Deep-sea Manganese Nodules as a Novel Resource of Metals

Abstract

Deep-sea minerals such as manganese nodules and crusts, which contain valuable metals such as Co, Ni, Cu and Zn besides Mn and Fe, have been expected to be an alternative metal source from 1960’s. In recent years, a stable supply of rare metals indispensable for cutting-edge industries has been concerned all over the world because of the depletion of land based mineral resources or an oligopoly of the market for some metals. Then, the value of marine resources including manganese nodules increases since valuable metals such as rare earth metals were recently identified in marine minerals. However, there are some issues to be considered for their commercial use, that is, the economic evaluation for the metals of which prices wildly fluctuate and the establishment of the mining technology. Several studies on metal leaching from mining nodules were reported, however there are almost no examples on the metal separation from the leaching solutions. In this article, we provide a brief introduction to manganese nodules as a resource of rare metals and review the hydrometallurgical methods for the recovery of the metals from manganese nodules.