Abstract: Sodium fluoride was prepared with trisodium phosphate and fluorine in the waste liquid from phosphate chemical industry as raw materials.Influences of various factors,such as mix ratio of raw materials (amount-of-substance ratio of trisodium phosphate to ammonium fluoride）,reaction temperature,reaction time,and stirring speed,on yield of sodium fluoride were investigated.Optimum conditions were as follows:amount-of-substance ratio of trisodium phosphate to ammonium fluoride was 1.4,reaction time was 60 min,reaction temperature was 95 ℃,and stirring speed was 350 r/min.Under the optimum conditions,yield of sodium fluoride was 4.02 g per 100 g waste liquid,and the recovery rate of fluorine in waste liquid reached 85%. 

Key words: waste liquid in phosphate chemical industry, fluorine resource recovery, sodium fluoride