The Vein Things of the World ©2010 Dr B. C. Paul Materials in these slides have been organized by...

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Transcript of The Vein Things of the World ©2010 Dr B. C. Paul Materials in these slides have been organized by...

The Vein Things of the World

©2010 Dr B. C. Paul

Materials in these slides have been organized by the author but many of the facts and images are taken from other sources.

Vein Minerals

• Fractures and voids in rock masses are available to be filled in by something else

• Often water solutions will precipitate minerals to fill those voids

• Solutions commonly come from 3 places– Water percolating down from the surface– Water forced out of volcanic magma– Water forced out of rocks that are under great

heat and pressure

Where Solutions Get Their Minerals

• They can leach them out of the rocks around them

• They can pick them up from the molten rock mass they come from

• They can pick them up from rock that is being metamorphosed

The Hydrothermal Driver

• Solutions normally pick up minerals when they are hot and then deposit them in vein fillings as they cool down

• Example – The Carlin Trend Gold Deposits of Nevada (about 8% of world gold production)– Water percolated down from the surface– Mantle convection was trying to rip North America

apart under Nevada so the crust was thinning and the Mantle heat was near the surface

– The water heated up – dissolved gold out of granetic rock masses and then deposited dispersed veinlets of gold.

More Drivers

• The Rand in South Africa (about 40% of Worlds Gold Reserves)– About 3 billion years ago before continents were well

developed mantle intrusives rich in gold spewed out in lava flows

– These mantle lava flows became elevated around a basin (the Rand)

• Erosion weathered away other rock and left placer deposits of gold in the basin.

– The gold placers became trapped in new rock deposits that were metamorphosed

Gold

• Gold tends not to react well with other elements– Thus it is very common as native gold

• Native gold metal is usually always loaded up with something else– Silver will almost always be present, but other

things can be there too.

• Gold does form minerals with Tellurium so you do get Gold Telluride minerals

Native Gold

Load in QuartzPlacer Nuggets

Electrum (Gold/Silver)

AuHardness 2.5-3Density 15 to 19.31 depending on purity

Calaverite

AuTe2 43.5% Gold

Color Yellow to Yellowish WhiteHardness 2.5S.G. 9.04Non Fluorescent Non Magentic

Sylvanite

(Au,Ag)2Te4 34.4% Gold

Color Yellowish silver white to whiteHardness 1.5-2S.G. 7.9-8.3Non Fluorescent Magnetic after heating

Petzite

Ag3AuTe2 25.4% Gold 41.7% Silver

Color Iron Black to Steel GrayHardness 2.5S.G. 8.92Non Fluorescent Non Magnetic

Native Silver

Ag

Color Silver White, Gray White, GrayHardness 2.5-3S.G. 10-11Non Fluorescent Non Magnetic

Chlorargyrite

AgCl 75.3% Silver

Color Purplish Gray, Green, White, ColorlessHardness 1-1.5S.G. 5.55Non Fluorescent Non Magnetic

Acanthite

Ag2S 87.1% Silver

(Low Temperature crystal structureArgentite is high temp structure)Color Lead Gray, Gray, Iron BlackHardness 2-2.5S.G. 7.3Non Fluorescent Non Magnetic

Proustite

Ag3AsS3 65.4% Silver

Color Blood Red, Redish grayHardness 2-2.5S.G. 5.55Non FluorescentNon Magnetic

Gold UsesGold Uses

72

7

21

Jew elry/ Art

Electronics

Dental/ Other

Processing Gold

• How coarse is the gold? (and is it in a native state)– Grind the ore– Use shaking tables or gravity concentrators to get

coarse “free milling gold”• If gold is fine an old method is mercury

amalgamation– Gold and mercury form a heavy complex that settles

to the bottom of the reaction vessel– Heating will drive off the mercury and leave the gold– Mercury water pollution makes method unacceptable

in many areas for large scale work.

Method of Choice is Cyanide Leach

Solution

Ground Ore

Heap Leach

Boosting Solution Concentration(If Needed)

Carbon will adsorb gold from cyanide solutions

Can back flush the columns with strong alkali to release the gold back to highGrade solutions

Merrill Crowe Process

Solutions are clarified (crud settled or filtered out). Zinc is added under vacuumAnd the gold precipitates out.

Overcoming Challenges

• Other minerals or Gold in Telluride– Boost cyanide strength– Roast the ore to destroy interfering sulfides

• The Preg Robbing Problem– Carbon in the ore will adsorb the gold back if

you leach it• Roast the ore to destroy the carbon – hope you

have plenty of money• Bubble through Chlorine to destroy the carbon

Carbon in Pulp – Carbon in Leach

Load it with your own activated carbon and suck up the gold right out of theLeach with your own better carbon.

Gold Production and ReservesGold Production and Reserves

0

500

1000

1500

2000

2500

Production Reserves/20

Met

ric

To

nn

es

Other

Uzbekistan

South Africa

Russia

Peru

Papau New Guinea

Mexico

Indonesia

Ghana

China

Chile

Canada

Brazil

Australia

United States

What is Gold Worth?

Gold Value

0

5000

10000

15000

20000

25000

19

00

19

09

19

18

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27

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19

45

19

54

19

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19

72

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19

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08

$2

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9 p

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po

un

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Gold Price

About $5000 to $15000 a pound

Silver Uses

Silver Uses

Coins/ Medals

Electrical / Solders/Biocides

Jewlry/ Silver Ware

Photography

Production and Reserves

Silver Production and Reserves

0

5000

10000

15000

20000

25000

Production Reserves/20

Met

ric

ton

nes

Other

Russia

Poland

Peru

Mexico

China

Chile

Canada

Bolivia

Australia

United States

What is Silver Worth?Silver Price

0

100

200

300

400

500

600

700

800

900

19

00

19

09

19

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19

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19

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63

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$2

00

9 p

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Lb

Silver Price

About $100 to $250 per pound

Tellurium Uses

• A metal alloy to increase machinability without changing electrical resistance– Reduces metal fatigue problems

• Biggest use is in chemicals and catalysts– Vulcanizing, rubber, synthetic fibers

• Electronics and imaging devices• Cadmium and Tellurium based solar cells

may be a coming breakthrough technology– Not a fact yet

Tellurium Processing and Reserves

• When copper is electrorefined elements left behind in the “slimes”– Selenium– Tellurium

• They are byproducts

Tellurium Recovery

• Electrowinning of copper leaves solid residues at the bottom of cells (Copper Anode Slimes)

• The Slimes are Sulfuric Acid Leached– Dissolves residual copper and tellurium

• Iron is added to precipitate copper and tellurium

• Precipitate is leached with caustic soda– Dissolves out the Tellurium

Tellurium Recovery Continued

• Acid is then used to neutralize the caustic solution– Tellurium precipitates as Tellurus Acid

• Re-dissolve the Tellurus Acid with Caustic Soda– Put it in a electrowinning cell and electrowin

Tellurium

What is Tellurium Worth?Tellurium Price

0

20

40

60

80

100

120

1917

1926

1935

1944

1953

1962

1971

1980

1989

1998

2007

$200

9 p

er L

b

Tellurium Price

About $40 to $60 per pound

Arsenic Uses

• About 50% is used as a wood preserving agent – use is declining due to public fear

• A hardening agent in metal alloys

• Added to lead shot

• Pure forms used in gallium arsenide for computer chips and electronics

Arsenopyrite

Massive

Crystalline

FeAsS 46% arsenic

Color Tin white, light steel grayHardness 5S.G. 6.07Non FluorescentMagnetic after heating

Orpiment

As2S3 60.9% Arsenic

Color Lemon Yellow, Brownish Yellow, Orangish YellowHardness 1.5-2S.G. 3.52Non Fluorescent Non Magnetic

Realgar

AsS 70% Arsenic

Color Auro Red Dark Red, Orange YellowHardness 1.5-2S.G. 3.56Non Fluorescent Non Magnetic

Sources of Arsenic

• Usually a coproduct or byproduct• Can roast arsenopyrite for direct

production• Copper often comes with arsenic minerals• Arsenic minerals are markers found with

Gold• Actual arsenic production may follow more

where production takes place than original source

What is Arsenic Worth

Arsenic Price

0

0.5

1

1.5

2

2.5

3

3.5

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

$200

9 p

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b

Arsenic Price

Around 50 cents a pound

Mercury Uses

Uses of Mercury

Caustic Soda

Fluorescent Lights /Dental / Other

Cinnabar

HgS 86.2% Mercury

Color Red, Brownish Pink, Brown, can be grayHardness 2-2.5S.G. 8.1Non Fluorescent Non Magnetic

Processing of Mercury

• Cinnabar will sweat mercury and break down on heating

• Is a lot of byproduct recovery from gold operations

Production and Reserves of Mercury

Mercury Production and Reserves

0

200

400

600

800

1,000

1,200

1,400

Production Reserves/50

Met

ric

To

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es Other

Peru

Kyrgyzstan

China

US actually has byproduct production and is considered to have a surplus ofMercury from recycle.

What is Mercury Worth?

Mercury Value

0

10

20

30

40

50

60

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19

10

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19

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19

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$2

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9 p

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Lb

Mercury Value

About $3 to $10 per pound

Antimony UsesAntimony Uses

Flame Retardants

Transportation /Batteries

Chemicals

Ceramics / Glass

Other

Stibnite

Sb2S3 71.7% Antimony

Color Gray, Bluish Gray, BlackHardness 2 S.G. 4.63Non Fluorescent Non Magnetic

Tennantite

(Cu,Fe)12As4S13 20.4% Arsenic, 47.51% Copper

Color Steel Gray, BlackHardness 3.5-4S.G. 4.65Non Fluorescent Non Magnetic

Production and Reserves of Antimony

Antimony Production and Reserves

0.000

50000.000

100000.000

150000.000

200000.000

250000.000

Production Reserves/10

Me

tric

To

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es

Other

Thailand

Tajikistan

South Africa

Russia

China

Bolivia

What is Antimony WorthAntimony Value

0

1

2

3

4

5

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7

8

9

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19

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19

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19

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19

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19

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19

81

19

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19

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20

08

$2

00

9 p

er

Lb

Antimony Value

About $1 to $3 per pound

Fluorspar Uses

Fluorspar Uses

60

15

15

HF for Flourine Chem

Petroleum Ref

Flux/ Glass/ Enamel

Fluorite

CaF2 48.7% FluorineColor White, Yellow, Green, Red, BlueHardness 4S.G. 3.13Fluorescent Non Magnetic

Processing Fluorite

• Fluorspar can be a direct fluxing agent as a mineral in its own right– Recovered by grinding and floatation– Trick is that there are usually things like

Galena, Sphalerite, and Barite with it• Have to float these sulfides out first• Then have to float fluorspar in heated floation cells

• If acid HF is to be produced for chemicals the Fluorite is treated with sulfuric acid in a reactor

World Production and ReservesFluorspar Production and Reserves

0

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3000

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5000

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Production Reserves/40

Th

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es

Other

Spain

South Africa

Russia

Namibia

Morocco

Mongolia

Mexico

Kenya

China

What is Fluorspar Worth?Fluospar Value

0

0.05

0.1

0.15

0.2

0.25

1900

1911

1922

1933

1944

1955

1966

1977

1988

1999

$2

00

9 p

er

Lb

Fluospar Value

Around 10 to 15 centsPer Pound