Abstract: Ammonium fluoride is a kind of intermediate product of fluoride production and its impurities restrict the quality of other fluoride products.There are two production methods of ammonium fluoride,i.e.hydrofluoric acid method and by-product fluosilicic acid from phosphate fertilizer method.The second method uses the fluosilicic acid,a by-product of phosphate fertilizer production to produce ammonium fluoride,which is the industry′s development direction and the requirement of Chinese policy guidance,but the impurity is inevitably high during the preparation.Especially,the content of silicon is inevitably high,and thus the upgrading and application of ammonium fluoride raw material are limited.Silicon removing experiment were carried out with ammonia and KOH.Results showed that this method not only can remove silicon,but also can eliminate phosphorus so as to improve the quality of ammonium fluoride products.

Key words: ammonium fluoride, ammonia, KOH, silica