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化工学报  2015 

可溶磷对常压水热法制备高强α-半水石膏的影响

DOI: 10.11949/j.issn.0438-1157.20141449, PP. 1983-1988

Keywords: 可溶磷,水热,相变,制备,高强a-半水石膏

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Abstract:

研究了水热CaCl2溶液中可溶磷对CaSO4·2H2O脱水形成α-半水石膏相以及晶形调控的影响,并从高强α-半水石膏相的晶体生长角度探讨了可溶磷的作用机理。结果表明:在98℃24%的水热CaCl2溶液中,pH的大小是决定二水石膏能否发生脱水相变反应形成α-半水石膏的主要因素;当pH不超过2.0时,可以得到针状的α-半水石膏,加入多元羧酸类媒晶剂NS后,可以得到长径比0.5~3.0的短柱状高强α-半水石膏,抗压强度超过20MPa;可溶磷的存在可以降低体系的pH,增大α-半水石膏的过饱和度,降低晶体与液相界面的表面自由能,有利于α-HH相的形成;另一方面,酸根离子会影响到α-HH的结晶习性,减弱羧酸类媒晶剂的吸附效果。

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