Tens of millions of tons of desulfurized gypsum can be produced in China every year. Desulfurization gypsum is used as an admixture to replace part of cement in concrete. And the smaller the particle size of desulfurized gypsum, the better the mechanical properties of cement mortar. The compressive and flexural tests show that the cement mortar with …
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6–79.8% of Hg in FGD gypsum could be reemitted at 100–200 °C.. The Hg release ratio is directly related to the HgClx content in FGD gypsum.. Wallboard production and being used as cement retarder were two main Hg re-emission pathways of FGD gypsum utilization.. The secondary Hg emission from FGD gypsum utilization …
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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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It is feasible to use desulfurized gypsum as retarder of Portland cement. When the content of desulfurized gypsum after 80℃ heat treatment is 4% of Portland cement, the setting time can meet the use requirements of cement. Compared with natural gypsum, the retarding effect of desulfurized gypsum
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After many grinding mixture ratio tests in laboratories,the paper studies the effect on ordinary cement and slag cement of desulfurized gypsum as cement retarder,instead of raw gypsum.The result shows that the cement is strengthened,finer with normal setting time and no adverse effects.It is suggested that desulfurized gypsum granulators be …
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This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum...
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Through experiment,the influence on the desulfurization gypsum cement mechanical performance and hydration processes was researched.The result shows that adding desulfuration gypsum instead of gypsum to cement can improve and strengthen properties of the cement.So,it can be used instead of natural gypsum to produce cement.
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Alternative calcium-sulfate-bearing materials as cement retarders: part II. FGD gypsum. Cem Concr Res. (2004) M.A. Pedreño-Rojas et al. Life cycle assessment of natural and recycled gypsum production in the Spanish context. J. Clean. Prod. ... Moreover, the solid waste desulfurized gypsum is used as a sulfate activator. The …
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The theoretical analysis and the studies on the feasibility on the basis of a series of experiments utilizing manganese slag as retarder in stead of gypsum in cement manufacture were carried out.The results indicated that the indexes including setting time,soundness and radioactivity of portland cement measure up to the national …
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The invention discloses a desulfurized gypsum retarder, a preparation method and application thereof in sulphoaluminate cement, wherein the method comprises the following steps: the temperature of the rotary kiln is reduced from 300 ℃ to 400 ℃, the temperature reduction process is divided into a plurality of temperature reduction sections, the …
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This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum was …
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Citric acid, sodium gluconate, and sodium tripolyphosphate were used to design and prepare a desulfurized gypsum paste containing single or combined …
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Desulfurization-gypsum-based composite cementitious materials were prepared by adding certain proportions of sulfoaluminate cement, mineral powder quick lime, retarder, and water reducer into the ...
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Desulfurized ash from semi-dry flue gas desulfurization and α-hemihydrate gypsum were collected from Baotian New Building Materials Co.,Ltd. Their chemical components are shown in Table 1.Desulfurized ash contains about 21.33% hemihydrate calcium sulfite, 18.11% calcium carbonate, 28.55% dihydrate gypsum, 25.81% calcium …
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The invention discloses a desulfurized gypsum retarder, a preparation method and application thereof in sulphoaluminate cement, wherein the method comprises the following steps: the temperature of the rotary kiln is reduced from 300-400 ℃, the temperature reduction process is divided into a plurality of temperature reduction sections, …
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The desulfurization gypsum are widely utilized in cement retarder, building material, embedment and neutralizer or regulator of soil in agriculture [3, 4]. At same time, decomposing of desulfurization gypsum or Phosphogypsum to producing ( {text{CaO}} ) and ( {text{S}}{{text{O}}_2} ) is another promising utilization method for cement as ...
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In this paper, the possibility of flue gas desulphurization (FGD) gypsum as an admixture in cement and concrete was explored. The gypsum was baked at the proper temperature of 200 °C for 60 min ...
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The undisturbed desulfurization gypsum used in the experiments was obtained by natural air drying for 14 d, crushed by a crusher, and then passed through a 0.15-mm square-hole sieve. The obtained semi-aqueous desulfurized gypsum was the original desulfurized gypsum, which was placed in an oven at 180 °C and. Results and …
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The massive deposition of sediment in the Yellow River leads to the waste of land resources and is also prone to environmental disasters. In this study, the industrial by-product, flue gas desulfurization gypsum (FGDG), was incorporated with Portland cement (PC) and fly ash (FA) to treat the dredged soil (DS) from the Yellow River. The …
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DOI: 10.1016/j.cscm.2022.e01413 Corpus ID: 251650878; Effect of soluble phosphate, fluoride, and pH in Brazilian phosphogypsum used as setting retarder on Portland cement hydration
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DOI: 10.1016/j.conbuildmat.2022.127630 Corpus ID: 248445855; Modification of phosphogypsum using circulating fluidized bed fly ash and carbide slag for use as cement retarder @article{Li2022ModificationOP, title={Modification of phosphogypsum using circulating fluidized bed fly ash and carbide slag for use as cement retarder}, …
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Fig. 4 (a) shows that gypsum crystals without any retarder are mainly needle-like, with many overlap points among the crystals, compact structures and better pore structure. Download: Download high-res image (887KB) Download: Download full-size image; Fig. 4. Effects of different retarders on setting times of building gypsum under …
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The obtained semi-aqueous desulfurized gypsum was the original desulfurized gypsum, which was placed in an oven at 180 °C and dehydrated for 2 h under synchronous heating with the box. The microscopic morphology of desulfurization gypsum from SEM and XRD analysis is shown in Fig. 1. The original desulfurization …
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1. Introduction. Flue gas desulfurization gypsum (FGDG) is an industrial byproduct produced by limestone-gypsum wet desulfurization to treat SO 2 produced by thermal power plants and coal-fired plants, whose main component is CaSO 4 ·2H 2 O. In wet desulfurization, 1 t of SO 2 produces about 2.7 t of FGDG [1], [2].Some 130 million …
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The aim of this paper is to investigate the possible displacement of natural gypsum (CaSO4·2H2O) in cement with an alternative setting retarder, such as the industrial by-product derived from ...
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ABSTRACT: This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum was used …
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The desulfurization gypsum are widely utilized in cement retarder, building material, embedment and neutralizer or regulator of soil in agriculture [3, 4]. At same …
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The results showed that when the content of desulfurized gypsum after 80 °C heat treatment was 4% of Portland cement, the initial setting time was 136min, and the …
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In order to explore the influence of the types of waste gypsum on the properties of alkali slag cement, fluorogypsum (FG) and flue-gas desulfurization (FGD) gypsum were comparatively investigated. Moreover, the action mechanisms of FG and FGD gypsum on the properties of alkali slag cement were analyzed. The results …
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the limestone gypsum flue gas desulfurization process, 2.7 ton of desulfurized gypsum can be generated for each 1 ton of SO2 removed [3]. A 300 MW coal-fired thermal power unit discharges about 30,000 ton of desulfurized gypsum every year (assuming 1.0% sulfur in coal) [4]. A substantial amount of desulfurized gypsum is generated as a by …
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