Separation Leaching Behaviors of Cobalt(Co) and Tungsten(W) from Tungsten Carbide Sludge by Sulfuric Acid Solutions

Abstract

Cemented carbide is an important material in strategic materials, and nd the development of recycling technologies for valuable metals such as cobalt(Co) and tungsten(W) is urgently needed to ensure sufficient domestic raw material supply, supply chain stability, and high-tech industrialization. In this study, an experiment was conducted to leach Co and W from roasted WC-Co cemented carbide sludge by sulfuric-acid leaching. From this experiments, the optimal conditions for Co leaching included a sludge/leachate solid–liquid ratio of 1:20, Co/sulfuric acid molar ratio of 1/5.8, leaching temperature of 80°C, and leaching time of 7 h. Under these conditions, the leaching rate was calculated to be approximately 72.6%. In addition, up to 83% Co can be recovered when two-stage leaching is applied. By contrast, the leaching rate of W was less than 5%. The results of this experiment demonstrate the possibility of separating and recovering Co from W in cemented carbide sludge by sulfuric-acid leaching.