Direct transformation of FGD gypsum to calcium sulfate hemihydrate whiskers: Preparation, simulations, and process analysis--颗粒学报PARTICUOLOGY

Miao, M., Feng, X., Wang, G., Cao, S., Shi, W., & Shi, L. (2015). Direct transformation of FGD gypsum to calcium sulfate hemihydrate whiskers: Preparation, simulations, and process analysis. Particuology, 19, 53–59. https://doi.org/10.1016/j.partic.2014.04.010

Direct transformation of FGD gypsum to calcium sulfate hemihydrate whiskers: Preparation, simulations, and process analysis

Miao Miao, Xin Feng^*, Gangling Wang, Shaomei Cao, Wen Shi, Liyi Shi

Nano Science and Technology Research Center, Shanghai University, Shanghai 200444, China

10.1016/j.partic.2014.04.010

Volume 19, April 2015, Pages 53-59

Received 7 March 2014, Revised 26 March 2014, Accepted 3 April 2014, Available online 30 July 2014.

E-mail: fengxin@shu.edu.cn; fengx01@hotmail.com

Highlights

• Calcium sulfate hemihydrate (CSH) whiskers were prepared via phase transition of CSD.

• Uniform and regular morphology CSH whiskers with high aspect ratio were obtained.

• Impurities in FGD gypsum were found to have little effect on whisker growth.

• The results suggested a possible application for FGD gypsum.

Abstract

Calcium sulfate hemihydrate (CSH) whiskers were synthesized by phase transition in CaCl₂ solution under atmospheric pressure. Analytical-grade calcium sulfate dihydrate (AR CSD) was used as the raw material for the synthesis of CSH whiskers, according to orthogonal experiments. The effects of reaction temperature, AR CSD content, H₂SO₄ content, and reaction time were investigated, and the crystallization conditions were optimized. The as-prepared CSH whiskers displayed a regular morphology and a highly uniform size, with an aspect ratio of 105. A simulation system was also established by blending various sulfates with AR CSD, to evaluate the effects of impurities in flue gas desulfurization (FGD) gypsum. The main aim was to prepare CSH whiskers directly from FGD gypsum, without any purification, using the optimized conditions. This is a facile potential alternative process for large-scale production of CSH whiskers using abundant FGD gypsum as source materials.

Graphical abstract

Keywords

FGD gypsum; Calcium sulfate; Whisker; Direct transformation; Simulation analysis

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