Optimization of indium recovery from waste crystalline silicon heterojunction solar cells by acid leaching

Abstract Recovery of rare metal indium from waste crystalline silicon heterojunction (HJT) solar cells is important with the large-scale development of photovoltaic industry, is becoming economically and environmentally justified. Thus, the objective of this work is to study hydrometallurgical recovery of indium and valuable materials from HJT solar cells. In addition, to study some parameters used in this process. In this study, three key processes including pretreatment, acid leaching and optimization design on singer-factor to minimize waste of resources were proposed and implemented. Firstly, the samples were characterized by Inductively coupled plasma optical emission spectrometer (ICP-OES) showed indium concentrations of 2950 mg/kg. Then, reacting with NaOH 10% at 90 °C for 8 min can separate the silver electrodes on the surface of the cells, which realize the primary recovery of the silver electrode. After this, the influence of acid type, acid concentration, retention time and temperature on indium leaching was analyzed. Subsequently, the BBD method under response surface methodology was used to optimize the leaching rate. Optimum operating conditions include a leaching step for 148 min at 93.2 °C in the presence of H2SO4 6 mol/L with extraction rate of 95.2% and validate the feasibility with determination coefficient (99.55%) of the RSM model.