Modern methods for processing of secondary platinum-bearing raw materials
25 December 2012

Scrap and products containing platinum and non-ferrous and precious metals, as well as platinum concentrates are largely used in processing of second raw materials.

Recycling of old catalytic converters using aluminum oxide is carried out by two methods. The first method produces a Al2O3 base and a precious metal concentrate, while the second method produces the metals without affecting the base.

The first method is known as sulphatization. In this process, the material is bathed in concentrated sulfuric acid and heated at a temperature of 300 C. This takes place in hearth furnaces or in rotating tube furnaces. After this, the sintered material is leached out with water. The volume of the insoluble residue can be 12% to 13% of the total weight of the material. If the sintered material is bathed in a 10% H2SO4 solution, the amount of platinum in the concentrate may be 8.5%.

In order to produce a concentrate containing up to 22% platinum, a combination of processing technologies is used. First, the aluminum oxide is subjected to sulfuric acid leaching, in an H2SO4 solution, then roasting at a temperature of 550-600° C, then leached again in a special solution.

In the sulphatization method, the platinum is transformed into a solution. "Dry" sulphatization causes ionization of soluble metal compounds. Of all recent technological advances, only the latter leads to reduced dissolution of the platinum.

Platinum can also be extracted from old catalytic converters as a copper-based alloy. The smelting is carried out at temperatures of 1500 - 1550 °C, after which the copper alloy containing platinum-group metals is sent for refining.