关键词: 氟硅酸, 氟化氢, 偏硅酸钠, 氟化钙

Abstract: A new manufacturing technology of fluorine hydride and sodium metasilicate with wet-process phosphoric acid and hydrofluosilicic acid by-produced from phosphate fertilizer industry as raw materials was studied.Experiment principle:hydrofluosilicic acid and limestone reacted to prepare slurry mixture,which contained solid calcium fluoride and silica,then the slurry mixture sequentially reacted with NaOH solution (i.e.silica react with NaOH) to prepare sodium metasilicate,liquid sodium metasilicate could be prepared by centrifugal separation,and remained solid reacted with concentrated sulfuric acid to obtain fluorine hydride gas.Results indicated that when the amount-of-substance ratio of hydrofluosilicic acid to limestone was 1∶3,reaction temperature was at 70～80 ℃,and stirring reaction lasted 2 h,the reaction efficiency of limestone could be as high as 93% and the yield of calcium fluoride could achieved above 95%.But sodium metasilicate productivity was low because of low reaction rate of active silica and NaOH solution,so further research should be carried out. 

Key words: hydrofluosilicic acid, fluorine hydride, sodium metasilicate, calcium fluoride