/'

Abstract

RECOVERY OF BY-PRODUCTS FROH FELDSPAR PLANT TAILINGS U.S .B.H., Project No. G 0180 260

Feldspar Tailings, Report No. 3 April 1969 Progress Report

by Immo ll. Redeker

CONTENTS

Introduction

Feldspar Production in the Spruce Pine Area

Description of Feldspar Flotation Plant

Description of Tailings Plants

Lawson-United Feldspar ancl Hineral Company Tailings Plant

International Minerals and Chemical Corporation Tailings Plant

Feldspar Corporation Tailings Plant

Preliminary Tailings Evaluation

Daily Sam~ling - January and February 1968

H'eekly Sampling - July, Augus t and Septemher 1968

Discussion of Results of Daily and 1.Jeek1y Sampling

Feldspar Recovery From the Finer Fractions of the Tailings

Current Hork and Plans

Recommendations

Table 1 - The Five Tailings Streams

Table 2 Summary of Prelinunary Tailings Sampling in Tons Per Day

Table 3 and 3A - Summary of Results of Daily and toJeekly Sampling of Spruce Pine Feldspar Tailings

Table 4 - Screen Analysis of Feldspar Products, Percent t.Jeight in Fraction From Flotation t.Jork on Daily and t-Jeek1y Composites

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Figure I - Feldspar Nines, lUlls and Tailings Disposal Dumps in the Spruce Pine, N.C. Area

Figure 2 - Flowsheet of Spruce Pine Feldspar Plants

Figure 3 - Feldspar Tailings Problem

Figure 4 - Lal-ISOn-Uni ted Feldspar and Mineral Company Tailings Plant

Figure 5 - International Minerals and Chemical Corporation Tailings Plant

Figure 6 - Feldspar Corporation Tailings Plant

Figure 7 - Flowsheet of Proposed Tailings Flotation Pilot Plant

Appendix I - Feldspar Taili~gs Report No. I

Appendix 2 - Feldspar Tailings Report No. 2

RECOVERY OF BY-PRODUCTS FROH FELDSPAR PLANT TAILINGS U.S.B.H., Project No. G 0180 260

Feldspar Tailings Report No. 3 April 1969 Progress Report

by Immo H. Redeker

Abstract

Work at the Asheville Minerals Research Laboratory sponsored by Feldspar Corporation, International Minerals and Chemical Corpora­tion, Lawson-United Feldspar and Hineral Company, the State of North Carolina and the U. S. Bureau of Mines is aimed at reducing the feldspar tailings disposal problem at above mentioned three companies in the Spruce Pine area. The tailings material as produced at the tailings plants of the three companies has been sampled to determine uniformity from day to day and from lveek to week. Samples representing every ten to twenty tons lvere taken and combined into samples representing daily and lveekly tailings production. The samples were processed at the Asheville Laboratory to check variables such as size distribution, chemical analysis and moisture. By applying mineral dressing techniques, attempts were made to determine if saleable mineral products such as feldspar, quartz, and mica could be recovered and if more uniform material for possible ceramic uses could be produced from the tailings.

On the basis of results obtained so far it can be stated that each of the five different tailings materials is fairly uniform in size, chemical analysis and mineral content from day to day and from lveek to lveek and over periods of months in beoveen sampling periods. The samples responded to mineral dressing techniques for recovery of feldspar, quartz and mica. There are a total of about 850 tons per day of tailings material from which about 300 tons per day of feldspar, 250 tons per day of quartz, some mica and about 350 tons of very uni­form finer material, with possible uses as clay brick material, can be produced by fairly standard mineral dressing procedures. Additional process research is aimed at higher feldspar recoveries out of the fine materials. Process research aimed at continuous pilot plant testing for feldspar, quartz and mica recovery is planned.

Representative samples of all five tailing streams have been submitted to the Engineering Research Department of N. C. State Univer­sity for testing of ceramic properties. The Civil Engineering Depart­ment of N. C. State University is conducting test work to see if uses for high,,,ay construction can be found. The N. C. State University Industrial Engineering Service has been contacted to conduct consumer market studies as soon as saleable materials have been defined from the tailings as they are produced now or for materials produced from the tailings by reprocessing.

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Introduction

In 1966 the three feldspar companies in the Spruce Pine area, Lawson-United Feldspar and }tlneral Company, International Minerals and Chemical Corporation and Feldspar Corporation, and the Asheville Hinerals Research Laboratory requested assistance from the Bureau of }fines for a project aimed at reducing the feldspar tailings problems. The request was made under the provisions of the Solid Waste Disposal Act (P.L. 89-272, 79 Stat. 997 approved October 20, 1965). A proposal was first submitted on December 13, 1966. A second proposal with a revised budget as requested by the Bureau of Mines was submitted September 5, 1967.1 The project was approved by the U.S. Bureau of Mines as project no. G 0180 260 (St07-2l), Recovery of By-Products from Feldspar Plant Tailings, and is supported by a grant of $27,642 for the period March 18, 1968 to March 17, 1969. The grant is supple­mented by $7,000 from the three feldspar companies and $15,566 from North Carolina State University. The project was proposed and planned for a duration of 3 years.

Feldspar Production in the Spruce Pine Area

Three feldspar companies in the Spruce Pine area, Feldspar Corporation, International Minerals and Chemical Corporation and Lawson-United Feldspar and Mineral Company, produce ahout 40% of the feldspar produced in the U.S.A. The main products of these companies are glass grade flotation feldspar, ceramic grade feldspar, quartz and mica. Each of the companies mines a coarse-grained granitic ore, called alaskite, by open pit methods. Drop balls reduce the blasted ore in the pit before loading by shovels onto dump trucks. The ore is hauled to the mills a maximum of 4.2 miles in the case of Feldspar Corporation's Chalk Mountain mine. Lawson-United Feldspar and Hineral Company has the shortest haulage way of about 1.5 miles. Figure 1 presents a map containing main features pertaining to feldspar production and tailings disposal, such as location of mines, plants, tailings plants (disposal units) and tailings dumps. The main drainage, the North Toe River, rail­road and main highways, and roadways used by the three feldspar companies are also shown.

A total of about 2,500 tons of ore is processed per operating day by the three companies and about 1000 to 1200 tons ,of feldspar products is recovered by the flotation process. Approximately two­thirds of the feldspar produced is sold to glass producers as dried flotation concentrate in the minus 20 mesh plus 200 mesh size range, with a combined alumina (Al203) potash (K20) and soda (Na20) percentage of about 31% and an iron (Fe203) content of less than 0.08 percent. The other third is sold as pottery feldspar after grinding to minus 200 mesh for ceramic purposes. }finor amounts of feldspar ar~ sold as fillers. A high grade quartz is produced and sold and the plus 60 to 80 mesh mica recovered in the flotation process is sold to mica

1 A proposal to Bureau of }fines for research grant concerning recovery of by-products from feldspar plant tailings. By tol. T. McDaniel. Submitted September 5, 1967

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grinding companies in the Spruce Pine area for drill well mica and roofing mica. Approximately 800 to 900 tons of solid waste material has to be disposed of per day. Origin of this waste material in the plant and make-up are described later.

The feldspar production in the Spruce Pine area started in 1911, when coarse grained pegmatites were mined and feldspar, quartz and sheet mica were hand picked and hand sorted. The relatively small tonnage production was obtained in the area from a great number of small mines. The fine grained pegmatite material could not be used or had to be wasted. Manpower requirements were high and overall re­covery of feldspar was low. In the late 1930's the flotation process was developed and introduced to the feldspar industry. This process could separate mica, iron minerals, feldspar and quartz from the . large alaskite ore bodies in the Spruce Pine area. Betto1een 1945 and 1957 the flotation process replaced most of the hand cobbing operations. Only a few tons of high potash feldspar are still hand picked in the Spruce Pine area and are ground for special ceramic uses.

Description of Feldspar Flotation Plant

A flowsheet of a feldspar flotation plant is presented in Figure 2. This flowsheet gives a fair picture of all three plants and shows in heavy, black lines where in the plants waste streams origina te. The flowsheet can be des cribed as follo,o1S: alaski te ore containing approximately 60 to 70 percent feldspar, 25 to 30 percent quartz, 3 to 6 percent muscovite mica, 2 percent iron minerals (principally garnet), and a small percentage of clay minerals is trucked to the mill, weighed and dumped onto an apron feeder at the primary ja,01 crusher. The ore is reduced to about minus 4 inch and is recrushed in a standard Symons cone crusher to about 80', percent passing 3/4 inch.

The ore is stock piled and blended, reclaimed by belt conveyor, metered and fed with water into rod mills. The rod mills grind either in series or parallel circuits. The circuit is closed by screens which return plus 20 to 28 mesh material to the mills. The screen undersize is des limed at about 200 mesh in rake classifiers or cyclones. The minus 200 mesh rna terial is '-las ted.

The des limed and dewatered plus 200 mesh material is con­ditioned for mica flotation with sulfuric acid, amine acetate, fuel oil and frother. Hica is removed by flotation. Usually the fairly clean mica from the first few flotation cells is screened at 60 to 80 mesh. The coarse clean mica is sold. The screen undersize is wasted. The flotation product from the remaining mica cells is also wasted.

The mica flotation cell discharge is deslimed and dewatered by cyclones or rakes. The overflow is wasted. The dewatered sands are conditioned with sulfuric acid, sodium petroleum sulfonate and

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frother. By flotation, garnet, iron minerals and iron-stained minerals are then removed and wasted.

The iron flotation discharge is conditioned ~-lith hydrofluoric acid, amine acetate, fuel oil and frother. The feldspar is removed as float product and is filtered and dried after reagent removal with caustic soda. The drainage ~-1ater is wasted. The drained or filtered feldspar and quartz are dried in rotary dryers. The feldspar is sometimes treated by dry high-intensity magnetic separators for removal of residual iron and iron-stained minerals. The removed iron material is t-lasted.

The feldspar is stored and shipped as is to the glass in­dustry, or is ground in pebble or fluid energy mills before shipment to ceramic manufacturers.

The feldspar flotation cell discharge is screened, at times, on 28 mesh for removal of some coarse feldspar which is wasted, and is treated at times by flotation for removal of small amounts of finer feldspar which is also wasted. The quartz thus obtained is of glass grade quali ty •

At each of the three companies all waste streams are com­bined into one tailing stream which is moved by gravity or pumps to the tailing plants.

In Figure 3 the problems of feldspar and tailings production are demonstrated. The average alaskite ore contains about 60 to 70 percent feldspar. The feldspar recovery in the three plants is about 40 to 50 percent by t-leight of the ore. With 3 to 4 percent of the tonnage milled recovered as saleable mica and 8 to 15 percent of the overall tonnage sold as quartz product about 35 to 45 percent of the tonnage milled reports as waste tailings. Laboratory test work on the same alaskite ore recovered about 60 percent of the ore as feld­spar product and with laboratory quartz and mica products sold in the ideal case 85 percent of the ore could be used and only 15 percent would be wasted. The challenge to the mineral engineer is there-fore to reduce wasted tailings through increased feldspar recovery. This could be done by verification of laboratory batch results on alaskite ore in continuous pilot plant and transformation to plant operation. An example of this approach to waste reduction through feldspar and quartz recovery was the Kings Mountain Silica Co. project at the Asheville Laboratory, in which batch '-lork results were dup­licated in pilot plant aod in a 400~ton per day production plant. Another example of transformation of batch results at the Asheville Laboratory through pilot plant to commercial plant is the 25,000 ton per day Texas Gulf Sulphur Company phosphate flotation plant. In both cases batch results were closely duplicated in the production plants.

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The other approach to the tailings problem which was taken by the laboratory at the request of the three feldspar producers is to work on the tailings as they are produced now in the existing tailings plants, to find possible uses for the material as it is produced or after ~eprocessing.

Description of Tailings Plants

Until about 1964 the three feldspar companies discharged all of their waste tailings material into the North Toe River. Commendable efforts to reduce stream pollution have been made by the three companies by installation of tailings plants ~vhich remove practically all solid material from the used process water before it is discharged into the stream. The solid material is de~'latered in these plants so that it can be handled by loading equipment and hauled to dump areas by truck. Each company installed about $100,000 worth of tailings disposal equipment. The fact that game fish are again being caught in the Toe River is a credit to the feldspar and other mining industries in the area as lolell as to the Spruce Pine municipality, which installed and operates a new sewage treat­ment plant in tHe area to clear sewage waste before discharging into the River. Schematic flOlvsheets and descriptions give a picture of how feldspar tailings are treated at the three plants and lolhere the tailings streams origina te •

Lawson-United Feldspar and Mineral Company Tailings Plant

In Figure 4 a schematic flololsheet of the tailings plant at Lawson-United Feldspar and Hineral Company is presented. The com­bined tailings stream, about. 1000 GPH, is pumped continuously during the three-shift-per-day operation into an upper settling pond where 85 to 95 percent of the tailings solids settle out. The overflow from the upper pond runs into a lower pond lolhere the rest of the finer solids settle out and which is cleaned out at about 6 month intervals. The overflolv from the lower settlings pond discharges into the North Toe River. The material lolhich settles out in the upper tailings pond is removed every day by a 0070 cubic yard Sauerman scraper, which dumps onto a pile for drainage. The drained material is loaded by a 3/4 cubic yard shovel into a l6-ton dump truck and· is hauled about ~ mile to a dump area. One scraper operator and one 'loader­truck driver operate the Lawson-United tailings plants during the day shift. Lawson-United Feldspar and Mineral Company spends about $44,000 per year to operate and maintain the tailings plant.

International Hinerals Corporation Tailings Plant

The schematic flowsheet of International Minerals Corporation's tailings disposal plant is presented in Figure 5. The total tailings stream is pumped continuously during the three-shift-per-day operation to a bank of four 12-inch cyclones. The coarse cyclone underflow is

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dewatered and deslimed in a screw classifier and transported by belt to the coarse tailings stock pile from which it is loaded by front­end loader into 17-ton dump trucks and hauled l~ miles to a leased mined-out clay pit where it is dumped.

The cyclone overflow and screw overflow containing the fine fraction of the tailings stream - about one-third of the disk filter for final dewatering. The thickener overflow is dis­charged free of solids into the North Toe River, from which Inter­national Minerals and Chemicals Corporation obtains all process water for its flotation operation. The filtrate water from the filter is returned to the thickener. The filter cake drops onto a belt which moves it onto the filter cake stock pile, from which it is loaded, moved and dumped in the same area as the coarse tailings. The tail­ings plant is operated continuously during the three-shift-per-day flotation plants operation, with minimum supervision by flotation plants operating personnel. Loading and haulage is contracted out to a local haulage firm. Usually one man loads and trucks all tailings material during the day shift. International Minerals and Chemical Corporation spends about $80,000 per year to operate and maintain the tailings plant.

Feldspar Corporation Tailings Plant

A schematic flowsheet of Feldspar Corporation's tailings plant is presented in Figure 6. The combined tailings stream is fed by gravity to a rake classifier, where a small tonnage of coarse tail­ings material is removed. This coarse material is moved by belt to a stock pile, from which it is loaded by front-end loader into 20-ton dump trucks and hauled to dump areas.

The overflow from the rake classifier flows to a thickener where the solids content is increased for subsequent filtering. The thickener overflow is free from solids and is discharged into the North Toe River. The thickener underflow is pumped onto a disk filter. The water is returned to the thickener and the filter cake drops onto a belt and is moved to the filter cake stock pile. Loader and dump-truck move the filter cake to dump areas.

The tailings plant is operated continuously during three-shift­per-day plant operation with minimum supervision by flotation plants operating personnel. Loading and haulage is performed by company personnel, usually one man during the day shift. Feldspar Corpora­tion reported expenses of about $50,000 per year for operation and maintenance of the tailings disposal plant.

On Figure I locations of tailings disposal plants, haulage ways and dump areas for the different plants are shown. At this time the longest tailings haulage distance is 1.5 miles at International Minerals and Chemical Corporation.

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At the three disposal plants there are a total of 5 different tailings materials which are hauled separately but , ... hich could easily be combined. The tailings streams are tabulated in Table 1 as re­ferred to in the follotdng report.

Tailings Streams

Lawsons Tailings Feldspar Co. Filter Cake Feldspar Co. Coarse LN.C. Filter Cake LN. C. Coarse

The

TABLE 1

Five Tailings Streams

Approximate Tons Per D~y Dry

235 to 300 250 to 230

25 to 30 105 to 130 175 to 180

Total 790 to 870

Preliminary Tailings Evaluation

i. ~oisture As Produced

17-19 18 7-8

23-24 11-19

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During the year 1967 random samples of all feldspar tailings were taken on different trips to Spruce Pine. The objects were to gain preliminary supporting data for the U.S. Bureau of Hines project, and to find out if saleable feldspar and quartz could be recovered from the tailings. The results obtained at each company were reported separately to each company in April 1968, and are reported together in Feldspar Tailings Report No.1, April 1968, Ashevi11e-Ninerals Laboratory Progress Report. This entire report is included as Appendix 1. Only the summary is presented here. The figures in Table 2 pre­sent daily tonnages of products that could be recovered by mineral dressing procedures from the tailings material of the three companies.

TABLE 2

(Table 4 of Feldspar Tailings Report 1)

Summary of Preliminary Tailings Sampling in Tons Per Day

Companies

Feldspar Laws on-Products Corp • LN. C. United Total i. of Total

Feldspar 103 59 110 272 31.4 Quartz 48 119 82 249 28.8 Hica-Fe. 28 13 21 62 7.2 Slimes 118 76 73 267 30.8 + 28 Nesh 3 13 16 1.8

Total 300 267 299 866 100.0 % Total 35 30.5 34.5 100.0

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Based on results of this preliminary evaluation, the three feldspar companies in the Spruce Pine area dispose of approximately 870 tons of tailings per day. Out of these tailings about 270 tons per day of feldspar could be recovered for the ceramic industry and approximately 250 tons of high grade quartz could be recovered. About 60 tons per day of mica-iron float product and 270 tons per day of slimes of fairly uniform size and grade tl10uld still have to be dis­posed of. Because of uniformity of the last ttlTo materials, possible markets might be found.

The above data are based on a few samples taken at random whenever the writer was in the Spruce Pine area. A more detailed sampling program to obtain more exact material variation and tonnage data is in progress.

Daily Sampling - January and February 1968

On January 7, 1968 laboratory personnel met with representa­tives of the three feldspar companies in Spruce Pine to plan the first phase of the tailings project. To determine variation of the tailings streams from day to day, it was decided to sample all five tailings streams for a period of about 10 days. The daily sampling was conducted during January and February of 1968. During this sampling period about 10,000 tons of tailings were produced. From each truckload of tailings a sample was obtained and composited into a sample representing the total daily production of the respective tailings product. This was done for each of the five tailings streams produced at the three plants. The samples thus obtained were taken to the Asheville Laboratory where the major part of the sample evaluation was conducted after the official start of the Bureau of Hines participation in l-Iarch 1968. Details of procedures employed to obtain, process and evaluate the samples are presented in Feldspar Tailings Report No.2, December 1968, Progress Report by Robert D. Kauffman. This report is Appendix 2. The following information was obtained for each of the five tailings samples.

Rate of production, tons per day wet. Rate of production, tons per day dry. Size analysis. Chemical analysis. Approximate mineral content. Flotation response.

Products: Slimes Hica Iron Minerals Feldspar Quartz

Chemical analysis of feldspar and quartz products. Mineral content of feldspar products.

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The same information was obtained on five composites made up of the daily samples in proportion to their daily production rates and representing the five different tailings materials over a ten day period.

The five composites were also further composited to a composite representing all five tailings streams combined over a ten day period.

For the daily screen fractions, for the chemical components of the different daily samples, and for some flotation results averages and standard deviations were calculated. To present the degree of variation of samples from day to day, 95 percent confidence limits (plus and minus two times standard deviation) are reported together \V'ith calculated averages, results on actual composites and checks in Table 3 and 3A.

Weekly Sampling - July, August and September 1968

On June 3,. 1968, the second meeting of representatives of the three feldspar companies and laboratory staff members was held in Spruce Pine. An advisory committee consisting of one representative of each feldspar company, Dr. Robert Stoops, Director of Engineering Research of the N. C. State University and Immo H. Redeker, Asheville Minerals Research Laboratory, lV'as formed. The available results of the lO-day sampling period were presented to the feldspar companies and it was decided to confirm apparent uni­formity of the five sampled tailings streams by sampling on a week to week basis for a period of 10 weeks. The sampling and characteri­zation of the tailings should be completed during the first nine months or year of the project.

The weekly sampling was conducted during July,August and September 1968. During this sampling period about 50,000 tons of tailings \V'ere produced. From each truckload of tailings hauled a sample was obtained. These samples lV'ere composited into samples representing \V'eekly production of each tailings stream. Large re­ference samples of each weekly sample lV'ere kept in Spruce Pine in closed 55-gallon containers. Thirty to fifty lb. samples of the weekly samples were taken to Asheville for processing. Detailed procedures employed to obtain data which can be compared tV'ith the daily samples are presented in Feldspar Tailings Report No.2, December 1968, Progress Report by Robert D. Kauffmann.

The results of daily and weekly sampling, as far as available at report time, are presented in Summary Table No. 3 and Table No~ 3A of this report.

For each of the five tailings streams fhe following informa­tion is presented for each variable determined.

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Average of sampling period, daily. 95% confidence limit. Actual composite representing overall daily sampling period. Check of actual composite.

Average of sampling period, weekly. 95% confidence limit. Actual composite representing overall weekly sampling period. Check of actual composite.

The results obtained on composites of composites of all daily tailings streams, representing the total tailings during the January -February 1968 sampling period, are shown at the bottom of Table 3, and results obtained on composites of composites of all weekly tailings streams representing the total tailings of the three companies during the July-August-September 1968 sampling period, are shown at the bottom of Table 3.

Discussion of Results of Daily and Weekly Sampling

The results and conclusions of the daily and weekly sample programs are presented in Feldspar Tailings Report No.2 by Robert D. Kauffmann as follows.

Results

The following is a summation of the results of the data, on the tailing samples obtained from the three feldspar companies at Spruce Pine. Where possible, a comparison is made between the daily samples (taken January 1968) and the weekly samples (taken July-September 1968).

Lawson Tails

Screen Analyses - The data indicate that the daily samples are slightly coarser than the weekly samples, by about 4.0 per­cent at 200 mesh. The actual data for these screen analyses is shown in Appendix A.

Chemical Analyses of Head Samples - The difference between the head analysis of the daily and weekly is insignificant.

Flotation Results - The data indicate that the flotation results of the calculated and actual composites of the daily and weekly samples are very close to being within the limits of the experimental error.

The data also indicate that an average of 44.7 percent of the daily samples constitutes the feldspar product while an average of 39.1 percent of the feed of the weekly samples is in the feldspar product. The quartz product constitutes an average of 28.5 percent of the feed of the daily samples and 33.8 percent of the feed of the weekly samples. The difference between the chemical analyses of the daily and weekly samples

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of the spar and quartz products is insignificant. The flotation carried out on Lawson tails showed there ll7aS no difficulty in obtaining feldspar of satisfactory grade.

Feldspar Corporation Filter Cake

Screen Analyses - Data shol-1 that the percent plus 200 mesh in the daily samples is greater than that in the weekly samples (± 11 percent).

Chemical Analyses of Head Samples - Data show there is a difference in the head analyses of the daily and weekly samples. The average alkali of the weekly samples is about 0.8 percent greater than the daily samples.

Flotation Results - The average percent slimes (minus 200 mesh) for the ll7eekly samples is about 10 percent greater than for the daily samples.

The average percent material in the feldspar float of the daily sample (35.6" percent) is about ten percent greater than that of the weekly samples (24. 6 percent) while the percent material in the quartz product is approximately the same in the daily and ll7eekly samples. The total alkali in the feldspar from the weekly samples is slightly higher than in the daily samples. Grade of the feldspar product was not difficult to obtain by flotation of the samples of Feldspar Corporation filter cake.

Feldspar Corporation Coarse Tails

Screen Analyses""- Data show no difference between the screen analyses of the daily and weekly samples.

Chemical Analyses of Head Samples - Data show no signifi­cant difference between the chemical analyses of the daily and weekly samples.

Flotation Results - Flotation tests carried out on Feldspar Corporation coarse tails indicate the material contains a high " percent of feldspar. Thus far, it has proven difficult to obtain grade on either the daily or weekly samples. This tailing product represents a small tonnage (about 20 tons per day).

IHC Filter Cake

Screen Analyses - Data show there is a wide variance in" the individual screen analyses of both the daily and weekly samples. Thus based on these data, no definite conclusion can be assumed as to its significance.

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Chemical Analyses of Head Samples - Due to the difference in analysis between various daily samples (calculated composite and actual composite), any difference between daily and weekly samples could be attributed to experimental error.

Flotation Results - Due to incomplete results, it is difficult to make a comparison between daily and weekly samples. Those results thus far compiled indicate that, for both the daily and weekly samples, the feldspar float product represents about 15 percent of the feed weight, while the quartz product constitutes about 9.5 percent of the total feed. The flotation of IMC filter cake is carried out on plus 400 mesh material. The minus 400 mesh slime constitutes about 70 percent of the total feed.

IMC Coarse Tails

Screen Analyses - Data indicates there is no signifi­cant difference between the screen analyses of the daily and weekly samples.

Chemical Analyses of Head Samples - Data indicates the total alkali for the weekly samples averages slightly higher than that for the daily samples (± 0.9 percent).

Flotation Results - Although data is not complete, it does indicate that approximately the same percentage of the feed of both the daily and weekly samples is floated in the feldspar float. The chemical analyses of the feldspar and quartz products of the daily and l'1eekly samples is approximately the same. It has proven difficult to obtain grade in the feldspar product of UiC coarse tails.

Actual Composites of Daily and Weekly Composites

Screen Analyses - A comparative evaluation of data indicates there is no significant difference between the com­posite of all the daily tailings samples and the composite of all the weekly samples in the plus 200 mesh range of the screen analyses. In the minus 200 mesh material the 'o1eekly composite consists of coarser material than the daily composite.

Chemical Analyses of Reao Samples - Data show there is little or no difference in the chemical analysis of the head sample of the daily and weekly composites.

Flotation Results - By the use of normal sample preparation and flotation procedures, feldspar grade is obtainable without difficulty on both the daily and weekly composite samples. Results indicate any differences obtained by the flotation of these two products could be attributed to experimental error.

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Summation of Results

Table C show's, based on daily samples, (1) that 812 tons per day of tailing were produced by the three feldspar companies at Spruce Pine, North Carolina. From this material, it is estimated that 287 tons per day of feldspar and 222.1 tons per day of quartz could be recovered. If the above products were recovered by beneficiation, it is estimated that approxi­mately 233.1 tons per day of slime would be produced.

Table C also shows, based on weekly samples, (2) that 864.3 tons per day of tailing were produced by the three feldspar companies. It is estimated from this material that 273.2 tons per day of feldspar and 244.4 tons per day of quartz could be recovered. If the above products were recovered by beneficiation, it is estimated that approximately 269.6 tons per day of slime l<1ould be produced.

Table C

Tailing and Product Rates

Dail~ Samples (TPD) Weekll SamEles (TPD) Tails Spar Quartz Slime Tails SEar Quartz Slime

DIC Filter Cake 129 20.9 10.2 91.1 126 20.7 10.7 85.2 nlc Coarse Tails 178 59.4 91.3 11. 4 177 65.5 75.5 18.4

307 80.3 101.5 112.5 303 86.2 86.2 103.6

FeId.Corp. Filter Cake 250 89.0 49.7 86.5 2.:h 56.8 45.3 106.7 Feld.Corp. Coarse Tail 20 12.7 4.0 0.9 28.3 12.1 10.8 3.2

Lawson

Total

270 101. 7 53.7 87.4 259.3 68.9 56.1 109.9

Tails 235 105.0 66.9 33.16 302 118.1 102.1 56.1

812 287.0 222.1 233.1 864.~-273.2 244.4 269.6

Results of flotation tests show it is not difficult to obtain grade on the feldspar product (10.5 percent total alkali and 19.0 percent A120 3) l<1ith INC filter cake, Feldspar Corporation filter cake and Lal<1son tails. Thus far it has proved difficult to re­cover a feldspar product of satisfactory grade from IMC and Feldspar Corporation coarse tails. The latter product constitutes only small tonnage.

(1) Daily samples were taken in January 1968 (2) t.Jeek1y Samples were taken from July - September 1968

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Results of screen analyses and chemical analyses of head samples of the various tailing samples and composites of such indicate that in some instances there is a significant difference between the daily and lo1eekly samples. This is true of Lawson tails, Feldspar Corporation filter cake and for the chemical analysis of INC coarse tails. Due to the large experimental error of the screen analysis and chemical analysis of INC filter cake, no definite conclusions can be drawn.

Table D gives an approximation of the reagent consumption and reagent cost per ton of feed* for the flotation of a sample of the composite of weekly composites.

Table D

Reagent Consumption and Cost

Reagent Consump tion Reagent Cost/Lb. Lbs/Ton Cost/Ton

H2SO4 2.2 ¢ 1.9 4.2 ¢

N-70 16.4 0.5 8.2

F.O. 1.5 0.6 0.9

25-H. :\ 25.0 0.12 2.9 ~ ~ .

HF 21.5 0.92 19.7

Armac-T 27.0 0.29 7.8

NaOH 5.5 1.3 7.1

50.8

*This is not flotation feed but total feed which includes slimes and plus 28 mesh mica

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Conclusions

The conclusions that can be drawn from the data thus far correlated are as follo'"s.

1) It has proved difficult in the laboratory to produce a good quality feldspar product from Feldspar Corporation coarse tails and IMC coarse tails.

2) Feldspar, quartz and mica products can be produced without much difficulty from samples of the other tailing streams.

3) It did not prove difficult to produce, by flotation, feldspar, quartz and mica products from composites of the daily composites and composites of the 't-1eekly composites.

4) Results show that in some instances there is a significant difference between the daily and weekly samples. This difference may be in the screen analysis, chemical analysis of the head sample and/or flotation results.

5) The screen analyses of the calculated composite of the daily and weekly composite, in some instances showed the confidence limits (95 percent confidence) for certain screen fractions to be relatively high.

6) The calculated composites of the daily and weekly composite, for the chemical analyses of the head sample, sho," the confidence limits for some of the analyses to be relatively high.

7) The calculated composites of the daily and weekly composite, for results of flotation tests (where possible), show in some instances the confidence limits (95 percent) for the ,,,eight percent of some of the products to be relatively high. l\T11ile the confidence limits for the analysis of the feldspar and quartz products are not significant.

The outs tanding result of preliminary, daily and ,,,eekly sampling is the high feldspar content in the five tailings streams, and the possibility to recover a large part of the feldspar ,·,ith low iron content by Nineral Dressing Hethods. The screen analysis of the feldspar produced from composites of daily and weekly samples are presented in Table I,.

Daily Samples

\oleek1y Samples

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Table 4

Screen Analysis of Feldspar Products, Percent Height in Fraction From Flotation '-lork on Daily and Weekly Composites

ComEanx Lawson Feldspar Co. International Com;eosite

Tyler United Filter Filter Hesh Tailings Cake Coarse Cake Coarse Check

+35 14.8 1.7 22.5 9.9 8.5 11.3 -35+48 16.6 4.1 28.2 12.9 11.6 12.6 -48+65 14.4 6.7 9.7 10.8 11.1 11.6 -65+100 18./, 11.1 17.7 0.6 14.8 15.5 13.8

-100+150 12.4 14. {, 8.6 0.9 13.6 13.6 14.2 -150+200 13.6 25.7 7.0 6.2 21.0 19.2 18.2 -200 8.5 36.2 5.3 92.3 17.1 20.4 18.3

ComEosite Deslimed at

200 400 700 t>lesh Nesh Hesh

+35 12.3 2.2 0.4 0.8 0.4 10.0 14.3 --=r;g 7:T -35+48 13.0 3.9 28.3 1.0 16.4 12.8 16.0 11.0 9.0 -48+65 12.3 6.4 28.8 1.0 18.3 11.5 13.8 8.7 8.2 -65+100 13.1 10.0 18.4 1.4 15.7 11.9 13.8 11.0 10.5

-100+150 13.3 13.1 10.0 2.1 14.0 12.2 12.2 11. 0 "9.2 -150+200 17.3 25.3 7.9 8.5 18.1 18.4 16.0 15.8 14.4 ,

13.8 34.6 -200 17.9 39.1 6.1 85.2 17.2 23.2 41.5

Surprisingly only about 20 percent of the feldspar recovered is finer than 200 mesh w'hen employing the standard evaluation procedure. There is solid indication that still more feldspar can be recovered from the finer fractions of the tailings, and a special study is under way.

Feldspar Recoverx From the Finer Fractions of the Tailings

Because a large amount of fine material (slimes) and because of low feldspar recoveries when desliming at 200 or 400 mesh as was done for the eval ua tion 0 f the tai lings, a special study was conduc ted on International Ninerals and Chemical Corporation I s filter cake. 'TIle

-17-

object of this study '-las to find out hOltl much more feldspar could be recovered when des liming at about three microns.

Fine feldspar that could be recovered should have ceramic uses without further grinding. The data of this work are not com­pletely available at this time, but it can be stated that about 40 percent by weight could be recovered from International Mineral and Chemical Corporation's filter cake as feldspar low in iron and slightly higher in potash content than the average glass grade of feldspar pro­duced. The feldspar recovered has an average particle size of 15 microns (800-900 mesh equivalent). Application of this result to the total tailings will increase the recoverable feldspar from 30 to 40 percent by '-leigh t 0 f the to tal tailings. A tes t on a compos i te 0 f all plan ts employing desliming at about 700 mesl1, presented at the bottom of Table 3, has confirmed this. The amount.of feldspar finer than 200 mesh in the concentrate of this test was 41.5 percent of the feldspar recovered.

Current Work and Plans

As soon as Feldspar Tailings Report No. 2 is in the hands of the feldspar companies, the third meeting will be held in Asheville to determine the best ,,,ay to proceed with the tailings project.

The Engineering Research Department's Pyrochemical Research Section at the N. C. State University in Raleigh is conducting ceramic studies to find possible uses for the tailings as they are produced now. The Indus­trial Engineering Extension Service will assist with market studies for saleable products developed.

The Civil Engineering Department is conducting test work to determine if uses for high~"ay construction and maintenance can be found. Highway construction would be a fairly high tonnage outlet if the material would be accepted.

At the Asheville Laboratory studies are under way to improve mineral recovery methods, aimed at recovery of feldspar and quartz. Variables in different flotation procedures are tested to gain informa­tion for continuous pilot plant testing of feldspar and quartz recovery from the tailings. These studies are conducted on tailings as they are produced now separately, combined, and mixed in different proportions as could be expected from plant operation variations. The recovery studies of feldspar from the finer material will also be applied to the tailings material.

After confe~ring with experts in the container glass manufactur­ing field, agglomeration studies are planned to see if the fine tailings material, as it is produced now, can be pelletized. Sized material could be used in glass melting furnaces for the manufacturing of amber glass throw-a-way bottles, a field of grol-ling importance. Lime as a possible binder with added benefits to the melt should be investigated.

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Recommendation

Based on the experience of the Asheville Laboratory, the tonnage of tailings produced, and the high feldspar content in the tailings streams, the approach that '''ould mos t likely lead to a solu­tion of the tailings problem would be to try to recover and market the feldspar and quartz nOt" lost in the tailings. There are a total of 1,700 to 2,000 tons per ,,,eek of recoverable feldspar or 85,000 to 100,000 tons per year. At an estimated low sale price of $8.00 per ton, F.O.B. Spruce Pine, this represents $680,000 to $800,000 per year, when using a high reagent cost figure of $1.50 per ton of feldspar recovered, and the high processing cost figure of $1.50 per ton of feldspar recovered and $2.00 for plant amortization (20 percent of $1,000,000 over 5 years) that would leave an interesting $3.00 per ton of feldspar from the tailings, or $255,000 to $300,000 per year. This is a return of 25 to 30 percent on a million dollar investment and proportionally higher for a lower investment figure. Part of the feldspar produced from the tailings already ,.Jill be fine-ground ceramic spar, '''hich could be sold for at least $16.00 per ton, F.O.B. Spruce Pine. The proceeds of reclamation of feldspar should be able to pay for all other still incurring tailings disposal expenses including farther haulage of a smaller tonnage of unsold material to the many mined-out open pi ts in the Spruce Pine area, '''hich should be backfilled to original contour, and should show a profi t.

Quartz will be a saleable product too if offered at a low price and could be the raw material for calcium silicate brick and foamed calcium silicate light-,,,eight building material. These building materials are produced in great quantity in up-to-date automated plants in Europe and would offer to the building industry bricks, blocks and panels in a variety of sizes, strength and colors.

The added feldspar supply should reduce overall mining cost, lower overtime operating expenses, and should provide time for more scheduled preventive maintenance in the main plants.

Because of the fineness of at least one third of the added feldspar, feldspar grinding cost can be reduced or total tonnage out­put of this material can be increased.

It would be most economic to treat the five tailings streams of the three plants together in a 800 to 1,000 tons per day plant, '''hich would produce 300 to 400 tons of feldspar per day. The schematic flOt"sheet of such a plant is presented in Figure 7. Even if one or the other companies wanted to treat their own tailings alone for the re­covery of feldspar and quartz, the smaller plant having higher amorti­zation and operating cost per ton of feldspar reclaimed seens to be a profitable venture.

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It is highly recommended to pursue the feldspar and quartz recovery through further process test work and through pilot plant work.

The Asheville Laboratory is in the unique position to set up a pilot plant for this specific purpose in a minimum of time and operate it with minimum expense, because of trained personnel and available special equipment.

l.Jith the help of people knowledgeable in the glass indus try, highway construction field and other high-tonnage-low-cost mineral consuming industries, attempts will be made to find uses for the 850 tons per day of unprocessed tailings material.

CONFIDENTIAL

PRELHlINARY FELDSPAR TAILINGS EVALUATION Feldspar Tailings Report #1, April 1968 Progress Report

Introduction

Lab. No. 3185 - Book 231, p. 1-28 by

Immo H. Redeker

Samples of Feldspar Corporation, International Mineral Company

and Lawson-United Feldspar Company's tailings were taken on different trips

to Spruce Pine during 1967. The samples were taken to gain preliminary

data for the U. S. Bureau of Mines' Tailings Project. The object of lab-

oratory testwork was to find out if saleable feldspar and quartz, products

now sold by the three companies, could be recovered from the tailings as

produced in the dewatering plants of above companies.

Samples

The samples were taken and designated as follows:

Feldspar Corp. Filter Cake Approx. 285 TPD

Rake Sand " 15 TED

I.M.C.C. : 111 Sand " 90 TPD

112 Fe-Waste " 90 TPD

1F3 Filter Cake " 90 TPD

Lawson-United Co.: Scraper Pile or Dump " 300 TPD

Procedure

The samples were treated by grinding of oversize, scrubbing,

des liming, removal of mica and iron by flotation and standard feldspar-

- 2 -

quartz flotation separation methods. Usually only one test was run for

rapid evaluation of the samples. Even better feldspar recovery and lower

iron in the spar could be achieved by optimizing of reagents and test

conditions as planned for the later project. The results of this prelimi-

nary work are tabulated for the three feldspar companies separately on

tables 1, 2, and 3 and are summarized on table 4.

Table 4

Summary Of Preliminary Tailings Sampling in TPD

Companies Products Feldspar Corp. I.M.C.C. Lawson-United Total % Of Total

~ Feldspar 103 59 110 272 31.4

Quartz 48 119 82 249 28.8

Mica-Fe 28 13 21 62 7.2

Slimes 118 76 73 267 30.8

+28 Mesh 3 13 16 1.8

Total 300 267 299 866 100.0

% Of Total 35 30.5 34.5 100.0

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Summary

The three feldspar companies in the Spruce Pine area dispose of

approximately 870 tons of tailings per day. Out of these tailings about

270 tons per day of feldspar could be recovered for the pottery industry

and approximately 250 tons of highgrade quartz could be recovered. About

60 tons per day of mica-iron float product and 270 tons per day of slimes

of fairly uniform size and grade would still have to be disposed of.

Because of uniformity of the last two materials, possible markets might

be found.

The above data are based on a few samples taken at random whenever

the writer was in the Spruce Pine area. A more detailed sampling program

to obtain more exact material variation and tonnage data is in progress.

- 4 -

Table 1 Feldspar Corporation, 300 TPD Total Tailings (285 TPD Filter Cake, 15 TPD Sand)

Spar guartz Sample Date % Wt. TPD % K20 % Na20 % Fe20

9 % Wt. TPD % K20 % Na20 % Fe2O)

Cake 7-21-67 35.2 100 4.31 6.46 0.064 18.9 54

Sand 7-21-67 58.2 9 3.66 6.77 0.065 17 .8 3

Cake & Sand 7-27-67 33.8 101 5.74 5.95 0.05 13.0 39 0.16 0.15 0.014

Cake 9-6-67 29.6 84 4.58 6.38 0.07 18.5 53 0.08 0.08 0.012

Sand 9-6-67 56.3 8 4.08 6.33 0.07 29.8 4 0.09 0.11 0.020

Cake 10-25-67 35.5 98 4.57 6.53 0.11 13.3 38 0.11 0.14 0.012

Sand 10-25-67 73.2 11 3.67 6.73 0.08 15.7 2 0.05 0.11 0.014

Average 103 48

I (

i Mica Fe Slime +28 Mesh

. % Wt. TPD % wt. TPD % Wt • TPD

13.0 37 31.3 89 1.6 5

12.0 2 8.8 1 2.4 0

9.2 28 43.6 131 0.4 1

7.4 21 43.3 123 1.2 3

8.5 1 4.7 1 0.7 0

6.3 18 43.9 125 1.0 3 : .. 25.4 4 4.8 1 0.9 0

I , . ;

28 118 3

"

- 5 -

Table 2 I.M.C.C., 270 TPD Total Tailings (90 TPD #1, 90 TPD #2, 90 TPD #3)

SEar guartz SamEle Date % Wt. TPD % K20 % Na20 % Fe20a % Wt. TPD % KaO % NaaO % Fe203

1F!+2+3 April 165 20.6 57 4.14 6.10 0.11 49.2 133 0.05 0.06 0.057

1Fl+2+3 7-27-67 22.3 60 3.79 6.26 0.10 39.8 107 0.06 0.61 0.020

I 1F! 9-6-67 13.5 12 3.22 4.96 0.07 79.5 72 0.04 0.04 0.007

112 9-6-67 31.5 28 4.27 6.30 0.09 54.8 49 0.05 0.06 0.018 t

1;3 9-6-67 14.0 13 4.81 6.37 0.10 5.9 5 0.14 0.13 0.027

Ifo1 10-25-67 10.0 9 3.78 5.27 0.15 84.5 76 0.05 0.08 0.045

:in 10-25-67 49.4 44 4.55 6.42 0.22 33.4 30 0.5 0.8 0.14

1;3 10-25-67 14.2 13 4.23 6.73 0.11 6.1 5 0.07 0.11 0.012

Average 59 119

Mica Fe Slime +28 Mesh % Wt. TPD. % Wt. TPD % Wt. .'!!!! -

6.5 17 23.5 63 0.2 0.5

6.2 17 31.5 85 0.2 0.5

3.2 3 3.5 3 0.3

6.9 6 6.6 6 0.2

7.1 6 73.8 66 0.2

2.1 2 3.4 3

8.1 7 8.5 8 0.6

4.4 4 75.2 68 0.1

13 76

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Table 3 Lawson-United Feldspar Co •• 300 TPD Total Tailings

Spar Sample Date % Wt. TPD % K20 % Na

20 % FeaO~ % Wt.

Scraper 6-30-67 36.6 110 4.55 6.19 0.061 28.7

Scraper 7-12-67 30.0 90 4.09 6.28 0.14 24.5

Dump 7-12-67 30.7 92 4.29 6.45 0.08 21.0

, Scraper 7-27-67 43.7 131 4.25 6.46 0.063 32.3

Scraper 9-6-67 40.3 120 4.05 6.33 0.07 30.5

Dump 10-25-67 39.6 119 4.91 6.58 0.19 26.7

Average 110

guartz TPD % Ka°

86 0.03

74 0.08

63 0.06

97 0.07

92 0.06

80 0.18

82

% NaaO

0.06

O.ll

0.10

0.07

0.08

0.19

% Fe20a

0.01

0.08

0.018

0.09

0.018

0.014

,. , !

Mica Fe Slime +28 Mesh Remarks % Wt. TPD % Wt. TPD % wt. TPD Spar % Si02 Spar % A120a

7.7 23 16.9 51 10.0 30 67.12 19.92

6.8 20 29.0 87 8.7 26

6.6 20 35.9 108 5.8 17

6.5 20 16.6 50 0.9 3 :1

7.6 23 21.1 63 0.5 2

7.3 22 26.2 78 0.8 2

21 73 13