Refining stage optimisation

VITO (BE) is leading the development and upgrade of the Microwave-assisted leaching (MWAL) and the Gas-diffusion electro-crystallization (GDEx) technologies for extracting Platinum Group Metals (PGMs) from end-of-life (EoL) autocatalysts.

Improved Microwave-assisted leaching (MWAL) processing speed for the extraction of PGMs from spent automotive catalysts

One year after the launch of the project, partners succeeded in shortening the MWAL time, and significantly decreased the amount of chemicals needed to extract over 90% of PGMs. Subsequently, the dissolution of unwanted elements also drastically decreased, further allowing a more efficient downstream processing and better control of residues produced during the leaching phase.

Additional preliminary theoretical and experimental tests have been performed to assess the implementation of MWAL process applied in the extraction of valuable metals (Au and Ag) from low- and mid-grade printed circuit board assemblies (PCBAs) and EoL photovoltaic (PV) panels.

VITO research teams have conducted additional analysis of existing filtration units to identify optimal recovery solutions of the solid residue and the PGM-containing lixiviant resulting from the MW-assisted leaching process.

Gas-diffusion electrocrystallisation (GDEx). A new route to Precious Metals (PMs) recovery

Gas-diffusion electrocrystallisation (GDEx), a novel low cost technology successfully validated within the predecessor project , and awarded with the Innovation Radar Prize as excellent innovation, will serve as refining stage for the recovery of PMs from EoL products. Within the PEACOC project, GDEx is used to recover PMs from leachates and other extracting solutions (e.g., from MW-assisted leaching process). The technique is based on a rapid one-pot process occurring at the three-phase junction between a porous electroactive material, an aqueous electrolyte, and a gas (e.g., air, O2, CO2)— in a so-called gas-diffusion electrode. This electrochemical reduction of gas generates in situ all the chemicals necessary for the further reaction with the PMs.

The latest results obtained during this first year of the PEACOC project, confirm the feasibility of the leaching solutions (provided by MWAL process) from EoL autocatalysts, achieving a selective recovery efficiency of the PGMs higher than 95%.

Descriptive scheme of the gas-diffusion electrocrystallisation GDEx process

Description of GDEx process