Studies on lignite reduction of manganese sea nodules for extraction of nickel, copper and cobalt.

Process feasibility studies have been initiated to determine the possibilities of extraction of nickel, copper and cobalt from manganese sea nodules by lignite reduction followed by ammoniacal leaching route. Lignite has been found to be an effective carbonaceous substance for selective reduction of oxides of sea nodules. The ammoniacal-ammonium carbonate leaching of the reduced product resulted in over 93%, 92% and 65% recovery of nickel, copper and cobalt respectively, while rejecting iron and manganese in the residue. Parameters for roasting and leaching in the extraction of above metals from the sea nodules have been optimised and are reported in this paper.