How are they mined?
PGM mining is a capital and labour intensive process, taking up to three months, and requiring 7 to 12 tonnes of ore to produce one troy ounce (31.135 grammes) of platinum. PGM ore is mined underground and less usually in open pits. It is blasted out of the ground before being crushed and milled into smaller rock particles which are mixed with water and reagents and pumped through with air to form a “froth flotation”. PGM-rich particles adhere to the bubbles created by the process and float to the surface where they are removed, and the remaining material is put through the process a second time. When dried, the flotation concentrate is smelted at temperatures that may be over 1500 °C (2732 °F) and a mixture of the metals is separated from unwanted minerals such as iron and sulphur by air being blown through. A long and complex series of chemical processes is then required to separate the individual PGMs from each other to produce pure metals.
