The Effect of Process Conditions on the Preparation of α-Calcium Sulfate Hemihydrate from FGD Gypsum Using the Hydrothermal Method under Atmospheric Pressure

Abstract:

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This paper studies the laws of crystal growth, percent conversion and the rate of reaction of α-calcium sulfate hemihydrate from FGD gypsum under different conditions using the hydrothermal method under atmospheric pressure. The crystal morphology was observed by using SEM, polarizing microscope profile, and percent conversion and the rate of reaction were obtained by assaying crystal water content and calculating. The results showed, (1) with the increase of reaction temperature, the dehydration rate increased and the formed α-calcium sulfate hemihydrate crystal had a larger particle size; (2) with the increase of salt concentration or slurry concentration, the formed α-calcium sulfate hemihydrate crystal was smaller, percent conversion and the rate of reaction was nearly unchanged; (3) with the increase of pH value of solution, the rate of reaction increased and percent conversion was nearly unchanged, and with pH value ranging from 5 to 7 the formed α-calcium sulfate hemihydrate crystal was crassitude. In conclusion, the perfect technological parameters were as follows: reaction temperature ranging from 95°C to 100°C, salt concentration ranging from 15% to 20%, slurry concentration ranging from 15% to 20%, pH value ranging from 5 to 7, and reaction time not exceeding 90min.

Info:

Periodical:

Advanced Materials Research (Volumes 250-253)

Edited by:

Guangfan Li, Yong Huang and Chaohe Chen

Pages:

881-889

DOI:

10.4028/www.scientific.net/AMR.250-253.881

Citation:

X. F. Liu et al., "The Effect of Process Conditions on the Preparation of α-Calcium Sulfate Hemihydrate from FGD Gypsum Using the Hydrothermal Method under Atmospheric Pressure", Advanced Materials Research, Vols. 250-253, pp. 881-889, 2011

Online since:

May 2011

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Price:

$35.00

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