Abstract
People has regarded manganese nodules as an increasingly important source of valuable metals, including nickel, cobalt, copper, and manganese. From both technical and economical points of view, it is necessary for exploitation of manganese nodules to develop a suitable metallurgical process. It is difficult to recover nickel, copper, and cobalt contained in manganese nodules by any usual process, for such metals are present as oxides and oxyhydoroxides of the manganese and iron phases. Moreover, a French institute (IFREMER-GEMONOD) estimated that the cost of processing would account for more than half of the total cost of exploitation.
Since 1989 Metal Mining Agency of Japan (MMAJ) has performed studies on the recovery of iron, manganese, copper, cobalt, and nickel from manganese nodules under the umbrella of the Ministry of International Trade and Industry's Development of Deep Ocean Minerals Program. After investigating existing processes and comparing their respective performance with the same manganese nodules, the MMAJ developed a smelting and chlorine leaching process. The process is the combination of pyrometallurgical and hydrometallurgical treatments, which enables the efficient recovery of manganese, nickel, copper and cobalt.
