Coextraction - selective stripping for the recovery of nickel and copper from the leach liquor of ocean nodules

Ferromanganese deep sea nodules of the Indian Ocean have recently been recognised as a potential source of metals like copper, nickel, cobalt and manganese. For the treatment of the sea nodules following the reduction roast-ammonia leach process, the leach liquor containing copper, nickel and cobalt was processed to separate and recover these metals by solvent extraction (SX) using 25% LIX 64N in kerosene. Almost quantitative extraction of copper and nickel was realized in a continuous run. During nickel stripping, the small amount of copper in the nickel solution was removed by incorporating a copper extraction step using 10% LM 64N in kerosene. The purified pregnant nickel electrolyte was electrowon in a non-diaphragm cell. Copper was similarly recovered by electrowinning (EW). A closed circuit of SX-EW was run to produce cathodes of nickel and copper with energy consumptions of 3.85 and 2.01 kWh/kg for the respective metals.