Passage: Iridium is also 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 separation methods are available depending on the nature 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 the mixture is dissolved, iridium is separated from the other platinum group metals by precipitating ammonium hexachloroiridate ((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.Iridium prices have fluctuated over a considerable range. With a relatively small volume in the world market (compared to other industrial metals like aluminium or copper), the iridium price reacts strongly to instabilities in production, demand, speculation, hoarding, and politics in the producing countries.

Question: What is the first step to separating the metals?
brought into solution