Determination of leaching parameters for the recovery of platinum group metals from secondary materials

The leaching parameters for the recovery of platinum group metals were investigated with potentiostatic measurements using wire electrodes. The dissolution rates of Pt, Pd and Rh were measured in concentrated NaCl solution. The parameters inspected were the temperature, redox potential and chloride content. Measurements were done at temperatures 25–94 °C using four different NaCl concentrations, 62.5–250 g/l. Measurements were done at potentials of 950–1250 mV vs. SCE for Pt and Rh and 380–470 mV vs. SCE for Pd. Although higher temperature, potential and chloride content generally increased the dissolution rate, the effect was found to be nonlinear and slightly different for different metals. Based on the results, strongly oxidizing conditions are needed for the leaching process in order to achieve reasonable dissolution rates.