Simulation study of the gas-liquid system in the GDEx process for PGMs recovery

The FIREFLY project promotes sustainable recovery of platinum group metals (PGMs) from spent catalysts and industrial waste, reducing reliance on raw material extraction. It integrates physical, chemical, and electrochemical methods to recover high-value metals for reuse.

A central technique is Gas-Diffusion Electrocrystallization (GDEx), where CO₂ is introduced into a water-NaCl solution through a porous electrode. The electrochemical reduction of CO₂ and H₂O generates H₂ and CO, which drive the precipitation of PGMs.

To optimize this process, a mathematical model simulates gas-liquid interactions using a two-phase laminar flow and level set method to track bubble formation and ascent. It also couples species transport to assess how dissolved H₂ and CO influence metal precipitation. Experimental validation shows strong agreement with simulations, confirming the model’s reliability under varying flow rates and current densities.