Oxidative breakup of cemented carbide scrap by CuO-flux roasting

Tungsten carbide‑cobalt (WC-Co) composites are widely used in industry as hardmetals with superior properties and performance; however, these qualities make it difficult to recycle components made of WC-Co at their end-of-life. Herein, we present a one-step CuO-flux roasting process in which a solid-state flux supplies sufficient oxygen for the full oxidation of a hardmetal tool piece when melted. Computational assessments of the Gibbs energy of formation and its tendency to form alloys reveal that CuO is suitable for oxidizing WC cutting tools at high temperatures. After roasting a WC-Co cutting insert covered with CuO powder at 1048 °C, the insert loses its shape and changes into a friable solid oxide mass. As the oxidation reaction is highly exothermic and sustainable, the temperatures of the reactants can exceed the melting points of the oxides produced. Meltable oxide-flux roasting can be applied to the recycling of hardmetals, such as carbides and nitrides.