WC recovery from waste cemented carbides by tailored oxygen-containing molten salt electrorefining
Molten salt electrorefining offers a promising approach for green and efficient recycling of waste cemented carbides. However, the conventional halide-based electrolytes suffer from volatile tungsten halide losses and only recover metallic tungsten, necessitating energy-intensive carburization to recover tungsten carbide (WC). Herein, we propose a novel electrolytic refining and recovery method based on an oxygen-containing CaCl 2 -CaO molten salt electrolyte. The introduction of CaO suppresses the formation of volatile tungsten halides, enabling simultaneous dissolution of carbon (C) and tungsten (W) in the WC-Co anode to non-volatile CaCO 3 and CaWO 4 , respectively. Retention of Co in the anode slime is achieved through controlling anodic potential, realizing component separation. The dissolved CaCO 3 and CaWO 4 are reduced at the cathode, resulting in the generation of WC powder. This work accomplishes the direct recycling of WC from spent cemented carbides without intermediate stages. The composite products of WC and carbon are deposited on the cathodes, of which morphologies are comprised of granular aggregates and flakes. The presence of carbon suppresses the formation of W 2 C and W. However, the residual carbon does not affect hard alloy reprocessing since the W/C ratio can be adjusted via controlled W addition during subsequent alloying. This paper proposes a novel short-process green recycling technology for strategic tungsten resources.
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