The invention discloses a preparation method of
ammonium bifluoride. The method comprises steps as follows: a, dilute
ammonia water and
ammonium bifluoride mother liquor are mixed to adsorb gas containing
fluorine and
silicon, and a
mixed solution is obtained; b, the
mixed solution and filter-press residues obtained in Step d are mixed for
slurry making and filter-press separation, and a filtrate and a silica by-product are obtained; c,
ammonia is introduced into the filtrate; d,
slurry is subjected to filter-press separation, and an
ammonium fluoride filtrate and filter-press residues are obtained; e, the
ammonium fluoride filtrate is subjected to vacuum concentration; f, concentrated
slurry is dissolved, the pH value of the solution is adjusted with
hydrogen fluoride, and cooling
crystallization is performed; g,
ammonium bifluoride crystals are filtered, separated and dried, and the
ammonium bifluoride product is obtained. With the adoption of the method, the
utilization rate of
fluorine and
ammonia is increased, the gas containing
fluorine and
silicon is changed into the
ammonium bifluoride product with the high economic value in the
phosphoric acid production process, the production cost is low, the economic benefit is significant, meanwhile, the purity and other indexes of the product meet the requirement for superior products, and the method is suitable to be popularized and applied in the field.