A significant amount of critical minerals is found in the marine sediments of the continental shelf. The important minerals are manganese, phosphorites, zeolite, rare earths, evaporite minerals, and precious metals. The depletion of land-based high-grade deposits has warranted the recovery and processing of marine minerals present in the continental shelf and in the deep ocean. The objective of this research program is to develop an efficient beneficiation technique for the recovery of much-needed critical minerals at high tonnage capacity. In keeping with that objective, the Marine Mineral Technology Center funded for 1 year the use of an innovative air-sparged hydrocyclone for the flotation of marine shelf phosphates. The air-sparged hydrocyclone (developed at the University of Utah) is a high-capacity flotation unit which is unique for the processing of phosphorites. The air-sparged hydrocyclone uses the high centrifugal force field and numerous freshly formed fine bubbles to increase the selectivity and rate of flotation. The processing capacity of the air-sparged hydrocyclone is at least an order of magnitude higher than that of a conventional flotation machine on a per cubic basis. Preliminary results with marine shelf phosphates have shown that this unit can conveniently be used for the beneficiation of offshore minerals. Because of high capacity and low specific space requirements, it can be operated on a barge at the site. Although the project was not funded after September 1989, some in-house funding was used to obtain important base line information.