Characterisation of wastes from processing of sea nodules

The processing of polymetallic sea nodule by reduction-roasting ammoniacal leach process generates two types of wastes viz., spent liquor and nodule tailings. Spent liquor characterised so far with respect to its physical and chemical characteristics reveals that its discharge would have no deleterious effect on the surrounding environment. Further studies are being recycled in the process. Results obtained for leachate characterisation of nodule tailings so far is also very encouraging and this indicates that tailings generated from laboratory/pilot scale plant may be environmentally acceptable. This is judged from the fact that toxicity test conducted for leachates by Extraction Procedure (EP) shows that the nodule tailings produced in the laboratory are nonhazardous. None of the tailings exceed maximum allowable limit for eight regulated metals viz., Ag,As, Ba, Cd, Cr, Se, Hg and Pb.