Regular Article

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

¹ School of Metallurgy and Environment, Central South University, Changsha 410083, PR China
² Changsha Research Institute of Mining & Metallurgy CO., Ltd., Changsha 410012, PR China

^* e-mails: swinxiao@126.com; zhliu@csu.edu.cn

Received: 28 May 2020
Accepted: 11 June 2020

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.