Abstract: A method for removing phosphorus and boron impurities in an industrial silicon melt by secondary refining is provided. According to the present disclosure, inorganic zinc chloride is adopted as an impurity removal medium and is quickly decomposed into zinc and chloride ions at high temperatures; the phosphorus and boron impurities can react with the zinc and chloride ions to yield low-melting and high-melting compounds during contact with a silicon melt, the low-melting compounds volatilize and escape from the industrial silicon melt at the high temperature of the secondary refining. The high-melting compounds are segregated at the grain boundary along with silicon solidification and removed by crushing and pickling, or sink to the very bottom of the silicon melt and are removed by cutting off a deposition layer at a bottom of a silicon ingot after the silicon melt is solidified.

Abstract: A method for removing phosphorus and boron impurities in an industrial silicon melt by secondary refining is provided. According to the present disclosure, inorganic zinc chloride is adopted as an impurity removal medium and is quickly decomposed into zinc and chloride ions at high temperatures; the phosphorus and boron impurities can react with the zinc and chloride ions to yield low-melting and high-melting compounds during contact with a silicon melt, the low-melting compounds volatilize and escape from the industrial silicon melt at the high temperature of the secondary refining. The high-melting compounds are segregated at the grain boundary along with silicon solidification and removed by crushing and pickling, or sink to the very bottom of the silicon melt and are removed by cutting off a deposition layer at a bottom of a silicon ingot after the silicon melt is solidified.