Synthesis of wollastonite from the carbonate-containing gaize of Lithuania

Abstract

We studied wollastonite synthesis from Lithuanian gaize containing calcium carbonate that does not provide the CaO/SiO2 molar ratio from 0.95 to 1 required for the synthesis of wollastonite. To correct the charge, the following methods were suggested: the addition of calcium oxide under hydrothermal conditions, solid-phase synthesis, and charge granulation. Wollastonite was synthesized from a charge prepared in a muffle furnace at temperatures from 1000 to 1200°C over the course of two hours and identified by chemical analysis and X-ray diffraction, as well as by the characteristics of the resulting product. From the suggested versions to be realized under industrial conditions, the economically and technologically expedient version involves the cogranulation of gaize with calcium oxide in a rotating furnace at a temperature of 1100°C providing for an easily regulated technological mode of wollastonite synthesis with a stable chemical composition without the application of a mineralizer.