Abstract:Separation of hard phase WC and binder phase Co from WC-Co cemented carbide scraps by vacuum metallurgy under the condition of 1 550~2 000 ℃ and <1.73 Pa was theoretically analyzed based on thermodynamic calculation. WC-Co cemented carbide scraps with cobalt content of 3%~15% was applied as raw material to analyze relationship between cobalt content and cobalt volatilization rate, cobalt purity rate, and WC powder quality. The results show that cobalt volatilization rate rises first and drops later with increase of cobalt content in raw material, and the maximum cobalt volatilization rate is 86.63% upon cobalt content raw material is 8%. There is no regular relationship between cobalt content and cobalt purity rate, when cobalt content in raw material is 12%, cobalt purity rate is up to 99.95% of the maximum value. As shown by XRD spectrum of WC powder, Co diffraction peak appears upon cobalt content in raw material of 3% and 15%, and cobalt does not volatile completely; while Co diffraction peak does not appear upon cobalt content in raw material of 5%, 8% and 12%. W2C phase does not appear in all experiments, no significant decarburization is presented. SEM microstructure of WC powder shows that powders are nearly spherical with smooth surface and 1~8 μm particle size. Qualified WC powder and metal cobalt are produced from experiment.