关键词: 硅灰石;含碱硅酸钠溶液;常压;水热合成

Abstract: With alkaline sodium silicate solution used as raw material and lime milk been poured into at the atmospheric pressure , CaO · SiO2 · H2O was first obtained after hydrothermal treatment , and after calcinated for 2 h at 850 ℃, CaO · SiO2 · H2O was transformed to wollastonite .The effects of SiO 2 concentration , molar ratio of silicon to calcium ( C/S ) and the reaction time on synthesis of wollastonite were examined.The thermodynamics calculation results indicated that CaO · SiO2 · H2O and 2CaO· SiO2 · 1.17H2O were most likely formed in Na2O-CaO-SiO2-H2O system at atmospheric pressure .The experimental results reveal that:When C/S is 1.0, silicate anions polymerization degree increases with the increasing of the concentration of silicon in solution , which will be conducive to the preparation of wollastonite.With the extension of time, the wollastonite crystallinity is higher.When C/S is 0.6、0.8、1.0, the product is CaSiO3.When C/S is 1.5、2.0, a large number of Ca2SiO4 produced in the final product.The optimum condition for preparation of wollastonite is:SiO2 concentration is more than 30 g/L, the hydrothermal temperature is 98 ℃, C/S is 0.6-1.0 and the hydrothermal time is more than 3 h.

Key words: wollastonite;alkaline sodium silicate solution;atmospheric pressure;hydrothermal synthesis