CIESC Journal ›› 2013, Vol. 64 ›› Issue (7): 2701-2707.DOI: 10.3969/j.issn.0438-1157.2013.07.053

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Preparation of α-calcium sulfate hemihydrate from phosphogypsum in Ca-Na-Cl solutions under atmospheric pressure

MA Baoguo, RU Xiaohong, ZOU Kaibo, LU Siwen, FU Haobing   

  1. State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, Hubei, China
  • Received:2012-10-28 Revised:2013-04-18 Online:2013-07-05 Published:2013-07-05

常压水热Ca-Na-Cl溶液中用磷石膏制备α-半水石膏

马保国, 茹晓红, 邹开波, 卢斯文, 付浩兵   

  1. 武汉理工大学硅酸盐材料与工程国家重点实验室, 湖北 武汉 430070
  • 通讯作者: 马保国(1957- ),男,博士,教授
  • 作者简介:马保国(1957- ),男,博士,教授。
  • 基金资助:

    "十二五"国家科技支撑计划项目(2011BAJ03B03);湖北省科技计划重大专项项目(DZS0005)。

Abstract: Preparation of α-calcium sulfate hemihydrate from phosphogypsum in hydrothermal electrolyte solutions under atmospheric pressure has been a promising way of effective utilization of phosphogypsum. In this paper preparation of α-calcium sulfate hemihydrate from phosphogypsum in Ca-Na-Cl solutions at 95℃was studied.Reaction time and solid products identification in 18.8% NaCl solution,24% CaCl2 and CaCl2+NaCl solutions were investigated through morphologic observation,water of crystalization determination and phase analysis methods.The results showed that NaCl solution was not favorable as the dehydration reaction medium of phosphogypsum though reaction time was only 20 min,because the dehydration product was α-calcium sulfate hemihydrate containing omangwaite (Na2Ca5(SO4)6·3H2O)which had no hydration property of gypsum.In 24% CaCl2 solution α-calcium sulfate hemihydrate phase could be obtained at reaction time of 240 min,reaction time was reduced obviously with increasing NaCl content in Ca-Na-Cl solution,but it was accompanied by increase of Na2O content and irregular uncompleted crystal shapes in the reaction product.Therefore,Ca-Na-Cl solution could be a suitable medium for dehydration reaction of phosphogypsum to form α-calcium sulfate hemihydrate in hydrothermal electrolyte solution under atmospheric pressure.Meanwhile NaCl content should be limited to 2%.

Key words: phosphogypsum, α-calcium sulfate hemihydrate, CaCl2 solution, NaCl solution

关键词: 磷石膏, α-半水石膏, CaCl2溶液, NaCl溶液

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