Direct Acid Leaching of Zinc from Marmatite Ores 3 Acid Leaching of Marmatite Ores and the Electrode Potential Behavior of Sulfides

Marmatite 鑛의 直接酸浸出에 關한 硏究 (第3報) Marmatite 鑛의 酸浸出과 黃化物의 電極電位에 關한 硏究

In order to explain the positive catalytic action of copper compound for the rate of leaching of zinc sulfide minerals, the electrode and redox potentials of both synthetic and natural sulfides were measured at various conditions of temperatures and pressures. The potentials of Chalcopyrite and copper sulfide were considerably higher than that of zinc sulfide, whereas lead sulfide and Galena had slightly lower potentials than that of zinc sulfide. At elevated temperatures and pressures, the same tendency was obtained. By means of comparing the calculated and measured values of potentials for sulfides, it was suggested that the electrode potentials in acid solution were generated by oxidation of sulfur ion. As a result, it was concluded that the catalytic action of copper compound in the leaching of synthetic zinc sulfide should be arised from the galvanic action between sulfides keeping intimate contact one another in which copper sulfide worked as cathodic and zinc sulfide as anodic part analogous to the metal corrosion under galvanic action.