Formation of calcium sulfate whiskers from CaCO₃-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 CaSO₄·2H₂O (93.45 wt%) and CaCO₃ (1.76 wt%) were treated with dilute H₂SO₄ at room temperature to convert CaCO₃ to CaSO₄; the latter was then treated at 110–150 °C to form CaSO₄·0.5H₂O whiskers. The removal of the CaCO₃ impurity from the desulfurization gypsum favored the formation of CaSO₄·0.5H₂O whiskers with high aspect ratios.