Effect of impure components in flue gas desulfurization (FGD) gypsum on the generation of polymorph CaCO3 during carbonation reaction

Bo Wang; Zihe Pan; Zhiping Du; Huaigang Cheng; Fangqin Cheng

doi:10.1016/j.jhazmat.2019.02.002

Effect of impure components in flue gas desulfurization (FGD) gypsum on the generation of polymorph CaCO₃ during carbonation reaction

J Hazard Mater. 2019 May 5:369:236-243. doi: 10.1016/j.jhazmat.2019.02.002. Epub 2019 Feb 4.

Authors

Bo Wang¹, Zihe Pan², Zhiping Du³, Huaigang Cheng⁴, Fangqin Cheng⁵

Affiliations

¹ Institute of Resources and Environmental Engineering, Shanxi Collaborative Innovation Center of High Value-Added Utilization of Coal-Related Wastes, Shanxi University, 92 Wucheng Road, Taiyuan, Shanxi 030006, China. Electronic address: wangbostudy@126.com.
² Institute of Resources and Environmental Engineering, Shanxi Collaborative Innovation Center of High Value-Added Utilization of Coal-Related Wastes, Shanxi University, 92 Wucheng Road, Taiyuan, Shanxi 030006, China. Electronic address: panzh@sxu.edu.cn.
³ Institute of Resources and Environmental Engineering, Shanxi Collaborative Innovation Center of High Value-Added Utilization of Coal-Related Wastes, Shanxi University, 92 Wucheng Road, Taiyuan, Shanxi 030006, China. Electronic address: duzhiping@sxu.edu.cn.
⁴ Institute of Resources and Environmental Engineering, Shanxi Collaborative Innovation Center of High Value-Added Utilization of Coal-Related Wastes, Shanxi University, 92 Wucheng Road, Taiyuan, Shanxi 030006, China. Electronic address: chenghg@sxu.edu.cn.
⁵ Institute of Resources and Environmental Engineering, Shanxi Collaborative Innovation Center of High Value-Added Utilization of Coal-Related Wastes, Shanxi University, 92 Wucheng Road, Taiyuan, Shanxi 030006, China. Electronic address: cfangqin@sxu.edu.cn.

PMID: 30776606
DOI: 10.1016/j.jhazmat.2019.02.002

Abstract

As one of the typical solid-wastes, FGD gypsum usually occupies land and causes resource waste and environmental pollution. Its high content of CaSO₄·2H₂O shows highly potential in synthesizing CaCO₃ by incorporating CO₂. Nevertheless, the impurities in FGD gypsum have significant effects on polymorph of CaCO₃ and the formation mechanism of CaCO₃ polymorph during FGD gypsum carbonation was still unclear. Here, we selected CaSO₄·2H₂O as model to explore the effects of impurities of muscovite and dolomite in FGD gypsum on polymorph of CaCO₃ during carbonation. Results showed that the carbonation products of FGD gypsum are a mixture of vaterite (˜60%) and calcite (˜40%), while only pure vaterite was obtained in CaSO₄·2H₂O carbonation reaction. Muscovite has negligible effects on obtaining pure vaterite during CaSO₄·2H₂O carbonation. Interestingly, the content of calcite increases to the maximum value (˜27%) at 1.0 wt% dolomite and then decreases with the increment of dolomite in CaSO₄·2H₂O carbonation reaction. Correspondingly, vaterite declines first and then increases. Mechanism study shows that hydrophilicity and negative surface charge of dolomite might be the key factors to selectively form calcite during the carbonation of FGD gypsum. These findings might contribute to further utilization of FGD gypsum.

Keywords: Calcite; Carbonation reaction; FGD gypsum; Impurities; Vaterite.