Galvanic Leaching of Chalcopyrite Using Manganese Oxides in Spent Zinc-Carbon Batteries

Abstract

It is well known that galvanic interaction between sulfide minerals and manganese oxides in manganese nodules accelerates the leaching of sulfide minerals. Zinc-carbon batteries contain a moist paste (hereafter, black paste) of manganese oxides and graphite powder as cathode mix. We have investigated the feasibility of galvanic leaching of chalcopyrite using chemical reagent MnO₂ and black paste. Addition of MnO₂ enhanced the leaching of chalcopyrite in sulfuric acid media with pH 1.0 and Mn concentration also increased remarkably. Extraction yields of Cu and Mn were 52% and 23% respectively at a MnO₂ to chalcopyrite mass ratio of 4 in 24 days. In the presence of black paste the kinetics of chalcopyrite leaching was accelerated dramatically and 83% of Cu in the concentrate was extracted in 40 hours. The graphite powder contained in black paste could play an important role in the galvanic leaching of chalcopyrite in the presence of MnO₂.