Simultaneous leaching of a deep-sea manganese nodule and chalcopyrite in hydrochloric acid

Abstract

Hydrochloric acid leaching of chalcopyrite and a manganese nodule, in combination, was studied using powder samples. Chalcopyrite, which does not dissolve well in HCl, was effectively leached in the presence of a manganese nodule at 3 to 4 M HCl. The rates of dissolution of metal values from the nodule were also enhanced in the presence of chalcopyrite. Dissolution was found to occur through three routes: (1) the galvanic interaction between CuFeS2 and MnO2, (2) the action of the Fe3+/Fe2+ redox couple, and (3) the action of Cl-2 gas generated from the MnO2-HCl reaction on CuFeS2. The last route appeared to make the major contribution to the dissolution. The combined leaching of a nodule and chalcopyrite appears to be promising from both technical and economic points of view.