Investigation of Hydrometallurgical Recycling Parameters of WC–Co Cutting Tool Scraps

The aim of the study is recovery of WC–Co cutting tool scraps through hydrometallurgical methods. Scraps contain 83.67 wt.% W, 5.56 wt.% C, and 8.76 wt.% Co. The study consists of two progressive stages. The first stage is based on selective leaching of cobalt and separation from tungsten carbide. The second stage is the precipitation of cobalt from leach solution. Before experiments, scraps were grinded and sieved to lower than 250 μm particle size. In the first stage, WC–Co powders were leached in HNO₃ solution. In order to achieve maximum dissolution of cobalt, acid concentration, temperature, stirring rate, and raw material particle size parameters were investigated. In the second stage of the study, dissolved cobalt ions from leach solutions were precipitated as Co(OH)₂ compound by using NaOH solution. Solution pH and temperature parameters were examined to reach maximum cobalt recovery from the solution. According to results, the optimum leaching conditions were found to be 2M HNO₃, 25 °C, 800 rpm, 2 h, and 1/10 solid/liquid ratio. Cobalt dissolution efficiency was detected as 94.87% under these conditions. Besides, dissolved cobalt in the leach solution was precipitated with an efficiency of more than 99.99% in the form of cobalt hydroxide by the addition of NaOH reagent at pH = 11 and 50 °C.