The R&D of "Manganese Nodule Mining System," a Japanese national project, started in 1981. The Technology Research Association of Ocean Mineral Resources Mining System was in charge of this project. Since fiscal year 1997 was the [mal year of this project, four ocean and on-land experiments to investigate the results of R&D so far and to collect various data that are useful for the future mining system were conducted. The following four experiments were conducted independently of each other:
Nodule collection at ocean;
Behaviors and handling of lift pipes at sea;
Behaviors of flexible hose in collector landing and recovery operation on land; and
Operation control of air-lift compressors on land.
This paper outlines the nodule mining system developed and reports the result of the above experiments.
The self-support ratio of rare metals in Japan is very low and the dependence on imports is 100% for cobalt and 95% for manganese. Hence, the development of manganese nodule mining technology is very important for Japan in order to secure long-term and stable supply of rare metals. On the other hand, the deep-sea where manganese nodules are abundant is an extremely hard environment with hydrostatic pressures of 500 times of the atmospheric pressure and a temperature of 2 to 3 °C. Thus, there are many problems to be solved technically in this development that needs large funding and a long lead time. Since early 1970"s a deep-sea mineral development was adopted as one of the government's principal mining policies in Japan. Then, the research institutes of the Ministry of International Trade and Industry (MITI) such as the Geological Survey of Japan (GSJ) and the National Institute for Resources and Environment (NIRE), played an important role in the geological study and the fundamental engineering research of the deep-sea mineral resources development (Kuriyagawa, 1995).
