Iridium - Production

Production

Iridium is obtained commercially as a by-product from nickel and copper mining and processing. During electrorefining of copper and nickel, noble metals such as silver, gold and the platinum group metals as well as selenium and tellurium settle to the bottom of the cell as anode mud, which forms the starting point for their extraction. To separate the metals, they must first be brought into solution. Several methods are available depending on the separation process and the composition of the mixture; two representative methods are fusion with sodium peroxide followed by dissolution in aqua regia, and dissolution in a mixture of chlorine with hydrochloric acid.

After it is dissolved, iridium is separated from the other platinum group metals by precipitating (NH₄)₂IrCl₆ or by extracting IrCl2−
6 with organic amines. The first method is similar to the procedure Tennant and Wollaston used for their separation. The second method can be planned as continuous liquid–liquid extraction and is therefore more suitable for industrial scale production. In either case, the product is reduced using hydrogen, yielding the metal as a powder or sponge that can be treated using powder metallurgy techniques.

The price of iridium fluctuates considerably, as shown in the table, because of unstable supply, demand, speculation, and hoarding, amplified by the small size of the market and instability in the producing countries. The sharp decrease around 2003 has been related to the oversupply of Ir crucibles used for industrial growth of large single crystals.