6. Environmental considerations

Recycling catalytic converters is indirectly an operation with ecological implications. To obtain 1 kg of platinum, some 500 t of ore must be mined, often underground. The platinum-bearing minerals are sulfides that are floated after the ore has been crushed. The result is fine tailings, the spreading of which poses environmental constraints (tailings dam, acid water). Flotation concentrates are then processed by pyrometallurgy and hydrometallurgy, which in turn generate waste (slag, acid solutions, etc.). The total quantity of waste generated by the production of 1 kg of platinoids is in the order of 300 t to 600 t. The total energy consumption calculated on the basis of the Bushweld example in South Africa is of the order of 10 ¹³ kJ/kg of PGMs. If we consider the recovery of PGMs from catalytic converters, the environmental constraints are...