As the result of a seven-year R&D project from 1989 to 1995, Japan selected the smelting chlorine leaching method for manganese nodule processing. In the first stage there were five candidate methods for the processing. Year-by-year, R&D geared toward their improvements and screening took place. However, the long duration and year-by-year screening might cause errors in judgment. A review of the screening and the final result, currently underway, is introduced. An economic re-evaluation of the methods conducted by application of a feasibility study model is discussed.
Among deep-sea mineral resources, manganese nodules on deep ocean floors first received attention as potential sources of a future metal supply (Mero, 1965). Cobalt, nickel, copper, and manganese are the target metals. Several registered Pioneer Investors have already identified promising sites in the deep-sea regions for manganese nodule mining under the Law of the Sea (ISA, 1998), and appropriate mining technologies have been developed during the last thirty years by the international consortium and several nations (Welling, 1981; Kaufman et al., 1985; Bath, 1989; Charles et al., 1990; Yang and Wang, 1997; Yamada and Yamazaki, 1998; Hong and Kim, 1999; Muthunayagam and Das, 1999). Additionally some important results and reviews of nodule metallurgical processing have also been reported (Agarwal et al., 1979; Hubred, 1980; Black, 1982; Haynes, 1987; Kim and Park, 1997; Kojima, 1997; Zhong et al., 1999; Das, 2001). The mining feasibility of manganese nodules, including an economic evaluation, has been examined in detail using the technological results (Andrews et al., 1983; Hillman and Gosling, 1985; Charles et al., 1990; Soreide et al., 2001; Yamazaki et al. 2002). These feasibility studies show that metallurgical processing is the most important subsystem in the nodule mining venture; it represents almost half of the investment and operating costs.
