Zhang Jianwu, Wang Xiao, Hou Pengtao, Jin Biao, Zhang Xiaoting, Li Zhixin
School of Materials and Chemical Engineering, Henan University of Urban Construction, Pingdingshan 467036, China.
Materials (Basel). 2023 Aug 28;16(17):5878. doi: 10.3390/ma16175878.
The effects of phosphoric acid (HPO) in pressurized aqueous solution on the dehydration of CaSO·2HO to form α-hemihydrate gypsum (α-HH) phase and the regulation of crystal shape were studied in this paper in order to provide guidance for the low-cost and high-value utilization of phosphogypsum. The results showed that HPO can significantly accelerate the formation rate of the α-HH phase and that it did not participate in the formation of the α-HH phase in the form of eutectic phosphorus during crystalline phase transformation. In terms of crystal shape regulation, HPO can impact the effect of a citric acid crystal regulator on α-HH crystal shape regulation. The more HPO added, the greater the aspect ratio of α-HH. Accordingly, the water consumption and 2 h dry compressive strength of α-HH products were gradually increased and decreased with an increase in HPO content, respectively. Despite this, the compressive strength of α-HH can still meet the requirements of the α20 grade in JC/T 2038-2010 "α High Strength Gypsum" in China when the HPO content was limited to less than 0.4%.
本文研究了磷酸（H₃PO₄）在加压水溶液中对CaSO₄·2H₂O脱水形成α-半水石膏（α-HH）相的影响以及对晶体形状的调控，旨在为磷石膏的低成本高值利用提供指导。结果表明，H₃PO₄能显著加快α-HH相的形成速率，且在晶相转变过程中不以共晶磷的形式参与α-HH相的形成。在晶体形状调控方面，H₃PO₄会影响柠檬酸晶体调节剂对α-HH晶体形状的调控效果。H₃PO₄添加量越多，α-HH的长径比越大。相应地，α-HH产品的用水量和2 h干燥抗压强度分别随H₃PO₄含量的增加而逐渐增加和降低。尽管如此，当H₃PO₄含量限制在小于0.4%时，α-HH的抗压强度仍能满足中国JC/T 2038-2010《α高强石膏》中α20等级的要求。
