Bioleaching of End-of-Life Printed Circuit Boards: Mathematical Modeling and Kinetic Analysis
Alessandro Becci, Alessia Amato, José Miguel Rodrı́guez-Maroto, Francesca Beolchini
Abstract
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 R2 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.