Exploring Ultrasound-Assisted Cementation to Enhance the Recovery of Platinum Group Metals from Process Streams

Abstract

Catalytic converters, essential for reducing automotive emissions, rely on platinum group metals such as platinum, palladium, and rhodium. The increasing number of end-of-life catalytic converters presents a significant opportunity for PGM recovery, critical due to the scarcity and strategic importance of these metals. Traditional extraction methods are not sufficient to meet the growing demand so in densely populated areas, recycling offers a viable solution for securing PGM supply. This study investigates the removal of PGMs from concentrated process solutions in hydrochloric medium with the cementation of palladium, platinum, and rhodium onto copper. This work focuses on optimizing parameters such as temperature, agitation, Cu/PGM molar ratio, and the use of ultrasound to enhance efficiency. Three solutions were examined: a synthetic solution to assess the feasibility of cementation, and two process solutions derived from catalytic converter leachates. The synthetic solution demonstrated complete platinum cementation at 65°C, 200 rpm, and a Cu/PGM molar ratio of 16. In the real-life solutions, optimal conditions varied, but a general trend was observed: high temperatures and agitation with a Cu/PGM molar ratio of 15 achieved high removal percentages. Ultrasound significantly improved the results, doubling efficiency in some cases and accelerating reaction kinetics. These findings contribute to developing more effective recycling methods for PGMs, supporting sustainable metal recovery practices.