| Zhengzhou Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences | Host |
| Citation: |
LI Xianbo, YE Junjian, WANG Xianchen, LI Longjiang, ZHANG Qin. Effect of Salt Medium on Preparation of α-hemihydrate from Phosphogypsum Using Salt Solution Method[J]. Conservation and Utilization of Mineral Resources, 2017, (6): 79-86. doi: 10.13779/j.cnki.issn1001-0076.2017.06.015
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Effect of Salt Medium on Preparation of α-hemihydrate from Phosphogypsum Using Salt Solution Method
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Abstract
Phosphogypsum (PG) is an industrial solid waste from wet preparation of phosphoric acid using sulfuric acid to decompose phosphate ore. Preparation of α-hemihydrate gypsum(α-HH) using salt solution method is a new utilization way to recycle PG, in which the selection of salt media plays an important role. Therefore, the conversion rate, phase composition and morphology of α-HH in NaCl, NaNO3, MgCl2, CaCl2 and Ca(NO3)2 solution were investigated in this paper. The results show that the conversion rate of α-HH increases with increasing the concentration of NaCl, NaNO3 and MgCl2, which shortens the crystallization induction time and crystal growth time. The content of α-HH in product is above 95%, of which the morphology is long hexagonal prism with different end face. In NaCl and NaNO3 solutions, the α-HH present complete and polyhedral crystal face with a length-diameter ratio (L/D) of 14:1. While in MgCl2 solution, the end face is packed hollow pipe with the L/D of 11:1, which is uniformly distributed with large crystal defect. Compared with NaNO3 and MgCl2, NaCl has the advantages of low dosage and high conversion rate, which can be used as the salt medium for the preparation of α-HH. Due to the common-ion effect, PG can't convert to α-HH in CaCl2 and Ca(NO3)2 solutions, which are not suitable as salt media.
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Keywords:
- phosphogypsum /
- salt solution method /
- α-hemihydrate gypsum /
- salt medium
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References
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LI Xianbo, YE Junjian, WANG Xianchen, LI Longjiang, ZHANG Qin. Effect of Salt Medium on Preparation of α-hemihydrate from Phosphogypsum Using Salt Solution Method[J]. Conservation and Utilization of Mineral Resources, 2017, (6): 79-86. doi: 10.13779/j.cnki.issn1001-0076.2017.06.015
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Figure 1.
XRD pattern of phosphogypsum
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Figure 2.
TG-DSC curves of phosphogypsum
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Figure 3.
Effect of NaCl concentration on dehydration reaction
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Figure 4.
Induction period and crystal growth period in different NaCl concentrations
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Figure 5.
XRD patterns of reaction products in different NaCl concentrations
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Figure 6.
SEM images of α-hemihydrate gypsum
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Figure 7.
Effect of NaNO3 concentration on dehydration reaction
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Figure 8.
Induction period and crystal growth period in different NaNO3 concentrations
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Figure 9.
XRD patterns of reaction products in different NaNO3 concentrations
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Figure 10.
SEM images of α-hemihydrate gypsum
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Figure 11.
Effect of MgCl2 concentration on dehydration reaction
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Figure 12.
Induction period and crystal growth period in different MgCl2 concentrations
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Figure 13.
XRD patterns of reaction products in different MgCl2 concentrations
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Figure 14.
SEM images of α-hemihydrate gypsum
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Figure 15.
Effect of CaCl2 concentration on dehydration reaction
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Figure 16.
Effect of Ca(NO3)2 concentration on dehydration reaction