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“A NEW VARIABLE IN FLOTATION: THE EFFECT OF PRESSURE/ALTITUDE ON PERFOMANCE” Courtney A. Young Dept Head and ASARCO Professor Metallurgical & Materials Engineering Montana Tech Butte MT 59701

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Page 1: Courtney Young01

“A NEW VARIABLE IN FLOTATION: THE EFFECT OF PRESSURE/ALTITUDE ON PERFOMANCE”

Courtney A. Young

Dept Head and ASARCO ProfessorMetallurgical & Materials Engineering

Montana TechButte MT 59701

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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Butte, MontanaPopulation 40,000Heart of the Rocky MtnsNearby National ParksHistorical Mining DistrictHead FramesBerkeley PitMontana Tech

Montana

Background

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Art Chateau

Granite Mtn Memorial

Old No. 1 Trolley (HUB)

BerkeleyPitlake

Stamp Mill Park

Background

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Orphan GirlHead Frame

Ladyof

TheRockies

MineralMuseum

WorldMuseum

of Mining

Background

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Background

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ELC BuildingBackground

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Main Street

Basin School

Welcome to Basin!

Basin, Montana25 Miles NW of ButtePopulation 255Historic Mining District

Background

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Merry Widow – Au, Ag, Cu, Pb, Zn and U

Now, a Radon Health Mine !

Background

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Hope/Katy ComplexJib Mill – Ag & Au

Background

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Smelter – processed area concentrates

Background

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Basin & Atwater Mills are historically significant

Background

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Butte & Superior Copper Company1909 Leased Basin Mill50 TPD Zn Gravity Mill5-8% Zn in tails

1911 Built Atwater Mill1st froth flotation in US30% Zn concentrate

1st rougher-cleaner cells54% Zn concentrate

1912 Built Butte Mill1200 TPD of ore at 20% Zn2nd rougher-cleaner cells49% Zn con (>90% rec)Among the largest !

Rougher-Cleaner Cells in Atwater Mill

Background

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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IntroductionHistory of Flotation (Highlights)

1860 – Haynes develops the bulk oil flotation process1877 – Bessel brothers show enhanced separation by boiling1885 – Everson improves selectivity using sulfuric acid1886 – Bessel brothers generate gas by acid/carbonate rxns1902 – Potter and Froment generate gas electrolytically but

were first to attribute separation to buoyant forces1902 – Cattermole uses soap to reduce oil consumption1904 – Elmore enhances bubble formation with a vacuum1905 – Sulman, Pickard and Ballot form bubbles by agitation1905 – Mineral Separations Limited at Broken Hill, Australia

employs their technology on an industrial scale1909 – Sulman, Greenway and Higgins employ frothers1911 – Hyde establishes the first US operation in Basin, MT1923 – Keller uses soluble oils (xanthate collectors) which

sets the stage for “froth flotation” to develop

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IntroductionToday, froth flotation is used to treat ores in excess of 600,000,000 TPY:

Metal sulfides (40%) Industrial minerals (30%)Metal oxides (20%) Coal (10%)

The technology has expanded outside the mineral industry:Food PetroleumPulp/Paper Recycling

Valuable materials in these primary and secondary industries Valuable materials in these primary and secondary industries are separated from waste materials in various ways. To do are separated from waste materials in various ways. To do this, some difference in a physical and/or chemical property this, some difference in a physical and/or chemical property must be exploited. In froth flotation, the must be exploited. In froth flotation, the primary propertyprimary property is is hydrophobicityhydrophobicity..

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IntroductionA variety of flotation cells have been developed to do this for all of these industries and include but are not limited to:

Conventional Cell Column CellJameson Cell Air-Sparged Hydrocyclone (ASH)

One design will be preferred over the others depending on the conditions and, of course, the many secondary process variables involved in trying to control the hydrophobicity:

commodity types and quantitiescommodity types and quantities conditioning timeconditioning time particle sizeparticle sizecollector type and quantitycollector type and quantity impellor velocityimpellor velocity liberationliberationfrotherfrother type and quantitytype and quantity percent solids percent solids pulp pHpulp pHmodifier type and quantitymodifier type and quantity airflow rateairflow rate bubble sizebubble size

An examination of the literature will show that pressure has been used to control the solubility of gases and, in the case of a vacuum, used to generate bubbles; however, it has been ignored as a process variable for controlling bubble size.

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Introduction

“So many variables influence flotation that it will be long before every one of them can be investigated and its influence on the process determined.”

Ian W. Wark

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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Objectives

Explore the effect of pressure on flotationExplore the effect of pressure on flotationperformance. To do this:performance. To do this:

Conduct tests at various elevations as well asConduct tests at various elevations as well asin the controlled atmosphere of a glove box.in the controlled atmosphere of a glove box.

Identify and monitor/control, as best asIdentify and monitor/control, as best aspossible, the interdependence of secondarypossible, the interdependence of secondaryvariables (in this case, airflow rate andvariables (in this case, airflow rate andbubble size).bubble size).

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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ProceduresPrepare ore samples using traditional means:Prepare ore samples using traditional means:

receiving receiving –– obtain 200 pounds of obtain 200 pounds of tetrahedritetetrahedrite ore from U.S. Silver Corp.ore from U.S. Silver Corp.crushing crushing –– crush with lab jaw/roll crushers to 100% crush with lab jaw/roll crushers to 100% --1/16 inch (1.6 mm), 1/16 inch (1.6 mm), homogenizing homogenizing –– use broom/shovel cone & quartering technique,use broom/shovel cone & quartering technique,sampling sampling –– prepare 1000prepare 1000--g samples with various Jones splitters, andg samples with various Jones splitters, andgrinding grinding –– dry grind for 45 min with lab ball mill using 94 onedry grind for 45 min with lab ball mill using 94 one--inch ballsinch balls

10

20

30

40

50

60

70

0 10 20 30 40 50

Grinding Time (minutes)

Cum

% P

assi

ng 2

00 M

esh

65% Passing

45 minutes

Dry GroundCopper Ore

U.S. Silver Corp. noted their optimal flotation response occurreU.S. Silver Corp. noted their optimal flotation response occurred near 65% d near 65% passing 200 Mesh (75 um) which ore microscopy showed to be near passing 200 Mesh (75 um) which ore microscopy showed to be near liberationliberation

10

100

1000

5 10 15 20 25 30 35 40 45 50

Grind Time (minutes)

Size

@ 6

5% P

assi

ng (u

m)

X65 = 75 um (liberation size) 45 min

Dry GroundCopper Ore

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ProceduresTransport materials to various sites:Transport materials to various sites:

drydry--ground oreground ore flotation reagentsflotation reagents flotation cellflotation cellpH probepH probe electrical generatorelectrical generator timertimergas flow metersgas flow meters compressed aircompressed air pH bufferspH bufferswaterwater pressure gagepressure gage sample containerssample containers

Conduct tests at various altitudes:Conduct tests at various altitudes:66.9 kPa/9.7 66.9 kPa/9.7 psipsi -- Cooke Pass (elevation 3350 m/11000 ft)Cooke Pass (elevation 3350 m/11000 ft)82.0 kPa/11.9 82.0 kPa/11.9 psipsi -- Montana Tech (elevation 1735 m/5700 ft)Montana Tech (elevation 1735 m/5700 ft)91.0 kPa/13.2 91.0 kPa/13.2 psipsi -- Galena Mill (elevation 610 m/2000 ft)Galena Mill (elevation 610 m/2000 ft)110 kPa/16.1 110 kPa/16.1 psipsi -- Galena Mine (elevation Galena Mine (elevation --760 m/760 m/--2500 ft)2500 ft)

Conduct tests in a glove box:Conduct tests in a glove box:107.6 kPa/15.6 107.6 kPa/15.6 psipsi ((--610 m/610 m/--2000 ft)2000 ft)82.0 kPa/11.9 82.0 kPa/11.9 psipsi (1735 m/5700 ft)(1735 m/5700 ft)31.7 kPa/4.6 31.7 kPa/4.6 psipsi (9144 m/30,000 ft)(9144 m/30,000 ft)

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ProceduresConduct tests with other variables fixed:Conduct tests with other variables fixed:

WemcoWemco laboratory flotation machinelaboratory flotation machine55--liter batch cell with automatic paddlesliter batch cell with automatic paddles20% solids20% solids1800 rpm impellor speed for conditioning1800 rpm impellor speed for conditioning1500 rpm impellor speed for floating1500 rpm impellor speed for floatingLime as pH 8 modifier (0.9 kg/MT; 1.8 lbs/ton)Lime as pH 8 modifier (0.9 kg/MT; 1.8 lbs/ton)KK--ferrocyanideferrocyanide as pyrite depressant (0.05 kg/MT; 0.1 lbs/ton)as pyrite depressant (0.05 kg/MT; 0.1 lbs/ton)Aero 31 as collector (0.25 kg/MT; 0.5 lbs/ton)Aero 31 as collector (0.25 kg/MT; 0.5 lbs/ton)MIBC as MIBC as frotherfrother (0.1 kg/MT; 0.2 lbs/ton)(0.1 kg/MT; 0.2 lbs/ton)Conditioning time of 16 minutesConditioning time of 16 minutesFlotation time of 10 minutesFlotation time of 10 minutesAirflow Rate was ambient (uncontrolled) or 5 liters/min (contrAirflow Rate was ambient (uncontrolled) or 5 liters/min (controlled)olled)

Repeat tests 4 times (statistical confidence)Repeat tests 4 times (statistical confidence)

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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Results

75

80

85

90

95

4 6 8 10 12 14 16 18

Pressure (psi)

Rec

over

y (%

)

Increasing Air FlowDecreasing Bubble SizepH 8 (CaO - 1.8 lbs/ton)

K2Fe(CN)6 (0.1 lbs/ton)Aero 31 (0.5 lbs/ton)MIBC (0.2 lbs/ton)45-min Dry Grind

Pressurized FlotationCopper Ore

+11,000 ft

+5700 ft

-2500 ft

4

6

8

10

12

14

16

4 6 8 10 12 14 16 18

Pressure (psi)

Gra

de (%

)

Pressurized FlotationCopper Ore

+11,000 ft

+5700 ft

-2500 ft

pH 8 (CaO - 1.8 lbs/ton)K2Fe(CN)6 (0.1 lbs/ton)Aero 31 (0.5 lbs/ton)MIBC (0.2 lbs/ton)45-min Dry Grind

Increasing Air FlowDecreasing Bubble Size

75

80

85

90

95

4 6 8 10 12 14 16 18

Pressure (psi)

Rec

over

y (%

)

pH 8 (CaO - 1.8 lbs/ton)K2Fe(CN)6 (0.1 lbs/ton)Aero 31 (0.5 lbs/ton)MIBC (0.2 lbs/ton)45-min Dry Grind - at altitude - glove box

Pressurized FlotationCopper Ore

Constant Air FlowDecreasing Bubble Size

4

6

8

10

12

14

16

4 6 8 10 12 14 16 18

Pressure (psi)

Gra

de (%

)

Pressurized FlotationCopper Ore

Constant Air FlowDecreasing Bubble Size

pH 8 (CaO - 1.8 lbs/ton)K2Fe(CN)6 (0.1 lbs/ton)

Aero 31 (0.5 lbs/ton)MIBC (0.2 lbs/ton)45-min Dry Grind

- at altitude - glove box

Without Airflow ControlWithout Airflow Control With Airflow ControlWith Airflow Control

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Results

0

2

4

6

8

10 11 12 13 14 15 16Pressure (psi)

Bub

ble

Size

(mm

)

Theoretical (PV = nRT)

Without Airflow Control

With Airflow ControlIncreasingCoagulation

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ResultsImplementation Implementation –– To control pressure, the designTo control pressure, the design

must handle slurries under pressure/vacuum:must handle slurries under pressure/vacuum:introduction of the feedintroduction of the feeddischarge of the con/tailing productsdischarge of the con/tailing products

must provide for:must provide for:agitation/aeration controlagitation/aeration controlfroth level controlfroth level controlmaintenance/accessmaintenance/access

can be done by:can be done by:modifying existing flotation cells (conventional, modifying existing flotation cells (conventional,

column, ASH, Jameson, etc.)column, ASH, Jameson, etc.)pressurizing the room (pressurizing the room (hyperballichyperballic chambers)chambers)constructing/purchasing new flotation cellsconstructing/purchasing new flotation cells

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ResultsEconomic Evaluation Economic Evaluation –– Assume a small mill:Assume a small mill:

10000 STPD (approximately 9000 MTPD)10000 STPD (approximately 9000 MTPD)10 flotation cells10 flotation cells

8 rougher/scavenger conventional cells8 rougher/scavenger conventional cells2 cleaner/2 cleaner/recleanerrecleaner column cellscolumn cells

modification costs will be ~US$200,000modification costs will be ~US$200,000copper con at 75% of current market value of copper con at 75% of current market value of US$3.15/pound (US$6.93/kg)US$3.15/pound (US$6.93/kg)

recovery increases by a mere 2%recovery increases by a mere 2%annual profits will increase by US$1.82Mannual profits will increase by US$1.82M

Excluding interest and downtime, the ReturnExcluding interest and downtime, the Return--onon--Investment (ROI) will be approximately one month!Investment (ROI) will be approximately one month!

This does not include increased profits from This does not include increased profits from other products and/or credits: Au, Ag, other products and/or credits: Au, Ag, PbPb, Zn, etc., Zn, etc.

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ResultsOther benefits will include:Other benefits will include:

Decreased environmental concernsDecreased environmental concernsReduced costs for environmental permitsReduced costs for environmental permitsincreased con gradesincreased con gradesImproved smelter contractsImproved smelter contracts

Could be used at highCould be used at high--elevation operations:elevation operations:TintayaTintaya -- Peru (4200 m/13800 ft Peru (4200 m/13800 ft aslasl; 63.4 kPa/9.2 ; 63.4 kPa/9.2 psipsi))Grasberg Grasberg -- Indonesia (3990 m/13100; 64.8 kPa/9.4 Indonesia (3990 m/13100; 64.8 kPa/9.4 psipsi))AntaminaAntamina -- Peru (4300 m/14200 ft Peru (4300 m/14200 ft aslasl; 62.8 kPa/9.1 ; 62.8 kPa/9.1 psipsi))

Such operations would gain the greatest inSuch operations would gain the greatest inflotation performance with recoveries andflotation performance with recoveries andgrades estimated to improve 5% or more.grades estimated to improve 5% or more.

These estimates are dependent on differences inThese estimates are dependent on differences inminerals being concentrated as compared to minerals being concentrated as compared to the the tetrahedritetetrahedrite examined in this study on oreexamined in this study on orefrom the Galena Mine of US Silver Corp.from the Galena Mine of US Silver Corp.

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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ConclusionsFlotation is used to process ores and concentrates around Flotation is used to process ores and concentrates around

the world at a variety of elevations but the effect of pressure the world at a variety of elevations but the effect of pressure on its performance, as usually determined by recovery and on its performance, as usually determined by recovery and grade, has been ignored.grade, has been ignored.

Based on the results in this study, operations can improve Based on the results in this study, operations can improve both recovery and grade by as much as 5% both recovery and grade by as much as 5% pending the pending the characteristics of the ores and characteristics of the ores and mineral(smineral(s) being separated) being separated..

Pressure was also found to influence flotation results by Pressure was also found to influence flotation results by affecting bubble size (and coagulation) as well as frothing affecting bubble size (and coagulation) as well as frothing action thus making airflow rate an important interrelated action thus making airflow rate an important interrelated variable to consider.variable to consider.

Economics should be extremely favorable because capital Economics should be extremely favorable because capital and operating costs to control pressure will be greatly offset and operating costs to control pressure will be greatly offset by improved profits.by improved profits.

However, further studies are needed to fully examine the However, further studies are needed to fully examine the economics, effects of bubble size/airflow rates, and design of economics, effects of bubble size/airflow rates, and design of pressurized flotation cells and systems.pressurized flotation cells and systems.

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• Background– Butte (Montana Tech)– Basin (Froth Flotation)

• Introduction– History– Variables

• Objectives• Procedures• Results• Conclusions• Acknowledgements

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Acknowledgements

National Science Foundation for funding the National Science Foundation for funding the Undergraduate Research Program at Montana Tech.Undergraduate Research Program at Montana Tech.

Undergraduate students who worked on this project: Undergraduate students who worked on this project: Tyler Anderson, Adam House, Hubert Tyler Anderson, Adam House, Hubert SchimannSchimann, Darby , Darby Stacey, Amy Stepan, Randy Hamilton and Dave Douglas.Stacey, Amy Stepan, Randy Hamilton and Dave Douglas.

US Silver Corporation for sending the ore samples, US Silver Corporation for sending the ore samples, conducting most of the analyses, and allowing the conducting most of the analyses, and allowing the students to conduct flotation tests at the surface and students to conduct flotation tests at the surface and depth of their Galena Mine in Idaho.depth of their Galena Mine in Idaho.

Mr. Bill Huestis, Lab Director, whose patience and Mr. Bill Huestis, Lab Director, whose patience and experience helped this project succeed.experience helped this project succeed.

The Technical Papers Committee and Organizers for The Technical Papers Committee and Organizers for the 28the 28thth Mining Convention of Peru and Mining Convention of Peru and ExteminExtemin 2007.2007.

Gustavo & Ana Maria Plenge and Tatiana Castro.Gustavo & Ana Maria Plenge and Tatiana Castro.Miriam Young, my beloved wife, who made the trip!Miriam Young, my beloved wife, who made the trip!

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