containing heavy metal cations, usually in excess of drinking water standards and effluent guidelines established by the National Pollutant Discharge Elimination System (NPDES), which are now enforced under the Water Pollution Control Act Amendments of 1977 and 1972. waste slurries must be treated prior to discharge by the best established practicable control technology, which has been identified to be lime neu- tralizarion and clarification for most of the industries producing such waste slurries (100).

The acid

In order to meet NPDES guidelines, low-pH mine and beneficiation

2.11.2 Resource Recovery Technology Desc r ip t ions I

Several r e p o r t s were found d e t a i l i n g methods of recovering metals from a c i d mine waters. These r e p o r t s are l i s t e d i n t h e r e fe rence s e c t i o n (34, 57, 63, 1 0 4 ) , bu t t h e d e s c r i p t i o n s of t h e t echno log ie s w i l l no t b e discussed h e r e , as t h e s e metal recovery techniques are considered waste t reatment o r pol lu- t i o n c o n t r o l p rocesses r a t h e r t han waste u t i l i z a t i o n processes.

However, one product of t h e n e u t r a l i z a t i o n of a c i d m i n e drainage by e i t h e r lime or l imestone is a p r e c i p i t a t e (s ludge) of no t less than 10 per- c e n t s o l i d s . Cur ren t ly , t h i s waste product is e i t h e r permanently impounded i n l a r g e lagoons or pumped i n t o mined-out underground workings or abandoned s u r f ace mines.

These d i s p o s a l methods are n o t t h e i d e a l s o l u t i o n f o r a number of reasons. Thus r e sea rche r s a t t h e Coal Research Bureau (CIIB), West Vi rg in i a Un ive r s i ty , i n i t i a t e d an e x t e n s i v e i n v e s t i g a t i o n i n t o p o s s i b l e methods of u t i l i z i n g t h i s mterial (57). R e s u l t s of t h i s s tudy are p resen ted below.

2.11.2.1 Acid Mine Drainage Sludge i n S t r i p Mine Revegetation

Acid mine d ra inage s ludge appears t o b e u s e f u l i n t h e r evege ta t ion of s t r i p mine s o i l , e s p e c i a l l y i f used i n combination w i t h some f e r t i l i z a t i o n and i n s e c t c o n t r o l . The s ludge f u n c t i o n s i n two ways: f i r s t , i t increases t h e pH of the s o i l and second , i t improves t h e s o i l t e x t u r e by t h e a d d i t i o n of f i n e , c l ay - s i ze p a r t i c l e s .

However, s ludge i s n o t being used for t h i s purpose. David Akers of t h e CRB s ta tes t h a t u se of t h e s ludges for t h i s purpose i s n o t c o s t compe t i t i ve wi th o t h e r types of s o i l cond i t ion ing such as d i r e c t a d d i t i o n of materials l i k e b a s i c s l a g , l imes tone or lime. As y e t t h e c o s t of impounding t h e s l u d g e s a t or nea r t h e mine s i t e i s much less than t h a t involved i n d ry ing and t r a n s p o r t i n g t h e s ludge , o r i n t r a n s p o r t a t i o n o f t h e moist s ludge t o s t r i p mine areas (166, 167).

2.11.2.2 Acid Mine Drainage Sludge as Rock Dust

Another area of s ludge u t i l i z a t i o n which h o l d s promise is t h e spray

Spray d ry ing invo lves pumping t h e s ludge d r y i n g of t h i s waste and i t s subsequent u s e as rock d u s t f o r explosion con- t r o l in c o a l mining ope ra t ions . through an atomizing nozz le i n t o a chamber where t h e s ludge mixes wi th h o t air . r e d d i s h co lo r . Th i s powder i s c a r r i e d from t h e chamber by t h e flow of warm air and i s c o l l e c t e d i n a cyclone p r e c i p i t a t o r .

The h e a t qu ick ly d r i e s t h e s ludge i n t o a f i n e powder wi th a l i g h t

97

A t y p i c a l mining o p e r a t i o n i n t h e northern West V i r g i n i a area was s t u d i e d t o determine i f t h e a c i d water treatment p l a n t f o r that mine could produce enough d ry s ludge t o handle the rock d u s t requirements for t h e mine. day, while only 1 3 t o n s of rock d u s t were required by t h e mine. a d i r e c t s u b s t i t u t i o n , approximately 40 percent of t h e t reatment p l a n t d i scha rge could provide enough rock d u s t t o s a t i s f y t h e requirements of t h e mine.

The treatment p l a n t w a s found t o produce 33 t o n s of s o l i d s p e r Assuming

According t o M r . David Akers of t h e Coal Research Bureau a t West V i r g i n i a Universi ty (167), t h e u s e of s ludge for rock d u s t i n g has poten- t i a l . The sludge, for t h e m o s t p a r t , seems t o meet Federal and s ta te s p e c i f i c a t i o n s w i t h r e g a r d t o p a r t i c l e s i z e and s i l i ca content . major drawback t o u t i l i z a t i o n i s t h e c o s t of drying t h e s ludge f o r use i n e x i s t i n g dus t ing machinery. Mr. Akers s t a t e d t h a t t h e r e i s more than enough sludge t o m e e t t h e needs of t h e c o a l mining i n d u s t r y bu t since convent ional rock d u s t i s r e l a t i v e l y less expensive due t o t h e c o s t of drying t h e s ludge, and i s r e a d i l y a v a i l a b l e , s ludge w i l l no t be used for rock Gusting.

The

2.11.2.3 Ceramically Bonded Sludge

A ceramical ly bonded s t r u c t u r a l material w a s produced us ing BMD sludge and AMD s ludge mixed wi th c l a y ( b e n t o n i t e ) . B r i q u e t t e s of s ludge w e r e formed and f i r e d t o temperatures of 1,250"C producing a s t r u c t u r a l product w i th a c r u s h s t r e n g t h i n excess of 8,000 pounds per square inch.

While t h e a b i l i t y t o make r e l a t i v e l y good b r i c k from sludge i s known, t h e indus t ry i s not a t p r e s e n t app ly ing t h i s knowledge. The abundance of conventional materials for manufacturing b r i c k and t h e manufacturing problems encountered i n using t h e s ludge are s e r i o u s d e t e r r a n t s t o t h e use of s ludge for t h i s purpose (166).

2.11.2.4 Chemically Bonded Sludge

S t r u c t u r a l p roduc t s were also i n v e s t i g a t e d us ing AMD sludge as an a d d i t i v e t o po r t l and cement. Type lA (air e n t r a i n i n g ) and Type I1 (sul- f a t e r e s i s t i n g ) p o r t l a n d cements were i n v e s t i g a t e d w i t h ve ry similar r e s u l t s .

Mixing 5 pe rcen t s ludge w i t h sand as aggregate i n cement mixtures does n o t appreciably lower t h e c r u s h s t r e n g t h of t h e cement; however,no advantage i s gained o t h e r t han d i spos ing of t h e sludge.

While t h e use of 5 p e r c e n t , or less, of AMD s ludge as a cement a d d i t i v e h a s been shown t o produce a cement n e a r l y equal t o cement a lone, t h e i n d u s t r y i s no t using t h e material. only b e n e f i t t o be de r ived from u s i n g t h e sludge would be t o p a r t l y a l l e v i a t e t h e d i s p o s a l problems a s s o c i a t e d w i t h i t s impoundment (166).

Qual i ty-control led materials are p r e f e r r e d and t h e

98

It is apparent that the outlook for using AMD sludge for the various suggested applications is discouraging. or pumped into abandoned mines. Until the cost of impoundment becomes so ex- cessive as to dictate its use for one or more of the suggested applications, it will continue to be disposed of by the least costly method available.

At present the sludge is impounded

2.12 MISCELLANEOUS MINING INDUSTRIES

These following mining industries are being included in this report, but in an abbreviated manner. The reason for this is to draw a distinction between actual mining waste utilization techniques that are capable of reducing existing o r future wastes, and non-utilization recovery techniques which recover selected materials from the waste piles but do not actually use or reduce the existing waste piles.

In molybdenum, uranium, and zinc mines the principal resource recovery techniques involve only retreatment of tailings to recover additional minerals. Only in minor instances are the tailings physically removed from the waste pile and utilized.

2.12.1' Molybdenum Mining

2 . 1 2 . 1 . 1 Waste Stream Characterization and Quantification

The waste rock and tailings resulting from the production of molybdenum are not tabulated here because these quantities could not be ascertained. ever, significant quantities of waste, particularly tailings, do result from the processing of the molybdenum ores.

HOW-

The mining of molybdenum is concentrated in the Rocky Mountain area of central Colorado with additional mining in north-central New Mexico. Climax molybdenum mine operating in Climax, Colorado, has been in operation for over 50 years and has accumulated over 350 million tons of tailings and generates over 45,000 tons per day. generates approxiniately 35,000 tons per day of tailings ( 4 6 , 150).

The

The Henderson mine, opened in 1976,

2.12.1.2 Potential Hazardous Waste Streams

It has been determined that there appears to be a significant potential for migration of heavy metals from the estimated 30 million tons of molybdenum tailings generated yearly. The tailings are ponded and con- 4

tain elevated levels of arsenic, lead, selenium, and cadmium. In addition, cyanide is used in the beneficiating process. The waste rock dumps and the tailing ponds both exhibit corrosivity characteristics (152).

99

2.12.1.3 Resource Recovery Technology Descriptions

Very little information regarding the utilization of molybdenum mining wastes could be found in the literature. were discovered, and information from them is sununarized below.

Only two brief reports

Climax Molybdenum Co. operated a hydrometallurgical plant at Climax, Colorado, from August 1966 to August 1968 to recover molybdenum from an oxidized ore. The feed, tailings from sulfide flotation, was first upgraded by cycloning. The concentration plant handled 6,000 TPD of feed and produced 2,000 TPD of slime concentrate. sulfurous acid solution at 6 5 O C . of "molybdenum blue." a resin-in-pulp t y p e circuit. charcoal was screened from the pulp and washed. The washed charcoal was pumped to columns where it was ammoniated and air-blown. The oxidized molybdate was then washed from the charcoal. molybdate crystallized out. denum 'trioxide ( 4 2 ) .

The concentrate was leached by a sulfuric- The molybdenum w a s solubilized in the form

Activated charcoal was added to the leach tailings in The Molybdenum was absorbed on the charcoal.

The eluate was evaporated until ammonium di- The ammonium dimolybdate was calcined to molyb-

Reference 46 states that both the waste rock and tailing from a

The waste rock is andesite and aplite, varying molybdenum mining operation in northern New Mexico have been used as bituminous paving aggregate. in size up to 3 feet in diameter and crushed to meet gradation requirements for coarse aggregate.

2 . 1 2 . 2 Uranium Mining

2 . 1 2 . 2 . 1 Waste Stream Characteristics and Quantification

Waste rock and overburden from open pit and underground mining operations are disposed of in either surface waste dumps or in mine back- filling operations. Some mines segregate the waste rock from the overburden and store the waste rock in open surface piles for future use as a low grade fuel ore (151). In 1979, approximately 306 million tons of wastewere generated in surface and underground mining operations (150). treatment and disposal operations practiced in the uranium mining and concentrating industry are conducted on the plant sites by the operating companies, and no waste materials are sold (151).

All domestic waste

The overburden generally consists of particles of soil, sand,stone, clay, and shale. contains chert, feldspar, quartz, and small amountsof radioactive minerals (151).

The waste rock can vary widely in composition, but usually

In some underground mines, groundwater must be .pumped from the mine to the surface. This water frequently contains significant amounts of dissolved uranium values.

In uranium ore concentrators, the uranium values are recovered from the crude ore and concentrated to yield an intermediate, semi-refined product containing U3O8 or Na2U2O7. This product, which is commonly referred to in the industry as yellow cake, is shipped to refineries and reprocessed to obtain either uranium metal, U 0 2 or UT6 for use in the nuclear industry (151).

The only concentrator waste from uranium ore concentration plants, regardless of process, is the tailings slurry. These slurries contain sands, slimes, and liquids, which are pumped to a tailings pond. The slimes and tailings occur after the leaching and filtration steps. The weight ratio of dry solids in the tailings slurry to ore is 1 to 1; the composition of the dry solids is 70 percent sands and 30 percent slimes. The total weight of waste solution accompanying the sands and slimes to the tailings pond is 1.5 times the weight of the ore processed (151). This amounted to 16.1 million tons of dry concentrator tailings and 24 million tons of wet concentrator vaste. The total amount of tailings slurry pumped to ponds in 1979 was an estimated 40.1 million tons.

2 . 1 2 . 2 . 2 Potential Hazardous Waste Streams

A l l uranium mining waste rock, whether generated from underground or open-pit operations is considered potentially hazardous. The waste rock contains above background levels of radioactive materials, such as natural uranium and its decay products. The decay products of uranium include several potentially hazardous radioactive substances such as radium, radon gas, and thorium. earlier in concentrations above the background level.

Tailings slurries from concentrator operations as described are potentially hazardous because they contain radioactive materials

Only 90 to 95 percent of the uranium in the uranium ore is recovered, while the remaining fraction is discharged with the slimes and tailings. anium-238, the major isotope in naturally occurring uranium, is only feebly

, radioactive and therefore is not a hazardous source of radiation. The mill waste also contains most of the radium originally present in the uranium ore and is a potential source of human internal and external radiation exposure. Failure to properly contain mill tailings can cause radiological pollution of water, soil, and air with long-lived radium and its decay products (163).

Ur-

101

Although weakly penetrating alpha particles emitted by radium and its decay products are not generally a hazardous source of external radiation, damaging internal radiation may result when radium is ingested by drinking contaminated water, breathing radium-bearing dust, or breathing the daughters of gaseous radon-222 (163).

Table 2-14 shows a partial analysis of the hazardous waste content in the tailings from an acid leach process and an alkaline leach process.

Table 2-14

HAZARDOUS MATERIAL CONTENT OF URANIUM TAILINGS

Acid Leach Alkaline Leach Isotope Process Process Ealf Life

9 U238 (pCi/g) 52 40 4.5 x 10 years

1,620 years Fk226 (pCi/g> 56 7 560

Th230 (pCi/g) 567 565 80,000 years

Th234 (pCi/g) 52 40 24 days 0.018 0.014 - u3'8 (%>

Source: References 151 and 163.

Emission

Alpha, gamma

Alpha, gamma

Alpha, g a m Beta, gamma

-

! -


In the late Sixties, the Bureau of Mines conducted tests on several uranium mill tailings to determine feasibility of uranium and vanadium recovery (54).

Sulfuric acid leaching tests were made on a representatlve tailings sample assaying 0 . 3 3 percent V2O5 and 0.045 percent U O8 to obtain data for

an 80 percent solids pulp was prepzred by pugging with 100 pounds H2SO4 and 20 pounds CaF2 per ton of tailings, holding for five days, and water leaching. This treatment solubilized 65 percent of the vanadium and 78 percent of the uranium. This method is not being applied at present because of the high acid consumption and because the leaching process resulted in a recovery that did not exceed 30 percent of the original uranium content of the reworked tailings. However, after World War I1 there was a commercial operation to recover uranium by acid leaching of gravity tailings at Park City, Utah. This operation ceased over 30 years ago (177).

a cost study on the recovery of the elements. An aci a cure was made in which

Two alternatives to stabilization or controlled storage of mill tailings are to either remove the hazardous radium from existing tailings ponds or to extract radium during uranium ore processing. apply to new milling processes. to be extracted by either method to render the tailings non-hazardous.

The latter alternative would best More than 95 percent of the radium would have

In laboratory tests conducted by the Bureau of Mines (163), radium was leached from tailings using either hydrochloric acid or ethylenediamine tetra- acetic acid. A hydrochloric acid leaching method was used to extract both radium and uranium from the ore to yield tailings containing less radium than those produced by either conventional sulfuric acid or alkaline leaching processes. by sedimentation in slime fractions representing nearly 25 weight-percent of the original sample.

From 77 to 94 percent of the radium in mill tailings was concentrated

None of’the radium removal methods tested were able to produce tailings containing 20 or less picocuries of radium per gram.

The East Rand and Gold Uranium Company, South Africa, recovers uranium from its gold and gold/uranium mine slime ponds (155). First the slurry from the slime ponds is diluted, conditioned with reagents and agitated in flotation cells where a pyrite concentrate as froth is separated. The concentrate from the flotation plant is thickened to a series of air-agitated vessels for conventional acid leaching. uranium-bearing solution from which uranium is recovered by solvent extraction.

The leached pulp is fed to filters to separate the

Uranium is also recovered from mine waters by means of an ion-flotation process (40) or countercurrent ion exchange (164). About 100 tons per year of U3O8 are recovered at the Kerr McGee operation in Grants, New Mexico, using -the ion exchange method (166).

103

A process was developed at Oak Ridge National Laboratory for in-

The waste slurry or solids were mixed with commercial emul- corporating radioactive waste sands and slimes from uranium milling into asphalt ( 4 6 ) . sified asphalt o r molten base asphalt and the temperature raised to evap- orate the waste fluid. waste was neutralized with lime to precipitate radium and sulfates. Pos- sible uses suggested are for roofing materials and road surfacing.

The concentrated slurry was evaporated while the

2.12.3 Zinc Mining


Approximately 59 percent of zinc ore production comes irom ores designated as zinc ores. Twenty-three percent comes from lead ores, 14 percent from zinc-lead ores and the remaining 4 percent is derived as a . by-product from the mining of other mineral ores. In many mines, zinc and lead are produced together in varying degrees (see Section 10.2 and 10.3). Zinc ranges from the major product of the mine as in Tennessee, PennsylGania, and New Jersey deposits, to a coproduct as in the complex western ores and in the Missouri Lead Belt.

According to the Bureau of Mines (1501, 1.27 million tons of waste rock and overburden were generated by the production of 6.9 million tons of zinc ores in 1978. The waste rock and overburden are usually deposited in open stock piles.

The national average ratio of ore treated to marketable product is 28.7 to 1. 240,000 tons of zinc was extracted and 6.66 million tons of tailings were generated (150).

Thus in processing 6.9 million tons of zinc ore in 1978,

The milling of zinc ores results in the production of two tailing waste products. One is a coarse fraction from jigs or ball mines, and the other is a fine fraction from the flotation cells. The composition of these wastes can be expected to vary from one location to another, depending upon the nature of the parent ore. The jig tails contain minimal amounts of lead or zinc, and are dolomitic in nature. Flotation tailings or slimes are also dolomitic with traces of iron, lead, and sulfur as indicated in the chemical analysis of Table 2-15 (144).

104

Table 2-15

CHEMICAL ANALYSIS OF ZINC-LEAD TAILINGS

Composition

Silica ( S i 0 2 ) Alumina (A1203) Iron (Fe) Magnesium (MgO) Calcium (CaO) Manganese (Mn) Zinc (Zn) Sulfur !S> Loss on Ignition

Percentage

9.8 0.3 10.8 17.8 29.4 0.037 0.18 0.24 42.0

~~~~ ~


2.12.3.2 Potential Hazardous Waste Streams

The waste stream generated in the mining of domestic zinc ores, waste rock, and overburden is not considered to be potentially hazardous (151). However, according to an EPA preliminary draft report (152) zinc/ lead tailings ponds contain elevated levels of lead, zinc, mercury, cadmium, chromium, selenium, and silver. Because of the potential for migration of these heavy metals from the 16 million tons of zinc/lead tailings generated annually, these ponds are receiving more comprehensive study.


Ecstall, a Canadian zinc refining company owned by Texas Gulf, Inc., has built and operates a full scale tin from zinc tailings recovery plant.

The Kidd Creek mine in Timmins, Ontario, described as the world's largest zinc mine, supplies the concentrator with 10,000 tons per day of ore. From the concentration circuits 7,700 tons of tailings and slimes are generated daily. are treated daily. The tailings contain pyrite (iron sulfide), silver, and tin. The basic process is a desliming step, flotation, which separates most of the pyrite fraction, a gravity concentration process, a sulfide flotation and a final leaching step. trate are produced at the facility.

The slimes are separated and about 6,500 tons of tailings

Nearly 4 tons per day of tin concen-

Zinc chat tailings from Mascot, Tennessee have been used as aggregate in portland cement concrete highway structures for more than 50 years. Bridges in which these materials were used in the concrete have demonstrated excellent performance ( 4 6 ) .

105

f -

An i n v e s t i g a t i o n was made i n t o p o s s i b l e u t i l i z a t i o n of t h e z inc mine t a i l i n g s accumulations i n t h e southwestern p a r t of Wisconsin. Severa means of u t i l i z i n g these t a i l i n g s were i n v e s t i g a t e d , i nc lud ing production of i r o n oxide feed f o r b l a s t fu rnaces and recovery of s u l f u r from i r o n s u l f i d e . After conducting an economic a n a l y s i s of t h e s e alternatives, It w a s concluded that it i s not economically p r o f i t a b l e t o u t i l i z e t h e s e z inc mine wastes (165, 144) .

The Young M i l l , of ASARCO, east of Knoxvil le , Tennessee processes a z inc ore t o recover z inc s u l f i d e concent ra tes which are shipped t o ASARCO p l a n t s f o r re t rea tment . The t a i l i n g s from the heavy media separa t ion- f lo ta - t i o n concent ra tor y i e l d products ranging from coa r se aggrega tes t o f i n e r road b inder material.

A coa r se f r a c t i o n from t h e heavy media s e c t i o n i s used f o r highway conc re t e aggrega te and i s a l s o ground t o produce a f i n e sand f o r a spha l t mix and another po r t ion i s a source of coarse l imestone f o r o t h e r purposes. The f l o t a t i o n t a i l i n g i s f r a c t i o n a t e d i n t o a commercial mortar sand and ag r i - c u l t u r a l l i m e (178).

3.0 STATE-OF-THE-ART OF RESOURCE RECOVERY I N THE MLNING INDUSTRY

In t h i s s e c t i o n , t h e c u r r e n t s ta te-of- thz-ar t of resource recovery, by ind iv idua l mineral mining wastes, i s presented. A matr ix summarizing resource recovery technologies by s t a g e of development and range of t r ans fe r - a b i l i t y has been compiled and can be seen in Figure 3-1. The fol lowing sec- t i o n s descr ibe how t h e ma t r ix may be used and what i t means.

3 . 1 MATUX DEVELOPMENT AND STRUCTL.

The lssis of t h i s ma t r ix i s founded on a thorough review and analysis of more than a decade of t r a d e j o u r n a l r e p o r t s , government documents, and genera l s c i e n t i f i c l i t e r a t u r e . A complete b ib l iography of r e fe rences can be found a t t he end of t h i s r e p o r t . Current s t a t u s and ex ten t of use have been confirmed by indus t ry o f f i c i a l s , independent r e sea rche r s and from discuss ions with au tho r s of t e c h n i c a l papers being reviewed.

Key a r e a s of t h i s i n v e s t i g a t i o n and a n a l y s i s include:

a Mining indus t ry waste streams a Applicable r e source recovery technologies e

a Range of t r a n s f e r and use of the recovered

Stage of development and ex ten t of u se f o r t he ind iv idua l recovery technologies

ma te r i a l

These four key areas d e f i n e t h e parameters of t h e ma t r ix t h a t summarize the s ta te -of - the-ar t of waste recovery i n t h e mining indus t ry . The matr ix presented i n Figure 3-1 i s designed as fo l lows: t h e mining indus t ry waste stream products on t h e ho r i zon ta l axis are c o r r e l a t e d with t h e appl icable resource recovery technologies on t h e v e r t i c a l a x i s ; t hese two parameters a r e l inked by codes t h a t represent bo th t h e s t a g e of development and ex ten t of u se of each recovery technology as appl ied t o a waste stream (numeric code) and t h e area t o which t h e waste o r recovered material i s t r a n s f e r r e d f o r r e u s e (a lphabet ic code).

3.1.1 Matrix Waste Streams

The mat r ix inc ludes a l l indus t ry waste streams wi th recoverable materials f o r which r e source recovery technologies have been i d e n t i f i e d o r proposed. Fourteen waste streams from 13 sepa ra t e subindus t r ies are iden- t i f i e d and arranged ac ross t h e top of t h e columns i n a l p h a b e t i c a l o rder .

3.1.2 Matrix Resource Recovery Technologies

This area inc ludes those technologies t h a t have a t least been proposed f o r recovering materials from t h e i d e n t i f i e d subindus t ry waste streams; only those technologies c i t e d by persons i n t h e indus t ry o r with- i n t h e surveyed l i t e r a t u r e are included on the mat r ix .

107

1 1 Acid Mine Asbestos

Process Drainage T a i l i n g s

MineraliMetal Recovery 1 I I’ r ec i p i t a t i o n Leaching F l o t a t i o n Phys ica l Sepa ra t ion 1 I 2.3 Chemical SeDaration 1

Waste Stream Lise 1 ~

I S o i l Condi t ioner 2b Growing Medium Mine Explosion Cont ro l 2b tlr ic k Por t land Cement A Mineral Wool

* . Product ion 2c 2c - . ~~

d d i t i v e 2c Product ion I 2c

* Foreign c o u n t r i e s .

Key :

Development S taee 1. Proposed r e sea rch a r e a 2 . Bench scale r e sea rch p r o j e c t 3. P i l o t scale r e sea rch p r o j e c t 4 . Full scale demonstration p r o j e c t 5 . F u l l scale, s p o r a d i c a l l y p r a c t i c e d 6. F u l l scale, commonly p r a c t i c e d 7 . Formerly p r a c t i c e d

I 1 I I Gold 6 1

I Coal Copper S i l v e r B a r i t e Mine Mining Feldspar Mine

T a i l i n g s Refuse Refuse Ta i l ings T a i l i n g s

Waste Material Transfer a . Within a s i n g l e f a c i l i t y b . Between f a c i l i t i e s , w i th in the i ndus t ry c . Between f a c i l i t i e s , between i n d u s t r i e s

Figure 1. S t a t u s of Resource Recovery i n the Mining Indus t ry (SIC Divis ion B).

c

5

01 u

v

ur

l

... In

*-

For the purposes of displaying increased detail in the recovery techniques, the subtitles under the heading ''Mineral/Metal Recovery" represent the method used to separate the desired material from the vaste stream. For example, in the "Barite Tailings" column and in the row titled "Flotation," the figure Sa is shown. This indicates that the material recovered from tailings i s recovered by means of flotation and that this is sporadically practiced on a full scale between facilities and between industries. Recovery Process titles, beginning with "Used as soil conditioner" represent actual methods of utilization of the corresponding vaste stream.

The remaining Resource

'3.1.3 Matrix Technology Development Stage and Waste Material Transfer Costs

The waste streams on the horizontal axis of the matrix and the resourcerecoverytechnolcgies on the vertical axis development stage and waste transfer codes that appear in the boxes on the matrix. It should be noted that, due to the matrix design, only appropriate technology/waste stream combinations are coded. Such combinations are defined as those resource recovery technologies that this .investigation- has shown can or potentially could be applied to a particular waste stream to recover 'a valuable material. Hence, those combinations with technologies that are not being or cannot be applied to a particular waste stream, according to this investigation, are not coded.

are correlated by the

The development stage codes for the resource recovery technologies are ranked according to a numerical scale that indicates the degree to which the processes are applied throughout the industry. the following definitions :

The numbers correspond to

1.

2.

3 .

4 .

Proposed Research Area. performed on any systems. Investigation has revealed a citation to the effect that the technology could theoretically be used to recover potentially valuable materials from a waste stream. ,

No actual testing has been

Bench Scale. Laboratory testing and experiments have been done to perform initial evaluation on the possi- bility of recovering potentially valuable materials from a waste stream using a specific technology.

Pilot Scale. Evaluations of a small version of a planned recovery system applied to a waste stream to recover a potentially valuable material have been completed.

Full Scale Demonstration Project. factory-size systems installed within plants for recovering potentially valuable materials from actual process waste streams have been completed.

Evaluations of

110

5 .

6.

7.

The

F u l l Sca le , Sporad ica l ly Prac t iced . Actua l i n d u s t r i a l recovery process used by a small segment of t h e indus t ry t o recover v a l u a b l e materials from process w a s t e streams.

Fu l l Sca le , Commonly Prac t iced . Actual i n d u s t r i a l recovery process used by a ma jo r i ty of t he indus t ry t o which t h e process can be app l i ed t o recover va luable materials from process waste streams.

Formerly P rac t i ced . Was used a t one t i m e , b u t is n o t being used c u r r e n t l y .

second p a r t of t h e technology/waste stream matr ix code is t he waste marerial t r a n s f e r code. This code denotes where t h e waste stream, any p a r t of the waste stream, o r any recovered product of t h e waste stream is t r a n s f e r r e d f o r use upon recovery. The a lphabe t i c code corresponds t o the fol lowing material t r a n s f e r activit ies:

a. Within t h e gene ra t ing f a c i l i t y b. Between t h e gene ra t ing f a c i l i t y and another

f a c i l i t y ; which are i n t h e same indus t ry c . Between the gene ra t ing f a c i l i t y and another

f a c i l i t y ; which are i n d i f f e r e n t i n d u s t r i e s .

The development s t a g e and w a s t e t r a n s f e r codes assigned t o each recovery process are der ived from conversa t ions wi th persons i n t h e indus t ry o r information obtained from t h e l i t e r a t u r e . While most recovery technology/ waste stream combinations are c o r r e l a t e d by a s i n g l e p a i r of codes, some have mul t ip l e codes i n d i c a t i n g d i f f e r e n t development s t a g e s f o r d i f f e r e n t waste t r a n s f e r areas. In these s i t u a t i o n s , a recovered material can, o r p o t e n t i a l l y could, be t r a n s f e r r e d f o r use i n more than one area. I n each case, the development f o r each waste t r a n s f e r area is noted.

3 . 1 . 4 Iden t i fy ing Recovery Process Technical Pub l i ca t ions

The coded f i g u r e s i n t h e ma t r ix should be used i n conjunct ion with Table 3-1,which b r i e f l y d e s c r i b e s each recovery technology l i s t e d in t he ma- t r i x columns and i d e n t i f i e s t h e p u b l i c a t i o n s i n which t h e technologies are descr ibed. i s seen i n the row t i t l e d "Soi l Condi t ioner ." By r e f e r r i n g to t h e "Acid Mine Drainage Treatment Sludge" heading i n Table 3-1, t h e code 2b i s shown fo l - lowed by "Revegetation of S t r i p Mine S o i l , 57." This r e p r e s e n t s a b r i e f recovery process d e s c r i p t i o n w i t h r e fe rence numbers f o r t h e pub l i ca t ion desc r ib ing the process. The r e f e r e n c e s w i l l be found a t t h e back of t h i s r e p o r t .

For example, under t h e column "Acid Mine Drainage" t h e f i g u r e "2b"

In another example, under t h e column "Coal Mine Refuse" i n the row Used--in ceramic products" w e see two entries--2c and 6c. This i n d i c a t e s two I 1

sepa ra t e u t i l i z a t i o n technologies f o r use i n ceramic products which a r e a t d i f - f e r e n t s t ages of development. Once aga in , these two codes can be loca ted i n Table 3-1 f o r a more expanded d e s c r i p t i o n .

3 . 2 MATRIX APPLICATION

The matrix in Figure 3-1 represents the most important part of this report. A n understanding of the parameters and associated codes allows the user to derive frorn the matrix the two overall objectives of the report. First, this graphic summarization of Fa's investigation allows the reader to surmise the current state of resource recovery practices within the mining industry. The waste streams with recoverable resources, the nature of the recovery technologies available, the development stage of the technologies, and the transfer of recovered materials are all summarized within the matrix.

The second major objective of the report, to identify those areas in which the current state of resource recovery can be advanced, can also be surmised from this matrix. ings, the state-of-the-art can be advanced in three fundamental ways:

Based upon this graphic summary of F a ' s find-

a Increasing resource recovery technology development

a Expanding application and reuse of recovered waste

a Increasing research into and application of new

stage

material

or proposed recovery areas.

By increasing the technology development stage, a technology may be further implemented throughout the industry. A l l those technologies that are less than full scale, commonly practiced (i.e., those ranked at 5 o r below) could be further developed. technology process may be increased, for example, by moving from an experimental stage to a small-scale functional version of the process, or by moving from a process being sporadically practiced in the industry to commonly practiced. to recover iron. . Increasing its current development stage from full scale sporadically practiced to full scale commonly practiced would result in the advancement of the state-of-the-art. This advancement would be reflected in the matrix by a change from a five (5) to a six ( 6 ) .

The development of a resource recovery

An example is the retreatment by flotation of iron ore mine tailings

Increasing the transferability of the recovered material will also advance the state-of-the-art. A l l those recovered materials that are transferred on a limited basis could be greater utilized. finding new areas for use of recovered materials. there is little room for advancement in transferability of materials. to the massive amounts and weights of most mine wastes, further transfer of materials becomes economically impossible.

This would require In the mining industry

Due

112

Addi t iona l ly , f u r t h e r r e sea rch i n t o t h e app l i ca t ion of tech- no log ie s no t i d e n t i f i e d in t h e ma t r ix t o waste streams generated by the i n d u s t r y may i d e n t i f y o t h e r s u i t a b l e resource recovery p r a c t i c e s . This i nc rease i n t h e s ta te -of - the-ar t of resource recovery would be r e f l e c t e d through an inc rease i n t h e scope of t h e matrix. The mat r ix may a l s o be expanded by i d e n t i f y i n g o t h e r w a s t e s t reams i n t h e indus t ry t o which resource recovery processes may be appl ied .

In summary, t he mat r ix i n F igure 3-1 rep resen t s a synopsis of FAL's exhaus t ive i n v e s t i g a t i o n of t h e cu r ren t s t a t u s of resource recovery i n t h e mining indus t ry . Yet, due t o t h e scope of the i n v e s t i g a t i o n , n e i t h e r t h e mat r ix nor t h e accompanying text d i scusses every p o t e n t i a l o r e x i s t i n g resource recovery technology/waste stream combination. combinations not included i n t h e surveyed l i t e r a t u r e nor discussed w i t h indusf ry r e p r e s e n t a t i v e s are n o t included i n t h i s r epor t .

Those

11 3

Table 3-1 i s a summary of t h e mining waste recovery processes and corresponding ar t ic les r e l a t e d t o those processes . l i n e d mining waste heading are b r i e f d e s c r i p t i o n s of recovery techniques followed by numbers corresponding t o t h e numbered a r t i c l e s i n the r e fe rence s e c t i o n . The two-digit f i g u r e be fo re each recovery technique r e f e r s t o t h e s t a g e of development and area of t r a n s f e r of t h e technique. A descr ip- t i o n of t hese c l a s s i f i c a t i o n s can be found on pages 110 and 111.

Lis t ed below each under-

Table 3-1

SUMMARY OF MINING WASTE RECOVERY PROCESSES

1. Acid Mine Drainage Treatment Sludge 2b Revegetation of s t r i p mine s o i l , 57 2b

zC Brick product ion, 57 zC Port land cement a d d i t i v e , 57

Dried s ludge used as rock dus t f o r explosion c o n t r o l in coal mining ope ra t ions , 57

2 . Asbestos T a i l i n g s zC Mineral wool i n s u l a t i o n product ion, 1 zC Building cons t ruc t ion b r i c k s , 72, 93 za 4c Asphalt su r f ace mix, 46

Recovering a sbes tos f i b e r s from discarded o r e t a i l i n g s , 89

3 . Barite Ta i l ings 5a Recover b a r i t e from o l d m i l l t a i l i n g s ponds, 2 , 3 , 62 5c Highway cons t ruc t ion aggrega te , 46

4 . Coal Mine Refuse 2a 2a 2c

2c 2c 2c 2c

2c 2c

2c

-_

Magnetite recovery from c o a l washings, 110 Production of z inc concen t r a t e s from s l u r r y p i l e s , 9 Used as an aggrega te i n l o w q u a l i t y conc re t e , 4, 8, 10, 14, 15 , 16, 18, 20, 28, 108, 124, 126, 153 Manufacture of b r i c k s and blocks, 8, 10, 15, 16, 18 P l a s t i c r e s i n manufacture, 14 Raw material i n mineral wool product ion, 14, 26, 27, 124 Fine c o a l r e f u s e i s combined wi th waste crankcase o i l and p e l l e t i z e d , then used as a f u e l w i th 13,670 Btu/ lb , 17 Production of cement c l i n k e r from burned c o a l r e fuse , 32 Wash water s ludge i s d r i e d , then mixed w i t h a rock salt b inde r , then b r i q u e t t e d and s o l d as f u e l , 11, 19 Used as replacement f o r t h e c l a y f r a c t i o n of t h e feed i n product ion of por t land cement, 10, 31

114

P

Table 3-1 (continued)

4. Coal Mine Refuse (continued)

3c 4c 4c 5c

5c

5c

5c

6a

6c

Heavyweight a n t i - a b r a s i v e f l o o r t i l es , 80 Coal r e fuse as a s o i l c o n d i t i o n e r , synthet,: soil ..umus, 7, 134 Fluidized bed combustion of c o a l r e f u s e , 12 , 26, 29, 33, 111, 118, 137 Inc inera ted a n t h r a c i t e mine r e f u s e used as an an t i - sk id highway material spread over i ce and snow, 7, 1 4 , 26, 31, 124 Pmbankmcnt naterial , 5, 10 , 1 2 , 13, 14 , 16, 20, 21, 24, 31, 4 6 , 109, 128, 146 Aggregate manufacture 8, 10, 15, 16 , 20, 26, 27, 28, 29, 46, 86, 108, 124, 128, 144, 147 Coal shale used f o r f i l l material, road base material, su r f ac ing publ ic squares, pavements o r pa rk ing p l aces , 8, 10, 1 2 , 14 , 21, 23, 26, 30, 31, 108, 144, 147 Recovering c l e a n c o a l from t h e gob p i l e , 6 , 9, 2 2 , 121, 127, 131, 133, 138, 141 , 142 Chimney f l u e t i l e product ion , 8

5. Copper Mining Refuse 2a Bac te r i a l l each ing of copper mine waste, 39 z C Steam cured b r i c k s from t a i l i n g s , 72 3c Production of a n o r t h o s i t e concen t r a t e , a source of aluminum, from

f l o t a t i o n t a i l i n g s , 37 5a Recovery of copper from m i l l i n g wastes by l each ing or f l o t a t i o n ,

36, 43, 90, 91, 96, 101 5c Waste mine rock used f o r f i l l , road s u r f a c e , 35, 46, 49, 87, 144 6a Recovery of copper from m i n e waste and overburden by leaching , 38,

41, 61, 84

6 . Feldspar T a i l i n g s 2a Recovery of f e l d s p a r and q u a r t z from f e l d s p a r mine t a i l i n g s , 73, 88 zC Used i n mor ta r , a s p h a l t cements, cement f i l l e r s , and b r i c k s , 73

7. Gold Mine T a i l i n g s zC Used i n b r i c k and c o n c r e t e production, 85 4a Gold recovery from s l i m e s by p r e c i t p i t a t i o n , 155 5c Use i n embankment c o n s t r u c t i o n , 46 5c Aggregate use, 46, 49, 144 6a Gold recovery from m i n e waste t a i l i n g s by leaching , 65, 154,

156, 157

115

Table 3-1 (continued)

i

8. Granite Mining Wastes 5a Recovery of feldspar and glass by flotation, 5 9 7a Recovery of silicon carbide from granite sludge, 60

9 . Iron Ore Mine Tailings 4a Recovery of magnetite from tailings, 92 5a 5c Aggregate use, 46 , 4 9 , 1 4 4 , 159

Retreatment by flotatlon to recover iron, 51, 56

10. Lead Mine Tailings 5c Aggregate in bituminous paving, 4 6 , 144 5c Embankment construction, 46, 49 7a Recovery of sulfide minerals by flotation, 58

11. Phosphate Mining Wastes 2a Vanadium recovery from slime tailings, 136 2c Overburden and sand tailings used a s skid-resistant asphalt

2c Phosphate slimes processed into lightweight aggregate, brick,

5a Uranium recovery from phosphate wastes, 166

aggregate, 4 6 , 94

pipe, and tile, 49 , 78, 99

1 2 . Miscellaneous Mining Industries Molybdenum Mine Tailings 2a Recovering molybdenum from mine tailings by leaching, 42 5c Aggregate in bituminous mix, 46 Uranium Mine Tailings 2a Uranium, vanadium, and radium recovery from tailings, 5 4 , 155, 163 2c Waste sands and slimes mixed into asphalt, 46 5a Recovering uranium compounds from mine water by ion exchange, 1 6 4 ,

ion flotation, 40 - Zinc Mine Tailings 4a Upgrading process for tin in zinc mine tailings, 97 5c Aggregate use, 4 6 , 1 4 4 , 1 6 5 , 166

STAGE OF DEVELOPMENT AREA OF TRANSFER

1. Proposed Research Area a. Within a Single Facility 2. Bench Scale Research Project b. Between Facilities Within an Industry 3. Pilot Scale c. Between Facilities, Between Industries 4. Full Scale Demonstration 5 . F u l l Scale Sporadically

6 . Full Scale Commonly Practiced 7. Formerly Practiced

Practiced

-_

116

4.0 SELECTED RESOURCE RECOVERY PROCESS AND WASTE MANAGEMENT APPROACHES

The preceding s e c t i o n s of this r e p o r t have presented d e s c r i p t i o n s of t h e va r ious mining i n d u s t r i e s and the p a s t , p resent , and proposed resource recovery techniques a v a i l a b l e to the indus t ry . This has included d e s c r i p t i o n s of each resource recovery process , i t s s t a g e of development, t he waste streams t o which i t can be app l i ed , and t h e material that can be recovered. This s e c t i o n w i l l h i g h l i g h t s e l e c t e d r e source recovery p r a c t i c e s o r processes which have p o t e n t i a l f o r g r e a t e r a p p l i c a t i o n w i t h i n the industry. This i s no t t o say t h a t these waste u t i l i z a t i o n techniques w i l l be advanced by increased awareness, but t h a t t h e s e s e l e c t e d u t i l i z a t i o n s are among those which have t h e least amount of d i sadvantages t o overcome.

Sect ion 4 . 1 p resents t h c s e processes i d e n t i f i e d i n Sec t ion 2 t h a t are supported by s i g n i f i c a n t r e s e a r c h and/or proven experience. t h a t these could be f u r t h e r u t i l i z e d w i t h i n t h e indus t ry i f c e r t a i n condi- t i o n s changed. The f e a s i b i l i t y of us ing a s p e c i f i c waste resource depends on a number of f a c t o r s , many of which are i n t e r r e l a t e d . These resource recovery processes were evaluated f o r technologica l , economic, . r egu la to ry , and i q s t i t u t i o n a l f a c t o r s and were,in gene ra l , found t o be favorably in- f luenced by one o r more of t hese f a c t o r s . However, general ly no op t ion w i l l b e widely implemented un le s s i t i s e i t h e r economically p r o f i t a b l e o r requi red by l a w .

It i s f e l t

Sect ion 4.2 i d e n t i f i e s t hose resource recovery processes t h a t FAL f e e l s could p o t e n t i a l l y have g r e a t e r app l i ca t ion wi th in the i n d u s t r y but are only supported by l imi t ed r e s e a r c h o r appl ica t ions . These processes a r e under a c t i v e i n v e s t i g a t i o n and each could p o t e n t i a l l y reduce t h e waste accumulations, o r t h e c o s t s of t rea tment and d isposa l .

4 - 1 K F I AREAS FOR INCREASED RECOVERY

There are t h r e e ways t o increase t h e s ta te-of- the-ar t of resource recovery of t h e mining indus t ry :

0 Increas ing t h e level of development of recovery processes

0 Expanding t h e t r a n s f e r a b i l i t y of waste o r recovered materials

0 Developing a d d i t i o n a l r e c o v e r y / u t i l i z a t i o n processes o r i d e n t i f y i n g a d d i t i o n a l waste streams from which materials may be recovered .

I n o rde r t o success fu l ly expand c u r r e n t resource recovery/waste u t i l i z a t i o n p r a c t i c e s , t h e s e methods must b e a p p l i e d t o those areas w i t h t h e greatest l i ke l ihood of success. These t h r e e methods desc r ibe how t h e state-of-the- a r t can be advanced, b u t they a l o n e do n o t determine which resource recovery processes have t h e b e s t p o t e n t i a l f o r be ing advanced. be considered i n s e l e c t i n g those p rocesses t h a t have the g r e a t e s t p o t e n t i a l .

Addi t ional f a c t o r s must

117

Each of t h e 61 resource recovery processes or p r a c t i c e s reviewed i n t h i s s tudy has vary ing degrees of p o t e n t i a l for advancement. However, some of t h e processes have more p o t e n t i a l , as mentioned earlier, i n t h e form of fewer disadvantages t o overcome. This s e c t i o n presents those processes s e l e c t e d which were f e l t t o be r ep resen ta t ive of resource recovery processes i n t h e mining i n d u s t r y , which e x h i b i t fewer disadvantages, and t h u s t h e b e s t p o t e n t i a l f o r f u r t h e r use. Those s e l e c t e d are:

e e 0

0

0

0

0

0

0

0

Mining wastes as aggrega te Mining wastes i n embankment Mining wastes i n cons t ruc t ion products Mineral wool from asbes tos t a i l i n g s Retreatment of b a r i t e t a i l i n g s Clean c o a l recovery from re fuse p i l e Coal waste as an an t i - sk id material Uranium recovery from phosphate mining wastes Uranium, radium, and vanadium recovery from uranium mine t a i l i n gs Ion exchange uranium recovery from mine water

Resource recovery techniques appl ied t o mining wastes can be grouped under two c a t e g o r i e s : (1) phys ica l u t i l i z a t i o n of t h e waste; o r (2) retreat- nent of t h e wastes t o recover a d d i t i o n a l minerals . above, resource recovery processes f e l t t o be r ep resen ta t ive of each of t hese two broad c a t e g o r i e s were chosen. The f i r s t t h r e e s e l e c t i o n s , mining wastes as aggrega tes , embankment f i l l , and cons t ruc t ion products , are aggregat ions of many i n d i v i d u a l recovery processes descr ib ing research or actual u t i l i z a t i o n performed wi th many d i f f e r e n t mining wastes. These ind iv idua l processes are descr ibed i n the t e x t of t h i s r e p o r t , bu t f o r t he purposes of t h i s chapter , sunning toge the r t he i n d i v i d u a l processes w a s considered j u s t i f i e d .

I n s e l e c t i n g the l i s t

Se lec t ion of t hese r e source recovery and waste u t i l i z a t i o n processes w a s based on examination and cons ide ra t ion of va r ious f a c t o r s . used t o assess t h e advantages and disadvantages of each resource recovery process can be grouped i n t o four gene ra l areas:

These f a c t o r s

0 Technological 0 Economic 0 Regulatory e I n s t i t u t i o n a l

Included in these four general areas are such'factors as: application of the process to more than one waste stream; quality and volume of research suggesting the potential for advancement; stage of process o r technology development outside the United States; and current and future markct for recovered materials o r waste-derived products. Thus, the advancement potential for each process can be defined by examining each of these general analysis areas (selection criteria) within the context of the available information.

This section and following subsections present the analysis of these resource recovery and waste utilization areas with regard to the four selection criteria. These criteria are described in more detail below.

4.1.1 Technological Selection Criterion

The technological evaluation of a process primarily determines whether or not the technology is developed, or significantly far enough along, to successfully recover o r utilize waste materials. This evaluation includes the use of the process in the United States as well as the successful technological development of the same, or similar process, in other industries or countries. For example, a technology may be commonly practiced in Europe, but not implemented nor researched in the United States Under these circumstances, the technology would have good potential for advancement through implementation in the United States.

Even if the technology exists o r has been proven, there may be other technological considerations affecting its potential. These considerations include, but are not limited to, adaptability of present equipment, changes in product quality, limited process applications, o r equipment problems due to waste streams being treated. either enhance or prevent the use of a technologically proven system.

Such factors can

Figure 4-1 presents the various technological advantages and disadvantages that were evaluated for each resource recovery or waste utilization process in order to assess the overall influence of this criterion. Studying Figure 4-1, it can be seen that all of the processes are technically feasible and that the advantages generally outweigh the disadvantages. This corresponds to the need for a process to be technologically feasible in order f o r it to be considered for implementation within the industry. Few establishments will opt for a technologically unproven or problem-ridden process f o r resource recovery when other proven waste management practices exist.

A l l of these processes have technological potential for advance- These processes are the most likely to experience continued o r more ment.

widespread utilization in the future, due to the extent of their demonstrable technology. -_

119

IC, I i n l t l ~ E x l n c n 0 d; L<l~l l l ty l o 0 x 0 u 0 0 u u u r h c r Cuunir ler 0 0 0 -. , I P-- P 1

L -

0 1 0 0

z I I

Figure 4-1. Technological advantages and disadvantages of selected resource recovery processes.

0 0 x Mlnrr 0 '

u c s v r , - a d Ava 11 a b 111 t Y \p,,l l C . * I > l P t u a t4mJ"rity

0 I n I Ylntmal Egulpment or

Pro, rdirre Wlf l c a t i m a

LmprnvrslNo ChanRe i n P r wfuc t Our1 1 t y

, i g n l f l ~ m t Research Performed

~ y p l I c n t l o n Proven by Crlmncrc tal Use

F i t e n n t v e EqilLpWnt O r

P r a cdure k d l f I c a t h l r

c ) , , r l l tv r$r Conslatancy P r o b l e u

Pnvlronrnt .1 Problamr

Appl lcehle t o S U I 1 S a n u n t of Whoa

I Lilted A v a l l a b L l l t y ,

~ -

0 0 0 0 0 ry 0

0 x x 0 0 -7 0 0 0 0

o 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

v 0 0 0 0

x x X x 7 x

X X

0

4 . 1 . 2 Economic S e l e c t i o n C r i t e r i o n

The main purpose of t h e economic eva lua t ion is t o i l l u s t r a t e wherher o r not t h e process is economically f e a s i b l e . This considers c o s t compet i t ive- nes s with convent ional materials o r wi th convent ional waste t rea tment /d isposa l techniques. A l s o considered are f a c t o r s such as add i t iona l c a p i t a l investment requi red and market and marketing condi t ions .

Economics p l a y s a very d e c i s i v e s o l e i n t h e u t i l i z a t i o n of Ioining Technological ly proven p rocesses w i l l r a r e l y be considered i f they wastes.

cannot provide a sav ings of some s o r t . of marke tab i l i t y of t h e recovered material, reduced d isposa l c o s t s , reduc- t i o n i n raw material requirements o r some combination of these t h r e e f a c t o r s .

Thse sav ings can be i n t h e form

A s can be seen from Figure 4 - 2 , economic f e a s i b i l i t y must, i n most ca ses , be determined on an i n d i v i d u a l bas i s . za t ion processes depend a g r e a t d e a l on t r a n s p o r t a t i o n d i s t ances r equ i r e4 . For example, mine t a i l i n g s cannot gene ra l ly be t ranspor ted more than 10 t o 25 miles t o remain competi t ive w i t h convent ional materials. Also, many of t he mifiing waste re t rea tment p rocesses can be more expensive t o c o n s t r u c t and ope ra t e than t h e va lue rece ived from t h e recovered minerals . Mineral p r i c e s f l u c t u a t e i n many cases and can wreak havoc on w e l l planned and once economical recovery op t ions . For i n s t a n c e , gold and s i l v e r p r i c e s have moved up and down d rama t i ca l ly f o r t h e las t s e v e r a l years making re t rea tment of t a i l i n g s p r o f i t a b l e one month, c o s t l y the next . Retreatment of uranium t a i l i n g s i s another example of market p r i c e f l u c t u a t i o n s . from $40 per pound i n t h e 70s t o c u r r e n t l y (1982) around $25 p e r pound. This has dr iven most uranium t a i l i n g s r e t r ea tmen t opera t ions out of business .

The economics of phys i ca l u t i l i -

P r i ces have gone

Thus, t h e economic advantages of t h e processes presented i n Figure 4-2 are not as c l e a r l y def ined as are t h e technologica l advantages. How-

eve r , s eve ra l of t h e s e l e c t e d r e source recovery processes do enjoy economic advantages and, coupled wi th t h e i r t echno log ica l advantages, are c u r r e n t l y being p rac t i ced i n t h e indus t ry . These processes are:

0 Mining wastes as aggrega te 0 Retreatment of b a r i t e t a i l i n g s 0 Ion exchange uranium recovery from mine water

All o the r s have varying degrees of economic f e a s i b i l i t y depending on f a c t o r s p a r t i c u l a r t o each waste stream and i t s proposed u t i l i z a t i o n . Thus, no c l e a r "yes o r no" economic judgments can be made f o r most of t h e processes .

1 2 1

Figure 4-2. Economic advantages and disadvantages of s e l e c t e d resource recovery processes .

, I . ...

4.1.3 Regulatory Se lec t ion C r i t e r i o n

Federa l , s ta te , and l o c a l r e g u l a t i o n s can l i m i t t h e use of a resource recovery process o r a recovered material. These r e g u l a t i o n s may spec i fy con-

duc t s . Also, i n s t a l l a t i o n of p o l l u t i o n c o n t r o l devices f o r resource recovery processes may be requi red i n o r d e r t o meet emission, h e a l t h , and s a f e t y s tandards.

tami&nt l e v e l s i n products or t h e q u a l i t y of t h e material used i n o the r pro- --

Regulations can a l s o i n d i r e c t l y f o s t e r t h e use of a resource recovery process . The r e g u l a t i o n s may make c u r r e n t d i s p o s a l p r a c t i c e s uneconomical, t h u s fo rc ing t h e waste genera tor t o e i t h e r change t h e d i sposa l p r a c t i c e or recover the materials i n t h e w a s t e . Also, r e g u l a t i o n s may make resource recovery more cos t - e f f ec t ive than c u r r e n t d i sposa l p r a c t i c e s . In a d d i t i o n , reduct ion of s o l i d and l i q u i d waste streams through resource recovery may s i g n i f i c a n t l y reduce t h e impact of app l i cab le r egu la t ions .

Figure 4-3 summarizes t h e advantages and disadvantages a s soc ia t ed due t o va r ious r egu la t ions . w i t h t h e ind iv idua l r e source recovery processes

A key i s s u e i s whether or no t t h e process or product is of regula tory conce rn a t e i t h e r t h e Federa l , s tate, or l o c a l levels. The absence of regula- t o r y Concern can be viewed as a clear advantage t o a resource process s i n c e this eliminates the need t o conform t o r egu la to ry requirements.

S t a t e and l o c a l agencies are t h e a u t h o r i t i e s respons ib le for formulat ing and enforc ing most of t he r egu la t ions concerning m i n e waste d i sposa l and re t rea tment . Some of t h e resource recovery processes such as t a i l i n g s re t rea tment w i l l be included w i t h these r egu la t ions . p rocesses , p a r t i c u l a r l y the phys ica l u t i l i z a t i o n processes , w i l l be regu- l a t e d by Federa l , S t a t e , or l o c a l ordinances and s p e c i f i c a t i o n s . For example, Federa l o r S t a t e Departments of Transpor ta t ion may or may n o t have s p e c i f i - c a t i o n s f o r va r ious mining wastes t o be used in road cons t ruc t ion app l i ca t ions . Thus, laws a f f e c t i n g mining waste d i s p o s a l and/or u t i l i z a t i o n can vary g r e a t l y from s t a t e t o s t a t e .

Other recovery

4.1.4 I n s t i t u t i o n a l S e l e c t i o n C r i t e r i o n

Indus t ry a t t i t u d e s toward r e source recovery p r a c t i c e s depend on a number of f a c t o r s inc luding: f a v o r a b l e or unfavorable impression of success c r e a t e d by t h e o the r t h r e e s e l e c t i o n cri teria, r e s i s t a n c e t o change, and t h e s p e c i f i c n a t u r e of t h e mining indus t ry . i n c u r r e n t waste management p r a c t i c e s w i l l occur i s i f t h e o ther t h r e e criteria ( technologica l , economic, and r egu la to ry ) are p o s i t i v e . These f a c t o r s l a r g e l y govern an i n d u s t r y ' s pe rcep t ion as t o whether or no t a recovery process w i l l be success fu l . This pe rcep t ion , in tu rn , i n f l u e n c e s t h e wi l l i ng - n e s s of an indus t ry t o try a recovery process. recovery process is perceived as n o t being success fu l based on p o t e n t i a l or a c t u a l technologica l or economic problems, then i n d u s t r y i s l i k e l y t o be unwi l l ing t o implement t h e process whether or no t t h e percept ion i t s e l f i s ac-turate.

I n genera l , t h e only way a change

For example, i f a resource

123

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Limitm ytuntlcy U u d s t NA 0 NA NA a4

LLmlte Contolltunt 0 0 MA 0 0 WI n4

ln Pruduct 4

I Cuncentratbm tn Product I I I 1 I I 1 1

M: a Critarlon Appliaa Blank Crttwioo Do.. Uot Apply I

T -1. to d a t e r d m

l h y or may not b. t r u drD.tldin# upon h d l v i d w l riD. YAaCa c q o d t i o n and/or i n d l v i d r u l atat. r e g u h t l a a

M not 4 p i ~ e r b i .

Figure 4 - 3 . Regulatory advantages and disadvantages of selected resource recovery processes.

-..-

I

i -

A t t i t u d e s of i ndus t ry personnel and l o c a l r e s i d e n t s a l s o a f f e c t t h e implementation of resource recovery processes . A t t he management l e v e l , t h e r e may be r e s i s t a n c e t o changing o r rep lac ing proven processes o r materials w i t h newer ones, e spec ia l ly i f t h e o l d e r processes and materials have been used for a long time. Such s i t u a t i o n s may be perceived by t h e workers as a t h r e a t t o t h e i r job secu r i ty . Also, implementation of new processes may r e q u i r e workers t o l e a r n new j o b s or processing techniques. Add i t iona l ly , r e s i d e n t s near an i n d u s t r i a l f a c i l i t y may ob jec t t o t h e i n s t a l l a t i o n of new equipment, e s p e c i a l l y i f such equipment i s perceived as a source of sub- s t a n c e s t h a t may t h rea t en t h e i r h e a l t h o r t he surrounding environment.

Addi t iona i ly , t he re is a n a t u r a l r e luc t ance on t h e p a r t of i ndus t ry eng inee r s t o use materials t h a t by t h e i r very name, "waste materials," imply t h a t they are i n f e r i o r t o convent ional materials. On t h e o t h e r hand, one must guard a g a i n s t t he e n t h u s i a s t i c and sometimes exaggerated c la ims of r e sea rche r s who have inves t iga t ed t h e process i n labora tory s t u d i e s .

A t t i t u d e s toward resource recovery and w a s t e u t i l i z a t i o n depend on t h e o v e r a l l in f luence of t h e o t h e r t h r e e c r i t e r i a ( technologica l , economic, r egu la to ry ) as w e l l as a number of sub jec t ive cons idera t ions . Figure 4-4 p r e s e n t s t h e i n s t i t u t i o n a l f a c t o r s t h a t w e r e evaluated t o determine the o v e r a l i i n f luence of t h i s c r i t e r i o n on the advancement p o t e n t i a l of t h e s e l e c t e d resource recovery processes .

From Figure 4-4 i t can be seen t h a t i ndus t ry has been w i l l i n g t o r e sea rch and/or incorpora te these resource recovery processes , but t h i s w i l l - ingness has been tempered by a cons t an t concern about product q u a l i t y . Some of t h e processes have been used q u i t e f requent ly i n one p a r t of t h e count ry , wh i l e i n o t h e r p a r t s of the count ry , an ind iv idua l ' s nega t ive opin ions of u s ing a " w a s t e material" have completely ha l t ed at tempts a t mine waste u t i l i z a t i o n .

4.1.5 Summary of Analysis

This s e c t i o n p resen t s a summary of t he ana lyses of t h e key resource recovery and waste u t i l i z a t i o n areas wi th regard t o t h e four s e l e c t i o n cr i - teria. The r e s u l t s of t h i s a n a l y s i s are presented i n Figure 4-5. This f i g u r e i l l u s t r a t e s t h e in f luence of t h e s e l e c t i o n c r i t e r i a on t h e p o t e n t i a l for g r e a t e r a p p l i c a t i o n and development of t hese s e l e c t e d processes .

This in f luence may be p o s i t i v e , negat ive, o r even v a r i a b l e depending on s p e c i f i c i ndus t ry o r process parameters and c h a r a c t e r i s t i c s . The o v e r a l l p o t e n t i a l of a recovery process depends on a l l f o u r f a c t o r s , thus a nega t ive i n f l u e n c e of one f a c t o r does no t n e c e s s a r i l y preclude t h e process from having good advancement p o t e n t i a l . Although these four s e l e c t i o n cr i ter ia have been l a r g e l y d iscussed independently, they are i n f a c t interdependent . The inst i - t u t i o n a l s e l e c t i o n c r i t e r i o n i s most a f f e c t e d by the o the r t h r e e c r i t e r i a , as d i scussed i n Sect ion 4 . 1 . 4 . The o t h e r t h ree f a c t o r s ( technologica l , economic ,

12s

I

0

Y C

i

Figure 4 - 4 . Institutional advantages and disadvantages of selected resource recovery processes.

, . . . ., . .---

I

I -

and r egu la to ry ) are a l s o interdependent . For example, r egu la to ry c o n t r o l s on emissions can r e s u l t i n technologica l problems i n t r y i n g t o adapt t h e system t o meet t h e s e r egu la to ry s tandards . c o s t of t h e system t o t h e poin t t h a t i t is no longer economical.

Th i s i n t u r n can inc rease t h e

Analys is of F igure 4-5 reveals t h a t some of t h e se l ec t ed resource recovery processes have an advantage for continued o r increased u t i l i z a t i o n . Furthermore, it can be seen t h a t w i t h a change f o r t h e p o s i t i v e i n j u s t one of t h e fou r eva lua t ion facLors , many of t h e se lecced processes could r e a l i z e g r e a t e r u t i l i z a t i o n p o t e n t i a l . As noted earlier, t h e economics of a p a r t i c - u l a r process p l a y s t h e h e a v i e s t r o l e i n implementation dec i s ions , and t h e economics of most of t h e mining resource recovery processes must be evaluated on an ind iv idua l b a s i s .

O f t h e s e l e c t e d processes , t i o n c r i t e r i a c a t e g o r i e s . They are:

t w o scored p luses i n all of t h e se l ec -

0 Retreatment of b a r i t e t a i l i n g s 0 Ion exchange uranium recovery from mine water

It i s n o t s u r p r i s i n g t h a t t hese two processes are being appl ied c u r r e n t l y by indus t ry . However, they are not being appl ied t o a l l of t h e i r p a r t i c u l a r waste streams generated throughout t h e country.

Other processes scor ing h igh are usua l ly p r a c t i c e d by indus t ry at a sporadic ra te . These processes have t h e p o t e n t i a l of consuming l a r g e amounts of p a s t and c u r r e n t accumulations of mining wastes, pro- v id ing t h e r e i s a change i n one of t h e c r i t e r i o n f a c t o r s . These pro- c e s s e s are:

0 Mining wastes as aggrega tes 0 Mining wastes i n embankments 0 Clean c o a l recovery from t h e r e fuse p i l e 0 Coal waste as an an t i - sk id material 0 Uranium recovery from phosphate wastes

It i s i n t e r e s t i n g t o no te t h a t one of the processes , uranium, radium,

The economics of t h e process has precluded any commercial u t i l i - vanadium recovery from uranium mine t a i l i n g s , scored p luses i n a l l c a t e g o r i e s except one. za t ion .

127

D

Minima Mineral Ratrut- Urml iu U n l n a Ilinina Uaatma Uool m n t Claao Coal Coal l s c o v r ~

t Uaaraa i n C m - Prom of Recovery Umuta from U r a o l u . l i r d l u . V d u 10s lofhuya from Antl-Skld Phompluta Rscovacy from U r a o i u ~ C 0 V u - y aa io atfuctioa k b e a t o r b r i t .

Tactmolo8lcal + + +I- + t + + + + + Economic +I- +l- +I- + + +I - + +I- - + Imaulatory +I- +I- +/- +I - + + I IIUL i CUL l o ~ l +I - + 4

a - + + + - - - - + - +

t.

W r a

Figure 4 - 5 . Overview of selected resource recovery processes.

4.2 FURTHER RESEARCH AND INCENTIVE DEVELOPMENT

4.2.1 Emerging Technologies wi th Good P o t e n t i a l

I n add i t ion t o t h e s e l e c t e d recovery processes presented i n Sec t ion 4 .1 , t o t h e indus t ry i n the f u t u r e . These processes are:

the re a r e several o t h e r s t h a t are f e l t may prove va luable

0 Fluidized bed combustion of coa l r e fuse 0 Vanadium recovery from phosphate wastes 0 Pe l l e t i zed waste o i l - c o a l dust mixture

The f i r s t has reached a full s c a l e demonstration, t h e second i s s t i l l i n t h e research l a b phase, while t h e t h i r d one has been researched and proposed, bu t never u t i l i z e d . These t h r e e have the p o t e n t i a l f o r widespread use providing the i n i t i a l f avorab le r e s e a r c h r e s u l t s continue. Each is discussed i n t h e fol lowing pages.

4.2.1.1 F lu id ized Bed Combustion of Coal Yeruse

I n a p ro jec t sponsored by t h e U.S. Department of Energy and the Shamokin Area I n d u s t r i a l Corpora t ion , Shamokin, Pennsylvania, culm, t h e w a s t e product of a n t h r a c i t e c o a l mining, i s being used t o f i r e a steam p l a n t . Anthrac i te culm is f e d t o an atmospheric fluidized-bed combustion b o i l e r t h a t d e l i v e r s 23,400 pounds p e r hour of 200 p s i s a tu ra t ed steam. Cellu-Products Corp., a paper company located next t o the p l a n t , i s using the steam. about a t h i r d of t he hea t ing va lue of coa l ; ash content i s 65 t o 75 percent Some 900 m i l l i o n yards of a n t h r a c i t e culm has accumulated i n no r theas t e rn Pennsylvania (118).

Heating value of t h e culm is 3,000 t o 4,000 Bru p e r pound,

Fluidized-bed combustion of c o a l r e f u s e has been p rac t i ced throughout Europe, and e s p e c i a l l y France, for many years . Meanwhile, t h e United S t a t e s , r i c h i n v i r g i n sources of c o a l , has not shown much i n t e r e s t i n t h e process u n t i l j u s t recent ly . Much r e sea rch has been done bu t very l i t t l e commercial app l i ca t ion has been attempted. I f t h i s method of c o a l r e f u s e u t i l i z a t i o n can be demonstrated economically and t echn ica l ly f e a s i b l e , i t could p o t e n t i a l l y consume l a r g e tonnages of accumulated c o a l r e fuse .

4.2.1.2 Vanadium Recovery from Phosphate Wastes

Western phosphate o r e d e p o s i t s are one of the l a r g e s t p o t e n t i a l sou rces of domestic vanadium i n t h e U.S. today. t h e vanadium i s assoc ia ted w i t h t h e f i n e s t p a r t i c l e s of t h e matrix, which r e p o r t t o t h e slime t a i l i n g s du r ing bene f i c i a t ion . have an upgraded concent ra t ion of approximately a qua r t e r of a percent vanadium, by weight, and a t a mining ra te of 9.5 mi l l i on tons of phosphate o r e p e r yea r , t h i s amounts t o 7,150 tons of vanadium, more than t h e t o t a l U.S. consumption f o r 1980. A t y p i c a l phosphate bens f i c i a t ion p l a n t w i l l p rocess 7,200 tons of o re p e r day w i t h 30 percent of t he feed r e j e c t e d as slime t a i l i n g s . These t a i l i n g s , i f processed, could r ep resen t 5 tons of vanadium product per day wi th a va lue of $35,400.

Within t h e phosphate o r e ,

These t a i l i n g s thus

1 2 9

The total domestic usage of vanadium for 1980 was 6,500 tons, and this is predicted to increase to 13,000 tons by 1990 (136). There will be a definite need for additional domestic sources in the years to come.

Laboratory research conducted by the Bureau of Mines Albany Research

present in phosphate rock beneficiating The final vanadium product 1 s recovered at the end of the circuit

Center has found that a sulfuric acid leach process can dissolve virtually all of the vanadium, uranium, and P20 process. described in Section 11.4.5.

If this process is shown to be economically feasible, vanadium imports to this country could be cut drastically; in addition, it could lower costs connected with disposal and treatment of the tailings.

4 . 2 . 1 . 3 Pelletized Waste Oil-Coal Dust Mixture

In a University of Alabama research project, a stable pelletized fuel product has been made from a mixture of waste crankcase oil and coal dust ( 1 7 ) . Waste crankcase oil was mixed with -28 mesh coal dust, subjected to a pressure of 30,000 to 35,000 psi, and produced a pellet with an average heating value of 13,670 Btu per pound. This is equal to high grade virgin coal.

However, in a conversation with Dr. C. D. Haynes, who presented these results at the 4th Mineral Waste Utilization Symposium in 1974 , it was learned that no commercial application has been attempted. Dr. Haynes felt that the biggest hinderance to this process would be the metal content of the crankcase oil, which would be emitted as a toxic air pollutant. Also some minor problems with stored pellets dissolving were experienced.

The point is that positive results like these were obtained by college students working on a school project and if interest in this process wereshown by a serious research team, it is very likely that these problems mentioned above could be resolved. This could help t o alleviate some of the coal mining wastes and waste crankcase oil, and in the process, turn two waste products into a source of energy.

130

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Bingham, Edward, "Waste U t i l i z a t i o n i n the Copper Industry!' 1st Mineral Waste U t i l i z a t i o n Symposium IITRI.

Kennedy, Allen, "Recovery of Copper from Michigan Stamp Sands," 2nd Mineral Waste U t i l i z a t i o n Symposium IITRI.

Lawver, Jabes, "Production of Anorthosi te Concentrate from Minnesota Copper-Nickel T a i l i n g s by High Gradient Magnetic Separat ion," - Pro- ceedings: M M I J - A m Meeting, Denver, Colorado, September 1976.

McKinney, W. A , , "Recovery of Copper from Crushed and Sized Porphyry Mine Waste," Transac t ions of the Society of Mining Engineers, AIME, volume 254, number 4, December 1973.

Berry, V. K. , "Direct Observations of Bacteria and Quan t i t a t ive S tudies of Their C a t a l y t i c Role in t h e Leaching of Low-Grade Copper-Bearing Waste," X e t a l l u r g i c a l Appl ica t ions of Bacterial Leaching and Related Microbio logica l Phenomena,. Conference Proceedings, New Mexico, 1978.

Jude, E l v i r a , "Recovery of Cranium Compounds i n Mine Water by Ion F lo t a t ion , " Proceedings of t h e 9 th I n t e r n a t i o n a l Mineral Process ing Congress, Prague, Czechoslovakia, June 1970.

133

41. Malouf, E. , "Current Copper Leaching Practices:Mining Engineer, August 1972.

4 2 . Lane, J. W . , "Recovery of Molybdenum from Oxidized Ore a t Climax, Colorado," Society of Mining Engineers AIME Transact ions, volume 252, March 1972.

43. White, J . , "Recovering Copper from M i l l Ta i l i ngs , " Bureau of Mines R I 7868.

4 4 . Allen , A . S. , "Recent DeveloTments i? t h e Use cf F ine tr'aste for Subsidence Control ," 4 t h Mineral Waste U t i l i z a t i o n Symposium I I T R I .

45. Ashton, M.D. , "Some Aspects of Mineral Waste U t i l i z a t i o n Within t h e United Kingdom." 1st Mineral Waste U t i l i z a t i o n Symposium, IITRI.

46. "Ava i l ab i l i t y of Mining Wastes and Their P o t e n t i a l Use as Highway Material,"FHWA, - Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

47. * Blunden, J. R . , "The Economic U t i l i z a t i o n of Quarry and Mine Wastes f o r Amenity Purposes i n B r i t a i n , " 4 th Mineral Waste U t i l i z a t i o n Symposium I I T R I .

48. "Building Brick from t h e Waste P i l e , " Environmental Science and Technology, volume 6 , number 6 , 1972.

49. C l i f t o n , J. R. , "Uses of Waste Materials and By-products i n Con- s t r u c t i o n , " Nat ional Bureau of Standards Report No. NBSIR 77-R44.

50. C o l l i n s , R. J., "Construction Indus t ry E f f o r t s t o U t i l i z e Mining and Meta l lu rg ica l Wastes," 6 t h Mineral Waste U t i l i z a t i o n Symposium I I T R I .

51. Colombo, A. F., "Process for Scavenging I ron from T a i l i n g s Produced by F l o t a t i o n Bene f i c i a t ion and f o r Increas ing I ron O r e Recovery," U.S. Pa t en t #4,192,738.

5 2 . Cox, J . , "Phosphate Wastes (1968)," 1st Mineral Waste U t i l i z a t i o n Symposium I I T R I .

53. C u t l e r , I. B . , "Ceramic Products from Mineral Wastes," 2nd Mineral Waste U t i l i z a t i o n Symposium I I T R I .

54. Dean, K. C . , " U t i l i z a t i o n of Mine, M i l l , and Smelter Wastes," 1st Mineral Waste U t i l i z a t i o n Symposium IITRI.

134

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55. "Dust C o l l e c t o r s Reclaim P e r l i t e Fines ," Rock Products , volume 78, number 10, October 1975.

56. "Giant Air Classifier Reclaims Saleable F rac t ion from High Grade Rouessa Mine from Ore Ta i l ings , " Engineering Mining Journal , volume 176, number 6 , June 1974.

57. Grady, W., " U t i l i z a t i o n of Acid Mine Drainage Treatment Sludge," 5 t h Mineral Was:? U t i l i z a t i o n Synt?osimn IITRI.

58. Heins, R. W . , "Po ten t i a l U t i l i z a t i o n of Mine Waste Ta i l ings i n t h e Upper M i s s i s s i p p i Valley Lead-Zinc Mining Dis t r ic t , " 2nd Mineral Waste U t i l i z a t i o n Symposium I I T R I .

59. Eddy, W. H . , "Recovery of Feldspar and Glass Sand from Georgia Waste Grani te Fines ," Bureau of Mines R I 7928.

60. Llewellyn, T. D . , "Recovery of S i l i c o n Carbide from Grani te Sludge," . Bureau of Mines R I 8074.

61. Madsen, B . W . , "Prompt Copper Recovery from M i n e S t r i p Waste," Bureau of Mines R I 8012.

62. Wharton, H . , "Barite Ore P o t e n t i a l of Four T a i l i n g s Ponds," Missouri Geological Survey and Water Resources, Report of Inves t iga t ion N o . 53.

63. Klusman, R. W . , " P o s s i b i l i t i e s f o r Economic Recovery of Metals from Mine Drainage and Ta i l ings i n t h e Front Range, Colorado,' ' Transac t ions of t he Soc ie ty of Mining Engineers AIME, volume 260, number 1, b r c h 1976.

64. Lane, J. W . , "Recovery of Molybdenum from Oxidized Ore a t C l i m a x , Colorado," Transac t ions of t h e Socie ty of Mining Engineers AIME, volume 252., March 1972.

65. McClelland, G. E. , "S i lve r and Gold Recovery from Low Grade Resources," Mining Congress Jou rna l , May 1981.

66. McCrea, D. H. , "Evaluation of So l id Mineral Wastes f o r Removal of Sul fur from Flue Gases," 3rd Mineral Waste U t i l i z a t i o n Symposium I I T R I .

67. Merrill, C. C., "Separation of Columbium, Tantalum, Titanium, and Zirconium from Titanium Chlo r ina t ion Residues," Bureau of Mines R I 7671.

68. Mindess, S . , " f i o d u c ~ i o n of High Pressure Steam-Cured Calcium S i l i c a t e -,

Building Materials from Mining Indus t ry Waste Products, ' ' 1st Mineralwaste U t i l i z a t i o n Symposium I I T R I .

I

1 7 5

69.

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Mindess, Sidney, "Criteria f o r Se lec t ion of Mineral Wastes f o r Use i n the Manufacture of Calcium S i l i c a t e Bui lding Materials," 2nd Mineral Waste U t i l i z a t i o n Symposirun I I T R I .

Nakamura, H. H . , " U t i l i z a t i o n of Copper, Lead, Zinc, and I ron Ore Tai l ings ," 2nd Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Pe t t ibone , H. C . , "Engineering P r o p e r t i e s of Mine Tai l ings," Jou rna l of t h s Soil Mechanics and Foundaticns P i r . 949, September 1971.

P igo t t , P. G. , "Steam-Cured Br icks from I n d u s t r i a l Mineral Wastes,'' Bureau of Mines R I 7856.

Stoops, R . F . , "North Caro l ina Feldspar T a i l i n g s U t i l i z a t i o n , " 2nd Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Rule, A. R., "Recovery of Copper, Cobal t , and Nickel from Waste M i l l Ta i l ings ," 5 t h Mineral Waste U t i l i z a t i o n Symposium IITRI.

Scheiner, B. J . , "Recovery of S i l v e r and Mercury from M i l l T a i l i n g s by Elec t rooxida t ion ," Bureau of Mines R I 7660.

I 1 Spendlove, M . , Bureau of Mines Research on Resource Recovery Reclama- t i o n , U t i l i z a t i o n , Disposa l , and S t a b i l i z a t i o n , " Bureau of Mines I C 8750.

Su l l ivan , G. V . , "Physical Bene f i c i a t ion of Mining and I n d u s t r i a l Wastes," 5th Annual Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Vasan, S . , " U t i l i z a t i o n of F l o r i d a Phosphate Slimes," 3rd Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Watson, K. L . , "A P o t e n t i a l Use f o r Slate Waste," Precas t Concrete, volume 7 , 'number 9, September 1976.

Yutaka, T . , "Manufacturing Ceramic Goods Out of Mining Wastes," 4 t h Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Paulson, D. L. , "Cobalt and Nickel Recovery from Missouri Lead Ores," 7th Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Horiuchi, T. , " U t i l i z a t i o n of Spent O i l Sha le i n the Prepara t ion of Glass-Fiber and Glass-Ceramics," 6 t h Mineral Waste U t i l i z a t i o n Sym- posium I I T R I .

Lee, I>. Y., " U t i l i z a t i o n of Waste Retor ted O i l Shale f o r Highway Construction," 6 t h Mineral Waste U t i l i z a t i o n Symposium I I T R I .

1 3 6

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Murr, L. E., "Observations of Solu t ion Transpor t , Permeabi l i ty and Leaching React ions i n Large, Cont ro l led , Copper Bearing Waste Bodies," Hydrometallurgy 5 ( 1 ) , 1979.

Hansen, T. C . , "Sand-Lime Br icks and Aerated Lightweight Concrete from Gold M i n e Waste? ?laterials Research and Standards, August 1970.

Rose, J. G. , "Use of Energy-Eff ic ient S in t e red Coal Refuse i n Light- weight Aggregate," T ranspor t a t ion Research Record, #734, 1979.

Sul tan , H. A., " S t a b i l i z e d Copper M i l l T a i l i n g s f o r Highway Construc- t ion ," T ranspor t a t ion Research Record, 11734, 1979.

Redeker, I . H . , "How t o Make Money on Minerals Reclaimed from T a i l i n g s , " Mining Engineer ing, J u l y 1970.

S t a f f , "Canadian Johns-Manville Re t r ea t ing Asbestos O r e Ta i l i ngs , " , P i t and Quarry, November 1970.

S t a f f , "New T a i l i n g s Retreatment F a c i l i t i e s Produce 110 TPD of Con- c e n t r a t e a t Kennecott Operation, ' ' Engineering and Mining Journa l , August 1971.

McGarr, H. J . , "Liquid Ion-Exchange Recovers Copper from Wastes and Low-Grade Ores," Engineer ing and Mining Journa l , October 1970.

Taciuk, W . , "Recovery of Magnetite from S p i r a l Ta i l i ngs i n Labrador Ci ty ," Canadian Mining and Meta l lu rg ica l B u l l e t i n , January 1972.

A s e , P., "Asbestos Manufacturing Waste Disposa l and U t i l i z a t i o n ? 5 t h Mineral Waste U t i l i z a t i o n Symposium I I T R I .

Ramsey, D. E., "Fabr ica t ion of Ceramic Articles from Mining Waste Materials;" American Ceramic Society B u l l e t i n , March 1975.

S t a f f , "Output of Au and U from Slimes Dams Climbs a t Ergo," Engineerinp and Mining J o u r n a l , January 1979.

S t a f f , "Increase Profit-Recover Copper from F l o t a t i o n T a i l s , Engineering and Mining Journa l , Ju ly 1973.

"If I t 's There, I t ' s Recoverable," Canadian Chemical Processing, volume 57, number 10, October 1973.

I I

"Minerals F a c t s and Problems," Bureau of Mines B u l l e t i n 671, 1980 Edi t ion.

99. Vasan, S. , " U t i l i z a t i o n of Phosphate S l i m e s , " I c t e m a t i o n a l Minerals and Chemical Corporat ion, Skokie, I l l i n o i s .

100. S t a f f , "Study of Adverse E f f e c t s of So l id Waste from A l l Mining A c t i v i t i e s on t h e Environment," PEDCo Environmental, Inc . , f o r L.S. EPA, July 1979.

137

t 101. "Bureau of Mines Research on Resource Recovery," Information

C i r c u l a r 8750.

102. Valdez, E. G. , " U t i l i z a t i o n of Phosphorus Furnace Slag i n Ceramic Wall and Floor T i l e , " Bureau of Mines R I 7829.

103. "Compilation of A i r P o l l u t a n t Emission Factors ," U.S. Environmental P r o t e c t i o n Agency, PB 264-195.

104. Pr i sbrey , K. A. , "Ion Exchange Recovery of Cobalt and Copper from Blackbird Mine Drainage," Col lege of Mines and Earth Resources, Universi ty of Idaho, P r o j e c t A-067-IDA, January 1980.

105. Bowles, O . , "The Asbestos Indus t ry ," Bureau of Mines B u l l e t i n #552.

106. "Mining and M i l l i n g Methods and Costs , Vermont Asbestos Mines," Bureau of Mines Information C i r c u l a r 8068.

107.. Minerals Yearbook, 1976, Bureau of Mines.

108. Wenger, M. E . , "Anthraci te Refuse as an Aggregate i n Bituminous Concrete," Bituminous S e c t i o n , Bureau of Materials, Tes t ing and Research, Pennsylvania Department of Highways, June 1970.

109. Busch, R. A . , "Physical Propercy Data on Coal Waste Embankment Materials,'' Bureau of Mines RI 7964.

110. Maxwell, E.,"Magnetite Recovery i n Coal Washing by High Gradient Magnetic Separat ion," Massachuset ts I n s t i t u t e of Technology f o r U.S. Environmental P r o t e c t i o n Agency, September 1978, PB-290-91.5.

111. Szpindler , G. , " I n v e s t i g a t i o n of P o t e n t i a l for Heat and Material Recovery i n the Fluidized-Bed I n c i n e r a t i o n of Coal Washery Rejects and Some Other I n d u s t r i a l Wastes," CSIRO Minerals Research Labora- t o r i e s , North Ryde, A u s t r a l i a .

112. Goodboy, K. P., " I n v e s t i g a t i o n of a S i n t e r Process f o r E x t r a c t i o n of Al2O3 from Coal Wastes," M e t a l l u r g i c a l Transact ions, volume 7B, December 1976.

113. Encyclopedia Americana, 1980 Edi t ion .

114. Coal Data Book, P r e s i d e n t ' s Commission on Coal, February 1980.

115. Monthly Energy Review, Department of Energy, November 1981.

116:. C o l l i e r s Encyclopedia, 1979 Edi t ion .

117. Bland, A. E., "Kentucky Coal Prepara t ion P lan t Refuse Character i - II za t ion and Uses, Proceedings: Second Kentucky Coal Refuse Disposal

and U t i l i z a t i o n Seminar, May 1976.

133

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118. Chemical and Engineering News, page 2 5 , November 2 , 1981.

119. Gushue, J . , " F e a s i b i l i t y of A l t e r n a t i v e s f o r Surface U t i l i z a t i o n of Coal Wastes," Prepared f o r U.S. Department of Energy, FE/3105-1, Ju ly 1979.

120. P r i v a t e communication w i t h Dick Howe, D i rec to r , Bureau of Materials, Tes t ing , and Research, Pennsylvania Department of Transpor ta t ion .

121 . Maneval, D. R., "Reprocessing of Coal Refuse f o r a Second Yie ld of Steam Coal," Third Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1977.

122. Allen, A . S . , " U t i l i z a t i o n of Coal Mine Waste f o r S t r a t a Cont ro l , " F i r s t Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1975.

123. Augenstein, D . , "Methodology f o r t h e Charac te r iza t ion of An th rac i t e . Refuse," Pennsylvania S t a t e Un ive r s i ty , SR-87, Ju ly 1971.

1 2 4 . Charmbury, H. B . , " U t i l i z a t i o n of Pennsylvania Anthrac i te Refuse," F i r s t Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1975.

125. Martin, J . F. , "Water Qual i ty Aspects of Coal Refuse U t i l i z a t i o n , " F i r s t Kentuc'ky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1975.

126. Bland, A. E . , "Kentucky Coal P repa ra t ion P lan t Refuse Charac t e r i za t ion and Uses," Second Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1976.

1 2 7 . Col l in s , J . W . , "Cyclone Cleaning of F ine Coal Refuse," Second Kentucky Coal Refuse Disposa l and U t i l i z a t i o n Seminar, May 1976.

I# 128. Drake, W. 'B., "Coal Refuse i n Highway Embankments and Aggregates, Second Kentucky Coal Refuse Disposa l and U t i l i z a t i o n Seminar, May 1976.

129. Kinder, D . , "Coal Ash and Coal Refuse: New P o t e n t i a l Resources," Second Kentucky Coal Refuse Disposa l and U t i l i z a t i o n Seminar, May 1976.

130. Hudson, L. E . , "Aluminum From Coal Wastes?," Third Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1977.

131. Keller, D. V. , "Gob P i l e and S l u r r y Pond Sediment Bene f i c i a t ion Using t h e Otisca Process ," Third Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1977.

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1 4 2 .

143.

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Winer , A . , "Sources of Canadian Non-Bauxite Alumina," Third Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1977.

Gay, L. ,"Processing P lan t f o r t h e Reclamation of Coal:' Third Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1977.

Buxton, J. W . , "Sintered Coal Refuse as a Growing Medium for P l a n t s , Third Kentucky Coal Refuse Disposal and U t i l i z a t i o n Seminar, May 1977.

(I

"Pennsylvania Anthrac i te Refuse: on U t i l i z a t i o n and Disposal ," Pennsylvania S t a t e Universi ty , SR-79, March 1971.

A Summary of a L i t e r a t u r e Survey

Co l l in s , D . , "Ext rac t ion of Vanadium from Phosphate Bene f i c i a t ion Ta i l ings , " Bureau of Mines P resen ta t ion a t t h e P a c i f i c Northwest Metals and Minerals Conference, A p r i l 27, 1981.

"This New Steam P lan t i n Scotland w i l l Burn Co l l i e ry Waste," Power Engineer ing, September 1956.

&Lean, D. C . , " Inves t iga t ion of t h e Haldex (Simdex) Process f o r Bene f i c i a t ing Coal Refuse-Hungarian P rac t i ce , " ?enrsylvania S t a t e Univers i ty , Resource Report , SR-80.

C o l l e t t , H . , "Renkol C l a s s i f i e r May be Missing Link i n Coal Prepara- t i o n , " Coal Mining & Processing, volume 10, number 6, 1973.

"Fine Coal Recovery and Mine B a c k f i l l Prepara t ion ," Mechanization, v o l a e 2 6 , number 10, 1962.

Kindig, J. K . , "Reprocessing Bituminous Coal Refuse," Mining Congress Journa l , volume 51, number 7, 1965.

Browning, 'J. S., "Recovery of Fine-Size Waste Coal," Quar te r ly Report of A c t i v i t i e s , January-March, Mineral Resources I n s t i t u t e , S t a t e Mine Experiment S t a t i o n , The Univers i ty of Alabama.

P r i v a t e correspondence w i t h A s s i s t a n t P ro fes so r J e r r y Rose, Col lege of Engineering, Univers i ty of Kentucky.

C o l l i n s , R. J. , "Waste Ifaterials as P o t e n t i a l Replacements f o r High- way Aggregates," Valley Forge Labora to r i e s f o r Transpor ta t ion Re- search Board, Nat ional Cooperat ive Highway Research Program Report 166.

" Inves t iga t ion of Mining Related P o l l u t i o n Reduction A c t i v i t i e s and Economic Incen t ives i n t h e Monongahela River Basin! Report t o t h e AppalachianRegional Commission, A p r i l 1975.

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151.

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154.

155.

156.

157.

158.

159.

Bu t l e r , P. E . , " U t i l i z a t i o n of Coal Mine Refuse i n Highway Embankment Construct ion," AIME Transac t ions , volume 260, June 1976.

"Anthraci te Refuse in ID-2A Bituminous Concrete," Pennsylvania Depart- ment of T ranspor t a t ion , Bureau of Materials, Tes t ing , and Research, P ro jec t No. 70-8, F i n a l Report.

Whaite, R. H., "Pumped-Slurry Backf i l l i ng of Inaccess ib l e M i n e Work- ings for Subsidence Cont ro l , '' Bureau of a n e s , Information C i rcu la r 8667, 1975.

"Environmental Cons idera t ions of Selec ted Energy Conserving Manu- f a c t u r i n g Process Options," I n d u s t r i a l Environmental Research Laboratory, C inc inna t i , Ohio, f o r U.S. Environmental P ro tec t ion Agency, Report No. EPA-600/7-76-034n, December 1976.

Minerals Yearbook, Volume 1, Metals and Minerals , 1978-79, Bureau of Mines . "A Study of Waste Generation, Treatment and Disposal i n t h e Metals Mining Indus t ry , " Midwest Research I n s t i t u t e , Prepared f o r U.S. Environmental P ro tec t ion Agency, October 1976.

"Mining Indus t ry So l id Waste - An In te r im Report," Prel iminary Dra f t , U.S. Environmental P r o t e c t i o n Agency, Of f i ce of Sol id Waste, February 1981.

Lawrence, W . , "Gob Aggregate Concrete Products Report 120," West Virg in ia Un ive r s i ty , Coal Research Bureau.

Nichols , I. L. , "Leaching Gold-Bearing M i l l T a i l i n g s fromMercur, Bureau of Mines, R I 7395, June 1970.

Utah,"

Toens, P. I)., "The Recovery of Uranium, Gold and Su l fu r from Residues from South Afr ican Mines," Atomic Energy Board, P r e t o r i a , Republic of South Af r i ca , NTIS #PER-36.

P o t t e r , G. M., "Recovering Gold from S t r i p p i n g Waste and Ore by Perco- l a t i o n Cyanide Leaching," Bureau of Mines, TPR-20, December 1969.

Heinen, H. J., "Experimental Leaching of Gold from Mine Waste," Bureau of Mines, RI 7250, A p r i l 1969.

Nakamura, H. H., " U t i l i z a t i o n of Mining and Mi l l ing Wastes,' I l l i n o i s I n s t i t u t e of Technology, Research I n s t i t u t e P r o j e c t No. G6027, May 15, 1970.

LaRose, P. J. , "Carbonate Bonding of Taconi te Ta i l ings ," Applied Technology Corporat ion, Prepared f o r U.S. Environmental P ro tec t ion Agency, EPA-670/2-74-001, January 1974.

141

160. W i l l i a m s , R. E . , "The Role of Mines Ta i l ings Ponds i n Reducing t h e Discharge of Heavy Metal Ions t o t h e Environment," Bureau of Mines, Open F i l e Report 61(1)-73, PB 224-730, PB 224 731.

161. " S t a t i s t i c a l Abstract of t h e United S t a t e s , 1980," U.S. Department of Commerce, Bureau of t h e Census.

162. The EncycloTedia Britamica, 15 th Edi t ion , 1979.

163. Borrowman, S. R., "Radium Removal from Uranium Ores and M i l l Ta i l i ngs , " Bureau of Mines, R I 8099, 1975.

164. ROSS, J. R . , "Recovery of Uranium from Natural Mine Waters by Counter- cu r ren t Ion Exchange," Bureau of Mines, R I 7471, 1971.

165. Heins, R. W . , "U t i l i za t ion of Mine Waste T a i l i n g s i n Southwestern Wisconsin," Bureau of Mines Grant No. SWD-13, May 1972.

166. ' Rampacek, C . , "Current S t a t u s of Mining Waste Recovery Processes ," Mineral Resources I n s t i t u t e , Univers i ty of Alabama, Prepared f o r Frankl in Assoc ia tes , L td . , January 1982.

167. P r i v a t e communication wi th Mr. David J. Aksrs, Coal Research Bureau, West Vi rg in i a Univers i ty , Morgantown, West Vi rg in i a , Reference 166.

168. Co l l in s , R. K . , "Mineral Wastes as P o t e n t i a l Mineral F i l l e r s , " 7 th Mineral Waste U t i l i z a t i o n Symposium, 1980 ITTRI.

169. P r i v a t e communication wi th Robert A. C l i f t o n , Commodity S p e c i a l i s t , USBM, Washington, D.C. (166).

170. P r i v a t e communication w i t h W. E. Lamont, Research Assoc ia tes , Mineral Resource I n s t i t u t e (166).

171. P r i v a t e communication w i t h W. A. McKinney, Research Di rec to r , U.S. Bureau of Mines, S a l t Lake C i t y , Utah, Center (166).

172. "Process f o r Ext rac t ing Alumina from Nonbawi te Ores," Report of t h e Panel on P o t e n t i a l s of Aluminum Ex t rac t ive Processes , Nat iona l Ma- ter ia ls Advisory Board, D iv i s ion of Engineering, Nat iona l Research Council Publ ica t ion NMAB-278, Nat ional Academy of Science, Washing- ton, D.C., December 1970.

173. P r i v a t e communication w i t h Mr. Dewy Hall, P lan t Manager, IMC I n d u s t r i a l Mineral Div is ion , Spruce P ine , North Carol ina (166).

174.- P r i v a t e communication w i t h M r . J. S. Browning, Mineral Resources I n s t i t u t e , Universi ty of Alabama.

175. Private communication with Mr. Thomas Llewellyn, Tuscaloosa Metal- lurgy Research Laboratory, Bureau of Mines.

176. Private communication with M r . Gregg Detagter, Monsanto Company, Columbia, Tennessee.

1 7 7 . Private communication with M r . Ivan Nichols, Salt Lake City Research Center, U . S . Bureau of Mines.

178. L i , T. M., "The New Look at U X R C O ' s Tennessee Miaes??fi.ninF; Engineering, May 1976.

179. Private communication with Professor P. T. Luckie, Department of Mineral Preparation, Pennsylvania State University.

180. Private comunication with Dr. C. D. Haynes,Professor (retired) Mineral Resources Institute, University of Alabama.

181. Private communication with Mitch Edwards, spokesman at the Kennecott . Copper Corporation, Magna, Utah copper mine tailing retreatment plant.

182. Private communication with Jack Masters, Geologist, Illinois State Geological Survey, Urbana, Illinois.

183. Preprint from the 1980 Bureau of Mines Minerals Yearbook, Mining and Quarrying Trends in the Metal and Nonmetal Industries.

184. Private communication with L. K. Hudston, Alcoa Laboratories, Alcoa Technical Center, Alcoa Center, Pennsylvania.

RESOURCE RECOVERY BIBLIOGWHY

ACID MINE DRAINAGE

Barthel, G., "Solvent Extraction of Copper from Mine and Smelter Waters," Journal of Metals, volume 30, July 1978.

Grady, W., "Utilization of Acid Mine Drainage Treatment Sludge," 5th Mineral Waste Utilization Symposium IITRI.

Klusman, R. W., "Possibilities f o r Economic Recovery of Metals from Mine Drainage and Tailings in the Front Range, Colorado," Transactions of the Society of Mining Engineers AIME, volume 260, number 1, March 1976.

Staff, "Study of Adverse Effects of Solid Waste from All Mining Activities on the Environment,: PEDCo Environmental, Inc., for U.S. EPA, July 1979.

"Bureau of Mines Research on Resource Recovery," Information Circular 8750.

Prisbrey, K. A., "Ion Exchange Recovery of Cobalt and Copper from Blackbird Mine Drainage," College of Mines and Earth Resources, University of Idaho, Project A-067-IDAY January 1980.

Rampacek, C., "Current Status of Mining Waste Recovery Processes," Mineral Resource Institute, University of Alabama, Prepared for Franklin Associates, Ltd., January 1982.

ASBESTOS TAILINGS

h e , P., "Asbestos Manufacturing Waste Disposal and Utilization," 5th Mineral Waste Utilization Symposium IITRI.

Winer, A., "Mineral Wool Insulation from Asbestos Tailings," CIM Bulletin, December 1974.

Staff, "Canadian Johns-Manville Retreating Asbestos Ore Tailings," Pit and Quarry, November 1970.

Cutler, I. B., "Ceramic Products from Mineral Wastes," 2nd Mineral Waste Utilization Symposium IITRI.

Rampacek, C., "Current Status of Mining Waste Recovery Processes," Mineral Resources Institute, University of Alabama, Prepared for Franklin Associates, Ltd., January 1982.

144

BARITE TAILINGS

Wharton, H., "Barite Ore Potential of Four Tailings Ponds," Missouri Geological Survey and Water Resources, Report of Investigation No. 53.

Lamont, W. E., "Retreatment of Tailings to Recover Barite," 7th Mineral Waste Utilization Symposium IITRI.

Sullivaa, 2. V., "Xecovery of Barite iron! Tailings Ponds arrd Bypassed Mining Waste," Society of Mining Engineers, AXME Annual Meeting, Las Vegas, Nevada, February 2 4 , 1980.

"Availability of Mining Wastes and Their Potential Use as Highway Material," FHWA, Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

COAL HINING =FUSE

Breyenton, D., "Utilization of Coal Refuse as a Concrete Aggregate (Coal- Crete)," 5th Mineral Waste Utilization Symposium IITRI.

Butler, P. E., "Utilization of Coal Mine Refuse in Highway Embankment Construction," First Symposium on Kine & Preparation Plant Refuse D i s - posal, Louisville, Kentucky, October 1 9 7 4 .

Chambliss, Everett, "Modular-Design Plant Cuts Gob Recovery Cost," - Coal Mining Process, volume 16, nuinber 7, July 1979.

Charmbury, H. B., "The Utilization of Incinerated Anthracite Mine Refuse as Anti-Skid Highway Material," 3rd Mineral Waste Utilization Symposium, IITRI.

Chauvin, R., "Utilization of Solid Waste of the Coal Industry," 7th Inter- national Coal Preparation Congress, Australia, 1976.

Cobb, James, "Abundance and Recovery of Sphalerite and Fine Coal from Mine Waste in Illinois," 6th Mineral Waste Utilization Symposium IITRI.

Gutt, W., "Colliery Spoil," Materials and Structures, volume 12, number 70, 1979.

Crossmore, E. Y., "Utilization of Wash Water Sludge," Second Symposium on Coal Preparation, Louisville, Kentucky, October 1976.

Doyle, F. J. , "Utilization of Coal Mine Refuse," Michael Baker, Jr., Inc. , Beaver, Pennsylvania, November 15, 1972.

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145

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Ellison, R. D., "Synopsis of Engineering and Design Manual for Coal Refuse Embankments," First Symposium on Mine and Preparation Plant Refuse Disposal, Louisville, Kentucky, October 1974.

Gibson, J., "An Appraisal of the Utilization Potential of Colliery Waste," Mining and Materials Engineering, November 1970.

Gutt, W. H., ''Aspects of Waste Materials and Their Potential for Use in Concrete," Resource Recovery and Conservation, volume 1, number 4 , June 1976.

11 Hanquez, E., Shale As a Raw Material for Building Purposes," 6th International Coal Preparation Congress, Paris, France, March 1973.

Haynes, C. D., "Pelletized Waste Oil - Coal Dust Mixtures as a Fuel Source," 4th Mineral Waste Utilization Symposium IITRI.

Sixth International Conference on Coal Preparation Colliery

Franklin Institute Research Laboratories, "Utilization of Coal Dust Slurries," Final Report F-C1992, Philadelphia, Pennsylvania.

Kealy, C. D., "Those Waste Banks Could be Sources for Fuel," Coal Mining and Processing, volume 13, number 8, August 1976.

Maneval, D., "Coal Refuse Utilization Prospects, An Update of Recent Work," Second Synposium on Coal Preparation, Louisville, Kentucky, October 1976.

Maneval, D., "Utilization of Coal Reuse for Highway Base or Subbase Material," 4th Mineral Waste Utilization Symposium, IITRI.

Morris, G. H., "Reclaiming Coal from Slurry Ponds," Mining Congress Journal, volume 61, number 12, December 1975.

Moulton, L. K., '!Coal Mine Refuse: An Engineering Material," First Symposium on Mine & Preparation Plant Refuse Disposal, Louisville, Kentucky, October 1974.

Peterson, R., "Engineering Properties of Coal Waste Embankment Material," 1st Symposium on Underground Mining, volume 2, Louisville, Kentucky, October 21-23, 1975.

Robl, T., "Kentucky Coal Refuse: A Geochemical Assessment of its Potential as a Metals Source," Second Symposium on Coal Preparation, Louisville, Kentucky, October 1976.

Spicer, T. S., "Operation Anthracite Refuse," 2nd Mineral Waste Utilization Symposium IITRI.

Sullivan, G., "Coal Wastes," 1st Mineral Waste Utilization Symposium XITRI.

Toubeau, G., "?lanufacture of Lightweight Aggregates from Washery Screen Discards," 6th International Coal Preparation Congress, Paris, France, March 1973.

Waters, P. L., "Fluidized Combustion of Coal Washery Waste," Colliery Guardian, volume 227, number 1, January 1979.

Wilmoth, R. C., "Use of Coal Mine Refuse and Fly Ash as a Road Base Material," First Symposium on Mine & Preparation Plant Refuse Disposal, Louisville, Kentucky, October 1974.

Maneval, D. R., "Recent Foreign and Domestic Experience in Coal Refuse Utilization," First Symposium on Mine & Preparation Plant Refuse Disposal, Louisville, Kentucky, October 1974.

Katell, S., "The Potential Economics of the Recovery of Trace Elements in Coal Refuse," Coal Research Bureau, Report i1142, West Virginia University.

Leonara, J. W., "Waste Coal Reclamation," Coal Research Bureau, Report #92, West Virginia University.

"Availability of Mining Wastes and Their Potential Use as Highway Material," FMJA, Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Yutaka, T., "Manufacturing Ceramic Goods Out of Mining Wastes," 4th Mineral Waste Utilization Symposium IITRI.

Rose, J. G., "Use of Energy-Efficient Sintered Coal Refuse in Lightweight Aggregate," Transportation Research Record, f734, 1979.

Wenger, M. E., "Anthracite Refuse as an Aggregate in Bituminous Concrete," Bituminous Section, Bureau of Materials, Testing and Research, Pennsylvania Department of Highways, June 1970.

Busch, R. A., "Physical Property Data on Coal Waste Embankment Materials," Bureau of Mines, RI 7964.

Maxwell, E., "Magnetite Recovery in Coal Washing by High Gradient Magnetic Separation," Massachusetts Institute of Technology for U.S. Environmental Protection Agency, September 1978, PB-290-915.

i

Szpindler, G., "Investigation of Potential for Heat and Material Recovery in the Fluidized-Bed Incineration of Coal Washery Rejects and Some Other Industrial Wastes," CSIRO Minerals Research Laboratories, North Ryde, Australia.

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Goodboy, K. P., "Investigation of a Sinter Process for Extraction of Al 0 from Coal Wastes," MetallurRical Transactions, volume 7B, December 1976.

Coal Data Book, President's Commission on Coal, February 1980.

2 3

Bland, A. E., "Kentucky Coal Preparation Plant Refuse characterization and Uses," Proceedings: Seminar, May 1976.

Second Kentucky Coal Refuse Disposal and Utilization

Gusnue, J., "Feasibility of Alternhtives for Surface Utilization of Coal Wastes," Prepared for U.S. Department of Energy, FE/3105-1, July 1979.

Maneval, D. R., "Reprocessing of Coal Refuse for a Second Yield of Steam Coal," Third Kentucky Coal Refuse Disposal and Utilization Seminar, May 1977.

Allen, A. S . , "Utilization of Coal Mine Waste for Strata Control," First Kentucky Coal Refuse Disposal and Utilization Seminar, May 1975.

Augenstein, D., "Methodology for the Characterization of Anthracite Refuse," Pennsylvania State University, SR-87, July 1971.

Charmbury, H. B., "Utilization of Pennsylvania Anthracite Refuse," First Kentucky Coal Refuse Disposal and Utilization Seminar, May 1975.

Martin, J. F., "Water Quality Aspects of Coal Refuse Utilization," First Kentucky Coal Refuse Disposal and Utilization Seminar, May 1975.

Bland, A . E., "Kentucky Coal Preparation Plant Refuse Characterization and Uses," Second Kentucky Coal Refuse Disposal and Utilization Seminar, May 1976.

Collins, J. W., "Cyclone Cleaning of Fine Coal Refuse," Second Kentucky Coal Refuse Disposal and Utilization Seminar, May 1976.

Drake, W. B., "Coal Refuse in Highway Embankments and Aggregates? Second Kentucky Coal Refuse Disposal and Utilization Seminar, May 1976.

Kinder, D., "Coal Ash and Coal Refuse: New Potential Resources." Second Kentucky Coal Refuse Disposal and Utilization Seminar, May 1976.

Hudson, L. E., "Aluminum from Coal Wastes?," Third Kentucky Coal Refuse Disposal and Utilization Seminar, May 1977.

Keller, D. V., ".Zob Pile and Slurry Pond Sediment Beneficiation Using the Otisca Process," Third Kentucky Coal Refuse Disposal. and Utilization Seminar, May 1977.

Wineg, A . , "Sources of Canadian Non-Bauxite Alumina," Third Kentucky Coal Refuse Disposal and Utilization Seminar, May 1977.

14 8

Gay. L., "Processing Plant for the Reclamation of Coal," Third Kentucky Coal Refuse Disposal and Utilization Seminar, May 1977.

Bwton, J. W., "Sintered Coal Refuse as a Growing Medium for Plants," Third Kentucky Coal Refuse Disposal and Utilization Seminar, May 1977.

"Pennsylvania Anthracite Refuse: zation and Disposal," Pennsylvania State University, SR-79, March 1971.

A Summary of a Literature Survey on Utili-

"This New Steam Plant in Scotland will Burn Colliery Waste," Power Engineering, September 1956.

McLean, D. C., "Investigation of the Haldex (Simdex) Process for Beneficiating Coal Refuse-Hungarian Practice," Pennsylvania State University, Resource Report, SR-80.

Collett, H., "Renkol Classifier May be Missing Link in Coal Preparation," Coal Mining & Processing, volume 10, number 6, 1973.

"Fine Coal Recovery and Mine Backfill Preparation," Mechanization, volume 2 6 , number 10, 1962.

Kindig, J. K., "Reprocessing Bituminous Coal Refuse," Mining Congress Journal, volume 51, number 7, 1965.

Browning, J. S., "Recovery of Fine-Size Waste Coal," Quarterly Report of Activities, January-March, Mineral Resources Institute, State Mine Experiment Station, The University of Alabama.

Collins, R. J., "Waste Materials as Potential Replacements for Highway Aggre- gates," Valley Forge Laboratories for Transportation Research Board, National Cooperative Highway Research Program Report 166.

Butler, P. E., "Utilization of Coal Mine Refuse in Highway Embankment Construc- tion," AIME Transactions, volume 260 , June 1976.

"Anthracite Refuse in ID-2A Bituminous Concrete," Pennsylvania Department of Transportation, Bureau of Materials, Testing, and Research, Project No. 70-8, Final Report.

Lawrence, W., "Gob Aggregate Concrete Products Report 120," West Virginia University, Coal Research Bureau.

14 9

COPPER MINING WASTES

Bingham, E., "Waste Utilization in the Copper Industry," 1st Mineral Waste Utilization Symposium IITRI.

Kennedy, A., "Recovery of Copper from Michigan Stamp Sands," 2nd Mineral Waste Utilization Symposium IITBI.

Lawver, J., "Production of Anorthosite Concentrate from Minnesota Copper- Nickel Tailings by High Gradient Magnetic Separation," Proceedings: AIME Meeting, Denver, Colorado, September 1976.

McKinney, W. A., "Recovery of Copper from Crushed and Sized Porphyry Mine Waste," Transactions of the Society of Mining Engineers, AIME, volume 2 5 4 , number 4 , December 1973.

MMXJ-

b

Berry, V. K., "Direct Observations of Bacteria and Quantitative Studies of Their.Catalytic Role in the Leaching of Low-Grade Copper-Bearing Waste," Metallurgical Applications of Bacterial Leaching and Related Microbiological Phenomena, Conference Proceedings, New Mexico, 1978.

Malouf, E., "Current Copper Leaching Practices, Mining Engineer, August 1972.

White, J., "Recovering Copper from Mill Tailings," Bureau of Mines, RI 7868.

"Availability of Mining Wastes and Their Potential Use as Highway Material," R N A , Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Clifton, J. R., "Uses of Waste Materials and By-products in Construction," National Bureau of Standards Report No. NBSIR 77-R44.

Madsen, B. W., "Prompt Copper Recovery from Mine Strip Waste," Bureau of Mines RI 8012.

Pigott, P. G., "Steam-Cured Bricks from Industrial Mineral Wastes," Bureau of Mines RI 7856.

Murr, L. E., "Observations of Solution Transport, Permeability and Leaching Reactions in Large, Controlled, Copper Bearing Waste Bodies ,I' Hydrometallurgy 5(1), 1979.

Staff , "Increase Prof it-Recover Copper from Flotation Tails ," Engineering and Mining Journal, July 1973.

McGarr, H. J., "Liquid Ion-Exchange Recovers Copper from Wastes and Low-Grade Ores,w Engineering and Mining Journal, October 1970.

Staff, "New Tailings Retreatment Facilities Produce 110 TPD of Concentrate a t Kennecott Operation,'' Engineering and Mining Journal, August 1971.

150

Nakamura, H. H., "Utilization of Copper, Lead, Zinc, and Iron Ore Tailings," 2nd Mineral Waste Utilization Symposium IITRI.

Sultan, H. A., "Stabilized Copper Mill Tailings for Highway Construction," Transportation Research Record, #734, 1979.

Bureau of Mines Research on Resource Recovery," Bureau of Mines, IC 8750. 11

Collins, R. J., "Waste Materials as Potential Replacements for Highway Aggregates," Valley Forge Laboratories for Transportation Research Board, National Cooperative Highway Research Program Report 166.

Environmental Considerations of Selected Energy Conserving Manufacturing Process Options," Industrial Environmental Research Laboratory, Cincinnati, Ohio, for U.S. Environmental Protection Agency, Report No. EPA-600/7-76- 034x1, December 1976.

I1

"A Study of Waste Generation, Treatment and Disposal in the Metals Mining Industry," Midwest Research Institute, Prepared for U.S. Environmental Protection Agency, October 1976.

Rampacek, C . , "Current Status of Mining Waste Recovery Processes," Mineral Resources Institute, University of Alabama, Prepared for Franklin Associates, Ltd., January 1982.

"Process for Extracting Alumina from Nonbawite Ores," Report of the Panel on Potentials of Aluminum Extractive Processes, National Materials Advisory Board, Division of Engineering, National Research Council Publication ".AB- 278, National Academy of Science, Washington, D.C., December 1970.

FELDSPAR TAILINGS

Stoops, R. F., "North Carolina Feldspar Tailings Utilization," 2nd Mineral Waste Utilization Symposium IITRI.

Redcker, I. H., "How to Make Money on Minerals Reclaimed from Tailings," Mining Engineering, July 1970.

GOLD MINE TAILINGS

Collins, R. J., "Waste Materials as Potential Replacements for Highway Aggregates," Valley Forge Laboratories for Transportation Research Board, National Cooperative Highway Research Program Report 166.

"Availabij.ity oE Mining Wastes and Their Potential Use as Highway Material," - FHWA, VolLmes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Staff-; "Output of Au and U from Slimes Dams Climbs at Ergo, II Engineering and Mining Journal, January 1979.

151

"Mining Industry Solid Waste - An Interim Report," Preliminary Draft, U.S. Environmental Protection Agency, Office of Solid Waste, February 1981.

Nichols, I. L., "Leaching Gold-Bearing Mill Tailings from Mercur, Utah," Bureau of Mines, RI 7395, June 1970.

Heinen, H. J., "Experimental Leaching of Gold from Mine Waste," Bureau of Mines, RI 7250, April 1969.

Kampacek, C., "Current Stacus of Mining Waste Recovery Pracesses," 'Mineral Resources Institute, University of Alabama, Prepared for Franklin Associates, Ltd., January 1982.

Toens, P. D., "The Recovery of Uranium, Gold and Sulfur from Residues from South African Mines," Atomic Energy Board, Pretoria, Republic of South Africa, NTIS #PER-36.

Hansen, T. C., "Sand-Lime Bricks and Aerated Lightweight Concrete from Gold Mine Waste," Materials Research and Standards, August 1970.

Clifton, J. R., "Uses of Waste Materials and By-Products in Construction," National Bureau of Standards Report No. NBSIR 77-R44.

McClelland, G. E., "Silver and Gold Recovery from Low Grade Resources,'' Mining Congress Journal, May 1981.

Potter, G. M., "Recovering Gold from Stripping Waste and Ore by Percolation Cyanide Leaching," Bureau of Mines, TPR-20, December 1969.

GUYITE M I N i N G WASTES

Eddy, W. H., "Recovery of Feldspar and Glass Sand from Georgia Waste Granite Fines," Bureau of Mines RI 7928.

Llewellyn, T. D., "Recovery of Silicon Carbide from Granite Sludge," Bureau of Mines RI 8074.

IRON ORE TAILINGS

I f Nakamura, H. H., 2nd Mineral Waste Utilization Symposium IITRI.

Utilization of Copper, Lead, Zinc, and Iron Ore Tailings,"

Collins, R. J., "Waste Materials as Potential Replacements for Highway Aggregates," Valley Forge Laboratories for Transportation Research Board, National Cooperative Highway Research Program Re2ort 166.

Taciuk, W., '*Recovery of Magnetite from Spiral Tailings in Labrador City," Canadian Mining and Metallurgical Bulletin, January 1972.

152

"Giant Air Classifier Reclaims Saleable Fraction from Eigh Grade Rouessa Mine from Ore Tailings," Engineering Mining Journal, volke 176, number 6, June 1974.

Colombo, A. F., "Process for Scavenging Iron from Tailings Produced by Flotation Beneficiation and for Increased Iron Ore Recovery," U.S. Patent 114,192,738.

"Availability of Mining Wastes and Their Potential Use as Highway Material," - FHWA, Volumes T-, 11, 111, and Sxecutive S u m m a r y , RD 76-106; RD-76-107; RD 76-108; RD 78~28.

Nakamura, H. H., "Utilization of Mining and Milling Wastes," Illinois Institute of Technology, Research Institute Project No. G6027, May L5, 1970.

LaRose, P. J., "Carbonate Bonding of Taconite Tailings," Applied Technology Corporation, Prepared for U.S. Environmental Protection Agency, EpA-670/ 2-74-001, January 1974.

LEAD hINING WASTES

"A Study of Waste Generation, Treatment and Disposal in the Metals Mining Industry," Midwest Research Institute, Prepared for U.S. Environmental Protection Agency, October 1976.

Williams, R. E., "The Role of Mines Tailings Ponds in Reducing the Discharge of Heavy Metal Ions to the Environment," Bureau of Mines, Open File Report 61(1)-73, PB 224-730, PB 224 731.


"Mining Industry Solid Waste - An Interim Report," Preliminary Draft, U . S . Environmental Protection Agency, Office of Solid Waste, February 1981.

Rmpacek, C., "Current Status of Mining Waste Recovery Processes," Mineral Resources Institute, University of Alabama, Prepared for Franklin Associates, Ltd., January 1982. Collins, R. J., "Waste Materials as Potential Replacements for Highway Ag- gregates," Valley Forge Laboratories for Transportation Research Board, National Cooperative Highway Research Program Report 166.

Paulson, D. L., "Cobalt and Nickel Recovery from Missouri Lead Ores," 7th Mineral Waste Utilization Symposium IITRI.

Heins, R. W., "Potential Utilization of Mine Waste Tailings in the Upper Mississippi Valley Lead-Zinc Mining District," 2nd Mineral Waste Utilization Symposium IITRI.

"Availability of Mining Wastes and Their Potential Use as Highway Material," - FHWA, Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Nakamura, H. H., "Utilization of Copper, Lead, Zinc, and Iron Ore Tailings," 2nd Mineral Waste Utilizatioc Symposim IITRI.

PHOSPHATE MINING WASTES

"Availability of Mining Wastes and Their Potential Use as Highway Material," FHWA, Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Vasan, S., "Utilization of Florida Phosphate Slimes,"3rd Mineral Waste Utilization Symposium IITRI.


Staff, "Study of Adverse Effects of Solid Waste from All Mining Activities on the Environment," PEDCo Environmental, Inc., for U.S. Environmental Protec- tion Agency, July 1979.

Collins, D., "Extraction of Vanadium from Phosphate Beneficiation Tailings," Bureau of Mines Presentation at the Pacific Northwest Metals and Minerals Conference, April 27, 1981.

Rampacek, C., "Current Status of Mining Waste Recovery Processes," Mineral Resources Institute, University of Alabama, Prepared for Franklin Asso- ciates, Ltd., January 1982.

Cox, J., "Phosphate Wastes (1968)," 1st Mineral Waste Utilization Symposium IITRI.

MOLYBDENUM TAILINGS


"Availability of Mining Wastes and Their Potential Use as Highway Material," - FHWA, Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Lane, J. W., "Recovery of Molybdenum from Oxidized Ore at Climax, Colorado," Society of Mining Engineers AIME Transactions, volume 252, March 1972.' -_

154

URWITUM M I N I N G WASTES

Jude, E., "Recovery of Uranium Compounds in Mine Water by Ion Flotation," Proceedings of the 9th International Mineral Processing Congress, Prague, Czechloslovakia, June 1970.

"Availability of Mining Wastes ard Their Potential Use as Highway Material," - FMJA, Volumes I, 11, 111, and Executive Summary, RD 76-106; RD-76-107; RD 76-108; RD 78-28.

Dean, K. C . , "Utilization of Mine, Mill, and Smelter Wastes," 1st Mineral Waste Utilization Symposium IITRI.

Toens, P. D., "The Recovery of Uranium, Gold and Sulfur from Residues from South African Mines," Atomic Energy Board, Pretoria, Republic of South Africa, NTIS #PER-36.

ROSS, J. R., "Recovery of Uranium from Natural Mine Waters by Countercurrent Ion Exchange," Bureau of Mines, RI 7471, 1971.

Borrowman, S. R., "Radium Removal from Uranium Ores and Mill Tailings," Bureau of Mines, RI 8099, 1975.

A Study of Waste Generation, Treatment and Disposal in the Metals Mining Industry," Midwest Research Institute, Prepared f o r U . S . Environmental Protection Agency, October 1976.

I 1


ZINC MINING WASTES

Collins, R. J., "Waste Materials as Potential Replacements for Highway Ag- gregates," Valley Forge Laboratories f o r Transportation Research Board, National Cooperative Highway Research Program Report 166.

"A Study of Waste Generation, Treatment and Disposal in the Metals Mining Industry," Midwest Research Institute, Prepared f o r U.S. Environmental Protection Agency, October 1976.


155

"Availability of Mining Wastes and Their Potential Use as Highway Material," _c_ FIIWA, Volumes I, 11, 111, and Executive Summary, RD-106; RD-76-107; RD 76-108; RD 78-28.

Heins, R. W., "Utilization of Mine Waste Tailings in Southwestern Wisconsin," Bureau of Mines Grant No. SWD-13, May 1972.

"If It's There, It's Recoverable," Canadian Chemical Processing, volume 57, number 10, October 1973.


11 Nakamura, H. H., Utilization of Copper, Lead, Zinc, and Iron Ore Tailings," 2nd Mineral Waste Utilization Symposium IITRI.

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