GB2144206A - Calcination installation for producing various grades of alumina and a method of operation - Google Patents

Calcination installation for producing various grades of alumina and a method of operation Download PDF

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Publication number
GB2144206A
GB2144206A GB08418423A GB8418423A GB2144206A GB 2144206 A GB2144206 A GB 2144206A GB 08418423 A GB08418423 A GB 08418423A GB 8418423 A GB8418423 A GB 8418423A GB 2144206 A GB2144206 A GB 2144206A
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GB
United Kingdom
Prior art keywords
calcination
alumina
cooler
preheater
furnace
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.)
Granted
Application number
GB08418423A
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GB8418423D0 (en
GB2144206B (en
Inventor
Jean Lebesgue
Michel Wattelle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fives Cail Babcock SA
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Fives Cail Babcock SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fives Cail Babcock SA filed Critical Fives Cail Babcock SA
Publication of GB8418423D0 publication Critical patent/GB8418423D0/en
Publication of GB2144206A publication Critical patent/GB2144206A/en
Application granted granted Critical
Publication of GB2144206B publication Critical patent/GB2144206B/en
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
    • C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
    • C01F7/445—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination making use of a fluidised bed
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
    • C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
    • F27B15/003—Cyclones or chain of cyclones
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/2016—Arrangements of preheating devices for the charge
    • F27B7/2025—Arrangements of preheating devices for the charge consisting of a single string of cyclones
    • F27B7/2033—Arrangements of preheating devices for the charge consisting of a single string of cyclones with means for precalcining the raw material

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Dispersion Chemistry (AREA)
  • Furnace Details (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

The invention provides a calcination installation suitable for producing various grades of alumina calcined at different temperatures. The installation comprises a preheater, preferably of the cyclone type (10, 12, 13), a chamber for calcination in suspension (14, 16), a rotating tube furnace (18), a cooler, preferably of the cyclone type (22, 24), and an additional cooler (26), and switches (32, 36) are provided between the preheater (10, 12, 13), the rotating furnace (18) and the calcination chamber (14) in order to connect the materials outlet of the preheater (10, 12, 13) either to the inlet of the rotating furnace (18) or to the inlet of the calcination chamber (14) and in order to connect the gas inlet of the preheater (10, 12, 13) either to the gas outlet of the furnace (18) or to the gas outlet of the calcination chamber (14). The materials outlets of the rotating furnace (18) and of the cooler (22, 24) are connected to the inlet of the additional cooler (26). <IMAGE>

Description

SPECIFICATION Calcination installation for producing various grades of alumina and a method of operation The present invention relates to a calcination installation suitable for producing various grades of alumina calcined at different termperatures.
Usually, calcination of hydrated alumina takes place in a rotating tube furnace which may or may not be provided with an incorporated cooler formed by tubes disposed in a satellite arrangement around the end of the outlet of the furnace. When one single furnace is used for producing alumina of different grades. It is necessary to drain it completely when passing from one grade of alumina to the other, which takes time and reduces the profitability of the installation.
Moreover, the solution of providing as many rotating furnaces as there are grades of alumina to be produced would be costly and not profitable.
The object of the invention is to produce, at a lower cost, an installation which enables various grades of alumina, in particular alumina calcined at a high temperature, of the order of 1400-1500"C, and alumina calcined art a lower temperature, less than 1100"C, to be produced, and does not require prolonged production stoppages in order to pass from one grade of alumina to the other.
The present invention provides a calcination installation comprising a preheater of the cyclone type, a chamber for calcination in suspension, a rotating tube furnace, a cooler of the cyclone type and an additional cooler, switches provided between the preheater, the rotating furnace and the calcination chamber in order to connect the materials outlet of the preheater either to the inlet of the rotating furnace or to the inlet of the calcination chamber and in order to connect simultaneously the gas inlet of the preheater either to the gas outlet of the furnace or to the gas outlet of the calcination chamber, and the materials outlet of the rotating furnace and the materials outlet of the cyclone cooler are connected to the inlet of the additional cooler, the materials outlet of the calcination chamber being connected to the materials inlet of the cyclone cooler.
Installations, used in particular for producing cement clinker, which comprise a preheater, a chamber for calcination in suspension, a rotating tube furnace and a cooler, are known, but in these installations the calcination chamber and the furnace operate simultaneously and the products to be processed pass successively into the preheater, the calcination chamber, the rotating furnace and the cooler.
According to the present invention, the preheater, the rotating furnace and the additional cooler are used for high temperature calcination, the rotating furnace preferably comprising an incorporated cooler. For lower temperature calcination, the preheater, the calcination chamber, the cyclone cooler and the additional cooler are used. In order to heat the calcination chamber, either a fuel, which burns with the air coming from the cyclone cooler, can be injected directly into the chamber or hot gases, which come from a separate hearth which is equipped with a burner and is supplied with secondary air, may be introduced into the chamber.
The installation to which the invention relates has an energy output which is greater than that of conventional installations having a long rotating furnace, since in all cases, the hydrated alumina is dried and preheated in an exchanger of the cyclone type, which has a heat output greater than that of the rotating furnace. Moreover, its cost is not very different from that of conventional installations since the rotating furnace is much shorter than conventional furnaces, as the drying and preheating of the hydrated alumina takes place upstream of the furnace, and as the cost price of the chamber for calcination in suspension, which does not comprise any movable member, is relatively low.
Other features of the invention will appear from the following description which refers to the accompanying drawing whose single Figure is the diagram of an installation according to the invention.
This installation essentially comprises a preheater formed by two cyclones 10 and 12 and buy a connecting conduit 13, a calcination chamber 14, with which a cyclone 16 is associated, a rotating tube furnace 18 equipped with cooler tubes 20, a cyclone cooler 22-24 and an additional cooler 26.
The connecting conduit 13 comprises a vertical portion which is traversed upwards by the gases flowing from the cyclone 12 towards the cyclone 10 and at the base of which the hydrated alumina to be calcined is introduced by means of a feed device 28.
The gas outlet of the cyclone 16 and the fume hood 30 of the furnace 18 can be connected by means of a switch 32, to a conduit 34, connected to the inlet of the cyclone 12.
The tip of the cyclone 12 can be connected, by means of a second switch 36 and pipes 38 and 40, either to the inlet of the furnace 18 or to the conduit 42 connecting the outlet of the cyclone 22 of the cooler to the inlet of the calcination chamber.
The controls of the two switches 32 and 36 are coupled in such a way that when the materials outlet situated at the tip of the cyclone 12 is connected to the inlet of the furnace, the inlet of this cyclone is simultaneously connected to the fume hood of the furnace, the assembly of the calcination chamber, the cyclone 16 and the cyclone cooler 22-24 then being isolated, and when the materials outlet of the cyclone 12 is connected to the conduit 42, the inlet of this cyclone is simultaneously connected to the outlet of the cyclone 16, the furnace 18then being isolated.
The cooler 26, which for example may be of the fluidized bed type, receives the calcined alumina which is discharged from the cooler 20, incorporated in the furnace 18, or from the cyclone cooler 22-24, according to the method of operation chosen.
The calcination chamber 14 is in the general shape of a cyclone. The products to be processed are introduced in a tangential manner into the upper part of the chamber, in suspension in a current of air coming from the cooler 22-24. Afuel is dispersed in the current of air penetrating the chamber by means of an injection pipe 44 embedded in the ceiling of the chamber and the combustion of the fuel supplies the heat necessary for calcination. The calcined products and the gases of combustion leave the chamber by an aperture which is provided in the base thereof and is connected to the inlet of the cyclone 16. In the latter the calcined products are separated from the gas current and are discharged at the tip of the cyclone so as to be directed towards the cooler 22-24.In the definition of the invention given above and in the claims, the cyclone 16 was considered as being part of the calcination chamber and the gas and materials outlets of the cyclone as the gas and materials outlets of the chamber.
The rotating furnace 18 comprises, on the side of the materials outlet, a burner 46. The calcined products leaving the furnace fall into the cooler tubes 20 where they come into contact with fresh air which is flowing in the reverse direction and which is subsequently used as secondary air in the furnace.
In order to produce over-calcined alumina (floury alumina), formed almost exclusively from a alumina, the furnace 18 is used. The hydrated alumina introduced into the conduit 13 by means of the feed device 28 is dried and preheated during its stay in the conduit 13, the cyclone 10, the conduit 34 and the cyclone 12. At the outlet of the cyclone 12 the alumina is introduced into the furnace 18, where it is brought to a temperature which is able to reach 1500 C, then cooled in the cooler tubes 20 and subjected to a final cooling in the cooler 26 by means of air blown in by means of a ventilator 48.
In order to produce under-calcined alumina (sandy alumina) having a reduced specific surface area (70m2/g for example), the hydrated alumina is calcined at a temperature of approximately 1050 1100 C in the calcination chamber 14 by placing the switches 32 and 36 in the desired position. The calcined alumina is cooled in the cyclone cooler 22 and 24, by means of fresh air forced back by a ventilator 50, and then in the cooler 26.
In order to produce y alumina having a greater specific surface area (180m2/g instead of 70mug for example). the hydrated alumina must be calcined at a lower temperature, less than 1000 C. In this case the calcination chamber 14 is again used. Instead of injecting the fuel into the chamber, in order to avoid localized overheating, it can be burned in a separate hearth 52, shown in dashed lines in the drawing, and the gases of combustion, mixed with secondary air, delivered to the combustion chamber.
It is obvious that the rotating furnace is clearly shorter than the furnaces usually used for the calcination of alumina because it receives alumina which has already been dried and preheated in the conduit 13 and the cyclones 10 and 12.
The preheater and the cooler can comprise a number of cyclones other than two. In particular, for high temperature calcination of alumina, the number of cyclones of the preheater can be increased so as to bring the hydrated alumina to a high temperature, which is able to reach 800-850"C, before being introduced into the rotating tube furnace 18. In this case and for the same purpose, the hydrated alumina can also be passed into the calcination chamber 14, supplied with air and fuel, and into the cyclone 16, on leaving the preheater and before passing into the rotating furnace.In order to enable the installation to be used in this manner, the switch 32 has to be provided with a position such that the exhaust gas outlets of the cyclone 16 and of the rotation furnace 18 can be connected simultaneously to the conduit 34, and the controls of the switches 32 and 36 have to be independent, so that the latter can be positioned in order to direct the hydrated alumina, leaving the preheater, towards the calcination cham ber14orpartlytowardsthischamberand partly towards the rotating furnace 18; a third switch 53 is also provided so as to allow the tip of the cyclone 16 to be connected selectively to the cyclone cooler 22-24 and to the rotating furnace 18, by means of the pipe 38.
An injection or mixing device 54 can be provided for example on the pipe 38, to allow different products necessary for obtaining calcined alumina of given grades to be added to the alumina passing into the furnace.
The preheater and the cyclone cooler can be replaced by heat exchangers of a different design and the chamber for calcination in suspension can have a different structure from that described.
The switches can be formed simply by Y-shaped fittings comprising one main branch, two secondary branches and a flap allowing the connection between the main branch and one or other of the secondary branches to be interrupted with the possibility of maintaining the connection between the main branch and the two secondary branches for any intermediate position of the flap.

Claims (9)

1. An alumina calcination installation comprising a preheater, preferably of the cyclone type, a chamber for calcination in suspension, a rotating tube furnace, a cooler, preferably of the cyclone type, and an additional cooler, characterized in that switches are provided between the preheater, the rotating furnace and the calcination chamber in order to connect the materials outlet of the preheater either to the inlet of the rotating furnace or to the inlet of the calcination chamber and in order to connect the inlet of the preheater either to the gas outlet of the furnace or to the gas outlet of the calcination chamber and in that the materials outlets of the rotating chamber and of the cooler are connected to the inlet of the additional cooler.
2. An installation according to claim 1, characterized in that the rotating tube furnace is equipped on the side of the materials outlet with cooler tubes disposed in a satellite arrangement.
3. An installation according to claim 1 or 2, characterized in that it comprises a hearth which supplies hot gases to the calcination chamber.
4. An installation according to claim 1,2 or 3, characterized in that it further cc comprises a switch allowing the materials outlet of the calcination chamber to be connected either to the materials inlet of the cooler or to the inlet of the rotating furnace and in that the switch disposed between the gas outlets of the rotating furnace and of the calcination chamber and the inlet of the preheater is designed so as to allow these two outlets to be connected simultaneously to the inlet of the preheater.
5. An installation according to claim 1,2,3 or 4, characterized in that it comprises a device disposed at the inlet of the rotating furnace allowing added products to be mixed with the alumina passing into the furnace.
6. A method for high temperature calcination of hydrated alumina in order to produce over-calcined alumina in an installation according to claim 1,2,3,4 or 5, characterized in that the hydrated alumina is dried and preheated up to a temperature which is able to reach 850"C in the preheater and then is calcined at a temperature which is able to reach 1500"C in the rotating furnace.
7. A method for high temperature calcination of hydrated alumina in an installation according to claim 4, characterized in that the hydrated alumina is dried and preheated in the preheater is brought to a temperature which is able to reach 850"C in the calcination chamber and is subsequently calcined at a temperature which is able to reach 1500 C in the rotating furnace.
8. A method for the calcination of hydrated alumina in order to produce under-calcined alumina in an installation according to claim 1,2 or 3, characterized in tht the hydrated alumina is dried and preheated in the preheater, is calcined at a temperature of the order of 1050 C-1100 C in the calcination chamber and the calcined alumina is cooled firstly in the cooler then in the additional cooler.
9. A methodforthecalcination of hydrated alumina in orderto produce y alumina in an installation according to claim 1,2 or3, characterized in that the hydrated alumina is dried and preheated in the preheater, is calcined at a temperature which is lower than 1000 C in the calcination chamber and the calcined alumina is cooled firstly in the cooler then in the additional cooler.
GB08418423A 1983-07-28 1984-07-19 Calcination installation for producing various grades of alumina and a method of operation Expired GB2144206B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR8312459A FR2549816B1 (en) 1983-07-28 1983-07-28 CALCINATION PLANT FOR THE PRODUCTION OF SEVERAL QUALITIES OF ALUMINA AND METHOD FOR OPERATING THE SAME

Publications (3)

Publication Number Publication Date
GB8418423D0 GB8418423D0 (en) 1984-08-22
GB2144206A true GB2144206A (en) 1985-02-27
GB2144206B GB2144206B (en) 1986-11-19

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GB08418423A Expired GB2144206B (en) 1983-07-28 1984-07-19 Calcination installation for producing various grades of alumina and a method of operation

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DE (1) DE3426668A1 (en)
FR (1) FR2549816B1 (en)
GB (1) GB2144206B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2022100082B4 (en) * 2019-11-26 2023-06-22 Metso Metals Oy Optimized semi-dry process for sintering of aluminosilicates in the production of alumina

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3522883A1 (en) * 1985-06-26 1987-01-08 Krupp Polysius Ag Process and plant for the heat treatment of fine granular material
CN111807398A (en) * 2020-06-16 2020-10-23 汝州市小微结构陶瓷有限公司 Production process of alpha-alumina micropowder for microcrystal high alumina ball stone and lining brick

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1248038A (en) * 1959-10-28 1960-12-09 Electrochimie Electrometallurg Anhydrous aluminas manufacturing process
DE2048207A1 (en) * 1970-10-01 1972-04-06 Kloeckner Humboldt Deutz Ag Equipment for the production of alumina from alumina hydrate
DE2103949A1 (en) * 1971-01-28 1972-08-17 Kloeckner Humboldt Deutz Ag Device for the continuous feeding of an alumina calcination plant with hydrates of aluminum
AU471315B2 (en) * 1972-05-20 1976-04-15 Ishikawajima-Harima Jukogyo K.K. Apparatus for burning materials of cement andthe luce
US4071309A (en) * 1976-05-28 1978-01-31 Allis-Chalmers Corporation Method and apparatus for making cement with preheater, kiln and heat exchanger for heating combustion air
NO791174L (en) * 1978-04-20 1979-10-23 Smidth & Co As F L PROCEDURE FOR MANUFACTURE OF WATERLESS ALUMINUM OXIDES

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2022100082B4 (en) * 2019-11-26 2023-06-22 Metso Metals Oy Optimized semi-dry process for sintering of aluminosilicates in the production of alumina

Also Published As

Publication number Publication date
DE3426668A1 (en) 1985-02-07
GB8418423D0 (en) 1984-08-22
FR2549816B1 (en) 1985-11-15
FR2549816A1 (en) 1985-02-01
GB2144206B (en) 1986-11-19

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PCNP Patent ceased through non-payment of renewal fee