A novel process for cobalt and copper recovery from cobalt white alloy with high silicon

Abstract

The cobalt white alloy, an intermediate product of cobalt smelting, is difficult to leach at atmosphere due to its corrosion-resistant structure. The current study proposed a novel process to extract Co and Cu from the cobalt white alloy with high silicon content. The process mainly involves three steps: desilication of the alloy melt through oxidation smelting using MnO-MgO-SiO2 slag, powder making of the desilication alloy melt by water atomization and atmospheric sulfuric acid leaching of the alloy powders. The results showed that 83.64% of Si in the white alloy was removed effectively by oxidizing it preferentially into the MnO-MgO-SiO2 slag. 97.99% of cobalt and 97.78% of copper were leached under optimal conditions according to: temperature of 95 °C, liquid/solid ratio of 10/1, excess of sulfuric acid of 1.3 times the stoichiometric demand, stirring rate of 1500 rpm, leaching time of 8.0 hours, and oxygen gas flow rate of 0.15 L/min. The overall recovery in this process attained 93.41% for cobalt and 94.33% for copper, separately.