The recent state of technological development in the countries that have joined deep-ocean mining since the 90's is reviewed in terms of readiness for the development of a commercial mining technology. Previous R&D work performed on deep-ocean mining technology and systems is used as a baseline for review. The review includes discussions on most of the technical issues that have been already identified in the literature for manganese nodule production system design. While recent technological developments do not yet appear to identify new issues, it is likely that more issues remain to be identified and solved. The realization of a costeffective commercial deep-ocean mining system will take much longer than is claimed. The commercialization of deep-ocean resources would require a pool of experts, technical innovation and cost-effective technology, plus cost- and technology-sharing among the countries and/or companies. More clearly defined guidelines or regulations at the early stages can save time and cost for the system and technological development for commercialization. More importantly, a decision needs to be made to build on previous achievements and move forward, thus also saving time and funds.
Our primary minerals of present interest in the deep seafloor are manganese nodules and cobalt-rich manganese crusts, the former from a depth of 800 to 3,000 m, and the latter from a depth of 3,000 to 6,000 m. Essential metals from the nodules and crusts are for use in steel, aircraft, military equipment, machinery and cutting tools.
One of the greatest technological innovations in ship and deep-ocean technology of this century is the deep-ocean mining system with the Hughes Glomar Explorer (Fig. 1): A huge "moon pool" (270 ft or 82.3 m long) can be opened and closed in the bottom of the ship hull in the middle of the ocean.
