The invention discloses a method for reducing
ammonium fluorosilicate in
ammonium bifluoride. The method comprises the steps as follows:
fluorosilicic acid is subjected to an ammoniation reaction anda
silicon dioxide-containing
ammonium fluoride mixed solution is obtained, wherein the
mass concentration of
ammonium fluoride is 20%-35%, the
mass concentration of
silicon dioxide is 2%-15%, and thePH value is 8.0-10; the
ammonium fluoride mixed solution in step (1) is filtered by a
filter press, most
silicon dioxide is removed, a filtrate enters a filtrate tank and left to stand and clarified for 1-3 h, most
silicon dioxide settles to the bottom, and the upper layer is a clear
ammonium fluoride liquid; the upper clear ammonium
fluoride liquid in step (2) is finely filtered again by micropores with the
diameter being 3-10 micron, and a wet
filter cake returns to a feeding chute of the
filter press; a refined filtrate enters a concentrated
raw material chute to be left to stand and clarified for 1-3 h, an upper clear ammonium
fluoride liquid enters a concentration
system, conventional concentration, acid addition,
crystallization and
centrifugal separation are performed later, and anammonium
bifluoride product is obtained. The method can effectively reduce
ammonium fluorosilicate in
ammonium bifluoride, has low
energy consumption, introduces no other impurities and avoids waste emission.