autoclave autoclave process gypsum to alpha hemihydrate in Oman

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autoclave autoclave process gypsum to alpha hemihydrate in Oman

ChemInform Abstract: Autoclave-Free Formation of α …

The kinetics fit an autocatalytic process, with a very small initial [product]o (typically ∼10−4 M, consistent with a high purity gypsum starting material) and a rate …

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A Facile Synthesis Process and Evaluations of α-Calcium …

Alpha-calcium sulfate hemihydrate (α-HH) has been used effectively in grafting through its desired features to support bone regeneration. In recent years, many synthetic methods have been proposed. Among them, the autoclave method for manufacturing α-HH is best suited for cost-savings due to its simple operation and …

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Influence of α-Calcium Sulfate Hemihydrate on Setting, …

1. Introduction. Gypsum is a material in which the amount of water of crystallization varies with its surrounding conditions, such as temperature or humidity, and can be classified into three groups, namely, calcium sulfate anhydrite (CaSO 4), calcium sulfate hemihydrate (CaSO 4 ∙1/2H 2 O), and calcium sulfate dihydrate (CaSO 4 ∙2H 2 …

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Autoclave-Free Formation of α-Hemihydrate Gypsum

Under optimal working conditions the quality of the formed α-hemihydrate gypsum is similar to that of a material produced in an autoclave. References. 1 E. Eipeltauer, " Preparation of Crude Gipseous Rock and Its Conversion into Its Various Hemihydrate Plaster Forms " (in Ger.), Zem.–Kalk–Gips, 11, 264, 304 ( 1958 ).

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Effect of pH on the Preparation of α‐Calcium Sulfate Hemihydrate …

pH is one of the most important parameters that determine the crystallization process, but it is always neglected in the preparation of {alpha}-calcium sulfate hemihydrate ({alpha}-HH) from calcium sulfate dihydrate (DH) with the hydrothermal method. Flue gas desulfurization (FGD) gypsum, which is mainly composed of DH, was …

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Autoclave‐Free Formation of α‐Hemihydrate Gypsum

Flue gas gypsum may be converted to α-hemihydrate by suspending the starting material in inorganic salt solutions of high concentration or in diluted sulfuric acid and maintaining the suspension at boiling, or near boiling temperature for a period of time. The crystal morphology of the produced α-hemihydrate gypsum and, thus, its quality …

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Autoclave‐Free Formation of α‐Hemihydrate Gypsum

Under optimal working conditions the quality of the formed α-hemihydrate gypsum is similar to that of a material produced in an autoclave. Discover the world's research 25+ million members

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Studies on the Preparation of Calcium Sulfate Hemihydrate …

Several fabrication approaches are commonly adopted to prepare the a-CSH, including autoclave heating and chemical synthesize methods etc. 4,5,[18][19][20][21] Among them, autoclave heating is one ...

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Kinetic model for calcium sulfate α-hemihydrate

Modeling of the kinetics of the synthesis process for calcium sulfate alpha-hemihydrate from gypsum formed by flue gas desulfurization (FGD) is important to produce high-performance products with ...

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Autoclave-Free Formation of α-Hemihydrate Gypsum

that of a material produced in an autoclave. [Key words: gypsum, autoclaves, production processes, acids, flue.] I. Introduction U NDER industrial conditions, a-hemihydrate …

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[PDF] Preparation of α-calcium sulfate hemihydrate from …

DOI: 10.37190/ppmp/130795 Corpus ID: 229503933; Preparation of α-calcium sulfate hemihydrate from industrial by-product gypsum: A review @article{Guan2020PreparationO, title={Preparation of $alpha$-calcium sulfate hemihydrate from industrial by-product gypsum: A review}, author={Qingjun Guan and …

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Calcium Sulfate Hemihydrate

The α form material is also produced by heating gypsum, but this material is heated to 123 °C under approximately 1.2 kg/cm 2 (17 psi) of pressure, in steam for 5 to 7 hours in an autoclave. Processing gypsum in this way produces more dense crystals with little porosity, and these crystals require less water for setting and produce the dense ...

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Autoclave‐Free Formation of α‐Hemihydrate Gypsum

Here, a dynamic method, or an improved autoclaved process, was used to produce α-calcium sulfate hemihydrate from FGD gypsum. In this process, the …

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Studies on the preparation of calcium sulphate hemihydrate …

To enable further work to be carried out on the hydration of hemihydrate plasters, materials purer than the available commercial plasters and with reproducible properties were required. As a first stage in the attempted preparation of such materials, the process variables in the autoclave dehydration of gypsum were investigated. Methods …

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Crystallization kinetics of large-sized column α-hemihydrate gypsum …

Direct production of high-strength α-calcium sulfate hemihydrate (α-HH) with no additives was accomplished by the reaction of aluminum sulfate and waste CaCl2 discarded from Solvay soda plant.

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Preparation of alpha-calcium sulfate hemihydrate from FGD gypsum …

The optimum condition for α-HH prepared by hydrothermal autoclave method was pH of 4, temperature of 140 °C for 2.0 h with solid–liquid ratio of 4:5. ... sulfate hemihydrate from FGD gypsum ...

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Preparation of α-calcium sulfate hemihydrate from FGD gypsum …

DOI: 10.1016/J.FUEL.2009.01.004 Corpus ID: 98555701; Preparation of α-calcium sulfate hemihydrate from FGD gypsum in K, Mg-containing concentrated CaCl2 solution under mild conditions

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Characterization and precipitation mechanism of α …

Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. ... Zürz A, Older I, Thiemann F, et al. Autoclave-free formation of α-hemihydrate gypsum. J Am Ceram Soc, 1991, 74(5): 1117–1124. ... D G, Yang, X Y, Yang, S Z, et al. A …

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Synthesis of α-hemihydrate gypsum from cleaner phosphogypsum

Phosphogypsum (PG), as a waste by-product with high content and complicated impurities, is difficult to be utilised effectively. Herein, cleaner PG is prepared with "HCl H 2 SO 4 method", and thus is used to synthesise α-hemihydrate gypsum (α-HH) in CaCl 2 solution under atmospheric pressure. Morphology and mechanical …

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Process for producing alpha-hemihydrate gypsum

alpha-hemihydrate gypsum involves placing calcium sulfate dihydrate in an autoclave in the presence of saturated steam at elevated pressure over an extended period of time. This method can be used for autoclaving of lump or ground gypsum. Typical pressures for the autoclave can be from atmospheric to about 15 psi.

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Understanding gypsum in 3 diagrams

Alpha hemihydrate is formed in an autoclave above 100°C in a water (suspension autoclave) or in a steam autoclave. 5 - 7 This is possible as, above 100°C, …

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Research of some actors on influencing the granularity, …

Pouring time should be controlled in the time before α-hemihydrate decorative gypsum hydration, and the pouring temperature can be slightly lower than the autoclave temperature. The process of ...

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Calcining processes for natural and synthetic gypsum

With systems such as mill calcining systems for combined grinding and calcining, the rotary kiln, the kettle, and the rotary tubular calciner, as well as continuous autoclaves for the production of alpha hemihydrate, Grenzebach supports its customers so they can optimally process gypsum to ensure that the finished product has the desired qualities.

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Autoclave-Free Formation of α-Hemihydrate Gypsum.

Autoclave‐Free Formation of α‐Hemihydrate Gypsum. A. Zurz I. Odler F. Thiemann Katarina Berghöfer. Materials Science. 1991. Flue gas gypsum may be …

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during the Dehydration Process

process at around 100 C in an autoclave ﬁlled with gypsum slurry. In this process, larger In this process, larger hemihydrate crystals can grow with fewer surface defects.

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α-calcium sulfate hemihydrate preparation from FGD gypsum …

DOI: 10.1016/J.CEJ.2011.09.033 Corpus ID: 96659014; α-calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions @article{Guan2011calciumSH, title={$alpha$-calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions}, author={Baohong Guan and Li …

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What is the Difference Between Alpha and Beta Hemihydrate

The process of converting gypsum into alpha hemihydrate involves heating gypsum at a specific temperature to remove water molecules, resulting in a more concentrated and stable form of calcium sulfate. The term "alpha" in alpha hemihydrate refers to the unique crystal structure formed during this dehydration process. The alpha …

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Autoclave-Free Formation of α-Hemihydrate Gypsum.

Semantic Scholar extracted view of "Autoclave-Free Formation of α-Hemihydrate Gypsum." by A. Zuerz et al. Skip to search form Skip to main content Skip to ..., title={Autoclave-Free Formation of $alpha$-Hemihydrate Gypsum.}, author={A. Zuerz and Ivan Odler and Felicia Thiemann and Katarina Bergh{"o}fer}, …

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Formation of α-Hemihydrate Inside of a Gypsum Crystal …

None of the experiments were performed in an autoclave; gypsum crystals were only heated in a furnace and the crystal seems to be acting as an autoclave. Through several experiments, it was clearly shown that the new-formed crystals inside of the gypsum crystal are alpha-hemihydrate and the experimental proof for Fowler et al. theory was provided.

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Formation of α-Hemihydrate Inside of a Gypsum Crystal …

Gypsum (calcium sulfate dihydrate) is one of the most used inorganic binding materials in the world. During calcination, calcium sulfate subhydrates are formed and, …

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