Influence of Calcined Anhydrite Solubility on the Formation of Ettringite

Abstract

Abstract: In this research anhydrite calcined under the dry desulphurization temperature of circulating fluid bed (CFB) boiler was used to simulate dry desulphurization product.The formation of ettringite (AFt) was investigated by curing the mixture of calcined anhydrite and tricalcium aluminate (C₃A).It was discussed in this research that the feasibility of preparing building materials using CFB ash.The results show that the anhydrite calcined at 820 ℃ for 15 min is a plate-like crystal with sharp edges,and that calcined at 940 ℃ for 15 min is partly sintered.High temperature prepared anhydrite shows lower solubility.The formation of AFt reaches the top after 3 d curing.During the period,the anhydrite formed at 820 ℃ forms needle-shaped AFt by dissolving precipitation.While the anhydrite formed at 940 ℃ forms agglomerates by solid phase reaction.The carbonization reaction during long-term air curing will cause the decomposition of AFt.

Key words: anhydrite, tricalcium aluminate, ettringite, swell, desulphurization, carbonation, solubility

CLC Number:

TU526

QIAO Xiuchen, MA Dawei, XUE Yubing. Influence of Calcined Anhydrite Solubility on the Formation of Ettringite[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(1): 201-206.

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