1. Gold Mining
By Nick O’Brien

2. Today’s Golden Agenda Gold Gold Mining Environmental Impact Future
Facts
History
Gold Mining
Process
Players
Environmental Impact
Problems
Future
Movements within industry

3. Gold Gold – symbol Au Soft and shiny Usually yellow color
Comes from Latin aurum meaning “shining dawn”
Soft and shiny
Usually yellow color
Can be black or ruby

4. Golden Properties 79 on Periodic Table
MW g/mol
MP 3129 K
Cp 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

5. 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)

6. 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

7. 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

8. Purity of Gold
Done in carats or karats

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

10. Gold Mining Step 1
Exploration
Geologist discover a deposit

11. 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)

12. Gold Mining Step 2
Explorative Drilling

13. 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)

14. 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

15. Pictures of Open Gold Mining Pits

16. Underground Mining Adit is dug into earth
Surface containing the ore is loaded with explosives and blasted
Loaded into trucks
Backfilled with cement compound

17. Pictures of Underground Gold Mining

18. 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

19. Gold Mining step 5 Heap Leaching
Crushed ore is placed leach pads where weak cyanide solution percolates down through the ore

21. 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

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

23. Gold Mining Step 6 Stripping
The gold is removes from the carbon by pumping a hot caustic solution through the carbon.

24. Gold Mining step 7 Electro-winning
Gold-bearing solution is pumped through electro-winning cells or through a zinc precipitation circuit
Gold is recovered

25. Gold Mining Step 8 Smelting
The gold is melted in a furnace and poured into molds, creating dore’ bars at 60% to 90% gold

26. Gold Mining Last Step
The bars are sent to a refinery to be made into pure gold.

27. Largest Gold Producers
75% of the all gold ever produced has been extracted since 1910

28. 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

29. 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

30. 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

31. How much gold? Approximately 1/3 the size of the Washington Monument.
Approximately 1 cube at 20 meters a side.

32. References http://en.wikipedia.org/wiki/Barrick_Gold_Corporation

33. References Additional
SME Mining Engineering Handbook, 2nd edition volume 2
Google Images
Men’s Journal, Sept 2007