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.