Preparation of Calcium Sulfate Whisker by Hydrothermal Method from Flue Gas Desulfurization (FGD) Gypsum

2012 ◽  
Vol 268-270 ◽  
pp. 823-826 ◽  
Author(s):  
Liu Shuan Yang ◽  
Xiao Wang ◽  
Xin Feng Zhu ◽  
Ling Zhi Du
Keyword(s):  
Hydrothermal Method ◽  
Reaction Temperature ◽  
Flue Gas ◽  
Calcium Sulfate ◽  
Raw Materials ◽  
Flue Gas Desulfurization ◽  
Minor Effect ◽  
Fgd Gypsum ◽  
Excellent Quality ◽  
Calcium Sulfate Whisker

In this paper, utilizing the purified flue gas desulfurization (FGD) gypsum as raw materials to prepare calcium sulfate whisker (CSW) by hydrothermal method, the effects of the dosage of crystal modifier, reaction temperature, pH, etc. on the crystal morphology of CSW were discussed. The results show that the purified FGD gypsum can replace high-quality natural gypsum for the preparation of the CSW with excellent quality. The dosage of crystal modifier (K2SO4) and reaction temperature have a significant effect on the morphology and aspect ratio of CSW, while pH and reaction time have a minor effect. When the dosage of K2SO4 is 3 wt%, pH is adjusted to 2 and the solution is reacted at 130 °C for 60 min, CSW with excellent quality can be obtained.

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

2011 ◽  
Vol 250-253 ◽  
pp. 881-889 ◽  
Author(s):  
Xian Feng Liu ◽  
Jia Hui Peng ◽  
Chen Yang Zou ◽  
Leng Bai ◽  
Mei Li
Keyword(s):  
Hydrothermal Method ◽  
Reaction Temperature ◽  
Salt Concentration ◽  
Atmospheric Pressure ◽  
Calcium Sulfate ◽  
Ph Value ◽  
Fgd Gypsum ◽  
Rate Of Reaction ◽  
Percent Conversion ◽  
Calcium Sulfate Hemihydrate

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.

Surface modification of calcium sulfate whisker prepared from flue gas desulfurization gypsum

2016 ◽  
Vol 360 ◽  
pp. 263-269 ◽  
Author(s):  
Chengjun Liu ◽  
Qing Zhao ◽  
Yeguang Wang ◽  
Peiyang Shi ◽  
Maofa Jiang
Keyword(s):  
Surface Modification ◽  
Flue Gas ◽  
Calcium Sulfate ◽  
Flue Gas Desulfurization ◽  
Calcium Sulfate Whisker

On Experimental Study of Development Calcined Gypsum from Flue Gas Desulfurization by Microwave Technology

2013 ◽  
Vol 368-370 ◽  
pp. 780-784 ◽  
Author(s):  
Zhi Man Zhao ◽  
Chun Jie Wang ◽  
Can Qion Li ◽  
Xiao Mei Zhang
Keyword(s):  
Microwave Irradiation ◽  
Flue Gas ◽  
Calcium Sulfate ◽  
Setting Time ◽  
Flue Gas Desulfurization ◽  
Crystal Formation ◽  
Special Effect ◽  
Fgd Gypsum ◽  
Calcined Gypsum ◽  
Cylindrical Crystal

Flue gas desulfurization gypsum (FGD gypsum) was irradiated with microwave, it could be changed calcined gypsum from flue gas desulfurization (CGD). The microwave respectively irradiated five groups FGD gypsum at 100-110°C, 110-120°C, 120-130°C, 130-140°C and 140-150°C, then the fineness and setting time were respectively measured, and compressive/flexural strength were also determined after 2 hours. Experiments show that, CaSO4·0.5H2O crystal of CGD would be more quantity and bigger volume with irradiation temperature increasing. The reason was considered that there were special effect of microwave irradiation to calcium sulfate crystalsthat by scanning electron microscope, and found the Ca, S, O and other elements in cylindrical crystal by Edax. The formation mechanism of CaSO4·0.5H2O crystal by microwave irradiation is different from traditional CaSO4·0.5H2O crystal formation theories.

Research on Affecting Factor of Preparation of Calcium Sulfate Whisker with FGD Gypsum

2014 ◽  
Vol 624 ◽  
pp. 82-85
Author(s):  
Ying Wang ◽  
Dan Jun Tan ◽  
Xiao Li ◽  
Fan Li ◽  
Peng Qi Wang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Calcium Sulfate ◽  
Ph Value ◽  
Synthesis Method ◽  
Raw Material ◽  
Optimum Conditions ◽  
Fgd Gypsum ◽  
Slurry Concentration ◽  
Calcium Sulfate Whisker

Using FGD gypsum as raw material, calcium sulfate whisker was prepared by hydrothermal synthesis method. Through testing the aspect ratio of calcium sulfate whisker, the effect of reaction temperature, reaction time, desulfurization gypsum slurry concentration and pH value on the growth of calcium sulfate whisker were deeply researched. The optimum conditions for the preparation were that the reaction temperature was 150 °C, reaction time was 270min, the slurry concentration was 10% and the slurry pH value was 6.

scholarly journals Hydrothermal synthesis of calcium sulfate whisker from flue gas desulfurization gypsum

2016 ◽  
Vol 24 (11) ◽  
pp. 1552-1560 ◽  
Author(s):  
Chengjun Liu ◽  
Qing Zhao ◽  
Yeguang Wang ◽  
Peiyang Shi ◽  
Maofa Jiang
Keyword(s):  
Hydrothermal Synthesis ◽  
Flue Gas ◽  
Calcium Sulfate ◽  
Flue Gas Desulfurization ◽  
Calcium Sulfate Whisker

Kinetic model for calcium sulfate α-hemihydrate produced hydrothermally from gypsum formed by flue gas desulfurization

2015 ◽  
Vol 48 (3) ◽  
pp. 827-835 ◽  
Author(s):  
Mingliang Tang ◽  
Xuerun Li ◽  
Yusheng Shen ◽  
Xiaodong Shen
Keyword(s):  
Flue Gas ◽  
Calcium Sulfate ◽  
High Performance ◽  
Transformation Process ◽  
Flue Gas Desulfurization ◽  
Synthesis Process ◽  
Stable Phase ◽  
Hydrothermal Conditions ◽  
Simple Method ◽  
Kinetics Of

Modeling of the kinetics of the synthesis process for calcium sulfate α-hemihydrate from gypsum formed by flue gas desulfurization (FGD) is important to produce high-performance products with minimal costs and production cycles under hydrothermal conditions. In this study, a model was established by horizontally translating the obtained crystal size distribution (CSD) to the CSD of the stable phase during the transformation process. A simple method was used to obtain the nucleation and growth rates. A nonlinear optimization algorithm method was employed to determine the kinetic parameters. The model can be successfully used to analyze the transformation kinetics of FGD gypsum to α-hemihydrate in an isothermal batch crystallizer. The results showed that the transformation temperature and stirring speed exhibit a significant influence on the crystal growth and nucleation rates of α-hemihydrate, thus altering the transformation time and CSD of the final products. The characteristics obtained by the proposed model can potentially be used in the production of α-hemihydrate.

scholarly journals THE INFLUENCE OF THE USE OF RECYCLED GYPSUM ON THE PROPERTIES OF GYPSUM PRODUCTS IN LABOR CONDITIONS

2020 ◽  
Vol 26 ◽  
pp. 81-85
Author(s):  
Hana Sekavová ◽  
Jakub Herrmann ◽  
Zdeněk Prošek ◽  
Miroslav Nyč ◽  
George Karra’a
Keyword(s):  
Flue Gas ◽  
Flue Gas Desulfurization ◽  
Volume Changes ◽  
Fgd Gypsum ◽  
Labor Conditions ◽  
Setting Times ◽  
Elasticity Module ◽  
First Results ◽  
Recycled Gypsum ◽  
Recycled Material

The article presents the first results from research, which is deal with recycling of plaster boards and use of the resulting material. The research is carried out within the project MPO Trio c. FV30359 “Recyklace sádrokartonových desek a nová materiálová využití s pridanou hodnotou – GIPSRec”. The plasterboards are produced of stucco, which is calcinated of Flue Gas Desulfurization Gypsum (FGD Gypsum). There is possibility to replace a part of this stucco with recycled material. There is opportunity for saving costs for production. The question how this utilization can change the properties of the products is very important and it is necessary to find the possible improvement or deterioration. This is the objective of this research. The effect on properties was monitored on the samples which was prepared of only pure stucco and of stucco with part of recycled material. There was observed water ratio (splash test), setting times, volume changes, flexural strength, compressive strength and elasticity module.

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