METHOD OF RECOVERING PLATINUM METALS Russian patent published in 2004 - IPC

FIELD: precious metals technology.

SUBSTANCE: starting material is dissolved in nitric acid and sorption of platinum metals is accomplished on anionite followed by desorption with 3-8M ammonia solution. From ammonia solution, palladium in the form of poorly soluble complex salt [Pd(NH₃)₂NO₂NO₂] is selectively precipitates at pH 5-6. Supernatant solutions are routed to isolation of joined platinoid concentrate or to regeneration of anionite. Precipitated complex palladium salt is recrystallized and treated with sodium hydroxide in amount 0.37-0.5 g/g Pd at solids-to-liquid ratio 1:(15-25). Solution is separated from precipitate composed of metal hydroxide impurities and reduced with formic acid into metallic palladium. Mother liquors, after recrystallization of complex palladium salt, are reused in desorption stage. Regeneration of anionite after desorption of palladium is carried out at 60-70^оС. Invention can be utilized platinum group metal refining.

EFFECT: increased degree of recovery of platinum metals into finished produce and recovery of pure palladium when processing silver-containing materials with impurities.

5 cl, 3 tbl