| 摘要 |
PROBLEM TO BE SOLVED: To provided a method for producing, from drain water containing hydrosilicofluoric acid, calcium fluoride having a particle size and high purity suitable as a material for producing hydrofluoric acid.SOLUTION: A method for producing calcium fluoride using hydrosilicofluoric acid-containing water includes: a step [1] of reacting the hydrosilicofluoric acid-containing water with an ammonium compound and producing a first reaction product that includes insoluble silica and an ammonium fluoride aqueous solution; a step [2] of separating the insoluble silica from the first reaction product; a step [3] of reacting the first reaction product from which the insoluble silica has been separated, with calcium carbonate and producing a second reaction product that includes calcium fluoride and an ammonium carbonate aqueous solution; and a step [4] of separating the ammonium carbonate aqueous solution from the second reaction product. |
