How do you mine platinum?

Answer 1

The mining of platinum starts with finding an ore body containing platinum group metals (PGM), usually associated with copper and nickel ores. You dig and drill and blast and haul the rock up to the surface. Then the ore that you have mined has to be processed to remove the platinum and other valuable metals from the rock, and that is one of the greatest chemical engineering challenges in industry today. The best mine-run ore only contains roughly 5 grams of PGM per ton of ore. Flotation: The extracted ore is crushed and milled to small particles. The particles are placed in a mixture of water and chemicals, and air is blown through the mixture. The PGM particles adhere to the bubbles and float to the top where they can be captured. Particles that didn't float are re-crushed and re-milled and re-floated to increase the yield. At this point, the float concentrate contains between 100 and 1000 grams of PGM per ton of concentrate. Smelting: The float concentrate is placed in an electric furnace and heated to about 1500oC, where a "converter matte" containing the valuable metals is formed, allowing the unwanted minerals to be discarded. The matte contains about 1500 grams of PGM per ton. Electrolytic refining: Electricity is used to separate base metals (usually copper and nickel) from the PGM, which collects as a sludge under the electrical anode. Chemical refining: The anode sludge of precious metals then has to be separated into the individual metals through a series of intricate chemical processes such as solvent extraction, distillation, and ion-exchange reactions. First gold and silver are obtained, then palladium and platinum, and finally the elusive metals indium, osmium, rhodium and ruthenium. It can take 6 months or more to obtain metals from an ore batch. Electrolytic and chemical refining facilities are typically not located at mine sites, so that PGM converter matte and anode sludge are refined elsewhere and even in different countries from where they are mined. 90% of the world's platinum production presently originates at the Bushveld Igneous Complex in South Africa and the Norilsk-Talnakh mines in Russia. Platinum is also produced in Canada, Montana USA, and elsewhere, mainly as a byproduct of mining for copper, nickel and palladium.