Extraction of copper and nickel from ammoniacal leach liquor of Indian Ocean sea nodules

The ammoniacal leach liquor from the dissolution of polymetallic Indian Ocean sea nodules was treated using 25% LIX64N in kerosene as the extractant. The co-extraction of Cu and Ni and their selective stripping produced metal-rich solutions. The nickel solution required purification to remove copper using 10% LIX64N which was finally won by electrolysis in a non-diaphragm cell. The effect of impurities such as Mn and Fe building up due to extraction and nickel winning was observed and controlled by bleeding-off the electrolyte to avoid cracking the deposit. This was studied in a continuous test run of 100 h involving solvent extraction and electrowinning. Copper electrowinning was carried out in a similar way and good metal sheets were produced. Another trial of 55 h was carried out to obtain improved nickel stripping from the loaded organic phase and increased copper enrichment in stripping followed by electrowinning.