Recovery of copper, nickel and cobalt from manganese nodules by Arc furnace smelting

Abstract

Polymetallic sea nodule contains multiple metals like copper (1.1 %), nickel (1.2%), cobalt (0.08%), manganese (24%), iron (5.4%), silica, aluminum, etc. Of these, cobalt, copper and nickel are of much importance and in great demand world over. India has made remarkable progress in recovering these valuable metals from sea nodules following the hydrometallurgical routes. The present paper describes the attempt for recovering these metals from sea nodules by pyrometallurgical route. A number of experiments were carried out in 50 KVA electric arc furnace for reduction smelting of sea nodule. The smelting produced an alloy rich in Cu, Ni & Co. A typical composition of alloy is: Cu: 12.33%, Ni: 14.05 %, Co: 0.75 %, Mn: 8.23%, Fe: 55.96% and a slag consisting of MnO: 42.61%, Si02: 33.51%, FeO: 5.66%, (CaO+MgO): 5.42%, A1203: 6.1 %. The recovery of metals in alloy were Cu: 90-95%, Ni: 95-97% and Co:80-85% with 6 % coke addition at temperature of 1400-1550°C. The alloy obtained may be suitably treated further to recover these metal in pure form by pyro or/and hydrometallurgical routes. The slag contained high Mn/Fe ratio, which was suitable for ferromanganese or ferrosilicomanganese production by smelting in an electric arc furnace.