Abstract: Aqueous lead solutions obtained by hot chloride leaching of residues containing lead and silver ore are subjected to selective precipitation of the silver as silver sulphide, with e.g. hydrogen sulphide. The silver can then be recovered in a known manner. Lead can be precipitated from the remaining solution as a basic salt also in a known manner. If the initial residue contains copper, it is also precipitated as sulphide. The copper sulphide can be separated from the precipitate by selectively dissolving the copper with sulphuric acid under an elevated oxygen pressure. Elemental sulphur is formed and the silver sulphide can be separated from the elemental sulphur in a known manner.

Abstract: A method is provided for processing raw manganese nodules for the selective recovery of metal values of nickel, copper, cobalt and zinc contained therein by hydrometallurgical means. The raw nodules are suspended in water or dilute wash solution to form a suspension. The suspension and sulfuric acid are charged to a pressure vessel to provide a solid-liquid suspension of nodules and leach solution. The solid-liquid suspension of nodules and leach solution is heated in the pressure vessel to a temperature between about 150.degree. C and about 300.degree. C to cause the nickel, copper, cobalt and zinc to be selectively leached from the nodules into the leach solution to form a metal rich leach solution containing these metals and a residue, with the solid-liquid suspension having a sulfuric acid content of less than 35 g/l upon completion of the leaching. The metal rich leach solution containing nickel, copper, cobalt and zinc is separated from the residue.