In China, the resource utilization processes of FGD gypsum are mainly used for wallboard production and as cement retarder. For the wallboard production, FGD gypsum first needs to be dried (at temperatures < 128 °C) to remove any free moisture, and then to be calcined (128–163 °C), to produce β-CaSO 4 •1/2 H 2 O. Subsequently, …
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1. Introduction. Flue gas desulfurization (FGD) gypsum is a by-product of the wet FGD process of coal-fired power plants (Chen et al., 2001).Its main content is CaSO 4 or a mixture of CaSO 3 and CaSO 4.To meet clean air standards, almost all coal-fired power plants are required to be equipped with a desulfurization facility to remove SO 2 …
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The synergistic effect of red mud – desulfurized gypsum - fly ash was found. ... and the mechanical performances at each age were higher than the # 42.5 Portland cement standard. The microstructure results showed that under the synergistic action of alkali and sulfate, the active silicon and aluminum substances in RM and FA …
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Calcined gypsum as a low-energy material can be produced with advantage from the waste FGD gypsum by its dehydration at the temperatures of 110–150 °C. The solid structure of calcined gypsum ...
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However, desulfurization gypsum has some own features as relatively finer solid size (60 μm), high water content (10–15%) and impurity, these have special effect on the …
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Abstract. As a relatively fast-setting building material, desulfurized gypsum is difficult to use. Citric acid, sodium gluconate, and sodium tripolyphosphate were used to design and prepare a desulfurized gypsum paste containing single or combined retarders. The effects of the retarder type and content on the setting inhibition and mechanical …
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The decomposing of gypsum is commonly calcined in the rotary kiln. Because of the stability of ( {text{CaS}}{{text{O}}_4} ), it consumes large quantities energy to provide the high temperature for decomposition. Meanwhile, gas and solid in the rotary kiln mix together, which lower the decomposition efficiency.
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In order to improve the early strength of fly ash blended cement concrete under steam curing conditions, fly ash was partly substituted by calcined flue gas desulfurization (FGD) gypsum and active calcium aluminate. The effect of the composition and curing condition on the workability, mechanical property, and volume stability was …
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Flue gas desulfurized gypsum (FGD gypsum), mainly originates from thermal power plants, smelters, and large-scale enterprise boilers. This article reviews the production in China and the latest ...
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Scope 1.1 These test methods cover the chemical analysis of gypsum and gypsum panel products, including gypsum ready-mixed plaster, gypsum wood-fibered plaster, and gypsum concrete. 1.2 These test methods appear in the following order: Sections ... C0471M-20AE01|en-US Standard Test Methods for Chemical Analysis of …
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Leiva et al. (2010) used the desulfurization gypsum to produce fire resistant panels, and tested its different physico-chemical, mechanical, fire resistance and environment properties (leaching and radioactivity) and compared the test results with European commercial gypsum standards. The results showed that the physico …
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Abstract. The past several years have witnessed great progress in utilization of industrial waste gypsum. Newly developed carbonation technology toward CaCO 3 …
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Flue gas desulfurized gypsum (FGD gypsum), mainly originates from thermal power plants, smelters, and large-scale enterprise boilers. This article reviews the production in China and the latest beneficial utilizations of FGD gypsum. China is a large coal-consuming country and has always had serious SO 2 emissions. Therefore, the …
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Purpose Soil salinization is a major obstacle to the development and utilization of land resources in coastal areas. The purpose of the study is to explore the desalting effect of flue gas desulfurization gypsum (FGDG) on coastal saline-sodic soils by evaluating changes of soil chemical properties (soluble ions, exchangeable cations, and …
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Purpose Soil salinization is a major obstacle to the development and utilization of land resources in coastal areas. The purpose of the study is to explore the desalting …
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additives with calcined desulfurized gypsum; this was aimed at preparing a waterpro of gypsum block. Khalil A.A. 9) has investigated the preparation of gypsum-based compos-ites by mixing it with 0.2% 10% of unburned rice hulls, blast furnace slag, calcium carbonate and polyvinyl alcohol (PVA) to improve water resistance. Zhu Cong10) has
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2.1 ASTM Standards: 2 C11Terminology Relating to Gypsum and Related Build-ing Materials and Systems C 471M Test Methods for Chemical Analysis of Gypsum and Gypsum Products [Metric] C 472 Test Methods for Physical Testing of Gypsum, Gyp-sum Plasters and Gypsum Concrete 3. Terminology 3.1 Definitions—Definitions shall be in …
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At present, the continuous accumulation of the flue gas desulfurization (FGD) gypsum in steel plants leads to the serious environmental issues and resource waste. …
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Because of the complicated decomposition mechanism of desulfurized gypsum from sintering, ... resulting in a sulfur load of 0.110 kg/t. The Chinese national standard ... The gypsum and 1.18% iron ore powder are calcined to obtain calcium ferrite, which can replace 4.21% of the flux, resulting in 3.58 kg/t sintered desulfurization …
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Flue gas desulfurized gypsum (FGD gypsum), mainly originates from thermal power plants, smelters, and large-scale enterprise boilers.This article reviews the production in China and the latest beneficial utilizations of FGD gypsum. China is a large coal-consuming country and has always had serious SO 2 emissions. Therefore, the …
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Calcined gypsum as a low-energy material can be produced with advantage from the waste FGD gypsum by its dehydration at the temperatures of 110–150 °C. Then, β-form of calcined gypsum is formed according to the equation (1) CaSO 4 · 2 H 2 O → CaSO 4 · 1 / 2 H 2 O + 1 1 / 2 H 2 O.
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With steel slag and desulfurized gypsum as main raw material,mixed appropriate amount slag and compound addition a little of activator,and based on orthogonal test,we explored the slag dosage,the proportion of the combined admixture activator and the desulfurized gypsum dosage impact on the performance of clinker-free cementing material,such as …
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Red mud (RM), fly ash (FA) and desulfurized gypsum (DG) are harmful solid wastes that need to be treated. In this study, RM, FA, DG were used as the main raw materials to prepare road base materials based on the different (CaO + Na 2 O)/(SiO 2 +Al 2 O 3) molar ratio, and its mechanical properties, durability, microstructure and …
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Red gypsum (RG) is an industrial waste generated from the titanium dioxide process produced. For the low-cost and high-benefit utilization of RG, calcium sulfate (CaS) was prepared from recycled RG. Rod-like gypsum crystals with a rough surface, uniform size, 1 µm in diameter and 5 µm in length, were obtained, when the as-prepared CaS …
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Desulfurized building gypsum (DBG) has great application potential and can be used to produce lightweight plastering gypsum (LPG). In this work, DBG was modified by adding different proportions of sawdust, retarder, and hydroxypropyl methylcellulose (HPMC) water-retaining agent to prepare LPG. When the sawdust …
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Two different processes of the dehydration of calcium sulfate dihydrate are commonly employed. One is the dry method in which β-gypsum is produced by the calcination of gypsum at the atmospheric pressure and temperatures between 120 and 180 °C []; the product is known as stucco, kettle stucco, plaster, plaster of Paris, or calcined …
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Note: desulfurization gypsum in the table is desulfurization gypsum calcined at 800 ℃; SO3 is calculated according to sulfate content in desulfurization gypsum and Al 2 O 3 is calculated ...
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Investigation into shanghai comprehensive utilization of fly ash and desulfurized slag. May 2007 ... the crystallization of ettringite is stronger in fly ash cement with calcined gypsum than in ...
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The above research shows that the application of desulfurized gypsum in concrete systems will help improve the overall performance of concrete, realize the …
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Flue gas desulfurized gypsum (FGD gypsum), mainly originates from thermal power plants, smelters, and large-scale enterprise boilers. This article reviews the production in China and the latest beneficial utilizations of FGD gypsum. China is a large coal-consuming country and has always had serious SO 2 emissions. Therefore, the …
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