Electrochemistry as a tool for improved circular economy of metals

Traditional hydrometallurgical processes for metal production and recovery like are facing the challenges of economic and environmental concerns. Tailored electrochemistry can be considered being one of the most promising technologies to address challenges related to feasible metal recovery from dilute or impure solutions. The direct usage of clean electricity during electrochemical metal recovery can decrease the use of CO2 intensive chemicals and achieve higher holistic energy efficiency as losses due to chemical synthesis or preparation steps can be avoided. Recently, an innovative electrochemical method – electrodeposition and redox replacement (EDRR) – was proposed by the research group of Hydrometallurgy and Corrosion at Aalto University, for the valorization of valuable elements with trace concentration from hydrometallurgical solutions. To date, the recovery of silver, gold, platinum, and tellurium with low concentration (mg/L or μg/L level) from various complex hydrometallurgical solutions by EDRR have been investigated. Moreover, recent studies have demonstrated the versatility of EDRR to product high value-added metallic materials like nanoparticles, dendrites and alloy coatings. Unlike traditional electrodeposition, the EDRR method does not involve any complexing agents and the currently underutilized hydrometallurgical solutions or waste streams can be used as liquid raw materials in the production. All these previous studies suggest EDRR as an innovative method and a promising approach to achieve efficient metal recovery and/or sustainable direct manufacturing of metallic coatings. In this paper, the advances of the application of EDRR are summarized to highlight electrochemistry as a tool for improved circular economy of metals.