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calcination temperature of hemihydrate

Hemihydrate - an overview ScienceDirect Topics

The duration of calcination depends on preliminary drying and grinding rates and varies within 1–3 h, and the temperature of dehydration is 150–180°C. Equivalent fuel consumption is

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Calcination parameters on phosphogypsum waste recycling ...

30/09/2020  The calcination of calcium sulphate dihydrate at temperatures lower than 200 °C originates two different forms of hemihydrate: α-hemihydrate and β-hemihydrate.

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Determination of a partial phase composition in calcined ...

temperature of the calcination process [1]. In Table 1,we provide more details on the calcium sulfate anhydrite modifications. During the hydration of b-phases of gypsum sulfates in calcined gypsum, b-anhydrite III changes to b-hemihydrate V. Tydlita´t R. Cˇerny´ () Department of Materials Engineering and Chemistry, Faculty of

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US4744963A - Highly efficient calcination of gypsum to ...

Hydrodynamic pumping of the fluidized calcining mass in a kettle is set up by the continuous flow of the mass to and from heating rods immersed therein which are constantly emitting at least about 1 British Thermal Unit of heat per minute per square inch of the surface of the rods. The transfer of heat from the walls and bottom of the kettle is enhanced so that more of the available heat is ...

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Gypsum Calcination - Innogyps

Calcination temperature can be set at approximately 135-180℃ and can be tuned to minimize residual gypsum and soluble anhydrite production and maximize hemihydrate production. The kettle stirring rate can be adjusted by a variable DC motor controller and all calcination exhaust is drawn through a cyclone and baghouse dust collection system.

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Reactivity of Calcium Sulphate Hemihydrate - NASA/ADS

01/08/1961  After calcination the material was exposed to the atmosphere at room temperature to allow absorption of moisture until the composition of hemihydrate was attained 1. The reactivity of the product was assessed from the rate of increase in temperature of mixtures of 100 gm. of hemihydrate with 60 gm. of water, held in a Dewar flask 2. The ...

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Highly efficient calcination of gypsum to hemihydrate ...

Highly efficient calcination of gypsum to hemihydrate . United States Patent 4744963 . Abstract: Hydrodynamic pumping of the fluidized calcining mass in a kettle is set up by the continuous flow of the mass to and from heating rods immersed therein which are constantly emitting at least about 1 British Thermal Unit of heat per minute per square inch of the surface of the rods. The transfer of ...

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calcination temperature of hemihydrate

calcination temperature of hemihydrate. Calcium sulfate - Wikipedia, the free encyclopedia. Depending on the method of calcination of calcium sulfate dihydrate, specific ... The temperature and time needed depend on ambient partial pressure of H2O. Read more. Patent WO2013182587A1 - Method for stabilizing beta-hemihydrate ... 12 Dec 2013 ... moistening of said calcined β-Hemihydrate

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Calcination of gypsum to hemihydrate by United States ...

Calcination of gypsum to hemihydrate - AU1987078503. ABSTRACT PATENT DETAILS Inventor/s: Bounini, Larbi; Dozsa, Otto Louis; Janninck, Donald Richard; Stone, Richard Fletcher; Assignee/s: United States Gypsum Company.ii. i' 0 (12) PATENT ABRIDGMENT (11) Document No. AU-B-78503/87 (19) AUSTRALIAN PATENT OFFICE (10) Acceptance No. 602720 (54) Title CALCINATION OF GYPSUM TO HEMIHYDRATE ...

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Reactivity of Calcium Sulphate Hemihydrate Nature

After calcination the material was exposed to the atmosphere at room temperature to allow absorption of moisture until the composition of hemihydrate was attained1. The reactivity of the product ...

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Gypsum Calcination - Innogyps

Calcination temperature can be set at approximately 135-180℃ and can be tuned to minimize residual gypsum and soluble anhydrite production and maximize hemihydrate production. The kettle stirring rate can be adjusted by a variable DC motor controller and all calcination exhaust is drawn through a cyclone and baghouse dust collection system.

More

US4744963A - Highly efficient calcination of gypsum to ...

Hydrodynamic pumping of the fluidized calcining mass in a kettle is set up by the continuous flow of the mass to and from heating rods immersed therein which are constantly emitting at least about 1 British Thermal Unit of heat per minute per square inch of the surface of the rods. The transfer of heat from the walls and bottom of the kettle is enhanced so that more of the available heat is ...

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EP0277208B1 - Highly efficient calcination of gypsum to ...

Method and apparatus for calcining gypsum in a kettle (10) in which the calcined mass is fluidized. Heat for the calcination is supplied by heating rods (46) which are immersed in said bed. Said heating rods (46) supply about 1 British Thermal Unit (Btu) of heat per minute per square inch of surface area of rod. Heat is also supplied to the calcined mass by a hot gas produced by combustion of ...

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Reactivity of Calcium Sulphate Hemihydrate - NASA/ADS

After calcination the material was exposed to the atmosphere at room temperature to allow absorption of moisture until the composition of hemihydrate was attained 1. The reactivity of the product was assessed from the rate of increase in temperature of mixtures of 100 gm. of hemihydrate with 60 gm. of water, held in a Dewar flask 2. The ...

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Grinding and calcining of gypsum with Pfeiffer grinding ...

6 The crystal water content is reduced by a rising exhaust gas temperature. GPSE. GPSE. Gypsum powder . GPSE. For the production of plaster products natural gypsum, synthetic gypsum or a mixture of both are calcined. Depending on the production process two different modifications of the hemihydrate CaSO 4 x ½ H 2 O are obtained. When gypsum is calcined in an atmosphere sat­urated with water ...

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Influence of the Calcination Temperature of Synthetic ...

The transition of the hemihydrate into the unstable phase of anhydrite III in the phases takes place in the temperature range of 170–180C, followed by the occurrence of intense changes at

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Calcination of gypsum to hemihydrate by United States ...

Calcination of gypsum to hemihydrate - AU1987078503. ABSTRACT PATENT DETAILS Inventor/s: Bounini, Larbi; Dozsa, Otto Louis; Janninck, Donald Richard; Stone, Richard Fletcher; Assignee/s: United States Gypsum Company.ii. i' 0 (12) PATENT ABRIDGMENT (11) Document No. AU-B-78503/87 (19) AUSTRALIAN PATENT OFFICE (10) Acceptance No. 602720 (54) Title CALCINATION OF GYPSUM TO HEMIHYDRATE ...

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Influence of the Calcination Temperature of Synthetic ...

The transition of the hemihydrate into the unstable phase of anhydrite III in the β phases takes place in the temperature range of 170–180 °C, followed by the occurrence of

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Calcium sulfate hemihydrate Ca2H2O9S2 - PubChem

Decomposes at high temperature to generate toxic oxides of sulfur. Reacts exothermically but slowly with moisture in the air or water to form gypsum CaSO4.2H2O. CAMEO Chemicals. 10 Toxicity. Help . New Window. 10.1 Toxicological Information. Help. New Window. 10.1.1 Health Effects. Help. New Window. Health Effect Code(s) HE19 - Generally Low Risk Health Effects---Nuisance particulates,

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Reactivity of Calcium Sulphate Hemihydrate - NASA/ADS

After calcination the material was exposed to the atmosphere at room temperature to allow absorption of moisture until the composition of hemihydrate was attained 1. The reactivity of the product was assessed from the rate of increase in temperature of mixtures of 100 gm. of hemihydrate with 60 gm. of water, held in a Dewar flask 2. The ...

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Making of gypsum plaster in Bhutan – An experience

calcination temperatures was increased to 180°C and retained for 1 h at that temperature. The plaster on evaluation showed an improvement in the hemihydrate as well as the insoluble anhydrite contents. It was noted that the gypsum content was minimized to improve the hemihydrate content. Increased quantity of soluble anhydrite forms a coating over hydrating hemihydrate particles and thus ...

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Kiln for Calcing Temperatures Up to 300ºC – Trc-Monterde

Possibility of producing 100% hemihydrate or 85% hemihydrate + 15% anhydrite II; THERMAL ENERGY CONSUMPTION. New patented low-temperature calcination system. It further reduces consumption (approx. 15%) and increases the stability of the material. PRODUCTION AND DIMENSIONS. TYPES OF FUEL THAT CAN BE USED The necessary thermal energy in order to

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Grinding and calcining of gypsum with Pfeiffer grinding plants

The calcining of gypsum at ambient pressure and at a relatively low air humidity takes place much more frequently. The plaster obtained is b-hemihydrate. Its chemical formula is the same as that of a-hemihydrate. As, however, the crystal water escaping from the intermediate lattice struc - ture encounters less resistance through the sur-rounding atmosphere, this process is almost like an ...

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GYPSUM Beneficiation Equipment

23/08/2013  Two natural gypsum (CaSO4? 2H2O) also known as gypsum, calcined, ground available beta hemihydrate gypsum (CaSO4? 1/2H2O), which is also called the building gypsum, plaster, stucco. If the calcination temperature is 190 ° C available plaster model, its fineness and whiteness are high than building gypsum. If the gypsum at 400-500 ° C or higher than 800 ° C calcined gypsum, namely

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Features and Benefits - Rapidwall

Gypsum (calcium sulphate dihydrate) is a material that calcines at a relatively low temperature (150°C - 180°C) to produce the required hemihydrate product. The proportions and forms of dihydrate, hemihydrate and anhydrite in the plaster product are very sensitive to

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Influence of the Calcination Temperature of Synthetic ...

The transition of the hemihydrate into the unstable phase of anhydrite III in the β phases takes place in the temperature range of 170–180 °C, followed by the occurrence of

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The Mechanism of the First Hydration-Dehydration Cycle of ...

One of the major findings from this study was that the properties of the generated hemihydrate and dihydrate after the 1st reaction cycle were based on several factors such as type (α- or β-), purity, and properties of the hemihydrate in addition to the calcination mechanism and grinding procedure. The hydration rate of the recycled hemihydrate was varied due to the variation between the ...

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Calcination of gypsum to hemihydrate by United States ...

Calcination of gypsum to hemihydrate - AU1987078503. ABSTRACT PATENT DETAILS Inventor/s: Bounini, Larbi; Dozsa, Otto Louis; Janninck, Donald Richard; Stone, Richard Fletcher; Assignee/s: United States Gypsum Company.ii. i' 0 (12) PATENT ABRIDGMENT (11) Document No. AU-B-78503/87 (19) AUSTRALIAN PATENT OFFICE (10) Acceptance No. 602720 (54) Title CALCINATION OF GYPSUM TO HEMIHYDRATE ...

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Calcium sulfate hemihydrate Ca2H2O9S2 - PubChem

Decomposes at high temperature to generate toxic oxides of sulfur. Reacts exothermically but slowly with moisture in the air or water to form gypsum CaSO4.2H2O. CAMEO Chemicals. 10 Toxicity. Help . New Window. 10.1 Toxicological Information. Help. New Window. 10.1.1 Health Effects. Help. New Window. Health Effect Code(s) HE19 - Generally Low Risk Health Effects---Nuisance particulates,

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Influence of some conditions of calcination on the ...

Influence of some conditions of calcination on the reactivity of calcium sulphate hemihydrate M. J. Ridge Division of Building Research, Commonwealth Scientific and Industrial Research Organisation, Melbourne, Australia

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Kiln for Calcing Temperatures Up to 300ºC – Trc-Monterde

Possibility of producing 100% hemihydrate or 85% hemihydrate + 15% anhydrite II; THERMAL ENERGY CONSUMPTION. New patented low-temperature calcination system. It further reduces consumption (approx. 15%) and increases the stability of the material. PRODUCTION AND DIMENSIONS. TYPES OF FUEL THAT CAN BE USED The necessary thermal energy in order to

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Production of Synthetic Phosphoanhydrite and Its Use as a ...

17/08/2017  The β form is obtained by calcination and α-hemihydrate is derived from the autoclaving process. In the temperature range of 160–250 °C, anhydrite III or soluble anhydrite is formed, an unstable phase which becomes hemihydrate in the presence of moisture. Above 300 °C anhydrite III becomes anhydrite II (CaSO 4) which has a slower hydration rate, but this can be accelerated by

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METHOD AND APPARATUS FOR PRESSURIZED CALCINATION OF

11. A method for calcining gypsum, comprising: continuously injecting gypsum into a pressurized reactor; heating the gypsum to form a calcined hemihydrate with a lower water demand hemihydrate, the calcined hemihydrate having a water to stucco ratio in the approximate range of 0.45-0.55. 12. The method of claim 11 wherein said pressurized ...

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Restoration of Compressive Strength of Recycled Gypsum ...

hemihydrate (CaSO 4.1/2H 2 O) derived from gypsum, a calcium sulphate dihydrate, by firing this mineral at relatively low temperature and then reducing it to powder (Taylor, 1990). Calcination of the gypsum at higher temperature produces different types of anhydrites of CaSO 4. Calcium sulphate exists in various forms. In the form of γ-anhydrite, it is used as a dessicant. It is also used as ...

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What is Gypsum How Gypsum is Processed MC

Gypsum (CaSO 4 2H 2 O) can be calcined and grinded to obtain β-type hemihydrate gypsum (2CaSO 4 H 2 O), that is, building gypsum, also known as cooked gypsum or plaster. The model gypsum can be obtained when the calcination temperature is 190 °C, and its fineness and whiteness are higher than that of building gypsum. If raw gypsum is calcined at 400 °C or above 800 °C, floor gypsum can ...

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Plaster - Alphaplatre

Our calcination solutions are detailed below: Vertical kiln: Process description. This process enables a constant and slow calcination of the gypsum by direct contact with the hot gases. The high quality plaster obtained has similar characteristics to a mixture of 85% hemihydrate and 15% alpha-hemihydrate.

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Lab Scale Preparation of Gypsum Wallboard

This process is continued until all the excess water is removed. It is dried in the temperature range of 50 ËšC-200 ËšC. Starch paste such as denatured starch and dextrin is used as an auxiliary adhesive to prevent calcination of the crystal of gypsum dihydrate and dehydrated to give a gypsum hemihydrate in drying at high temperatures. Also ...

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Calcining Gypsum Patents and Patent Applications (Class ...

Abstract: Alpha gypsum hemihydrate is obtained by calcining calcium sulfate dihydrate, generated with flue-gas desulfurization of power plants or by chemical process, e.g. in the production of phosphoric acid. The calcining process comprises producing initially a dispersion from calcium sulfate dihydrate and diluted, sulfuric acid solution and heating same at a predetermined rate to about 373 ...

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Gypsum Powder Process Technology, Gypsum Grinding Mill

If gypsum is calcined at 400-500 ° C or above 800 ° C, it is floor plaster, its condensation and hardening time is longer, but after strength, abrasion resistance and water resistance are better compared with ordinary building plaster.

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