The potential of rare-earth elements in oxidic deep-sea mineral deposits (Ferromanganese nodules and crusts)

摘要

Deep-sea oxidic deposits like polymetallic manganese nodules and Co-rich ferromanganese crusts take up their metal content predominantly from seawater and contain distinctly higher concentrations in REEs than seawater. The REE amount of polymetallic nodules in the world oceans is 22.5 x 106 t, whereby a maximum of 15.0 × 106 t is considered to be mineable. This amount corresponds to 15.7 % of the tonnages of ΣREEs in land-based reserves (95.7 ×106 t). The ΣREE potential of Co-rich ferromanganese crusts in the world oceans adds up to at least 69.48 × 106 t, which corresponds to 72.6 % of the ΣREE reserves of land-based deposits. Since the marine oxidic deposits are economically interesting, in particular, because of their main metals, the REEs might be considered as significant byproducts. A great advantage of the marine oxidic deposits is the virtual absence of radioactive waste elements (Th and U).