Mining technology for cobalt rich manganese deposits on seamounts has not been sufficiently studied yet, though they have been considered as one of potential cobalt resources for the 21st century. Geotechnical properties of seamount sediments are discussed and compared with deep-sea sediments in the paper. The role of sandy nature of the seamount sediments on the mining technology for the deposits is also discussed.
Deep-sea manganese nodules and cobalt rich manganese deposits on seamounts have been focused as potential mineral resources for the 21st century. The mining technology for deep-sea manganese nodules has been developed during the last twenty years by several nations and the international consortium (Wakabayashi et al., 1986; Herrouin et al., 1989). But the mining technology for cobalt rich manganese deposits has not been sufficiently studied yet, because they have been recognized to be the potential mineral resources only recently. Therefore, the examinations of the similarity and the difference between the deep-sea nodules and the seamount deposits will play a very important role in the development of the seamount deposit mining system. The main basis of the examinations were the water depth, the topography, and the morphology. The morphology of the seamount deposits such as exposed crust type distribution have been considered to be the key factors of the bottom miner especially (Halkyard, 1985). Comparison of the sediments which are the bed of the deep-sea nodules and the coexistence materials of the seamount deposits, however, has been out of examinations to date. On the other hand, according to the exploration results of the distribution characteristics of the seamount deposits, it has been clarified that the existence of nodules on seamount sediments and shallow-buried crusts beneath the sediments are popular and they must be considered in designing the seamount deposit miner.
