Abstract: There are two methods,namely clay-bittern method and sodium fluosilicate method,being applied in Do-fluoride Chemicals Co.,Ltd to produce cryolite.Clay-bittern method produces massive acidic mother liquor and sodium fluosilicate method makes large amount of alkali mother liquor,in both of which there are useful fluorine and sodium ingredients for fluoride production.In production of cryolite by clay-bittern method,calcium chloride content in its raw material (i.e.industry salt)is high,which causes calcium oxide content in cryolite exceed the allowed figure.A comprehensive utilization method for cryolite mother liquors has been proposed,namely mix acidic mother liquor with alkali one,use the mixture to dissolve industry salt,remove calcium chloride by turning it into calcium fluoride and calcium hydoxide through the fluorine ions and hydroxid radicals in the mixture,and then use the purified salt water to replace primary water for diluting cryolite mother liquor,thus achieve the goal of reusing waste liquor.After the laboratory and pilot tests,effect of this method is good,not only has recycled the useful ingredients in waste liquor,but also greatly reduces calcium oxide content in cyrolite product produced by clay-bittern method.