Abstract:

In order to reduce energy consumption and improve product quality,the best method for industrial production of magnesium fluorosilicate was explored.The process parameters for the production of magnesium fluorosilicate crystal particles by using by-product fluorosilicic acid from phosphate fertilizer industry from phosphate fertilizer industry and magnesia powder were systematically studied and optimized.The physicochemical properties such as particle size and particle size distribution of magnesium fluorosilicate were listed.The optimum process parameters to provide the maximum yield of magnesium fluosilicate products were obtained,directly adding MgO powder into the synthesis tank and its adding sequence were determined.The optimum parameters were as follows：the content of fluorosilicic H₂SiF₆,was 16%（mass fraction） the mass ratio of m（MgO）/m（H₂SiF₆） was controlled at 0.244~0.260,the synthesis temperature was controlled at 40~50 ℃,the product solution with high concentration was obtained,the evaporation temperature was 35~45 ℃,and the evaporated slurry entered the MSMPR cooling crystallization tank,the cooling crystallization temperature was controlled at 30 ℃,the rotation frequency of crystallizer agitator was controlled at 20~40 Hz,and the product particle size could be controlled at 0.16~0.37 mm.The above-mentioned studies could be used as process technological reference for the related manufacturers.

Key words: phosphate fertilizer industry, by-product FSA, magnesia powder, magnesium fluorosilicate