Bioleaching of End-of-Life Printed Circuit Boards: Mathematical Modeling and Kinetic Analysis

This work reports a kinetic study of the bioleaching process for Cu extraction from waste printed circuit boards (WPCBs), using iron as an oxidant agent. The kinetic study considered both the Fe2+ oxidation by bacteria metabolism and the chemical reaction between Fe3+ and Cu within WPCBs. The model was composed of a system of three differential equations characterized by three dependent variables and seven parameters. The first equation describes the bacteria abundance trend, the second one represents the variation of Fe2+ concentration, and the third one focuses on the Cu extraction by the biogenerated Fe3+. The developed model was consistent with experimental data with an R 2 higher than 0.97. The results showed that the bacteria metabolism was 1.8–2.5 times faster than the chemical reaction. The determined mathematical model, suitable for the implementation at an industrial scale, could be an important tool to predict the bioleaching mechanism in a metal recovery process.