Study on Preparation of High-Strength Gypsum by FGD Gypsum

Abstract:

With the enlarging of industrial desulfurization, the amount of FGD gypsum is increasing rapidly. The preparation of alpha-calcium sulfate hemihydrate (α-HH) is one of the biggest concerns for FGD gypsum reclamation. The influence of mixed chlorate solution of Mg-Ca-Na concentrations (5-30 wt%) and FGD gypsum concentrations (5-30 wt%) by hydrothermal salt solution method at atmospheric were investigated at temperatures (75-99^°C) within a reaction time of 4h and a pH value of neutral. The results showed that 20 wt%, 20 wt% and 97^°C was respectively optimal parameter of salt media concentration, FGD gypsum concentration and temperature. Products obtained from the dehydration process of optional experimental conditions with mixed crystal modifier were characterized based on relevant standards in this study. The results showed that α-HH had integrity crystal structure, 2h flexural strength and oven dry compressive strength were 5.34MPa and 30.21MPa, which had meet the industry standards of α30 grade.

• Periodical: Advanced Materials Research (Volume 878)
• Pages: 292-297
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.878.292
• Online since: January 2014
• Authors: Xiao Shu Wang, Min Zhou, Hao Bo Hou, Wei Xin Wang, Yan Shao
• Keywords: FGD Gypsum, High-Strength Gypsum, Hydrothermal Method

References

[1] Telesca Antonio, Marroccoli Milena, Calabrese Daniela, et al. Flue gas desulfurization gypsum and coal fly ash as basic components of prefabricated building materials[J]. Waste Management, 2013, 33(3): 628-633.

DOI: 10.1016/j.wasman.2012.10.022

[2] Tesarek Pavel, Drchalova Jaroslava, Kolisko Jiri, et al. Flue gas desulfurization gypsum: Study of basic mechanical, hydric and thermal properties [J]. Construction and Building Materials, 2007, 21(7): 1500-1509.

DOI: 10.1016/j.conbuildmat.2006.05.009

[3] Zhibao Li , George P. Demopoulos. Model-Based Construction of Calcium Sulfate Phase-Transition Diagrams in the HCl-CaCl2-H2O System between 0 and 100℃[J]. Ind. Eng. Chem. Res. , 2006, 45(13): 4517-4524.

DOI: 10.1021/ie0600339

[4] Baohong Guan, Li Yang, Hailu Fu, et al. α-calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions[J]. Chemical Engineering Journal, 2011, 174(1): 296-303.

DOI: 10.1016/j.cej.2011.09.033

[5] Zurz Alfred, Odler Ivan, Thiemann Felicia, at el. Autoclave-free formation of α- hemihydrates gypsum[J]. Journal of the American Ceramic Society, 1991, 74(5): 1117-1124.

DOI: 10.1111/j.1151-2916.1991.tb04351.x

[6] Liuchun Yang, Baohong Guan, Zhongbiao Wu. Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution[J]. Sci China Ser E-Tech Sci, 2009, 52(9): 2688-2694.

DOI: 10.1007/s11431-009-0254-6

[7] Yuanbing Ling, George P. Demopoulos. Preparation of α-calcium sulfate hemihydrate by Reaction of Sulfuric Acid with Lime[J]. Ind. Eng. Chem. Res., 2005, 44: 715-724.

DOI: 10.1021/ie049316w

[8] Baohong Guan , Guangming Jiang , Zhongbiao Wu , et al. Preparation of α-Calcium Sulfate Hemihydrate from Calcium Sulfate Dihydrate in Methanol-Water Solution under Mild Conditions [J]. J. Am. Ceram. Soc., 2011 , 94(10) : 3261-3266.

DOI: 10.1111/j.1551-2916.2011.04470.x