Reclamation of tungsten from carbide scraps and spent materials

This paper reviews the state-of-the-art recycling of tungsten from carbide (WC) scraps and other spent alloys generated by various production and application industries. With an aim of direct reuse or chemical recovery of tungsten, the reclamation of WC is commonly divided into three parts: (1) pyrometallurgy, (2) hydrometallurgy, and (3) a combined (pyro + hydro) metallurgical process. The pyrometallurgical process consists of a thermal treatment under an oxidizing, reducing, or carburizing condition and of breaking the structure of hardmetals by dissolving the binder metal in a molten bath to obtain WC from spent/scrap materials. The hydrometallurgical process, based on leaching in acid and/or alkali solutions, follows precipitation/solvent extraction/ion exchange/crystallization operations to concentrate and recover the salt/s of tungsten and associated metals. The combination of both processes is employed mainly to convert the carbide phase of WC (along with the binder and/or additive metals) to their oxide forms prior to leaching in the acid/alkali solution to enhance the extraction efficacy in the aqueous solution. A critical analysis with respect to the processing conditions for extracting tungsten with the binder metal cobalt from various scrap/spent materials is given. The present paper will be helpful in developing an overall understanding of tungsten reclamation from the WC and other alloys that can provide future research directions to obtain the sustainability of this strategically conflict element.