CA1044014A - Calcining calcium sulphate dihydrate - Google Patents
Calcining calcium sulphate dihydrateInfo
- Publication number
- CA1044014A CA1044014A CA213,730A CA213730A CA1044014A CA 1044014 A CA1044014 A CA 1044014A CA 213730 A CA213730 A CA 213730A CA 1044014 A CA1044014 A CA 1044014A
- Authority
- CA
- Canada
- Prior art keywords
- vessel
- tube
- calcination
- mass
- calcining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
- Baking, Grill, Roasting (AREA)
- Adhesives Or Adhesive Processes (AREA)
- Noodles (AREA)
- Commercial Cooking Devices (AREA)
- Cookers (AREA)
Abstract
ABSTRACT
A method and apparatus for calcining calcium sulphate dihydrate in a calcination vessel in which the dihydrate is heated in the vessel to calcination temperature not only by heat applied to the exterior of the vessel but also by hot gas, especially hot gaseous combustion products, supplied into the interior of the mass of calcining material within the vessel.
The supply of hot gas according to the invention can improve the production rate in both batch and continuous calcination operations without adversely affecting the product quality, by permitting increase in the heat input to the vessel without entailing the risk of vessel bottom burn-out.
A method and apparatus for calcining calcium sulphate dihydrate in a calcination vessel in which the dihydrate is heated in the vessel to calcination temperature not only by heat applied to the exterior of the vessel but also by hot gas, especially hot gaseous combustion products, supplied into the interior of the mass of calcining material within the vessel.
The supply of hot gas according to the invention can improve the production rate in both batch and continuous calcination operations without adversely affecting the product quality, by permitting increase in the heat input to the vessel without entailing the risk of vessel bottom burn-out.
Description
~0~4~
This invention relates`to-a method and apparatus for calcining calcium sulphate dihydrate, and more especially to-the production of calcined plaster from gypsum employing a calcining kettie.
Gypsum calcination can be carried out as a batch or continuous operation In our view, the production rate in both batch and continuous kettle calcinations is at present limited by the maximum permissible heat transfer through the kettle bottom. The quantity of heat which can be transferred through the kettle bottom is limited because there is a maximum ~
allowed temperature of the bottom metal, steel, of the kettle. Above this ;
limit there is a danger of frequent kettle bottom burn-outs. The present invention aims to increase the heat inp;lt to the calcining kettles in both batch and continuous operations, thereby increasing the production capacity of the kettle, without risk of adversely affecting the product quality, or of significantly increasing kettle bottom temperatures.
According to the present invention there is provided a method of calcining calcium sulphate dihydrate in a calcination vessel which comprises heating the dihydrate in the vessel to calcination temperature by applying heat to the exterior of the vessel and simultaneously by supplying hot gases into the interior of the mass of calcining material within the vessel, through
This invention relates`to-a method and apparatus for calcining calcium sulphate dihydrate, and more especially to-the production of calcined plaster from gypsum employing a calcining kettie.
Gypsum calcination can be carried out as a batch or continuous operation In our view, the production rate in both batch and continuous kettle calcinations is at present limited by the maximum permissible heat transfer through the kettle bottom. The quantity of heat which can be transferred through the kettle bottom is limited because there is a maximum ~
allowed temperature of the bottom metal, steel, of the kettle. Above this ;
limit there is a danger of frequent kettle bottom burn-outs. The present invention aims to increase the heat inp;lt to the calcining kettles in both batch and continuous operations, thereby increasing the production capacity of the kettle, without risk of adversely affecting the product quality, or of significantly increasing kettle bottom temperatures.
According to the present invention there is provided a method of calcining calcium sulphate dihydrate in a calcination vessel which comprises heating the dihydrate in the vessel to calcination temperature by applying heat to the exterior of the vessel and simultaneously by supplying hot gases into the interior of the mass of calcining material within the vessel, through
2 a tube extending downwardly from the top of the calcination vessel into the mass of calcining material within the vessel. ~
The invention also provides apparatus for calcining calcium -sulphate dihydrate comprising a calcination vessel, means for heating the exterior of said calcination vessel, and a tube for leading hot gases to the interior of said calcination vessel, extending from the top of the calcination vessel downwardly into the interior thereof.
In the preferred form of the invention, use is made of a fuel burner enclosed within or connected to ~he tube~ the tube passing downwards from the top of the calcination vessel to lead and direct combustion gases into the bed of gypsum mineral or other form of calcium sulphate dihydrate.
'J~
The combustion gases are preferably distributed through rows of distribution holes located on the tube within the bed. The burner may be conveniently located on top of the gypsum calcining kettle, with the tube leading into -the bed. The tube should preferably be open-ended at the lower end. An auxiliary-air inlet should preferably be provided at the upper end of the tube whereby an auxiliary air flow can cool the walls of the tube in the free space above the bed, and control the temperature of the mixture of air and hot combustion gases in the tube as required, for the production of hemihydrate plasters, anhydrous plasters and/or mixtures including projection plaster.
For the insertion of the tube inside the existing conventional calcination kettles, modifications may have to be made to some of the existing stirrer blades to allow location of the tube within the kettle.
It may be possible to use a hollow stirrer shaft as the combustion tube, or the combustion tube may be mounted concentrically around the -.~ .
. . , : . , , . , . ~
~4~
shaft. These modifications will not, in general, adversely affect the performance of the kettle, or the characteristics of the plaster product.
The present invention will now he more fully described by way of example only, with reference to the accompanying drawings, in which:
Figure 1 illustrates schematically the control system for the heat-supplying tube used in the inven- ;
tion, Figure 2 shows partly in section the heat-supplying tube, and ;-Figures 3 and 4 show side elevations of two types of continuous calcination kettles provided with heat-supplying tubes.
Referring to Figures 1 and 2, a mixture of air and fuel gas, for example natural gas, is supplied through a pipe 1 to a gas burner 2. The fuel-air mixture is ignited / `
by a spark probe 3 and the hot, gasèous products of com-bustion pass downwardly through a tube 4 within which i~
the burner 2 is enclosed. The tube 4 in its preferred form is open-ended at its lower end and is provided with rows of holes 5 for distributing the hot gases to material in which ~ ~-the tube is immersed. Auxiliary air is supplied through an inlet 6 in the side of the tube 4 controlling the tempera-ture of the ho~ gases passing through the tube 4.
The fuel gas is supplied along a line 7 provided with a non-return valve 8, a governor 9 and a meter 11, to :: ' -4- ~
. . . . . .
~44(7~
an injector 12 where it mixes with combustion air supplied along a line 13. The fuel-air mixture is then blown by a booster fan 14 to the burner 2 along the line 1. Control valves 16 and 17 are provided in the fuel and air lines 7 and 13, respectively, for controlling the flow rates, whereby the heat generated by the burner can be controlled and the optimum fuel to air ratio can be selected.
An electrical control unit 18 is provided~ which supplies the electrical impulse l`or the ignition spark along a lead 19 to the spark pro~e 3. As a safety precaution a flame-sensing probe 21 is positioned within the heat-supplying tube 4 and-is arranged to be impinged `~
upon by the flame from the burner 2. The probe 21 is connected by a lead 22 to the control unit 18. In the ~`
event of flame failure, the control unit 18 automatically closes a solenold-operated valve 23 in the fuel supply line`
7, the valve 23 being connected to the control unit 18 by a lead 24.
The auxiliary air for the heat-supplying tube 4 is blown to the auxiliary air inlet from a fan 20 along a line 25, and the supply of the auxiliary air can be controlled by a valve 30 in the line 25.
Referring to Pigures 3 and 4, there are shown heat-supplying tubes 4, each similar to that shown in Figure 2, fitted into continuous calcination kettles of capacity of
The invention also provides apparatus for calcining calcium -sulphate dihydrate comprising a calcination vessel, means for heating the exterior of said calcination vessel, and a tube for leading hot gases to the interior of said calcination vessel, extending from the top of the calcination vessel downwardly into the interior thereof.
In the preferred form of the invention, use is made of a fuel burner enclosed within or connected to ~he tube~ the tube passing downwards from the top of the calcination vessel to lead and direct combustion gases into the bed of gypsum mineral or other form of calcium sulphate dihydrate.
'J~
The combustion gases are preferably distributed through rows of distribution holes located on the tube within the bed. The burner may be conveniently located on top of the gypsum calcining kettle, with the tube leading into -the bed. The tube should preferably be open-ended at the lower end. An auxiliary-air inlet should preferably be provided at the upper end of the tube whereby an auxiliary air flow can cool the walls of the tube in the free space above the bed, and control the temperature of the mixture of air and hot combustion gases in the tube as required, for the production of hemihydrate plasters, anhydrous plasters and/or mixtures including projection plaster.
For the insertion of the tube inside the existing conventional calcination kettles, modifications may have to be made to some of the existing stirrer blades to allow location of the tube within the kettle.
It may be possible to use a hollow stirrer shaft as the combustion tube, or the combustion tube may be mounted concentrically around the -.~ .
. . , : . , , . , . ~
~4~
shaft. These modifications will not, in general, adversely affect the performance of the kettle, or the characteristics of the plaster product.
The present invention will now he more fully described by way of example only, with reference to the accompanying drawings, in which:
Figure 1 illustrates schematically the control system for the heat-supplying tube used in the inven- ;
tion, Figure 2 shows partly in section the heat-supplying tube, and ;-Figures 3 and 4 show side elevations of two types of continuous calcination kettles provided with heat-supplying tubes.
Referring to Figures 1 and 2, a mixture of air and fuel gas, for example natural gas, is supplied through a pipe 1 to a gas burner 2. The fuel-air mixture is ignited / `
by a spark probe 3 and the hot, gasèous products of com-bustion pass downwardly through a tube 4 within which i~
the burner 2 is enclosed. The tube 4 in its preferred form is open-ended at its lower end and is provided with rows of holes 5 for distributing the hot gases to material in which ~ ~-the tube is immersed. Auxiliary air is supplied through an inlet 6 in the side of the tube 4 controlling the tempera-ture of the ho~ gases passing through the tube 4.
The fuel gas is supplied along a line 7 provided with a non-return valve 8, a governor 9 and a meter 11, to :: ' -4- ~
. . . . . .
~44(7~
an injector 12 where it mixes with combustion air supplied along a line 13. The fuel-air mixture is then blown by a booster fan 14 to the burner 2 along the line 1. Control valves 16 and 17 are provided in the fuel and air lines 7 and 13, respectively, for controlling the flow rates, whereby the heat generated by the burner can be controlled and the optimum fuel to air ratio can be selected.
An electrical control unit 18 is provided~ which supplies the electrical impulse l`or the ignition spark along a lead 19 to the spark pro~e 3. As a safety precaution a flame-sensing probe 21 is positioned within the heat-supplying tube 4 and-is arranged to be impinged `~
upon by the flame from the burner 2. The probe 21 is connected by a lead 22 to the control unit 18. In the ~`
event of flame failure, the control unit 18 automatically closes a solenold-operated valve 23 in the fuel supply line`
7, the valve 23 being connected to the control unit 18 by a lead 24.
The auxiliary air for the heat-supplying tube 4 is blown to the auxiliary air inlet from a fan 20 along a line 25, and the supply of the auxiliary air can be controlled by a valve 30 in the line 25.
Referring to Pigures 3 and 4, there are shown heat-supplying tubes 4, each similar to that shown in Figure 2, fitted into continuous calcination kettles of capacity of
3 cwt. and 1 ton, respectively. The same reference numerals will be used to refer to parts which are similar in each Figure.
The continuous calcination kettle, which is in the form of an open-topped vessel 26 having a lid 27 is positioned within a combustion chamber 28. A gas burner is mounted in the combustion chamber 28 beneath the closed bottom of the vessel 26, and heats a mass of gypsum contained in the vessel by conduction through the bottom and side walls of the vessel.
In each cf the kettles sho~n, a heat-supplying tube
The continuous calcination kettle, which is in the form of an open-topped vessel 26 having a lid 27 is positioned within a combustion chamber 28. A gas burner is mounted in the combustion chamber 28 beneath the closed bottom of the vessel 26, and heats a mass of gypsum contained in the vessel by conduction through the bottom and side walls of the vessel.
In each cf the kettles sho~n, a heat-supplying tube
4 is mounted in the lid 27 of the kettle, and heats the gypsum directly by introducing hot cnmbustion gases into the interior of the mass of gypsum through the distribution holes 5 and the open end of the tube 4. `;
Whilst the above system employs fuel gas, other fuels `
may be used. ~
In the continuous calcination process, raw gypsum ;
is fed into the kettle continuously through an inlet 29 in the lid 27 and displaces the calcined product which leaves ~-through a product overflow tube 31 leading from an opening in the side wall of the vessel 26. In Figure ~, a baffle ;`
plate 32 is mounted within the calcination vessel 26. In order to prevent freshly introduced raw gypsum from leaving through the overflow tube 31 before it has been sufficiently calcined, the plate 32 extends into the mass of gypsum below the level of the opening in the side of the vessel to which the overflow tube 31 is connected, and extends into contact with the inner surface of the vessel 26 on either side of ~CJ 4~
the said opening. In large-scale production it is preferred to employ a product outflow tube which is connected to the lower end of the vessel 26 and extends upwardly and outwardly. A downwardly and outwardly inclined discharge conduit communicates with this tube at a point below the level of the lid 27 of the vessel.
The product flows up the outflow tu~e and then passes down the discharge conduit to a hot pit storage area.
The kettles are each provided with a vent 33 which leads to a cyclone or other dust collection equipment, and have an outlet 34 at the bottom of ~he vessel through which the contents of the kettle can be dumped when desired. The kettle shown in Figure 3 has an inlet conduit 36 for returning to the interior of the mass of gypsum solids which have been separated at the cyclone. Each kettle has stirrer paddles -37 mounted on a rotating shaft 38 below the end of the tube 4, for stirring the mass of material in the vessel 26 during the calcination process. Instead of employing the tube 4, the shaft 38 could be made hollow and be provided with holes ;
along its length. Alternatively, the shaft 38 could be surrounded by a concentrically arranged combustion tube such as the tube 4. The modified shaft could then be used to `
introduce hot gaseous products of combustion into ~he mass of gypsum.
In the following Exam~le, a continuous operation was carried out employing the kettle shown in Figure 3 with and without auxiliary heating from the tube 4, and employing o~ ~
natural gas as the fuel for the tube 4 and the bottom burner ~ounted under the vessel. ~he produc~ion rate with only the conventional kettle bo-ttom burner in operation was 42 kg/hr at a natural gas flow rate throu~h the kettle bottom burner of approximately 4;2 m3/hr. l~hen an equal propoxtlon of additional heat was.supplemented through the .
heat-suppl~ing tube 4, the prod.uction rate could be increased substantially without considerably affecting the kettle bottom temperature or the chemical composi-tion of :
the product (hemihydrate plaster), although the plaster is more dispersive. ~he chemical analyses and kettle bottom ~. . :
temperatures of the product with and without the use of ..
submerged combustion are illustrated in the followin~ Table:
" ' . - . . . ~ . ` . ,:: ., ,: .. . ... ... .
_ _ , I
With only the I~ettle bottom con~entional burner plus kettle bo-ttom heat-supplyirlg burner tube 4 _ , _ __ _ _ Gypsum ~ineral feed (kOG/hr) 50 110 Product discharge (kg/hr) 42 74 Calcination temperature (~) 153 170 Natural gas flow rate to kettle bottom burner (m3/hr) 4.19 4.25 Natural gas flow rate to burner 2 (m3/hr) _ 4.25 Kettle bo~tom temperature (~' ') 269 266 _ . ;'.
Proxi~ate Analysis:
Free water c~o 0.57 Soluble anhydrite 50 _ 5 . 9 ¦ -:
He~ihydrate % 68 69.7 GYPSUm % ~8.36 0.98 .
While a continuous calcination process has been described in detail above, it is apparent that theheat~supplving~
tube could be used as an auxiliar~ heatinO~ source in batch calcination of calciu~ sulphate dihydrate.
.. . .
,, " ." ~ " . . . ~.i... .
Whilst the above system employs fuel gas, other fuels `
may be used. ~
In the continuous calcination process, raw gypsum ;
is fed into the kettle continuously through an inlet 29 in the lid 27 and displaces the calcined product which leaves ~-through a product overflow tube 31 leading from an opening in the side wall of the vessel 26. In Figure ~, a baffle ;`
plate 32 is mounted within the calcination vessel 26. In order to prevent freshly introduced raw gypsum from leaving through the overflow tube 31 before it has been sufficiently calcined, the plate 32 extends into the mass of gypsum below the level of the opening in the side of the vessel to which the overflow tube 31 is connected, and extends into contact with the inner surface of the vessel 26 on either side of ~CJ 4~
the said opening. In large-scale production it is preferred to employ a product outflow tube which is connected to the lower end of the vessel 26 and extends upwardly and outwardly. A downwardly and outwardly inclined discharge conduit communicates with this tube at a point below the level of the lid 27 of the vessel.
The product flows up the outflow tu~e and then passes down the discharge conduit to a hot pit storage area.
The kettles are each provided with a vent 33 which leads to a cyclone or other dust collection equipment, and have an outlet 34 at the bottom of ~he vessel through which the contents of the kettle can be dumped when desired. The kettle shown in Figure 3 has an inlet conduit 36 for returning to the interior of the mass of gypsum solids which have been separated at the cyclone. Each kettle has stirrer paddles -37 mounted on a rotating shaft 38 below the end of the tube 4, for stirring the mass of material in the vessel 26 during the calcination process. Instead of employing the tube 4, the shaft 38 could be made hollow and be provided with holes ;
along its length. Alternatively, the shaft 38 could be surrounded by a concentrically arranged combustion tube such as the tube 4. The modified shaft could then be used to `
introduce hot gaseous products of combustion into ~he mass of gypsum.
In the following Exam~le, a continuous operation was carried out employing the kettle shown in Figure 3 with and without auxiliary heating from the tube 4, and employing o~ ~
natural gas as the fuel for the tube 4 and the bottom burner ~ounted under the vessel. ~he produc~ion rate with only the conventional kettle bo-ttom burner in operation was 42 kg/hr at a natural gas flow rate throu~h the kettle bottom burner of approximately 4;2 m3/hr. l~hen an equal propoxtlon of additional heat was.supplemented through the .
heat-suppl~ing tube 4, the prod.uction rate could be increased substantially without considerably affecting the kettle bottom temperature or the chemical composi-tion of :
the product (hemihydrate plaster), although the plaster is more dispersive. ~he chemical analyses and kettle bottom ~. . :
temperatures of the product with and without the use of ..
submerged combustion are illustrated in the followin~ Table:
" ' . - . . . ~ . ` . ,:: ., ,: .. . ... ... .
_ _ , I
With only the I~ettle bottom con~entional burner plus kettle bo-ttom heat-supplyirlg burner tube 4 _ , _ __ _ _ Gypsum ~ineral feed (kOG/hr) 50 110 Product discharge (kg/hr) 42 74 Calcination temperature (~) 153 170 Natural gas flow rate to kettle bottom burner (m3/hr) 4.19 4.25 Natural gas flow rate to burner 2 (m3/hr) _ 4.25 Kettle bo~tom temperature (~' ') 269 266 _ . ;'.
Proxi~ate Analysis:
Free water c~o 0.57 Soluble anhydrite 50 _ 5 . 9 ¦ -:
He~ihydrate % 68 69.7 GYPSUm % ~8.36 0.98 .
While a continuous calcination process has been described in detail above, it is apparent that theheat~supplving~
tube could be used as an auxiliar~ heatinO~ source in batch calcination of calciu~ sulphate dihydrate.
.. . .
,, " ." ~ " . . . ~.i... .
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of calcining calcium sulphate dihydrate in a calcination vessel which comprises heating the dihydrate in the vessel to calcination temperature by applying heat to the exterior of the vessel and simultaneously by supplying hot gases into the interior of the mass of calcining material within the vessel, through a tube extending downwardly from the top of the calcination vessel into the mass of calcining material within the vessel.
2. A method according to claim 1 wherein the hot gases are hot gaseous combustion products.
3. A method according to claim 1 wherein the hot gases are supplied by a fuel burner located on top of the calcination vessel.
4. A method according to claim 1 wherein the hot gases are distributed through distribution holes in the tube within the mass of calcining material.
5. A method according to claim 1 wherein the tube is open at its lower end.
6. A method according to claim 1 including the step of introducing a flow of gas into the tube at a position upstream of the entry of the tube into the mass of calcining material in the vessel.
7. A method according to claim 1 wherein the calcination vessel has a stirrer for the calcining mass, said stirrer having a hollow shaft and the hot gases being supplied through said hollow shaft into the interior of the mass of calcining material within the vessel.
8. A method according to claim 1 wherein said calcination vessel has a stirrer for the calcining mass, said stirrer having a shaft, and the hot gases being introduced into the interior of the mass of calcining material within the vessel through a tube mounted around the said shaft.
9. A method according to claim 1 wherein said calcination vessel has an overflow outlet for calcined product, calcium sulphate dihydrate being fed continuously into the vessel and said continuously fed dihydrate dis-placing calcined product through said overflow outlet.
10. A method according to claim 9 wherein said overflow outlet communicates with a product outflow tube which is connected to the lower end of the vessel and extends upwardly and outwardly therefrom.
11. Apparatus for calcining calcium sulphate dihydrate comprising a calcination vessel, means for heating the exterior of said calcination vessel, and a tube for leading hot gases to the interior of said calcination vessel, extending from the top of the calcination vessel downwardly into the interior thereof.
12. Apparatus according to claim 11 wherein said tube is provided with distribution holes within the vessel.
13. Apparatus according to claim 11 including a fuel burner located on top of the calcination vessel for supplying hot gases to said tube.
14. Apparatus according to claim 11 wherein said tube is open at its lower end.
15. Apparatus according to claim 11 wherein said tube has an auxiliary inlet for the inflow of gas upstream of the entry of the tube into the mass to be calcined.
16. Apparatus according to claim 11 wherein the tube is the hollow shaft of a stirrer within the calcination vessel.
17. Apparatus according to claim 11 wherein the said tube surrounds the shaft of a stirrer within the calcination vessel.
18. Apparatus according to claim 11 wherein the calcination vessel has an inlet for the continuous introduction of raw calcium sulphate dihydrate and an overflow outlet for the continuous discharge of calcined products.
19. Apparatus according to claim 18 wherein the calcination vessel includes a plate which extends into the calcination vessel to below the level of said outlet.
20. Apparatus according to claim 19 wherein said plate extends into contact with the inner surface of the calcination vessel on either side of said outlet.
21. Apparatus according to claim 18 wherein said outlet is at the lower end of the calcination vessel, and is in communication with a product outflow tube which extends upwardly and outwardly from the vessel.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB54940/73A GB1488665A (en) | 1973-11-27 | 1973-11-27 | Calcining calcium sulphate dihydrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1044014A true CA1044014A (en) | 1978-12-12 |
Family
ID=10472525
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA213,730A Expired CA1044014A (en) | 1973-11-27 | 1974-11-14 | Calcining calcium sulphate dihydrate |
Country Status (18)
| Country | Link |
|---|---|
| JP (1) | JPS56370B2 (en) |
| AT (1) | AT363376B (en) |
| BE (1) | BE822555A (en) |
| CA (1) | CA1044014A (en) |
| CH (1) | CH605449A5 (en) |
| DE (1) | DE2454857C3 (en) |
| DK (1) | DK153939C (en) |
| ES (1) | ES432269A1 (en) |
| FI (1) | FI59383C (en) |
| FR (1) | FR2252308B1 (en) |
| GB (1) | GB1488665A (en) |
| IE (1) | IE40249B1 (en) |
| IT (1) | IT1026570B (en) |
| LU (1) | LU71346A1 (en) |
| NL (1) | NL181501C (en) |
| NO (1) | NO139823C (en) |
| SE (1) | SE7414838L (en) |
| ZA (1) | ZA747209B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA793953B (en) * | 1978-08-08 | 1980-08-27 | Coal Industry Patents Ltd | Heat treatment of material |
| IE49127B1 (en) * | 1979-01-08 | 1985-08-07 | Bpb Industries Ltd | Calcination method and apparatus |
| ZA817558B (en) * | 1980-11-10 | 1983-02-23 | Bpb Industries Plc | Improvements in calcining calcium sulphate dihydrate |
| GB2140702A (en) * | 1980-11-10 | 1984-12-05 | Bpb Industries Plc | Fluidised bed calcination |
| US4744961A (en) * | 1985-04-25 | 1988-05-17 | United States Gypsum Company | Submerged combustion calcination |
| US4626199A (en) * | 1985-04-25 | 1986-12-02 | United States Gypsum Company | Submerged combustion calcination |
| DE3536321A1 (en) * | 1985-10-11 | 1987-04-23 | Bischoff Gasreinigung | Process and reactor for producing alpha-hemihydrate gypsum from calcium sulphate dihydrate from flue gas desulphurisation plants operating by the wet scrubbing process with lime |
| GB8625964D0 (en) * | 1986-10-30 | 1986-12-03 | Bpb Industries Plc | Calcination apparatus |
| US5743954A (en) * | 1995-02-02 | 1998-04-28 | United States Gypsum Company | Method for continuous refractoryless calcining of gypsum |
| US5743728A (en) * | 1995-08-15 | 1998-04-28 | Usg Corporation | Method and system for multi-stage calcining of gypsum to produce an anhydrite product |
| US7175426B2 (en) | 2004-02-27 | 2007-02-13 | United States Gypsum Company | High efficiency refractoryless kettle |
| US7434980B2 (en) | 2004-02-27 | 2008-10-14 | United States Gypsum Company | Swinging agitator for a gypsum calcining apparatus and the like |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL285104A (en) * | 1961-11-13 |
-
1973
- 1973-11-27 GB GB54940/73A patent/GB1488665A/en not_active Expired
-
1974
- 1974-11-06 IE IE2281/74A patent/IE40249B1/en unknown
- 1974-11-11 ZA ZA00747209A patent/ZA747209B/en unknown
- 1974-11-14 CA CA213,730A patent/CA1044014A/en not_active Expired
- 1974-11-19 DE DE2454857A patent/DE2454857C3/en not_active Expired
- 1974-11-20 NO NO744190A patent/NO139823C/en unknown
- 1974-11-22 FI FI3379/74A patent/FI59383C/en active
- 1974-11-22 CH CH1558274A patent/CH605449A5/xx not_active IP Right Cessation
- 1974-11-25 BE BE150817A patent/BE822555A/en not_active IP Right Cessation
- 1974-11-25 LU LU71346A patent/LU71346A1/xx unknown
- 1974-11-25 JP JP13583574A patent/JPS56370B2/ja not_active Expired
- 1974-11-26 ES ES432269A patent/ES432269A1/en not_active Expired
- 1974-11-26 DK DK613974A patent/DK153939C/en not_active IP Right Cessation
- 1974-11-26 SE SE7414838A patent/SE7414838L/xx unknown
- 1974-11-27 AT AT0949574A patent/AT363376B/en not_active IP Right Cessation
- 1974-11-27 FR FR7438830A patent/FR2252308B1/fr not_active Expired
- 1974-11-27 NL NLAANVRAGE7415482,A patent/NL181501C/en not_active IP Right Cessation
- 1974-11-27 IT IT29899/74A patent/IT1026570B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| FR2252308B1 (en) | 1982-09-17 |
| GB1488665A (en) | 1977-10-12 |
| FI59383C (en) | 1981-08-10 |
| DE2454857B2 (en) | 1979-07-12 |
| FR2252308A1 (en) | 1975-06-20 |
| ES432269A1 (en) | 1976-12-16 |
| IT1026570B (en) | 1978-10-20 |
| DK153939B (en) | 1988-09-26 |
| NO744190L (en) | 1975-06-23 |
| FI337974A (en) | 1975-05-28 |
| SE7414838L (en) | 1975-05-28 |
| AT363376B (en) | 1981-07-27 |
| BE822555A (en) | 1975-03-14 |
| JPS56370B2 (en) | 1981-01-07 |
| AU7560974A (en) | 1976-05-27 |
| NO139823B (en) | 1979-02-05 |
| DK613974A (en) | 1975-09-29 |
| DK153939C (en) | 1989-02-20 |
| NL181501B (en) | 1987-04-01 |
| FI59383B (en) | 1981-04-30 |
| IE40249B1 (en) | 1979-04-11 |
| ATA949574A (en) | 1980-12-15 |
| NO139823C (en) | 1979-05-16 |
| JPS5084497A (en) | 1975-07-08 |
| DE2454857A1 (en) | 1975-05-28 |
| LU71346A1 (en) | 1975-06-11 |
| NL7415482A (en) | 1975-05-29 |
| IE40249L (en) | 1975-05-27 |
| ZA747209B (en) | 1975-11-26 |
| NL181501C (en) | 1987-09-01 |
| DE2454857C3 (en) | 1980-03-13 |
| CH605449A5 (en) | 1978-09-29 |
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