R Michael agreed to come back and explain how Gold in made.
Michael showed us again the gold mine in Alaska, built in a Nature Reserve. All underground.
He explained that mining today is much cleaner and environmental friendlier than at times past. Also a lot safer, at least in developing countries.
Compressed air is used for a lot of the equipment.
Rock bolts used to secure the back, keep rock from falling and caving in. In high traffic areas they also use wire mesh and shotcrete.
At deep depths, rock behaves differently than at surface. Under a lot of pressure and rocks can burst, shoot out of wall.
Michael gave a brief explanation between gold and fools gold. Often found in same area.
Gold very heavy with density of 19.32. Platinum also heavy. Most other minerals much lighter.
He explained 'intrusions' in the ground. An example was in Cobalt with silver.
They have to mine the rock and then crush it to start process to separate gold from the other rock. They use hardened steel to crush rock. This is done in stages, to get the rock to smaller pieces. Then they add lime to raise pH and then cyanide added. They have to keep pH high like about 12. In acid conditions cyanide in unstable and goes to gas and very dangerous. They add oxygen. All this to dissolve the gold and create a mud slurry. Carbon from roasted coconut shells is added as the carbon bonds with gold and process used to remove the gold from the slurry.
Then they strip gold from the carbon using steel wool and a lot of heat. A good operator keeps skimming off froth off top of molten rock, that is the impurities. Good operator can tell by the colour the quality of gold.
When right, the bars of gold are created. These bars are sampled and tested for purity. The refined gold about 99.9% gold.
Pure gold too soft to make products with.
14 karat gold about 58% gold
12 karat about 50% gold
24 karat almost pure.
Silver, copper and platinum used to mix with gold.