METHOD OF SEPARATING METAL VALUES

1,231,572. Entracting metals. BRANDHURST CO. Ltd. April 11, 1968 [April 11, 1967], No.16591/67. Heading C7D. A metal of the group consisting of cadmium and metals more noble than cadmium is separated from a metal less noble than cadmium by forming an aqueous solution containing the metal values, adding to the solution an alkali chosen from alkali metal carbonates and hydroxides and alkaline earth metal carbonates, oxides and hydoxides to form a mixed metal hydroxide precipitate in aqueous suspension, hydrogenating the aqueous suspension at an elevated temperature and pressure sufficient to achieve the selective reduction of the first mentioned metal and separting the reduced metal from the hydroxide of the second mentioned metal. The pressure may range from 20 psi when platinum is to be reduced up to 2000- 3000 psi when cadmium is to be recovered as metal. The temperature will also vary according to the metals concerned, being desirably in the range 150-350‹ C. the separation of nickel from chromuim copper from zinc and nickel from zinc is referred to.