Gold Mining

By Nick O’Brien

Today’s Golden Agenda

Gold– Facts– History

Gold Mining– Process– Players

Environmental Impact– Problems

Future– Movements within

industry

Gold

Gold – symbol Au– Comes from Latin

aurum meaning “shining dawn”

Soft and shiny Usually yellow

color– Can be black or

ruby

Golden Properties

79 on Periodic Table– MW 196.96 g/mol– MP 3129 K– Cp 25.418 J/mol K

Most malleable and ductile metal known– 1g can be beaten into a sheet one

square meter/ 1 ounce into 300 ft2

Good conductor of heat and electricity

Not affected by air or most corrosive agents

Easy to alloy with other metals

Golden History

May have been first metal human’s used

3500 BCE Egyptian Jewelry

Mentioned in Old Testament

World’s earliest coinage around 643 BCE in Lydia

Fueled European exploration of the America’s

Primary goal of Alchemists Gold Rushes Formed the basis for a

monetary standard (IMF)

Golden Uses

Jewelry Computers Jet Aircraft Gold (III) chloride is a

catalyst in Organic Chemistry

Gold Isotope AU-198 – cancer treatment

Gold Flake– $1,000 cocktail

Gold Standard Unit of currency was

equivalent to certain weight of gold (in troy ounce)– 1934 $35.00/oz ($1.13/g)– 1959 $518/oz– 2005 $37,831/oz

Open Market Value 1968– Highest 1980 $850/oz– Lowest 1999 $252.90/oz

Bans in US– From 1933 to 1975 private

possession banned Largest Gold reserve in

U.S.– Federal Reserve Bank in

NY

Purity of Gold

Done in carats or karats

Let’s take a look at Gold Mining in Step Form

Gold Mining Step 1

Exploration – Geologist

discover a deposit

Gold all around

Gold is widely distributed on the earth’s crust at a background level– .03g/1000 kg (0.03 ppm by

weight)– Occasionally as nuggets, but

mostly as small grains Gold in sea water

– .1 to 2 mg/t (0.1 to 2 ppb by weight)

Gold Mining Step 2

Explorative Drilling

Gold mines

Economic gold extraction – can be achieved from

ore grades as little as 0.5g/1000kg (0.5 ppm)

– Usually open pit mines 1-5 g/1000kg (1-5ppm)

– Underground or hard rock mines at least 3 g/1000kg (3 ppm)

– Gold not visible until 30g/1000 kg (30ppm)

Open Pit

Blasthole Drilling– Pattern of holes

filled with explosives

– The explosives are detonated so it can be loaded with large shovels into haul trucks

Pictures of Open Gold Mining Pits

Underground Mining

Adit is dug into earth

Surface containing the ore is loaded with explosives and blasted

Loaded into trucks

Backfilled with cement compound

Pictures of Underground Gold Mining

Gold Mining Step 4

Ore and Waste Haulage– Trucks transport

the ore to various areas for processing

– Higher grade ore goes to mills

– Lower grade ores to leach pads

Gold Mining step 5

Heap Leaching– Crushed ore is

placed leach pads where weak cyanide solution percolates down through the ore

Milling and oxidation

The ore is fed into a series of grinding mills where steel balls grind the ore to a fine slurry or powder

Sometimes the slurry is fed through a roaster to get oxidized

Leaching

The slurry is thickened and run through a series of leaching tanks. The gold adheres to the carbon in the tanks.

Gold Mining Step 6

Stripping– The gold is

removes from the carbon by pumping a hot caustic solution through the carbon.

Gold Mining step 7

Electro-winning – Gold-bearing

solution is pumped through electro-winning cells or through a zinc precipitation circuit

– Gold is recovered

Gold Mining Step 8

Smelting– The gold is

melted in a furnace and poured into molds, creating dore’ bars at 60% to 90% gold

Gold Mining Last Step

The bars are sent to a refinery to be made into pure gold.

Largest Gold Producers

75% of the all gold ever produced has been extracted since 1910

Environmental Issues

Cyanide in water– “Toxic Bob” Friedland– Summitville, CO gold

mine 1996 – Leach pad failed– Leaked cyanide and

had 1000 to 2000 lbs of dissolved heavy metals leaving the site daily

– No life in the river for 17 miles

– $200 million federal cleanup

More Environmental Issues Molycorp Molybdenum

Mine– New Mexico– Over 5 years 100 tailings

slurry spills into red river– 8 miles of the red river

dead– Local high schools had to

relocate because of toxic dust clouds

Baia Mare Gold Mine– Romania– 2000 tailings

impoundment dam failed, 130 cubic yards of waste contaminated with cyanide and heavy metals

– 24 locations of drinking water for 2.5 million people disrupted

– Massive fish kill in Tisza River

Future “No Dirty Gold”

Council for Responsible Jewelry Practices– London next January– Release responsible

mining standards for gold and metal mines

– Mostly volunteer audits Who’s joined in

– Zale Corporation (2006)– Tiffany uses gold from a

mine in Utah that doesn’t use cyanide

– Wal-mart is attempting to come up with a certification process

How much gold?

Approximately 1/3 the size of the Washington Monument.

Approximately 1 cube at 20 meters a side.

References http://en.wikipedia.org/wiki/Barrick_Gold_Corporation http://en.wikipedia.org/wiki/Tailings http://en.wikipedia.org/wiki/Gold_mine http://en.wikipedia.org/wiki/Gold_extraction http://en.wikipedia.org/wiki/Placer_mining http://www.bullion.org.za/MiningEducation/Images/GOLDBARS.jpg http://memory.loc.gov/afc/afccc/p000/p046r.jpg http://serc.carleton.edu/research_education/nativelands/ftbelknap/explorationanddevelopment.html http://www.tocqueville.com/images/upload/GoldSupply.gif http://www.acrat.com/DeLeon-SM.jpg http://www.expedition360.com/australia_lessons_science/mine_shaft_sign.jpg http://www.kengerbino.com/images/MoneySupplyGraph.gif http://www.pbs.org/frontlineworld/stories/peru404/images/environmentalchart2.gif http://www.pbs.org/frontlineworld/stories/peru404/environmental.html http://www.responsiblegold.org/codes.asp http://www.webpennys.com/images/new_mined_gold_output.gif http://www.cyanidepoisoning.org/img/map_users_county.gif http://www.cyanidepoisoning.org/pages/gold_mining.asp http://www.sonoraca.com/visitsonora/images/gold_mining.jpg http://img.dailymail.co.uk/i/pix/2007/03_02/GoldMineLM_468x310.jpg http://www.arizonagoldprospectors.org/ http://www.midwestprospector.com/glacialgoldinfo.html http://www.metalinecontactmines.com/pictures/GoldPour.jpg http://www.sikhspectrum.com/092002/gold.htm

References Additional

http://www.indybay.org/uploads/2007/06/23/marinduque.jpg http://money.howstuffworks.com/question213.htm http://maps.howstuffworks.com/gold-coast-overview-map.ht

m http://www.manifold.net/home/full_scrn_lode.png http://www.akmining.com/mine/bignug4.jpg http://www.akmining.com/mine/minclass.htm http://www.panama-guide.com/article.php/200609191646579

98 http://www.newscientist.com/blog/environment/labels/gold%2

0mine%20fred's%20blog.html http://www.msnbc.msn.com/id/8836974/ http://content.answers.com/main/content/wp/en/thumb/b/b0/

290px-Klondike_mining_camp.jpg SME Mining Engineering Handbook, 2nd edition volume 2 Google Images Men’s Journal, Sept 2007 www.newmont.com/en/about/goldmining