Effect of Lime on Properties of Filling Cementitious Material Prepared by Hemihydrate Phosphogypsum

被引：0
作者：
Jiang G. [1 ]
Wu A. [1 ]
Wang Y. [1 ]
Li J. [2 ]
机构：
[1] School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing
[2] School of Chemistry and Chemical Engineering, Guizhou University, Guiyang
来源：
Wu, Aixiang (wuaixiang@126.com) | 1600年 / Chinese Ceramic Society卷 / 48期
关键词：
Hemihydrate phosphogypsum; Lime; Material properties; Mining backfill; Modification mechanism;
D O I：
10.14062/j.issn.0454-5648.20190314
中图分类号：
学科分类号：
摘要：
The gelling activity of hemihydrate phosphogypsum (HPG) is poor and its setting process is slow due to the effect of soluble impurities such as P2O5 and F-. Compared to cement clinker, the strength of HPG modified with lime as a hemihydrate phosphogypsum filling cementitious material (HCM) for goaf filling can be improved. The setting time and bleeding rate of HCM decrease rapidly and then increase slowly, and the compressive strength reverses with the increase of lime. Also, the concentration of total phosphorus and fluoride in the HCM leaching solution gradually decreases to below the standard values from the National Standard of Class I Solid Wastes. For the filling performance and environmental protection, the optimum mass fraction of lime in HCM is 2.0%. Lime can transform soluble P2O5 and F- into insoluble precipitates such as Ca3(PO4)2 and CaF2 to accelerate HPG hydration, increase the number of dihydrate gypsum crystal contact points, and further improve the HCM filling performance. The experimental pH value of HCM leaching solution is lower than the theoretical value, indicating that P2O5 in crystal can dissolve into soluble P2O5 in the process of HPG hydration, thus leading to a decreased alkalinity of backfill. © 2020, Editorial Department of Journal of the Chinese Ceramic Society. All right reserved.
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页码：86 / 93
页数：7
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