PROCESS FOR THE EXTRACTION OF PRECIOUS METALS FOR CONCENTRATES THEREOF

摘要

A process for sequentially and selectively separating gold and platinum group metals from aqueous solutions containing them is disclosed. First, ruthenium and osmium are oxidised to their tetroxides and then removed from the solution. Then, gold is removed by solvent extraction preferably with dibutyl carbitol. Next, palladium and platinum are removed by solvent extraction with an alkyl sulphide and tributyl phosphate respectively, care being taken to reduce iridium in solution before platinum extraction to prevent it extracting with the platinum. Then the iridium is reoxidised and removed from solution. Finally, rhodium is removed from the solution. Using this process gold, platinum and palladium of saleable purity can be extracted directly without the need for further refining steps.