Synthesis of β-wollastonite on the basis of silica formed from silicate layers of serpentine

Abstract

Two-stage method for synthesis of β-wollastonite via reaction of calcium hydroxide and silica formed from silicate layers of serpentine and calcination of the resulting compounds was examined. It was found that the specifi c structural features of the silica used for this purpose make it possible to avoid a many hours' autoclave treatment and obtain such amorphous calcium hydro-and hydroxo-silicates that are converted under annealing, beginning at 800-810°C, to β-wollastonite by mixing a suspension of Ca(OH) 2 , SiO 2 , and H 2 O heated to its boiling point under atmospheric pressure. The optimal synthesis parameters, molar ratio of the starting substances and agitation duration, are determined.