Forsterite and magnesium aluminate spinel synthesis and silver extraction by calcination of silicon solar cell from discarded solar Pv panels with bischofite

Abstract

A novel pyrometallurgical process for the recovery of silicon, aluminum and silver from the silicon solar cell was developed. The aim of this work was to produce forsterite (Mg2SiO4) and magnesium aluminate spinel (MgAl2O4), and extract silver by calcination of the silicon solar cell with bischofite (MgCl2.6H2O). Isothermal and non-isothermal assays were carried out in air atmosphere. The effect of temperature and reaction time on the synthesis of forsterite and magnesium aluminate spinel, and the extraction of silver were studied. In addition, the reaction mechanism involved in the process was investigated. The reagents, products, and calcination solid residues were characterized by atomic absorption spectrometry (AAS), X-ray diffractometry (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy analysis (EDS). The experimental results showed that korshunovskite (Mg2(OH)3Cl.4H2O) is generated at 260 °C for 60 min. At 500 ºC for 15 min forsterite and magnesium aluminate spinel start to be produced. The extraction of silver in form of silver chloride (AgCl) begins at 500 ºC for 120 min.