Efficient and Sustainable Electrochemical Demolition of Hard-Metal Scrap with Co-Rich Binder

Cobalt and tungsten hold strategic importance in various industries, and fostering their circular economy could lead to cost reduction and a more sustainable use of natural resources. Eco- friendly electrochemical recovering processes are promising alternatives to the state-of-the-art pyrometallurgical approaches, but their productivity is too low for industrial standards. Low demolition rates are caused by hardmetal pseudopassivation phenomena. In previous work, we demonstrated that a pulsed-potential approach, employing a neutral aqueous solution and alternating pseudopassivating film formation with its mechanical removal by oxygen evolution reaction, thus refreshing an active HM surface, is effective in avoiding the corrosion-self-termination for corrosion-resistant grades. This study extends this approach to the most widespread grades, featuring Co-rich binders. This new application required fine-tuning of the operating conditions to adapt them to the target grades. Electrochemical characterization of the psudopassive film growth in this study is centered on cyclic voltammetry and potentiostatic polarization. Corroded hardmetal and detached pseudopassive films were subjected to morphological and compositional analyses with scanning electron microscopy and x-ray fluorescence mapping. We thus demonstrated that optimized pulsed anodic potentiostatic polarization enables efficient demolition of hard metal coupons, combined with separation of Co and W, at high rate and with low energy consumption.