The flexural and compressive strength of binding materials fabricated by calcining FGD gypsum at 190 ℃ for 30–120 min are presented in Fig. 7 b, showing that they increase with calcination time up to 90 min and then decrease with longer calcination time, their maximum values are 3.3 MPa and 7.3 MPa, respectively. This phenomenon is ...
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Calcination occurs at approximately 120 to 150°C (250 to 300°F), and 0.908 megagrams (Mg) (1 ton) of gypsum calcines to about 0.77 Mg (0.85 ton) of stucco. ... Gypsum and stucco are usually transferred from one process to another by means of screw conveyors or bucket elevators. Storage bins or silos are normally located downstream of roller mills
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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. ... After the calcination under 180 °C for 120 min, some smaller particles appeared on the surface of the desulfurized gypsum, and the specific surface area ...
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Red mud (RM) is the major waste with strong alkaline discharge produced in alumina manufacturing. The main chemical compositions are Fe 2 O 3, Al 2 O 3, and SiO 2, which are similar to those of the raw materials for SAC.RM is a kind of waste with large output and serious pollution, and its effective disposal is the important problem facing the environment at …
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Fly ash and desulfurized gypsum used in this experiment were from Shanxi Power Generation Co., Ltd. The coal gangue came from Yangquan, Shanxi. The cement was ordinary 42.5 cement sold on the market. The main chemical components of red mud, fly ash and desulfurized gypsum were analyzed by XRF, and the results are shown in
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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 Chinese government has …
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The results show that adding 1% porous mineral material to the desulfurization gypsum with higher chloride ion content can improve the wet-thermal bonding properties …
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The results indicate there are differences in the hydration swelling mechanism between α-gypsum and β-gypsum. The expansion of gypsum is the result of the combined effect of the crystal transformation and the release hydration heat during the hydration process.
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Fly ash and desulfurized gypsum used in this experiment were from Shanxi Power Generation Co., Ltd. The coal gangue came from Yangquan, Shanxi. The cement was ordinary 42.5 cement sold on the market. The main chemical components of red mud, fly ash and desulfurized gypsum were analyzed by XRF, and the results are shown in Table 1.
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The gypsum decomposition and formation mechanisms of calcium ferrite are the main focus areas of theoretical research (Higuchi et al., 2016; Dilner et al., 2017; Zheng and Ning, 2013) related to desulfurization gypsum.In a study on gypsum decomposition, Zhang (Zhang and Ren, 2015) evaluated the reduction of CaSO 4 using coke as a reducing agent, and concluded …
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The results show that the obtained hemihydrate gypsum mixing with water can prepare high-performance building gypsum after the FGD gypsum adding 3–5 wt% of CaO is …
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In this study, by adding a small amount of calcined desulfurization gypsum and aluminate cement into slag powder cement, the effects of calcined desulfurization gypsum and aluminate cement …
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A desulfurized gypsum and calcination technology is applied in the field of desulfurized gypsum calcination equipment, which can solve the problems of insufficient gypsum calcination and reduce gypsum calcination efficiency, and achieve the effects of ensuring sufficient integrity, simple structure and improving calcination efficiency.
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In the experiment, desulfurized gypsum is added as an admixture to a fly ash-slag-based geopolymer curing agent, and the resulting solidified soil is investigated through various …
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Hence, this study presents a novel environmentally friendly composite, formed by sodium hydroxide (used as an activator), desulfurized gypsum, and steel slag (S-GS). The main objective of this study is to synthetically evaluate the potential use of S-GS for solidifying Lead-Cadmium contaminated clay under the condition of carbonation curing.
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This work provides a novel approach to fabricate binding materials from flue gas desulfurization (FGD) gypsum. Results show that high performance binding materials composed of 96% hemihydrate gypsum (HH) and 4% anhydrite are prepared by calcining FGD gypsum at 190 ℃ for 90 min. They present low setting times and high mechanical strength, because HH …
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Desulfurized gypsum is widely applied to building material industry. Through different ways, it can almost replace majority of natural gypsum. Comprehensive disposal technology in china has taken steps. The utilization prospect contains a great market
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Calcination process of desulfurized gypsum (1) Low temperature and slow calcination. Low-temperature slow-speed calcination means that the material stays in the calcination equipment for a long time, and the feeding and discharging time is at least tens of minutes. Rotary kiln, indirect fluidized fluidized furnace, etc. are all low-temperature ...
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Specifically, we deal with the response of gypsum partitions subjected to fire exposures. While models do currently exist [2-4], most utilize a single energy conservation equation. To approximate the effects of mass transport through and chemical dehydration of the materials that comprise the core of the gypsum wallboard, the
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Gypsum is the crystalline chemical compound CaSO4·2H2O. A close chemical relation – and frequently occurring with Gypsum – is Anhydrite which is CaSO4. Gypsun has …
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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 Chinese ...
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Performance Analysis and Improvement of Gypsum Board Prepared from Desulfurized Gypsum with High Chloride Ion Content March 2020 IOP Conference Series Materials Science and Engineering 740(1):012048
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gypsum was calcined in the DRY-36 high temperature industrial furnace of Shanghai Kecheng Company. The calcination system was as follows: heating up from room temperature to 800 ℃, and constant temperature for 1h, and then reduced to room temperature. In addition, the desulfurization gypsum before thermal activation and the
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To solve the problem of the low early strength of the fly ash-desulfurized gypsum system, this study innovatively uses sulfate to increase its early strength without shrinking late …
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Additionally, after 500 °C calcination pre-treatment, the amounts of P 2 O 5, SiO 2, and CaO decreased while the amounts of SO 3 increased. However, raw and calcined PG had drastically different mineral compositions; CaSO 4 ·2H 2 O was the predominant mineral in the former, while CaSO 4.0.5H 2 O was the predominant mineral in the latter. In addition, the …
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In terms of using gel materials, the desulfurized steel slag and desulfurized gypsum, these methods can increase the soil EC by 400, 470 and 600 μs·cm –1, respectively (Li et al., 2024; Qi et al., 2024; Tian et al., 2023; Zhou et al., 2023). The increase in EC indicated an increase in soil salinity, further increasing the risk of soil ...
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Gypsum calcined at 500 and 600 °C did not hydrate completely even after curing at 100 % RH for 8 days and samples still contained > 40 and 70 wt% anhydrite II, respectively. Calcination at 700 °C rendered anhydrite even less reactive and only ∼ 5 wt% had transformed into gypsum after 8 days.
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In this paper, coal gangue, carbide slag and desulfurized gypsum (DG) were used as raw materials to calcine the all-solid-waste-based belite sulphoaluminate cement (BSAC), …
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Gao [18] used red mud, blast furnace slag, steel slag, desulfurized gypsum (DG) and carbide slag as raw materials to prepare BSAC. The result shows that the optimum calcination system was found that the calcination temperature was 1300 °C, and the holding time was 60 mins, and the compressive strength of cement reached 29.3 MPa at 28 d.
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FGD Gypsum: TS = FGD GYPSUM: 2010–01-01 to 2023–05-08 ... 55.67: 11.14: 18.01, calcination at about 1300 °C: Highest compressive strength upto 61.3 MPa attained [123] 3.5% of FGDG: ... The research findings of various scientists for water resistance, drying shrinkage, and compaction under freeze–thaw cycles of FGDG based building ...
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The calcination-treated FGD gypsum would not influence the type and morphology hydration products of the calcium sulfur aluminate cement-fly ash-FGD gypsum system, and the calcination of FGD gypsum is able to promote the hydration degree of fly ash especially in the presence of lime, making the hardened slurry more compact [8,9,10].
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desulfurized gypsum and natural gypsum, the more appropriate ratio is 1.0, and the setting time meets the setting time of cement when the mixing amount is 3%. Therefore, it is feasible to mix desulfurized gypsum and natural gypsum as retarder of Portland cement. Fig 5. Effect of ratio of desulfurized gypsum to natural gypsum on setting time of ...
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Gypsum has micro-expansion characteristic during the process of hydration and solidification, and there are certain differences in the hydration expansion characteristics of different types of ...
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Tan et al. studied the process parameters of direct wet mineralization of CO 2 with desulfurized gypsum and established a reaction model of direct wet mineralization of CO 2 with desulfurized gypsum in an ammonia medium system. 60 There is a competition between the CO 2 absorption reaction and NH 2 COO − hydrolysis reaction, in which the CO 2 ...
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