CALCIUM FLUORIDE PRODUCTION PROCESS Russian patent published in 2004 - IPC

FIELD: industrial organic synthesis. SUBSTANCE: invention designed for production of fluor-spar starting material for hydrogen fluoride production consists in that calcium carbonate and silicohydrogen fluoride are subjected to reaction in aqueous medium at temperature not higher than 40 C and pH 2.5-3.5 to give calcium fluoride as desired product, which is separated from colloidal silica solution. The latter is neutralized to pH not lower than 8, preferably 8.5- 9.5, at temperature not lower than 60 C, preferably 80-90 C, using sodium or calcium hydroxide, the latter being taken in the form of lime milk containing 100-150 g/l CaOm after which silica gel is recovered as second product. EFFECT: improved physico-mechanical properties of colloidal silica solution in the product isolation stage. 5 cl, 2 ex