Coprecipitation of platinum metals with iron hydroxide

A degree of co-precipitation of platinum metals, including ruthenium, with iron hydroxide in sulphate and sulphate-chloride solutions has been studied as a function of pH, temperature, iron to metal ratio, and contact time of hydroxide with the solution. Concentration of metals in initial (for co-precipitation) solutions has been 0.2-1 mg/ml; the Fe:Ru ratio = 100:1. It has been shown that co-precipitation of ruthenium with iron hydroxide ensures 100% extraction in a more acid medium (pH=4) than hydrolysis (pH=5). The co-precipitation process is caused by isomorphism complicated with the formation of hydroxoaquosulphate (chloride) complexes. Oxidation with subsequent hydrolytic precipitation in the presence of iron (3) can be used for separating platinum from other metals of this group