Pilot test of excavating and ore lifting conducted for seafloor polymetallic sulphides under the sea area near Okinawa Prefecture
The Ministry of Economy, Trade and Industry (METI) and the Japan Oil, Gas and Metals National Corporation (JOGMEC) conducted and succeeded in the world’s first pilot test of excavating and ore lifting for seafloor polymetallic sulphides under the sea area near Okinawa Prefecture. In this test, using excavating/ore-collecting test machines, METI and JOGMEC succeeded in excavating the seafloor polymetallic sulphides lying approximately 1,600m below sea level, continuously collecting and lifting them together with seawater by a submersible pump up onto the ore-lifting support vessel. The success of the test marked a large step toward the establishment of technologies required for the development of ocean mineral resources. METI and JOGMEC will make an economic evaluation in FY2018 based on the results of the test, as well as a variety of results of related research, e.g., estimation of resource amounts and environmental research.
Seafloor polymetallic sulphides distributed across sea areas near Okinawa Prefecture and other sea areas are Japan’s indigenous resources. The successful development of these potential resources in Japan is expected to bring about new domestic supply sources of mineral resources, the majority of which Japan relies on imports from overseas to provide it with.
According to the Basic Plan on Ocean Policy （approved by the Cabinet on April 26, 2013） and the Plan for the Development of Marine Energy and Mineral Resources （formulated by METI on December 24, 2013）, METI has been promoting initiatives, e.g., research for resource amounts of seafloor polymetallic sulphides under sea areas surrounding Japan and basic study and research concerning production technologies.
2. Outline of the Pilot Test
Based on the results of research for properties of geomorphology and marine environments of the target test sites in the sea areas near Okinawa Prefecture, METI and JOGMEC started the preparation for the pilot test from mid-August 2017. Following this, taking the opportunities of good weather conditions during the period until late September 2017, they collected （absorbed） ore, which had already been excavated and crushed in advance by a excavating test machine, and then, continuously lifted the ore above sea level onto the ore-lifting support vessel from the seafloor below approximately 1,600m multiple times using a submersible pump and an ore-lifting riser pipe, thereby successfully having conducted technical verification and data acquisition concerning a series of steps of this system.
This aims to appropriately verify technologies for continuous ore lifting together with seawater from the sea areas and to acquire data thereof. To this end, METI and JOGMEC meticulously organized conditions according to the purposes of the test, including crushing ore to such a fragment size prior to collecting and lifting to prevent clogging of the pump, manual adjustment of the density of target ore to seawater, and conducting the test only during the period when hydrographic conditions were met.
Before starting this test, METI and JOGMEC conducted research for the anticipated impact of the test on the surrounding environments and carefully confirmed that no serious impact might occur. In addition, even during and after the test, they also conducted environmental monitoring to measure and evaluate the impact of the test on the environment.
3. Coming schedule
For compiling a report of the test results, METI and JOGMEC will extract future challenges in commercialization involving excavating and ore lifting technologies, advance discussions concerning related production technologies, including mineral processing and smelting technologies, as well as mineral resources survey, economic evaluation, environmental study, and other studies. Through these efforts, they will comprehensively promote initiatives for commercialization involving seabed polymetallic sulphides.