Synthesis of Wollastonite From Rice Husk Ask in Viet Nam by Hydrothermal Method

Wollastonite is produced by the pyrolytic reaction of xonotlite. Xonotlite is a product of the hydrothermal reaction of silicon dioxide from rice husk ash (RHA), calcium hydroxide and water. The composition slurries were prepared with contents of RHA and calcium hydroxide are 45.79% and 54.21% in weight and the ratio of solid to the water is 1.25. Effect of the reaction temperature to formation of calcium silicate hydrate was studied. The obtained products were analyzed using XRF, FT-IR and XRD for determining the formation of xonotlite. The suitable temperature and reaction time for the synthesis of xonotlite are 2000C and 12 hours, respectively. Wollastonite is formed by calcining xonotlite at 950oC during 3 hours