Preparation of α-High-Strength Hemihydrate from Flue Gas Desulfurization Gypsum in AlCl3-MgCl2 Solution at Atmospheric Pressure
Preparation of α-High-Strength Hemihydrate from Flue Gas Desulfurization Gypsum in AlCl3-MgCl2 Solution at Atmospheric Pressure
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DOI：
10.1021/acs.iecr.2c02280
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发表时间：
2022-09-10
影响因子：
4.2
通讯作者：
Li, Zhibao
中科院分区：
文献类型：
--
作者：
Liu, Shuaifeng;Asselin, Edouard;Li, Zhibao
提出了一种工业上可行的无添加剂脱硫石膏生产α-半水硫酸钙的工艺。在该方法中，使用AlCl 3溶液来促进硫酸钙二水合物（DH）转化为在大气压下具有高强度的六方棱柱形α-HH。在363 K下，研究了脱硫石膏原料中AlCl 3（2 ~ 2.5 m）、MgCl 2（0 ~ 0.4 m）、固液比（或固含量%）为0.1 ~ 2的条件下，脱硫石膏的相变动力学。结果表明，MgCl_2浓度的增加有利于AlCl_3转化率的提高。结果表明，在2.5 mol/kg AlCl 3、0.4 mol/kg MgCl 2、固液比为2、363 K下平衡时间为2 h的条件下，可以得到尺寸均匀的六棱柱形HH产物。通过测定固体溶解度确定了AlCl_3-MgCl_2-H_2 O体系的相图。利用E-NRTL活度模型绘制了CaSO 4在AlCl 3-MgCl 2介质中的相变图，并判断了DH和HH的稳定范围。
An industrially feasible process was proposed to produce alpha-calcium sulfate hemihydrate (alpha-HH) from FGD gypsum without any additives. In this process, an AlCl3 solution was used to promote the conversion of calcium sulfate dihydrate (DH) to hexagonal prismatic alpha-HH with high strength at atmospheric pressure. The phase transition kinetics of FGD gypsum was experimentally investigated under conditions: AlCl3 (2-2.5 m), MgCl2 (0-0.4 m) existing in raw FGD gypsum, and the solid-liquid ratio (or solid content %) range of 0.1-2 at 363 K. It was found that increasing the concentrations of MgCl2 in AlCl3 solution accelerated the conversion. The uniform large hexagonal prism HH product was obtained at the folowing optimal conditions: 2.5 mol/kg AlCl3, 0.4 mol/kg MgCl2, solid-liquid ratio of 2, and equilibration time of 2 h at 363 K. The phase diagram of the AlCl3-MgCl2-H2O system was determined by measuring solubility of solids. The E-NRTL activity model was used to construct the phase transition diagram of CaSO4 in AlCl3-MgCl2 media and to judge the stable range of DH and HH.