Abstract: Using sodium fluoride as the main raw material, silica and sodium fluoride were prepared by fractional step method.Under the optimized process conditions, silica has amorphous structure with loose secondary aggregates, silica DBP value of 3.52 mL/g, primary particle diameter of 20 nm, a silica content of 98.97%.Sodium fluoride having a cubic crystal structure, the average particle diameter of 110 μm, sodium fluoride content of 98.63%.The process can make full use of fluorine source and silicon source, ammonia recycling, improving the quality and yield of sodium fluoride, greatly reducing the amount of fluorine-containing waste water.

Key words: sodium fluorosilicate;fractional step method;sodium fluoride;silica