Precious metals can be selectively removed from a solution containing an excess of base metals by electrolysis in a divided cell. This necessitates controlling the pH of the solution, and controlling the voltage applied to the electrodes, such that precious metals are deposited preferentially on the electrode in contact with the solution. For example the precious metals may be deposited selectively onto an anode, presumably with formation of a hydrous oxide, if the pH is held at say less than pH 1.0 and the cell voltage held less than 1.3 V.
