A new sustainable approach in recovering Cobalt from “hard metal” production by-products

The present work shows the capability of Maleic Acid solutions to tune the amount of Co in cemented carbide-based recovery powders with a Co content exceeding the threshold (10% Co) for industrial manufacturing in Hard Metal production and required by safety regulations. Maleic acid solutions react promptly and selectively in very mild conditions (0.5M, room temperature and pressure, EtOH as solvent) with Co contained in WC-Co sintered powders obtaining the [Co(Mal)2(H2O)4] compound almost quantitatively. Characterization of the resultant recovery powders (SEM-EDS, XRD) and reaction solutions (ICP-OES) after treatments confirmed the almost complete Co removal and high leaching efficiency. Recovery powders deprived of Co demonstrated proper quality to be re-employed in the production process. These results seem really promising in providing a novel, tunable and effective remediation of this hazardous industrial waste and preserve raw material depletion.