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Apr 24, 2014· A calcining kettle includes a cylindrical housing having a hot air chamber at one end, ... Plaster of Paris is also known as calcined gypsum, stucco, calcium sulfate semihydrate, calcium sulfate half-hydrate or calcium sulfate hemihydrate. It is the hemihydrate form that is mixed with water, then shaped to form a product having an interlocking ...
Feb 06, 1960· Kelley, Southard and Anderson1 have shown that the thermodynamic properties of calcium sulphate hemihydrate depend on whether the hemihydrate is produced from gypsum calcined in a steam-saturated ...
O) at about 100°C (212°F.) and then anhydrous calcium sulfate (CaSO 4 + 1.5H 2 O) at about 180°C (356°F.).5 Significant mass loss and a corresponding decrease in density occur within the calcined portion of the GWB during the calcination process. 6 (This loss of mass and density was re-confirmed in the laboratory bench testing conducted
Gypsum is usually referred to be CaSO 4.2H 2 O. Calcium sulfate dIiydrate undergoes calcination to form hemihydrate (CaSO 4 1/2H 2 O) or anhydrous form (CaSO 4). Initially the calcination process was achieved by heating the raw gypsum material in an open environment, later on with the development in science calcination was achieved by heating ...
The process of calcination derives its name from the Latin calcinare (to burn lime) due to its most common application, the decomposition of calcium carbonate to calcium oxide and carbon dioxide, in order to create cement.The product of calcination is usually referred to in general as "calcine", regardless of the actual minerals undergoing thermal treatment.
A method and system for calcining gypsum to recover gypsum in a form consisting essentially of calcium sulfate anhydrite is disclosed. The method includes the steps of feeding the ground gypsum material into a first kettle and heating the ground gypsum in the first kettle to the first predetermined temperature. The first predetermined temperature is preferably below 400.degree.
May 11, 1976· Calcination of gypsum, in its most common commercial form, involves heating gypsum, calcium sulfate dihydrate, and driving off some of the water of crystallization to form stucco, calcium sulfate hemihydrate. On subsequent addition of water to stucco, it will return to a rock-like calcium sulfate dihydrate.
Referring to FIG. 3, an exemplary process 300 for the post-calcination treatment of beta calcium sulfate hemihydrate (plaster) is shown. The described process is a batch process; however, it is contemplated that the process may be a continuous or semi-continuous process. ... The kettle calcination temperature was 147° C., operating at a ...
Calcining. Plaster or stucco is made by calcining the raw gypsum to convert the dihydrate into a hemihydrate, and is known as calcined gypsum. In some plants, landplaster is fed to kettle or flash calciners to produce plaster. Calcining occurs at about 250°-300°.
Any tea kettle that has seen good use is bound to develop some mineral buildup, which doesn't sound like the easiest thing to clean out. But it's a lot easier than you might think to get even electric kettles as clean as new. Calcium and lime buildups can be dissolved with .
gypsum kettle which may range between 60 and 200 minutes. Due to the kettle being heated indir-ectly the specific thermal energy requirement is about 20 % higher than when the gypsum is cal-cined directly in the gypsum calcining mill ( Tab 1). The quantity of the water to be evaporated in the calcining process also plays an important role.
Calcining of gypsum comprises converting calcium sulfate dihydrate by heating itinto calcium sulfate hemihydrate, better known as stucco. Prior calcining apparatus and methods have taken various forms. Traditionally, the calcining of gypsum has occurred in a large kettle, having a thickened domeshaped bottom, against which a gas-fired flame is ...
In calcium: Compounds. Calcium sulfate, CaSO 4, is a naturally occurring calcium salt.It is commonly known in its dihydrate form, CaSO 4 ∙2H 2 O, a white or colourless powder called gypsum. As uncalcined gypsum, the sulfate is employed as a soil conditioner. Calcined gypsum is used in making tile, wallboard, lath,.
kettle consistency Prior art date 1967-01-11 ... 238000001354 calcination Methods 0.000 description 21; ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound ...
Sep 12, 1978· The process of calcining gypsum which comprises heating a mass of finely ground gypsum in a kettle to a temperature sufficient to convert said gypsum to calcium sulfate hemihydrate, maintaining a substantially continuous supply of gypsum being fed to said kettle, allowing a substantially continuous flow of calcined gypsum at the top of said ...
Continuous calcination of gypsum is provided by uniformly feeding uncalcined gypsum into the calcining batch in a kettle to a location below the surface but above the uppermost agitator, and allowing calcined gypsum to be discharged from the kettle through a discharge outlet in the wall of the kettle at the top surface of the calcining gypsum.
EXAMPLE 2 Production of anhydrite from calcium sulfate hemihydrate The process of Example 2 is quite similar to that of Example 1, with the exception that instead of adding the sulfuric acid at the start of the operation, or when the material in the kettle reaches 2500 F., addition of the acidic material is delayed until calcination to the ...
EP2061731A1 EP07855582A EP07855582A EP2061731A1 EP 2061731 A1 EP2061731 A1 EP 2061731A1 EP 07855582 A EP07855582 A EP 07855582A EP 07855582 A EP07855582 A EP 07855582A EP 2061731 A1 EP2061731 A1 EP 2061731A1 Authority EP European Patent Office Prior art keywords temperature process plaster pressure steam Prior art date 2006-12-20 Legal status (The .
wallboard, gypsum must be partially dehydrated or calcined to produce calcium sulfate hemihydrate (CaSO4 ½H 2O), commonly called stucco. A flow diagram for a typical gypsum process producing both crude and finished gypsum products is shown in Figure 11.16-1. In this process gypsum is crushed, dried, ground, and calcined.
Abstract: A method and apparatus is disclosed for the continuous calcining of gypsum material in a high-efficiency, refractoryless kettle preferably heated by a multiple series of separate immersion tube burner coils, each coil operating within a specific calcining zone inside the kettle. The lowest, i.e., initial, burner tube coil is formed with a low profile to permit use of a small initial ...
US2418590A US534034A US53403444A US2418590A US 2418590 A US2418590 A US 2418590A US 534034 A US534034 A US 534034A US 53403444 A US53403444 A US 53403444A US 2418590 A US2418590 A US 2418590A Authority US United States Prior art keywords acid anhydrite gypsum kettle hemihydrate Prior art date 1944-05-04 Legal status (The legal status is an assumption and is not a .
Calcination of Gypsum. Gypsum or Calcium sulfate dihydrate (CaSo 4.2H 2 O) is a mineral of calcium that is mined in various parts of the world. It is also formed as a by-product of flue gas desulfurization in some coal-fired electric power plants.
Abstract: A process is disclosed for making a blend of alpha- and beta-stucco including a slurry calcination step to produce alpha calcium sulfate hemihydrate followed by a fluidized bed calcination step to produce beta calcium sulfate hemihydrate. The process starts with 50-75% gypsum-containing solids slurry, and then steam calcines the slurry in a first reactor to form partially calcined ...
Aug 01, 2005· The focus of this paper is the calcination step investigating only FGD gypsum wallboard; the impact of additives was not tested. Calcination changes the form of calcium sulfate from calcium sulfate dihydrate (CaSO 4 ·2H 2 O) or gypsum to calcium sulfate hemihydrate (CaSO 4 .
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