Heating – Work chamber having heating means – Having means by which work is progressed or moved mechanically
Patent
1995-08-15
1998-04-28
Bennett, Henry A.
Heating
Work chamber having heating means
Having means by which work is progressed or moved mechanically
432 58, 432135, 432197, 432214, 432223, F27B 1400
Patent
active
057437289
ABSTRACT:
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. F. so that the gypsum will still contain a sufficient amount of chemically-combined water so that it will self-fluidize by release of water vapor so that it will flow through the apparatus. The ground gypsum is then overflowed through at least one subsequent stage and heated to a final predetermined temperature to produce an anhydrite product. To produce insoluble calcium anhydrite or dead burn material, the final predetermined temperature is greater than 900.degree. F. and preferably within the range of about 900.degree. F.-1300.degree. F. In the subsequent stages, the gypsum powder is heated and simultaneously fluidized with a fluidizing media, preferably air, so that the ground gypsum will flow through the apparatus. In the preferred embodiment, the ground gypsum is fluidized by a plurality of mixing blades having air injection pipes along their breaking edges for injecting air into the gypsum and a plurality of air injection nozzles disposed radially about a periphery of the kettles. The fluidization of the ground gypsum in the subsequent stages ensures that it will flow through the apparatus for production of an anhydrite product.
REFERENCES:
patent: 2261872 (1941-11-01), Choate
patent: 3236509 (1966-02-01), Blair
patent: 3307840 (1967-03-01), Conroy, Jr.
patent: 3307915 (1967-03-01), Conroy et al.
patent: 3378246 (1968-04-01), Leding
patent: 3576599 (1971-04-01), Anderson et al.
patent: 3669435 (1972-06-01), Silverberg
patent: 3871829 (1975-03-01), Keith et al.
patent: 3901645 (1975-08-01), Rowland
patent: 4113836 (1978-09-01), O'Conner
patent: 4117070 (1978-09-01), O'Neill
patent: 4161390 (1979-07-01), Page et al.
patent: 4176157 (1979-11-01), George et al.
patent: 4188186 (1980-02-01), Ladwig
patent: 4215981 (1980-08-01), Von Dreusche, Jr.
patent: 4227873 (1980-10-01), Manshausen et al.
patent: 4238238 (1980-12-01), Kinkade et al.
patent: 4522587 (1985-06-01), Miller
patent: 4533528 (1985-08-01), Zaskalicky
patent: 4576573 (1986-03-01), Ruehenbeck
patent: 4626199 (1986-12-01), Bounini
patent: 4629419 (1986-12-01), Ward et al.
patent: 4744961 (1988-05-01), Bounini
patent: 4744963 (1988-05-01), Dozsa et al.
patent: 4915623 (1990-04-01), Ball et al.
patent: 5007825 (1991-04-01), Williams
patent: 5011668 (1991-04-01), Ball et al.
patent: 5139749 (1992-08-01), White
Page from Babcock--BSH catalog showing rotary drum calciners with coolers. Germany. Such rotary calciners were first used in 1925.
Page from Krupp Polysius catalog showing POLCAL calcining system. Netherlands. One such calcining system was in use starting in 1993.
British Gypsum Limited "High Efficiency Calcining of Gypsum", 1988, pp. 1-8 .
Cloud Michael L.
Moore Kirk S.
Bennett Henry A.
Lu Jiping
USG Corporation
LandOfFree
Method and system for multi-stage calcining of gypsum to produce does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for multi-stage calcining of gypsum to produce, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for multi-stage calcining of gypsum to produce will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1527135