Recovery of silicon and silver from pulverized solar cells

Abstract

The solar energy market has grown rapidly in the past decades, end-of-life silicon-based solar modules have accumulated as waste, which is one of the resources of silicon and silver. In recycling, the leaching by sulfuric acid, hydrochloric acid, and nitric acid is a high-efficiency metal recovery from solar cells, which nitric acid within them is acceptable to recover metals such as Al, Ag, Cu and Pb from solar cells according to the reports of many studies. The study aimed to examine the recovery of valuable metals using selective leaching with nitric acid from pulverized silicon-based solar cells and purify silicon that is undissolved alone isolating high-purity silicon. Nitric acid concentration for leaching experiments was prepared by molar solution with 1M, 2M, and 3M in an ultrasonic cleaner at a constant temperature of 60 °C. Further purification of silicon on the selective leaching by the concentration of 1M at 60 °C was also tested according to the leaching time. After selective leaching, Si phases in the residual detected the whole leaching experiments including on the concentration and reaction time, it was confirmed that the metals were removed effectively when the leaching time was more than 30 minutes. Silicon purification achieved above 99%. Extraction of silver from the solution was carried out by a reducing agent of copper, which is placed in silver nitrate solution a redox reaction occurs, added by 0.25, 0.5, 0.75, and 1g based on Stoichiometric calculation between a reaction of silver nitrate solution and solid copper. The silver precipitated by copper, when copper addition was 0.75 and 1.0 g, the precipitate was produced at 0.23 and 0.55 g, respectively.