Method for preparing a-calcium sulfate hemihydrate with calcium sulfate dihydrate

Abstract

A method for preparing α-calcium sulfate hemihydrate with calcium sulfate dihydrate includes steps of: uniformly mixing the calcium sulfate dihydrate with an additive solution, and obtaining a mixture, wherein weight percentages of the calcium sulfate dihydrate and the additive solution in the mixture are respectively 90.00-95.00% and 5.00-10.00%, and the additive solution contains water, inorganic salt, organic salt, organic acid, surfactant, and seed crystal; rising a temperature of the mixture to 130-150° C., keeping for 20-120 minutes, and the calcium sulfate dihydrate in the mixture transforming to the α-calcium sulfate hemihydrate; drying the mixture after reaction at 105-160° C., and thereafter obtaining α-calcium sulfate hemihydrate product. The used calcium sulfate dihydrate can be natural raw materials and industrial by-products. The industrial by-products can be directly applied. Through utilizing characteristics of the industrial by-products, a dehydration reaction time and a drying time are shortened, and a product quality is obviously increased.

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