Abstract��
Energy saving is the new target of many modern industries, and it can not only protect environment but also bring economic benefits. The production of alumina brings a great amount of filtrate, which can be hydrothermal synthesized to eliminate silicon and obtain tobermorite. After calcinations, tobermorite becomes wollastonite which is useful in mang fields. The optimum conditions are obtained by orthogonal tests. The Ca/Si ratio of the reactant is 0.6, the reaction temperature is 180 ��. Under this condition, wollastonite with high purity and good crystallity is produced .