Abstract: There is provided a method of recovering at least one target metal which is adhered to a stainless steel surface, while mitigating corrosion to the stainless steel surface. The target metal is nickel or cobalt. The method comprises contacting an operative aqueous treatment solution with an operative solid material adhered to a stainless steel surface. The target metal is nickel or cobalt. The operative solid material includes at least one target metal, and at least a fraction of the at least one target metal of the operative solid material is disposed in metallic form. The operative aqueous treatment solution includes soluble treatment material, wherein the soluble treatment material includes nitric acid and copper-comprising material.

Abstract: A method of treating a metalliferrous material source is provided. The metalliferrous material source includes at least one of nickel sulphide and cobalt sulphide, and also includes iron sulphide. The metalliferrous material source is leached with a preliminary leachant in a leaching zone to effect production of a preliminary leach product including a preliminary leach solution and a preliminary leach solid residue. The preliminary leachant includes an aqueous solution comprising ammonia and ammonium sulphate. The preliminary leach solution includes at least one of dissolved nickel comprising material and dissolved cobalt comprising material. The preliminary leach solid residue includes: (i) at least one of nickel sulphide and cobalt sulphide, (ii) at least one of other nickel comprising material and other cobalt comprising material, and (iii) other iron comprising material.

Abstract: There is also provided a method of treating a metalliferrous material. The method includes providing a metalliferrous material including nickel, cobalt, and iron. At least a fraction of the metalliferrous material is leached with an aqueous solution including dissolved sulphuric acid and dissolved sulphur dioxide in a reaction zone so as to effect production of a leachant including nickel sulphate, cobalt sulphate, and iron sulphate. The leachant is contacted with a reagent material in a reaction zone, wherein the reagent material is aqueous ammonia solution, so as to effect production of a reaction product including a product solution component and a solid residue component. The nickel and cobalt are concentrated in the product solution component, and the iron is concentration in the solid residue component.