Formation of calcium sulfate whiskers from CaCO_3-bearing desulfurization gypsum

摘要

Calcium sulfate whiskers can be used as the reinforcing agents in many composites, such as polymers, ceramics, cements, and papers, etc. This paper investigated the feasibility of preparing calcium sulfate whiskers using desulfurization gypsum as the raw material. The desulfurization gypsum composed mainly of CaSO_4·2H_2O (93.45 wt%) and CaCO_3 (1.76 wt%) were treated with dilute H_2SO_4 at room temperature to convert CaCO_3 to CaSO_4; the latter was then treated at 110–150 ℃ to form CaSO_4·0.5H_2O whiskers. The removal of the CaCO_3 impurity from the desulfurization gypsum favored the formation of CaSO_4·0.5H_2O whiskers with high aspect ratios.