China Nonferrous Metallurgy

In the early stage of production, a company used α-nitroso-β-naphthol process to recover cobalt from the purifying cobalt slag from wet zinc smelting. There were problems such as large consumption of chemical agents, low cobalt content in cobalt enrichment slag, and benefit deficit. The company later adopted ammonium persulfate oxidation precipitation method to enrich cobalt, forming a practical method for recovering cobalt from purification slag with high cobalt enrichment ratio, low cost, short process, easy operation and environmental protection. The method is divided into three stages. The acid leaching stage includes dilute acid selective leaching and countercurrent acid leaching. Under the better process parameters, the leaching rate of cobalt reaches 95.8%; the Fe content of the filtrate is less than 80mg/L under the better process parameters in the oxidation iron removal stage; the cobalt oxide precipitation stage can obtain cobalt-rich slag containing 20% cobalt and 18%-20% zinc. While the cobalt-precipitating slag is washed with acid water, a cobalt-rich slag containing less than 10% zinc and more than 30% cobalt can be obtained, which can be sold as cobalt concentrate. The process equipment is simple, the process is short, and the cost is controllable. It can provide a reference for the comprehensive recovery of valuable metals in purification slag from zinc hydrometallurgy.