Abstract
The cobalt rich manganese crusts are distributed on the flat top or the slope of seamounts in the economic zone and the open sea around Minami Torishima Island. Cobalt rich manganese crust and manganese nodule are iron manganese oxide mainly composed of oxide of Mn and Fe. However, their distribution condition and composition are different. Manganese nodule contains some 2.0% of copper and nickel together. On the other hand, the cobalt rich manganese crust includes less copper and nickel than manganese nodule does, but contains a higher level of cobalt and platinum. Metal Mining Agency of Japan (MMAJ), which is current Japan Oil, Gas and Metals National Corporation (JOGMEC), has selected“ Smelting and Chlorine Leaching” as the most suitable technique from the viewpoint of nickel, cobalt and copper's recovery from the manganese nodule. (Kojima, in 1996) For the treatment of cobalt rich crust, JOGMEC has established an improved metal recovery technology, which is called the“ Improved Smelting and Chlorine Leaching”, after the investigation from 2003 through 2008. . In the“ Improved Smelting and Chlorine Leaching”, JOGMEC has introduced“ slag cleaning” process for cobalt and another process for platinum in order to enhance the recovery level. Also JOGMEC found technique to recover metal using bioleaching effectively.
