PHASE TRANSFORMATION RELATIONSHIPS IN THE CaSO{sub}4-H{sub}2SO{sub}4-H{sub}2O SYSTEM

摘要

As part of a boarder research project, seeking the development of a cost-effective process for direct production of the high value material, α-calcium sulfate hemihydrate, from sulfuric acid at atmospheric as opposed to elevated pressure conditions, the fundamental work presented here has been undertaken. This includes experimental monitoring of phase transformation reactions and thermodynamic analysis of the relationships among the various phases, namely, calcium sulfate dihydrate, hemihydrate and anhydrite in aqueous sulfuric acid solution at temperatures ranging from 20°C to boiling point.