Proposal of Ball Milling System Suitable under the Seafloor for Development of Hydrothermal Deposits by Simulation

Seafloor hydrothermal deposits, which were formed by deposition of precipitates from hydrothermal fluids vented from seafloor, are one of unconventional mineral resources beneath deep seafloors in the Exclusive Economic Zone of Japan. The authors have proposed a concept for Mineral Processing of Seafloor, where useful minerals are separated on deep seafloor and then lifted while remaining gangue is disposed on seafloor in appropriate ways. In this paper the authors studied the new ball milling system which was adapted under seafloor mineral processing. A simulator for ball mill grinding using simple discrete element method was built for this analysis. In this simulation two conditions in ball milling were examined: the method of grinding by enclosing the inside of a ball mill with air and with sea water. Especially we discussed the implementability of the ball mill grinding fulfilled with water because of the ease of installation in the real operation. Consequently, it was suggested that the grinding phenomenon can be performed effectively by the increase in the existence ratio of iron ball in the first quadrant in the mill. In the case where the mill is filled up with the water, it can be expected that crushing efficiency increases by carrying out ball milling at high rotational rate and with the mixture of the small ball size.