For the commercial development of Cobalt-rich ferromanganese crusts, the new mining technology is necessary because of their unique morphology and topography of the mining site. Therefore, a new cutter head, which can automatically adjust the height of the cutter depending on the relative change of the topography, was developed. Then, the excavation and dredging test on the deep seafloor by using new cutter head was conducted in July 2020. The test results showed that 649 kg of the CRC ores was successfully collected as the first time in the world.


Numerous amounts of Cobalt-rich ferromanganese Crusts (CRCs) were discovered on the deep seafloor. They contain metals like Cobalt, Nickel and platinum, which are necessary for producing batteries, in high concentration. Thus, CRCs are expected as a new supply source of these metals.

The Japanese government established the Basic Act on Ocean Policy in 2007. Following the Act, the Cabinet approved the First Basic Plan on Ocean Policy in 2008 and revise it in every 5 years to promote measures related to the ocean. Then, the latest plan clearly mentioned that the government should promote commercialization of development of deep sea mineral resources including CRCs (Cabinet Office, 2018). For this purpose, The Ministry of Economy, Technology and Industry (METI) and Japan Oil, Gas and Metals National Corporation (JOGMEC) decided to conduct the excavation and dredging tests on the deep seafloor in 2020 to get fundamental information for designing mining system for commercial use. (METI, 2018) Finally, they successfully conducted the test on the deep seafloor. (JOGMEC, 2020)

In this paper, the project to develop new mining testing machine for CRCs and the result of the excavation and dredging test on the deep seafloor in the Takuyo No.5 seamount would be introduced.


Table 1 shows the general distribution characteristics of CRCs and comparison with other deep sea mineral resources (Manganese nodule (MN) and Seafloor Massive Sulfides (SMS)). CRCs distribute on the seamount slope and top of guyots with a very large area (>100 km2). They cover the substrate i.e. Basalt and Limestone up to several cm thick. Then, it is difficult to define the clear boundary between CRCs and substrates (Yamazaki, 1995).

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