It is estimated that seafloor polymetallic sulfide deposits are abundant in the waters around Japan. As Japan is a country with few natural resources, these deposits are considered to be promising mineral resources. To exploit these deposits, Japan Oil, Gas and Metals National Corporation (JOGMEC) conducted a pilot test for excavating and ore lifting in the waters off Okinawa and successfully performed continuous slurry ore lifting from seafloor polymetallic sulfide deposits for the first time anywhere in the world. Having been commissioned by JOGMEC, a consortium which we represent (the members are: Mitsubishi Heavy Industry, Ltd.; Mitsubishi Shipbuilding Co., Ltd.; Nippon Steel & Sumikin Engineering Co., Ltd.; National Institute of Maritime, Port and Aviation Technology; Shimizu Corporation; Sumitomo Metal Mining Co., Ltd.; Fukada Salvage & Marine Works Co., Ltd.; and Mitsui Miike Machinery Co., Ltd.) built a test system and carried out the pilot test by operating the test system and making measurements. We were responsible for building an ore collecting test machine and a submersible pump unit, both of which are the pivotal components of the test system. This report describes their development and summarizes the pilot test.
