Recovery of tungsten carbide from hard material sludge by oxidation and carbothermal reduction process

Optimum condition for the oxidation and reduction of WC–Co sludge was investigated for a low-cost and environmentally friendly recycling process. Upon oxidation, WC and Co in the sludge were converted to WO2, WO3, and CoWO4. Subsequently, carbon powder was mixed with oxidized sludge. The carbothermal reduction of the mixture of oxidized sludge and carbon powder was carried out in Ar atmosphere. The reduced products were further analyzed using XRD. Based on the XRD analysis and thermodynamic point of view, the possible reactions involved in the carbothermal reduction were proposed. The influence of the carbon mixing ratio and temperature was analyzed.