Hydrometallurgical Efficient Recovery Of Silver From Retired Crystalline Silicon Solar Cell Wafers And Preparation Process Of Silver Powder

Due to the rapidly increasing installed capacity and limited service life of crystalline silicon photovoltaic modules,during the "14th Five-Year Plan" period,my country will usher in a "tidal wave" of photovoltaic modules.As the core of decommissioned crystalline silicon photovoltaic modules,crystalline silicon solar cells have significant resources,and their efficient disposal is crucial to the recycling of photovoltaic modules.In view of the current complex and lengthy recycling process of crystalline silicon solar cells,low recovery rate of valuable elements,low purity of target products,and large amount of harmful reagents.This paper takes retired solar cells as the research object,and conducts in-depth and systematic research on the efficient leaching of silver and aluminum in retired solar cells and the preparation of high-purity silver powder.new solution.The main conclusions are as follows.(1)An inorganic mixed acid solution of nitric acid plus hydrofluoric acid was realized for the efficient leaching of aluminum and silver from retired crystalline silicon solar cells,simultaneous removal of antireflective layers and efficient recovery of crystalline silicon cells.Under the optimized conditions(nitric acid concentration of 3 mol/L,hydrofluoric acid concentration of 1 mol/L,leaching time of 1 h,leaching temperature of 50°C,and liquid-solid ratio of 15:1),the highest leaching rate of silver was 98.95%,the highest leaching rate of aluminum was 99.32%,and the highest recovery rate of crystalline silicon wafers was 91.56%.Response surface optimization experiments and data analysis were performed using Minitab software,and the optimal process parameters for leaching silver in this system were obtained as follows,nitric acid concentration of 3.76mol/L,hydrofluoric acid concentration of 2.14 mol/L,leaching temperature of 60 °C,and liquid-solid ratio of 18:1,and the model was highly reliable.(2)The reaction mechanism of leaching silver from decommissioned solar cell wafers with a mixed solution of monohydrate citric acid plus hydrogen peroxide organic acid was elucidated.The optimal process parameters were determined by single-factor experiments,the concentration of monohydrate citric acid was 2 mol/L,the dosage of 30%hydrogen peroxide was 375 ml/L,the leaching temperature was 60 °C,the leaching time was 2.5 h,and the liquid-to-solid ratio was 30:1,and the silver leaching rate was as high as 97.38%.Response surface optimization experiments and data analysis were carried out using Minitab software in this system,and the optimal process parameters for silver leaching were obtained as follows,citric acid monohydrate concentration of 2.35 mol/L,30% hydrogen peroxide dosage of 437.5 ml/L,leaching temperature of70 °C,and liquid-solid ratio of 10:1,and the model fit was good.(3)A chlorination precipitation-ammonia dissolution-liquid phase reduction process system was constructed to prepare high-purity silver powder for the recycling of valuable metal Ag from retired crystalline silicon cells.The effect of the optimal chlorine source-sodium chloride dosage on the precipitation behavior of silver ions in inorganic and organic acid leaching solutions was systematically investigated.The highest reduction rates of silver ions in the two systems of inorganic and organic acids were 99.96% and 99.57%,respectively,and the purity of silver powder was as high as 99.72% and 99.85%,respectively,and the average particle sizes of silver powder were 409.3 nm and 229.7 nm,respectively.