ABSTRACT:

A review of current NIRE" s research in deep-ocean mining technology is presented. Main targets in the research are manganese nodules and cobalt-rich manganese deposits on the seafloor at 800-6,000m deep. Geotechnical properties of deep-sea sediments and hydraulic lifting characteristics Of manganese nodules are clarified in the research. Processing and environmental studies related to the nodule mining are also conducted. For the cobalt-rich manganese deposits, the seafloor distribution characteristics are studied in some locations of the Pacific seamounts, and the physical characteristics and properties of only a fraction of the crust samples are tested.

INTRODUCTION

The deep seabed promises to make an enormous contribution to the world" s resources once its potential is fully realized. Manganese nodules and cobalt-rich manganese deposits in Pacific Ocean are resources of current interest for exploitation (Johnson and Otto, 1986; Manheim, 1986). These are deposited over and beneath the ocean floor at 8006,000m depth. International consortia and government projects have invested in exploration of manganese nodules, and in R&D of mining technology these 30 years (Takahara et aI., 1984; Kaufman et aI., 1985; Shaw, 1993). The amount of effort has varied during this period as a function of the metal market situation. However, efforts have succeeded to extend some selective technologies for subsystems to recover the nodules on" a commercial scale (Shimizu et aI., 1991; Ishikawa et aI., 1992; Shimizu et aI., 1992). Publicly sponsored projects have been active in the 1980s and 1990s in Japan, France, and India (Herrouin et aI., 1989; Yamazaki, 1990; Yates,1990). The industrial consortia were most active in the R&D in the 70" s Japanese research for manganese nodule mining was initiated in the 1970s by the National Institute for Resources and Environment (NIRE), which was reorganized from the National Research Institute for Pollution and Resources, and the Deep Ocean Minerals Association (DOMA).

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