Abstract:
A method for synthesizing a natural calcium sulfate based hydraulic bonding agent (gypsum), whereby the calcium sulfate is heated to obtain a high proportion of anhydrite III or alpha and thermal dipping occurs. Said method consists in the following : the calcium sulfate is completely dehydrated and the matter thus dehydrated is cooled in a brutal manner. Preferably, the present invention can be used in the construction industry in order to obtain a hydraulic bonding agent that can be used as cement.
Abstract:
The present application describes a process for the continuous production of alpha- calcium sulphate hemihydrate, the process comprising the steps of: providing particulate gypsum; providing water; mixing the particulate gypsum and the water to form a gypsum slurry; and maintaining said gypsum slurry under raised pressure and temperature to convert the particulate gypsum into alpha-calcium sulphate hemihydrate and provide an alpha-calcium sulphate hemihydrate slurry. Additionally, the particulate gypsum comprises a D10 value greater than or equal to 2 μm, a D90 value smaller than or equal to 90 pm and a D50 value smaller than or equal to 25 μm. Particulate gypsum for use in the process is also provided.
Abstract:
The present application describes an industrial calciner for particulate material, wherein the industrial calciner comprises: a calcination vessel; and a gas supply system in fluid communication with the calcination vessel, the gas supply system configured to supply a flow of calcination gas to the calcination vessel, wherein the industrial calciner further comprises at least one electric heater configured to heat the calcination gas, the industrial calciner further comprising at least one humidity modifier and a humidity control system for controlling the output of the at least one humidity modifier. Use of the industrial calciner and a method of calcining particulate material with the industrial calciner are also described.
Abstract:
A process for treating beta calcium sulfate hemihydrate is disclosed. The process comprises exposing beta calcium sulfate hemihydrate to steam at a pressure above atmospheric pressure.
Abstract:
The invention relates to the building material and binder industry and is used for producing high-strength alpha-semihydrate and alpha-anhydrite gypsum binders. The inventive device for hydrothermally treating and drying plaster stone comprises a working chamber-autoclave (1) provided with a hot heat-carrier supply system, a vacuum receiver (41), a vacuum pump (42), a gas-distributing manifolds and rapid-acting dampers (11, 13, 15, 17). Said plant also comprises an even number of gas- distributing segmental sections (3) which are symmetrically arranged with respect to the vertical axis of the working chamber and are separated from each other by a vertical tight partition (4), wherein vertical rectangular walls (5) separating the gas-distributing sections (3) from the service volume of the working chamber (1) are provided with a perforation increasing the flow through cross-section of gas windows from the top downward along the wall height. Each gas-distributing section (3) is connected to a gas-intake pipe (6) provided with an adjustable gas shut-off gate (7). All gas-intake pipes (6) are connected to symmetrical gas-distributing pipes (8) which are provided with adjustable gas gates (9) connected in the mid-length thereof to pipes (10) comprising rapid-acting dampers (11).
Abstract:
The present invention provides a process for treating a particulate material, in which particles of the material to be treated interact with non-static particles of a second material, the process comprising the steps of: (i) providing a processing chamber (1) having an inlet (7) and an outlet (10) spaced downstream therefrom, the base (15) of said chamber comprising a plurality of outwardly radiating inclined vanes (20, 25), (ii) providing a host bed of particles (30) in the chamber (1) and generating a flow of fluid through the vanes (20, 25) at the base (15) of the processing chamber such that the bed of host particles (30) circulates about an axis (102) of the chamber in a compact band, (iii) injecting particles of the material to be treated through an inlet (5) of the chamber (1) to contact with the circulating bed of the host particles (30), wherein the relative terminal velocity of the particles to be treated (45) and the host particles (30) is such that there is little or substantially no migration of the host particls to the outlet (10), and wherein substantially all of the particles of the material to be treated migrate downstream through the circulating host particles to the outlet (10).
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 gypsum charge, and hence, a quick kettle start-up cycle. That low profile initial burner design also helps keep the agitator motor's load at a minimum during cycle start-up. Due to the immersion tube burner coil construction, no refractory structure for the kettle is required. Also, no separate hot pit structure is required, as the kettle is used to merely hold the material being calcined and no residual heat is present. A relatively thin kettle can be constructed, as it needs only withstand relatively low operating temperatures. The kettle's staged, interiorly-disposed burner tube coils act to directly transfer burner tube heat to the kettle's contents, and the coils exhaust exteriorly of the kettle. The present calcining method and apparatus permit substantially improved tonnage output of calcined material, for a kettle of a given size. A modification to the present apparatus includes structure for recovering and recycling a portion of the spent burner gases, and also separate structure for forced aeration air, both preferably for introduction through the kettle bottom. One alternate embodiment concerns a differently-shaped kettle design. Another alternate embodiment concerns a modified kettle which uses a single immersion burner tube coil to provide the total heating of the kettle's contents, for use in certain calcining applications.
Abstract:
A system (100) for calcining natural gypsum, synthetic gypsum (112) or a combination thereof, the system including: a mill (114) for grinding and drying natural gypsum, synthetic gypsum (112) or a combination thereof, to produce dried gypsum (116); a flash calciner (118) for calcining the dried gypsum to produce an exhaust gas (130) and calcined gypsum (128); and a mechanism (134) for transporting at least a portion of the exhaust gas (130) produced by the flash calciner (118) to an air heater (126) that supplies hot gas (126a) to the flash calciner (118).
Abstract:
Verfahren zur Herstellung von Alpha-Calciumsulfat-Halbhydrat aus Calcium-Dihydrat mit den folgenden Merkmalen: a) Beschickung eines Rührautoklaven (1) mit Calciumsulfat-Dihydrat, b) indirekte Beheizung des Rührautoklaven (1), c) gesteuerte Zugabe und Einmischung von Wasser, d) Verhinderung von Anbackungen an Flächen des Reaktionsraums durch bewegte, an den Paddeln und/oder der Antriebswelle (16) des Rührautoklaven (1) angebrachte, Ketten (3), e) intervallmäßige oder kontinuierliche Regelung des Drucks im Reaktionsraum durch Dampfabfluss bei dem Erreichen eines bestimmten Drucks im Innenraum, wobei der Dampf über einen Zyklonabscheider (17) und ein Stellventil (18) geführt wird, f) Zufuhr von kalter Luft zur Resttrocknung, g) Entfernen des Prozessgutes, sowie entsprechende Vorrichtung zur Durchführung des Verfahrens.