CA1167641A - Calcining calcium sulphate dihydrate - Google Patents
Calcining calcium sulphate dihydrateInfo
- Publication number
- CA1167641A CA1167641A CA000389818A CA389818A CA1167641A CA 1167641 A CA1167641 A CA 1167641A CA 000389818 A CA000389818 A CA 000389818A CA 389818 A CA389818 A CA 389818A CA 1167641 A CA1167641 A CA 1167641A
- Authority
- CA
- Canada
- Prior art keywords
- vessel
- tube
- gypsum
- bed
- hot gas
- 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
-
- 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
- C04B11/028—Devices therefor characterised by the type of calcining devices used therefor or by the type of hemihydrate obtained
- C04B11/0281—Kettles; Marmites; Autoclaves
Abstract
A B S T R A C T
Method and apparatus for the continuous calcination of calcium sulphate dihydrate (gypsum) to hemihydrate plaster by heating A bed of gypsum in a kettle to the required calcination temperature at least in part by means of hot gas continuously introduced into the bed, moisture (e.g. in the form of water droplets or steam) being sprayed into the gaseous phase (e.g. into the hot gas before contact with the bed and/or into exhaust gas above the bed) to reduce the degree of production of insoluble anhydrite.
Method and apparatus for the continuous calcination of calcium sulphate dihydrate (gypsum) to hemihydrate plaster by heating A bed of gypsum in a kettle to the required calcination temperature at least in part by means of hot gas continuously introduced into the bed, moisture (e.g. in the form of water droplets or steam) being sprayed into the gaseous phase (e.g. into the hot gas before contact with the bed and/or into exhaust gas above the bed) to reduce the degree of production of insoluble anhydrite.
Description
1 1 ~7B ~ 1 This invention relates to an improvement in the method and apparatus for calcining calcium sulphate dihydrate or gypsum.
In calcining the dihydrate tohemihydrate, any tendency to produce insoluble anhydrite at the expense of hemihydrate is disadvantageous since in certain applications, this will reduce the effect use of the gypsum mineral feed. This tendency can be observed, under some conditions, in continuous methods of calcination based on direct heating of gypsum by hot gases, where the mineral feed is calcined to hemihydrate very quickly.
The present invention now provides a means for reducing the production of insoluble anhydrite in continuous calcination with direct gaseous heating of a gypsum bed, to levels which are typical of the production of, for example, a kettle operating with-out the direct action of hot gases on the mineral feed.
In accordance with the present invention, provision is made for spraying moisture into the gaseous phase above the bed, for example the exhaust gas space in or adjacent to the upper region of a calcination vessel or into the tube by which the hot gas is introduced into the bed, or in both these locations.
Thus, in the process of calcining gypsum in which a bed of powdered gypsum in a vessel is heated directly by the introduction of hot gas through a tube extending into the bed and regulation of the hot gas to maintain the bed at a temperature appropriate to the production of calcium sulphate hemihydrate, this invention provides the improvement which comprises spraying moisture into the gaseous phase in or above the bed whereby the formation of insoluble anhydrite is reduced.
7~
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1 1 6~64 1 Moreover, in an apparatus for calcining gypsum which comprises a calcination vessel for containing a bed of gypsum to be calcin~d and a tube extending into said vessel for direct introduction of hot gas into direct contact with said bed of gypsum, this invention also provides the improvement which comprises moisture spray means disposed in said tube or vessel.
The invention will be described in greater detail with particular reference to the production of calcined gypsum in accordance with our British Patent 1 488 665 and with our published UK Specification 2043219A. Whilst this detailed description of the invention relates to these two methods and apparatus, it should be 't .; ,~1 -la-~mderstood that the invention can be applied to other methods and apparatus for continuously calcining calcium sulphate, and more especially to equipment which calcines calcium sulphate dihydrate in a rapid manner by direct heating.
S In our British Patent 1 488 665 a method for calcining calcium sulphate dihydrate is described in which the dihydrate is heated in a calcining vessel with heat applied indirectly through the external walls of the vessel and heated additionally by the direct introduction of non-reactive hot gases, preferably hot gaseous combustion products, into the interior of the mass of the dihydrate within the vessel through a tube extending generally down-wardly from the top of the vessel and provided with at least one opening in its lower region, which is immersed in the mass of the material. To achieve maximum output and realise the full advantages of thls method it is preferred to operate the calcination vessel continuously, calcined material being discharged over a weir or other level-control device.
Adoption of this development increases both the thermal efficiency and thoughput of a conventional kettle. However, at higher input rates of heat supplied by the direct introduction of hot gases, the aforementioned tendency to produce insoluble anhydrite at the expense of hemihydrate has been observed.
Although a variety of sources of hot gas or gaseous combust-ion products can be used, it is at present preferred to use a fuel burner iocated at the top of the calcination vessel or tube. The burner may be conveniently located on top of the gypsum calcining kettle, with the tube leading intc the bed. The combustion gases are preferably distributed through holes in the side walls of the lower region of the tube within the bed, while the lower . .
region of the tube is preferably open-ended. In the preferred practice of this invention, water or other aqueous liquid (or steam) is introduced into the burner tube at a controlled rate.
The rate of water or aqueous liquid supply should be adjusted by a trial and error technique to achieve the best results and to avoid destabilisation of the flame of the burner in the tube. In a typical installation a suitable rate is 4.5 litres per minute.
Our Published United Kingdom Specification Number
In calcining the dihydrate tohemihydrate, any tendency to produce insoluble anhydrite at the expense of hemihydrate is disadvantageous since in certain applications, this will reduce the effect use of the gypsum mineral feed. This tendency can be observed, under some conditions, in continuous methods of calcination based on direct heating of gypsum by hot gases, where the mineral feed is calcined to hemihydrate very quickly.
The present invention now provides a means for reducing the production of insoluble anhydrite in continuous calcination with direct gaseous heating of a gypsum bed, to levels which are typical of the production of, for example, a kettle operating with-out the direct action of hot gases on the mineral feed.
In accordance with the present invention, provision is made for spraying moisture into the gaseous phase above the bed, for example the exhaust gas space in or adjacent to the upper region of a calcination vessel or into the tube by which the hot gas is introduced into the bed, or in both these locations.
Thus, in the process of calcining gypsum in which a bed of powdered gypsum in a vessel is heated directly by the introduction of hot gas through a tube extending into the bed and regulation of the hot gas to maintain the bed at a temperature appropriate to the production of calcium sulphate hemihydrate, this invention provides the improvement which comprises spraying moisture into the gaseous phase in or above the bed whereby the formation of insoluble anhydrite is reduced.
7~
rB
1 1 6~64 1 Moreover, in an apparatus for calcining gypsum which comprises a calcination vessel for containing a bed of gypsum to be calcin~d and a tube extending into said vessel for direct introduction of hot gas into direct contact with said bed of gypsum, this invention also provides the improvement which comprises moisture spray means disposed in said tube or vessel.
The invention will be described in greater detail with particular reference to the production of calcined gypsum in accordance with our British Patent 1 488 665 and with our published UK Specification 2043219A. Whilst this detailed description of the invention relates to these two methods and apparatus, it should be 't .; ,~1 -la-~mderstood that the invention can be applied to other methods and apparatus for continuously calcining calcium sulphate, and more especially to equipment which calcines calcium sulphate dihydrate in a rapid manner by direct heating.
S In our British Patent 1 488 665 a method for calcining calcium sulphate dihydrate is described in which the dihydrate is heated in a calcining vessel with heat applied indirectly through the external walls of the vessel and heated additionally by the direct introduction of non-reactive hot gases, preferably hot gaseous combustion products, into the interior of the mass of the dihydrate within the vessel through a tube extending generally down-wardly from the top of the vessel and provided with at least one opening in its lower region, which is immersed in the mass of the material. To achieve maximum output and realise the full advantages of thls method it is preferred to operate the calcination vessel continuously, calcined material being discharged over a weir or other level-control device.
Adoption of this development increases both the thermal efficiency and thoughput of a conventional kettle. However, at higher input rates of heat supplied by the direct introduction of hot gases, the aforementioned tendency to produce insoluble anhydrite at the expense of hemihydrate has been observed.
Although a variety of sources of hot gas or gaseous combust-ion products can be used, it is at present preferred to use a fuel burner iocated at the top of the calcination vessel or tube. The burner may be conveniently located on top of the gypsum calcining kettle, with the tube leading intc the bed. The combustion gases are preferably distributed through holes in the side walls of the lower region of the tube within the bed, while the lower . .
region of the tube is preferably open-ended. In the preferred practice of this invention, water or other aqueous liquid (or steam) is introduced into the burner tube at a controlled rate.
The rate of water or aqueous liquid supply should be adjusted by a trial and error technique to achieve the best results and to avoid destabilisation of the flame of the burner in the tube. In a typical installation a suitable rate is 4.5 litres per minute.
Our Published United Kingdom Specification Number
2 043 219A describes a method and apparatus for heat-treatment of lo particulate, i.e. powdered or granular~material and especially : suitable for calcination, in which all the necessary heat can be supplied directly into the material being calcined, thereby making it possible to dispense with much of the refractory brickwork associ-ated with conventional kettles and to thermally lag the system, so increasing the thermal efficiency and reducing capital and mainten-ance costs.
According to that application the method comprises intro-ducing the material to be calcined into a vessel, restricting the material in the bottom region of the vessel to the vicinity of the hot gas outlet, notably by using a vessel with reduced cross-section in its lo~est region, irtroducing hot gas downwardly through the vessel into direct contact with the material in the region of the bottom, whereby the material at the bottom is simultaneously heated and circulated and the resulting agitation and heating extends from the bottom region through substantially all the material in the vessel, and withd,dwing heat-treated material from the vessel. It is envisaged that in most cases the hot gases will provide all the heat required for treatment in the vessel, although some degree of ` 1167641 wall heating ~ay be provided without departing from the principles of the application.
In accordance with this invention, in this case also, water, other aqueous liquid or steam is introduced, either at a level above the contents of the vessel or, preferably,into the heating tube for the hot gases.
In the accompanying drawings:
Fig. 1 is a diagrammatic section of a calcining kettle according to Patent 1 488 665 modified in accordance with this invention:
Fig. 2 is a longitudinal section of a burner tube suitable for the kettle of Fig. l; and Fig. 3 is a diagrammatic section of a calcining vessel accordlng to U.K. published specificatlon No. 2043219A modified in accordance with this invention.
As shown in Fig. 1, a calcining kettle 10 comprises a vessel 11 surrounded by a heating chamber 12, which is provided with a burner 14 or other supply of hot gas to heat the contents of the vessel indirectly by conduction through the walls, and especially through the bottom, of the vessel. Conventional cross-flues 15 assist in the transfer of heat to the contents of the vessel. The lid 16 of the kettle is provided with openings 17 for the introduction, preferably continuously, of ground or otherwise powdered calcium sulphate dihydrate, and 18 for the withdrawal of exhaust gases to a dust collector. A mechanical stirrer or agitator 19 is driven by a shaft 20 extending through the lid. An overflow weir or dis-charge tube 21, protected by a baffle 22, is provided for discharge - ' t Ir 1 1 67~4 1 ~f calcined material in accordance with British Patent 1 018 464 and a conventional valved-bottom outlet 23 is also provided.
To apply the principles of Patent 1 488 665, a generally vertical tube 24 is located within the vessel and fitted with a burner supplied with fuel and air by respective line 25 and 26.
The hot combustion gases produced by the burner are introduced directly into the calcining mass by means of openings in the lower end 27 of the tube.
In accordance with the present invention, water, steam or an aqueous solution is sprayed into the calcination vessel above the mass of calcining materials. Examples of positions at which a water spray may be located in a kettle are indicated at 30 in the u~per region of the hot gas tube 24, at 31 towards the lower region and above the openings of the tube and at 32 in the free space above the level of the mass in the vessel 11 proper.
A preferred construction of the hot gas tube 24 and associ-ated equipment is shown in Fig. 2. At the head of the tube, above the level 34 of the kettle lid, are provided gas and air inlets 25 and 26 respectively together with water inlets 35. A radial type burner 36 surrounded by a conical skirt 37 is fitted within the tube 24 and connected to the gas inlet. In the embodiment shown in the drawing, the burner is provided just below the level 38 of the bed of material in the vessel 11, but in other embodiments the burner may be located at a higher position, for example immediately below the level of the kettle lid 34. The bottom of the tube 24 has lateral openings ~'J and the lower end of the tube is completely open.
. , . . .. .... . . ,, ,~ .
1 ~ 6764 1 T~o hollow cone spray jets 40 are mounted within the tube 24 at about the level of the burner 36 for the introduction of moisture in accordance with the present invention. The jets are connected by water inlets 35 to a supply of suitable water under pressure.
In operation, powdered gypsum is introduced continuously through the opening 17 onto the vessel 11, where it is partly heated indirectly from the heating chamber 12. At the same time, fuel and air introduced into the tune 24 provide further heat by the direct introduction of hot combustion gases, which also agitate the material in the vessel. m e contents of the vessel are also agitated and fluidised by the water vapour evolved during calcination, while the material in the vessel is further agitated by the stirrer 19. The calcined product overflows continuously from the discharge tube 21, the baf1e 22 preventing direct access of possibly uncalcined material from inlet 17 to thé outlet 21. Water or an aqueous solution is sprayed into the gases within the tube 24 by means of the spray jets 40 and has the effect of reducing to a negligible level the formation of insoluble anhydrite in the kettle.
As a further example, illustrated by Fig. 3, the invention will be described with particular refcrence to the production of calcined gypsum in accordance with U.X. published specification No. 2043219A.
As shown in Fig. 3, a vessel 45 of inv3rted conical form has a rounded bottom 46 of restricted area and carries a cylindrical upper portion 47, which in turn is closed by ~ lid 48 fitted with a - feed pipe 49 for the material to be calcined, such as powdered gypsum, and an exhaust gas outlet pipe 50 connçcted to a dust . .. .
~ ~ 6764 1 collector (not shown~. ~ heating tube 51 which is described in more detail below, also passes through the lid 48 into the interior of the vessel. m e gypsum feed pipe 49 is provided with a metering valve in the form of a rotary feeder 52, which is connected to a gypsum bunker 53. m e vessel 45 and upper portion 47 are suitably lagged as indicated at 54.
m e normal level of powdered material in the vessel when it is operating is indicated at 10. An outlet for calcined material is provided in ~he form of an external overflow weir 55 connected to a lead-off pipe 56. A valved bottom discharge gate 57 is also provided.
Ihe heating tube Sl extends downwardly substantially along the central vertical axis of the conical vessel 1. It is open at lts lower end 58 and terminates adjacent to the bottom 46 of the vessel. The tube is also provided in. the lower part of its wall with symmetrically disposed holes 61 further facilitating the distribution of hot gases into thé materiai being calcined. m e distribution of gases emerging from the tube 51 is further enhanced by the provision of an upright cone or other protrusion 62 of heat resistant material, which is seated on the bottom 46 of the vessel directly beneath the tube opening 58.
Fuel gas, for example natural gas, is supplied through a pipe 63 to a gas burner 64 of a nozzle-mix type located within the tube 51 at approximately the level 10 of the ma'erial in the vessel.
Air is supplied separately to this burner through an air pipe 65 from a fan 66. The hot gaseous products of co~ustion pass down-wardly through the tube 51 and leave through its open end 58 and the holes 61. An auxiliary air supply to the heating tube is not 1 ~ ~76~ 1 ~enerally used with this system.
In accordance with the present invention, water or an aqueous solution, steam or other form of moisture is preferably sprayed into the tube 51, either in the upper region of the vessel as indicated at 30, or lower in the tube, for example near the level of material 10 or in the vicinity of the burner 64, as indicated at 31. Alternatively or additionally, moisture can be sprayed into the free space in the vessel in the vicinity of the exhaust gas outlet 50 or at least partially into the outlet pipe itself, as indicated at 32.
... ,.. ~.. ,, _... .. ..... ... . . . . . ..
t
According to that application the method comprises intro-ducing the material to be calcined into a vessel, restricting the material in the bottom region of the vessel to the vicinity of the hot gas outlet, notably by using a vessel with reduced cross-section in its lo~est region, irtroducing hot gas downwardly through the vessel into direct contact with the material in the region of the bottom, whereby the material at the bottom is simultaneously heated and circulated and the resulting agitation and heating extends from the bottom region through substantially all the material in the vessel, and withd,dwing heat-treated material from the vessel. It is envisaged that in most cases the hot gases will provide all the heat required for treatment in the vessel, although some degree of ` 1167641 wall heating ~ay be provided without departing from the principles of the application.
In accordance with this invention, in this case also, water, other aqueous liquid or steam is introduced, either at a level above the contents of the vessel or, preferably,into the heating tube for the hot gases.
In the accompanying drawings:
Fig. 1 is a diagrammatic section of a calcining kettle according to Patent 1 488 665 modified in accordance with this invention:
Fig. 2 is a longitudinal section of a burner tube suitable for the kettle of Fig. l; and Fig. 3 is a diagrammatic section of a calcining vessel accordlng to U.K. published specificatlon No. 2043219A modified in accordance with this invention.
As shown in Fig. 1, a calcining kettle 10 comprises a vessel 11 surrounded by a heating chamber 12, which is provided with a burner 14 or other supply of hot gas to heat the contents of the vessel indirectly by conduction through the walls, and especially through the bottom, of the vessel. Conventional cross-flues 15 assist in the transfer of heat to the contents of the vessel. The lid 16 of the kettle is provided with openings 17 for the introduction, preferably continuously, of ground or otherwise powdered calcium sulphate dihydrate, and 18 for the withdrawal of exhaust gases to a dust collector. A mechanical stirrer or agitator 19 is driven by a shaft 20 extending through the lid. An overflow weir or dis-charge tube 21, protected by a baffle 22, is provided for discharge - ' t Ir 1 1 67~4 1 ~f calcined material in accordance with British Patent 1 018 464 and a conventional valved-bottom outlet 23 is also provided.
To apply the principles of Patent 1 488 665, a generally vertical tube 24 is located within the vessel and fitted with a burner supplied with fuel and air by respective line 25 and 26.
The hot combustion gases produced by the burner are introduced directly into the calcining mass by means of openings in the lower end 27 of the tube.
In accordance with the present invention, water, steam or an aqueous solution is sprayed into the calcination vessel above the mass of calcining materials. Examples of positions at which a water spray may be located in a kettle are indicated at 30 in the u~per region of the hot gas tube 24, at 31 towards the lower region and above the openings of the tube and at 32 in the free space above the level of the mass in the vessel 11 proper.
A preferred construction of the hot gas tube 24 and associ-ated equipment is shown in Fig. 2. At the head of the tube, above the level 34 of the kettle lid, are provided gas and air inlets 25 and 26 respectively together with water inlets 35. A radial type burner 36 surrounded by a conical skirt 37 is fitted within the tube 24 and connected to the gas inlet. In the embodiment shown in the drawing, the burner is provided just below the level 38 of the bed of material in the vessel 11, but in other embodiments the burner may be located at a higher position, for example immediately below the level of the kettle lid 34. The bottom of the tube 24 has lateral openings ~'J and the lower end of the tube is completely open.
. , . . .. .... . . ,, ,~ .
1 ~ 6764 1 T~o hollow cone spray jets 40 are mounted within the tube 24 at about the level of the burner 36 for the introduction of moisture in accordance with the present invention. The jets are connected by water inlets 35 to a supply of suitable water under pressure.
In operation, powdered gypsum is introduced continuously through the opening 17 onto the vessel 11, where it is partly heated indirectly from the heating chamber 12. At the same time, fuel and air introduced into the tune 24 provide further heat by the direct introduction of hot combustion gases, which also agitate the material in the vessel. m e contents of the vessel are also agitated and fluidised by the water vapour evolved during calcination, while the material in the vessel is further agitated by the stirrer 19. The calcined product overflows continuously from the discharge tube 21, the baf1e 22 preventing direct access of possibly uncalcined material from inlet 17 to thé outlet 21. Water or an aqueous solution is sprayed into the gases within the tube 24 by means of the spray jets 40 and has the effect of reducing to a negligible level the formation of insoluble anhydrite in the kettle.
As a further example, illustrated by Fig. 3, the invention will be described with particular refcrence to the production of calcined gypsum in accordance with U.X. published specification No. 2043219A.
As shown in Fig. 3, a vessel 45 of inv3rted conical form has a rounded bottom 46 of restricted area and carries a cylindrical upper portion 47, which in turn is closed by ~ lid 48 fitted with a - feed pipe 49 for the material to be calcined, such as powdered gypsum, and an exhaust gas outlet pipe 50 connçcted to a dust . .. .
~ ~ 6764 1 collector (not shown~. ~ heating tube 51 which is described in more detail below, also passes through the lid 48 into the interior of the vessel. m e gypsum feed pipe 49 is provided with a metering valve in the form of a rotary feeder 52, which is connected to a gypsum bunker 53. m e vessel 45 and upper portion 47 are suitably lagged as indicated at 54.
m e normal level of powdered material in the vessel when it is operating is indicated at 10. An outlet for calcined material is provided in ~he form of an external overflow weir 55 connected to a lead-off pipe 56. A valved bottom discharge gate 57 is also provided.
Ihe heating tube Sl extends downwardly substantially along the central vertical axis of the conical vessel 1. It is open at lts lower end 58 and terminates adjacent to the bottom 46 of the vessel. The tube is also provided in. the lower part of its wall with symmetrically disposed holes 61 further facilitating the distribution of hot gases into thé materiai being calcined. m e distribution of gases emerging from the tube 51 is further enhanced by the provision of an upright cone or other protrusion 62 of heat resistant material, which is seated on the bottom 46 of the vessel directly beneath the tube opening 58.
Fuel gas, for example natural gas, is supplied through a pipe 63 to a gas burner 64 of a nozzle-mix type located within the tube 51 at approximately the level 10 of the ma'erial in the vessel.
Air is supplied separately to this burner through an air pipe 65 from a fan 66. The hot gaseous products of co~ustion pass down-wardly through the tube 51 and leave through its open end 58 and the holes 61. An auxiliary air supply to the heating tube is not 1 ~ ~76~ 1 ~enerally used with this system.
In accordance with the present invention, water or an aqueous solution, steam or other form of moisture is preferably sprayed into the tube 51, either in the upper region of the vessel as indicated at 30, or lower in the tube, for example near the level of material 10 or in the vicinity of the burner 64, as indicated at 31. Alternatively or additionally, moisture can be sprayed into the free space in the vessel in the vicinity of the exhaust gas outlet 50 or at least partially into the outlet pipe itself, as indicated at 32.
... ,.. ~.. ,, _... .. ..... ... . . . . . ..
t
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In the process of calcining gypsum in which a bed of powdered gypsum in a vessel is heated directly by the introduction of hot gas through a tube extending into the bed and regulation of the hot gas to maintain the bed at a temperature appropriate to the production of calcium sulphate hemihydrate, the improvement which comprises spraying moisture into the gaseous phase in or above the bed whereby the formation of insoluble anhydrite is reduced.
2. The process as claimed in claim 1 wherein at least some of the said moisture is sprayed into said hot gas prior to contact of the latter with the gypsum.
3. The process as claimed in claim 1 wherein there is a region above said gypsum bed which is occupied or traversed by exhaust gases from said bed and at least some of said moisture is sprayed into said region.
4. The process as claimed in claim 2 wherein said tube extends generally downwardly from the top of said vessel and open-ing in the lower region of said vessel, said hot gas is introduced into said bed via said tube and moisture is sprayed within said tube.
5. The process as claimed in claim 4 wherein said hot gas is supplied by a burner mounted within said tube, and moisture is sprayed at substantially the same level as said burner.
6. The process as claimed in claim 2 or 3 wherein said gypsum is contained in a vessel and is additionally heated indirect-ly by thermal conduction through the walls of said vessel.
7. The process as claimed in claim 4 or 5 wherein said gypsum is contained in a vessel having a lower region which is shaped to direct said gypsum towards the vicinity of the lower end of said tube whereby hot gas from said tube agitates and heats all the material in the vessel.
8. The process as claimed in claim 1 wherein gypsum is introduced continuously into said vessel and exits continuously therefrom in a calcined condition.
9. In an apparatus for calcining gypsum which comprises a calcination vessel for containing a bed of gypsum to be calcined and a tube extending into said vessel for direct introduction of hot gas into direct contact with said bed of gypsum, the improve-ment which comprises moisture spray means disposed in said tube or vessel.
10. Apparatus as claimed in claim 9 wherein said tube for the introduction of hot gas extends generally downwardly within said vessel and opening in the lower region thereof, and wherein at least one spray jet for moisture is located within said tube.
11. Apparatus as claimed in claim 10 wherein a burner is fitted within said tube to provide a source of hot gas, and at least one water spray is fitted within said tube at about the level of the burner.
12. Apparatus as claimed in claim 9, 10 or 11 wherein said vessel has thermally conducting walls and is surrounded by a heating chamber for indirect heating of the contents of said vessel.
13. Apparatus as claimed in claim 9, 10 or 11 eherein said vessel has a lower region shaped to direct the contents of said vessel in operation towards the lower end of said tube.
14. Apparatus as claimed in claim 9 further comprises feed means for continuously introducing powdered gypsum and discharge means by which calcined material is continuously withdrawable.
15. Apparatus as claimed in claim 9 wherein at least one spray jet for moisture is mounted in or adjacent to said vessel at a level which is above said bed of gypsum during operation, in a region which is occupied or traversed by exhaust gases from said bed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8036035 | 1980-11-10 | ||
| GB8036035 | 1980-11-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167641A true CA1167641A (en) | 1984-05-22 |
Family
ID=10517196
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389818A Expired CA1167641A (en) | 1980-11-10 | 1981-11-10 | Calcining calcium sulphate dihydrate |
Country Status (20)
| Country | Link |
|---|---|
| JP (1) | JPS57111240A (en) |
| KR (1) | KR830007460A (en) |
| AR (1) | AR226757A1 (en) |
| AU (1) | AU7735781A (en) |
| BE (1) | BE891065A (en) |
| BR (1) | BR8107289A (en) |
| CA (1) | CA1167641A (en) |
| DE (1) | DE3144583A1 (en) |
| DK (1) | DK496981A (en) |
| ES (1) | ES8301850A1 (en) |
| FI (1) | FI813540L (en) |
| FR (1) | FR2493826A1 (en) |
| IT (1) | IT1140282B (en) |
| LU (1) | LU83742A1 (en) |
| NL (1) | NL8105079A (en) |
| NO (1) | NO813799L (en) |
| NZ (1) | NZ198927A (en) |
| PL (1) | PL233756A1 (en) |
| SE (1) | SE8106655L (en) |
| ZA (1) | ZA817558B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3615739A1 (en) * | 1986-05-09 | 1987-11-12 | Benckiser Gmbh Joh A | CONTINUOUS METHOD AND DEVICE FOR PRODUCING INDUSTRIALLY RECYCLABLE PLASTER FROM INDUSTRIAL WASTE PLASTER |
| FR2836913B1 (en) * | 2002-03-08 | 2006-11-24 | Lafarge Platres | DEVICE FOR DRYING AND / OR COOKING GYPSUM |
| DE102015223866A1 (en) * | 2015-12-01 | 2017-06-01 | Claudius Peters Projects Gmbh | Calcination plant and method for calcining |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1178806A (en) * | 1957-07-12 | 1959-05-15 | Ets Poliet & Chausson | Manufacturing process of plaster and equipment allowing the implementation |
| DE1940007B2 (en) * | 1969-08-06 | 1973-06-07 | Rheinstahl Ag, 4300 Essen | METHOD OF BURNING PLASTER IN A FLOW OF HEATING GAS |
| GB1488665A (en) * | 1973-11-27 | 1977-10-12 | Bpb Industries Ltd | Calcining calcium sulphate dihydrate |
| NL185896C (en) * | 1979-01-08 | 1990-08-16 | Bpb Industries Ltd | DEVICE FOR HEAT TREATMENT OF A GRANULAR MATERIAL. |
-
1981
- 1981-11-02 ZA ZA817558A patent/ZA817558B/en unknown
- 1981-11-06 JP JP56178904A patent/JPS57111240A/en active Pending
- 1981-11-10 BE BE0/206500A patent/BE891065A/en not_active IP Right Cessation
- 1981-11-10 IT IT24957/81A patent/IT1140282B/en active
- 1981-11-10 DK DK496981A patent/DK496981A/en not_active Application Discontinuation
- 1981-11-10 CA CA000389818A patent/CA1167641A/en not_active Expired
- 1981-11-10 ES ES507492A patent/ES8301850A1/en not_active Expired
- 1981-11-10 NO NO813799A patent/NO813799L/en unknown
- 1981-11-10 LU LU83742A patent/LU83742A1/en unknown
- 1981-11-10 BR BR8107289A patent/BR8107289A/en unknown
- 1981-11-10 SE SE8106655A patent/SE8106655L/en not_active Application Discontinuation
- 1981-11-10 FI FI813540A patent/FI813540L/en not_active Application Discontinuation
- 1981-11-10 KR KR1019810004310A patent/KR830007460A/en unknown
- 1981-11-10 NZ NZ198927A patent/NZ198927A/en unknown
- 1981-11-10 PL PL23375681A patent/PL233756A1/xx unknown
- 1981-11-10 AU AU77357/81A patent/AU7735781A/en not_active Abandoned
- 1981-11-10 NL NL8105079A patent/NL8105079A/en not_active Application Discontinuation
- 1981-11-10 DE DE19813144583 patent/DE3144583A1/en not_active Withdrawn
- 1981-11-10 AR AR287398A patent/AR226757A1/en active
- 1981-11-10 FR FR8121073A patent/FR2493826A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| AU7735781A (en) | 1982-05-20 |
| LU83742A1 (en) | 1982-02-18 |
| FR2493826A1 (en) | 1982-05-14 |
| KR830007460A (en) | 1983-10-21 |
| NZ198927A (en) | 1985-02-28 |
| AR226757A1 (en) | 1982-08-13 |
| NO813799L (en) | 1982-05-11 |
| IT8124957A0 (en) | 1981-11-10 |
| BE891065A (en) | 1982-03-01 |
| PL233756A1 (en) | 1982-05-24 |
| IT1140282B (en) | 1986-09-24 |
| DK496981A (en) | 1982-05-11 |
| JPS57111240A (en) | 1982-07-10 |
| BR8107289A (en) | 1982-08-03 |
| NL8105079A (en) | 1982-06-01 |
| ES507492A0 (en) | 1983-01-16 |
| ES8301850A1 (en) | 1983-01-16 |
| FI813540L (en) | 1982-05-11 |
| DE3144583A1 (en) | 1982-09-09 |
| ZA817558B (en) | 1983-02-23 |
| SE8106655L (en) | 1982-05-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |