METHOD OF PREPARING FINELY DISPERSED WOLLASTONITE Russian patent published in 1997 - IPC

FIELD: manufacture of pigments, plastic materials, industrial rubber products, paper, cosmetics and ceramics. SUBSTANCE: claimed method comprises reacting calcium containing waste resulting from phosphate fertilizers and silica containing waste resulting from aluminium fluoride production in the presence of hydroxides of I and II Group metals, ammonium or mixtures thereof and sodium chloride at CaO/SiO₂, molar ratio of (0.8- 1.0):1, CaO/OH^- molar ratio of (0.5-2.0):1, OH^-NaCl molar ratio of (0.5-2.0):1. Process is carried out under hydrothermal conditions at 70-100 C for 1-3 hours at solid to liquid phase ratio of (1:3)-(1:5). The resulting hydrosilicate is filtered off, washed, fried and calcined at 950-1050 C for 40-60 min to obtain wollastonite. The claimed method makes it possible to obtain wollastonite of high purity, whiteness and particles size homogeneity with particle size of 3-12 mcm that make up 75-85% of powders, utilize waste resulting from production of phosphate fertilizers and aluminium fluoride, simplify the process and make it cheaper. EFFECT: more efficient preparation method. 1 tbl