, Volume 37, Issue 2-5, pp 449-455
Date: 23 Feb 2011

Formation of calcium sulfate whiskers from CaCO3-bearing desulfurization gypsum

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Abstract

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.