WO2006106443A2 - Method and plant for manufacturing of alumina - Google Patents

Method and plant for manufacturing of alumina Download PDF

Info

Publication number
WO2006106443A2
WO2006106443A2 PCT/IB2006/050788 IB2006050788W WO2006106443A2 WO 2006106443 A2 WO2006106443 A2 WO 2006106443A2 IB 2006050788 W IB2006050788 W IB 2006050788W WO 2006106443 A2 WO2006106443 A2 WO 2006106443A2
Authority
WO
WIPO (PCT)
Prior art keywords
alumina
plant
processing unit
filter
extracted
Prior art date
Application number
PCT/IB2006/050788
Other languages
French (fr)
Other versions
WO2006106443A3 (en
Inventor
Benny Raahauge
Original Assignee
Ffe Minerals Denmark A/S
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 Ffe Minerals Denmark A/S filed Critical Ffe Minerals Denmark A/S
Publication of WO2006106443A2 publication Critical patent/WO2006106443A2/en
Publication of WO2006106443A3 publication Critical patent/WO2006106443A3/en

Links

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

Definitions

  • the present invention relates to a method for manufacturing alumina (AI 2 O 3 ) from raw materials containing aluminium hydroxide (AI(OH) 3 ), by which method the raw materials are preheated in a cyclone preheater, calcined in a furnace, cooled in a cyclone cooler, with dust filtration of process gases being effected in a filter.
  • the invention also relates to a plant for carrying out the invention.
  • a method of the aforementioned kind is generally known from the literature and from established practice. It has been ascertained that in connection with ordinary, steady-state operation at known plants, 3-5 per cent of the raw materials which are fed to the plant end up as fine dust which is removed in the filter, typically an electrostatic precipitator. Given that the volume of filter dust is so significant as to render a disposal of the dust inappropriate, it would be desirable to provide means for ensuring a trouble-free re-introduction of the dust into the process.
  • the filter dust typically contains large amounts of uncalcined material, often more than 50 per cent, and, therefore, it is not immediately suitable for blending into the finished product. Before the filter dust can be incorporated into the finished product, it must undergo further heat treatment.
  • the filter dust is re-introduced into one of the first stages of the cyclone cooler; however, this method has proved to generate an excessively high dust circulation, having an undesirable effect on the operating economy of the plant.
  • the plant for carrying out the method according to the invention comprises a cyclone preheater, a furnace, a cyclone cooler and a filter, and it is characterized in that it comprises means for extracting a portion of the calcined, not completely cooled alumina from the plant, a separate processing unit for blending the extracted alumina with filter dust, and means for introducing the extracted alumina and filter dust, respectively, into the processing unit.
  • the blending of the extracted, calcined alumina and the filter dust can be done in any appropriate manner.
  • studies conducted by the applicant filing the present patent application have indicated that blending should preferably be done in a gas suspension. According to the invention it is, therefore, preferred that blending is done in a processing unit comprising a fluidized bed.
  • volume of the extracted, calcined alumina is adjusted according to the volume and the desired degree of calcination of the filter dust.
  • the lowest reaction temperature at which calcination of alumium hydroxide is commenced has been determined to be within the range 245-250 -C. Also, operational data from plant have indicated that a temperature of 310-325 -C is sufficient if a sufficient retention time of the material is ensured. According to the invention, it is, therefore, preferred that the temperature in the processing unit is maintained at a level of minimum 310 -C.
  • the blended product is extracted from the processing unit, preferably in suspension, and subject to subsequent cooling.
  • cooling of the blended product may appropriately be done in conjunction with the final cooling of the finished product in a cooler with a fluidized bed. Hence it will be possible to obtain a very homogeneous product, while simultaneously providing the option of heat reutilization.
  • the means for extracting a portion of the calcined, not completely cooled alumina from the plant may appropriately comprise a splitter gate.
  • the separate processing unit for blending the extracted alumina with filter dust may appropriately be made up of a reactor with a fluidized bed.
  • the means for introducing the extracted alumina into the processing unit appropriately comprise an inclined duct which terminates in the processing unit, whereas the means for introducing the filter dust, which is typically directed to the processing unit in suspension, may comprise a separation cyclone and a duct which is also terminated in the processing unit.
  • the plant is seen to comprise a preheater 1 , a furnace 3, a primary cooler 5, a secondary cooler 7 and a filter 9.
  • the preheater 1 is typically made up of a cyclone preheater comprising two to three stages to which the raw materials are introduced in suspension from a not shown raw material store via a duct 2 in the first cyclone, and in which the material is preheated by heat exchange with hot gases from the subsequent furnace 3.
  • the gases from the preheater are directed via a duct 10 through to the filter 9.
  • the preheated material is introduced via a duct 1 a to the furnace 3, which typically comprises a calciner which consists of a substantially vertical duct which is swept by hot gases from the lower end and upwards and in which the preheated material and fuel 4 are introduced at the lower end.
  • the material is suspended in the hot gas stream and calcined while being transported up through the calciner from which the gas/material suspension is directed to a separation cyclone which divides the suspension into a section of material which is diverted for cooling and a section of gases which is led via a duct 1 b to the cyclone preheater 1.
  • the hot, calcined material is subsequently directed to and cooled in the primary cooler 5 which typically comprises a cyclone cooler comprising four stages, and then via a duct 5a to the secondary cooler 7 which typically consists of a cooler with fluidized bed which is fed with relatively cold air via a duct 8.
  • the actual cooling can be done by using air or a fluid as cooling medium.
  • the finished product is extracted from the secondary cooler 7 via an outlet 7a.
  • the cooling air from the primary cooler 5 is directed to the furnace 3 via a duct 3b, while the cooling air from the secondary cooler 7 is directed to the primary cooler 5 via a duct 5b.
  • the primary cooler 5 is further supplied with relatively cold air via a duct 6.
  • a portion of the calcined not completely cooled alumina material is extracted from the plant and blended with filter dust from the filter 9 in a separate processing unit 11.
  • the plant incorporates a splitter gate 13.
  • the splitter gate 13 may, as shown in the figure, be fitted immediately after the furnace 3, but it may also be fitted after one of the cyclones of the cyclone cooler 5, preferably the first cyclone if such a position is deemed to be necessary due to practical considerations.
  • the alumina material is directed to the processing unit 11 via a duct 15.
  • the filter dust is transported from the filter 9 to the processing unit 11 via a duct 17.
  • the plant comprises a separation cyclone 18 the material outlet of which is connected to the processing unit 11.
  • the separate processing unit 11 for blending the extracted alumina with filter dust is made up of a reactor with fluidized bed which is fed with fluidizing air via a duct 11 a.
  • the volume of the extracted calcined alumina is adjusted according to the volume and the desired calcination degree of the filter dust by means of the splitter gate 13, preferably so that the temperature in the processing unit 11 is maintained at a level of minimum 310 -C.
  • the blended product is extracted in suspension via a duct 11 b and is introduced into the secondary cooler 7 in which it is subjected to cooling in conjunction with the finished product from the plant.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
  • Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)

Abstract

Described is method as well as a plant for manufacturing alumina (Al2O3) from raw materials containing aluminium hydroxide (Al(OH)3), by which method the raw materials are preheated in a cyclone preheater (1), calcined in a furnace (3), cooled in a cyclone cooler (5), with dust filtration of process gases being effected in a filter (9). The method and the plant are peculiar in that a portion of the calcined, not completely cooled alumina is extracted from the plant, and that this portion is introduced into a separate processing unit (11) in which it is blended with filter dust which is fed to the processing unit (11) from the filter (9). As a result, final calcination of the filter dust is achieved without increasing the dust circulation in the plant, and without any adverse effect on the capacity of the filter.

Description

METHOD AND PLANT FOR MANUFACTURING OF ALUMINA
The present invention relates to a method for manufacturing alumina (AI2O3) from raw materials containing aluminium hydroxide (AI(OH)3), by which method the raw materials are preheated in a cyclone preheater, calcined in a furnace, cooled in a cyclone cooler, with dust filtration of process gases being effected in a filter. The invention also relates to a plant for carrying out the invention.
A method of the aforementioned kind is generally known from the literature and from established practice. It has been ascertained that in connection with ordinary, steady-state operation at known plants, 3-5 per cent of the raw materials which are fed to the plant end up as fine dust which is removed in the filter, typically an electrostatic precipitator. Given that the volume of filter dust is so significant as to render a disposal of the dust inappropriate, it would be desirable to provide means for ensuring a trouble-free re-introduction of the dust into the process. The filter dust typically contains large amounts of uncalcined material, often more than 50 per cent, and, therefore, it is not immediately suitable for blending into the finished product. Before the filter dust can be incorporated into the finished product, it must undergo further heat treatment. By a known method for such heat treatment of the dust, the filter dust is re-introduced into one of the first stages of the cyclone cooler; however, this method has proved to generate an excessively high dust circulation, having an undesirable effect on the operating economy of the plant.
It is the object of the present invention to provide a method as well as a plant for manufacturing alumina by which method the filter dust can be fully calcined and subsequently incorporated into the finished product in manner ensuring elimination of the aforementioned problem.
This is achieved by a method of the kind mentioned in the introduction and being characterized in that a portion of the calcined, not completely cooled alumina is extracted from the plant, and that this portion is introduced into a separate processing unit in which it is blended with filter dust which is fed to the processing unit from the filter. As a result, final calcination of the filter dust is achieved without increasing the dust circulation in the plant, and without any adverse effect on the capacity of the filter. This is due to the fact that the aluminium hydroxide contained in the filter dust is dehydrated/calcined when blended with the extracted portion, relatively hot alumina.
The plant for carrying out the method according to the invention comprises a cyclone preheater, a furnace, a cyclone cooler and a filter, and it is characterized in that it comprises means for extracting a portion of the calcined, not completely cooled alumina from the plant, a separate processing unit for blending the extracted alumina with filter dust, and means for introducing the extracted alumina and filter dust, respectively, into the processing unit.
In principle, the blending of the extracted, calcined alumina and the filter dust can be done in any appropriate manner. However, studies conducted by the applicant filing the present patent application have indicated that blending should preferably be done in a gas suspension. According to the invention it is, therefore, preferred that blending is done in a processing unit comprising a fluidized bed.
It is further preferred that the volume of the extracted, calcined alumina is adjusted according to the volume and the desired degree of calcination of the filter dust.
By means of independent tests, the lowest reaction temperature at which calcination of alumium hydroxide is commenced has been determined to be within the range 245-250 -C. Also, operational data from plant have indicated that a temperature of 310-325 -C is sufficient if a sufficient retention time of the material is ensured. According to the invention, it is, therefore, preferred that the temperature in the processing unit is maintained at a level of minimum 310 -C.
According to the invention it is preferred that the blended product is extracted from the processing unit, preferably in suspension, and subject to subsequent cooling.
Since the blended product is intended for subsequent incorporation into the finished product of the plant, cooling of the blended product may appropriately be done in conjunction with the final cooling of the finished product in a cooler with a fluidized bed. Hence it will be possible to obtain a very homogeneous product, while simultaneously providing the option of heat reutilization.
The means for extracting a portion of the calcined, not completely cooled alumina from the plant may appropriately comprise a splitter gate. The separate processing unit for blending the extracted alumina with filter dust may appropriately be made up of a reactor with a fluidized bed. The means for introducing the extracted alumina into the processing unit appropriately comprise an inclined duct which terminates in the processing unit, whereas the means for introducing the filter dust, which is typically directed to the processing unit in suspension, may comprise a separation cyclone and a duct which is also terminated in the processing unit.
The invention will now be described in further details with reference to the drawing, being diagrammatical and where the only figure illustrates a process diagram for a plant for carrying out the method according to the invention.
In the figure the plant is seen to comprise a preheater 1 , a furnace 3, a primary cooler 5, a secondary cooler 7 and a filter 9. The preheater 1 is typically made up of a cyclone preheater comprising two to three stages to which the raw materials are introduced in suspension from a not shown raw material store via a duct 2 in the first cyclone, and in which the material is preheated by heat exchange with hot gases from the subsequent furnace 3. The gases from the preheater are directed via a duct 10 through to the filter 9. From the last cyclone of the cyclone preheater 1 the preheated material is introduced via a duct 1 a to the furnace 3, which typically comprises a calciner which consists of a substantially vertical duct which is swept by hot gases from the lower end and upwards and in which the preheated material and fuel 4 are introduced at the lower end. In the calciner the material is suspended in the hot gas stream and calcined while being transported up through the calciner from which the gas/material suspension is directed to a separation cyclone which divides the suspension into a section of material which is diverted for cooling and a section of gases which is led via a duct 1 b to the cyclone preheater 1. Via a duct 3a, the hot, calcined material is subsequently directed to and cooled in the primary cooler 5 which typically comprises a cyclone cooler comprising four stages, and then via a duct 5a to the secondary cooler 7 which typically consists of a cooler with fluidized bed which is fed with relatively cold air via a duct 8. The actual cooling can be done by using air or a fluid as cooling medium. The finished product is extracted from the secondary cooler 7 via an outlet 7a. The cooling air from the primary cooler 5 is directed to the furnace 3 via a duct 3b, while the cooling air from the secondary cooler 7 is directed to the primary cooler 5 via a duct 5b. The primary cooler 5 is further supplied with relatively cold air via a duct 6.
According to the invention a portion of the calcined not completely cooled alumina material is extracted from the plant and blended with filter dust from the filter 9 in a separate processing unit 11. For the extraction of a portion of the calcined, not completely cooled alumina the plant incorporates a splitter gate 13. The splitter gate 13 may, as shown in the figure, be fitted immediately after the furnace 3, but it may also be fitted after one of the cyclones of the cyclone cooler 5, preferably the first cyclone if such a position is deemed to be necessary due to practical considerations. From the splitter gate 13 the alumina material is directed to the processing unit 11 via a duct 15. The filter dust is transported from the filter 9 to the processing unit 11 via a duct 17. In the preferred embodiment of the invention where the filter dust is transported in suspension, the plant comprises a separation cyclone 18 the material outlet of which is connected to the processing unit 11.
In the preferred embodiment, the separate processing unit 11 for blending the extracted alumina with filter dust is made up of a reactor with fluidized bed which is fed with fluidizing air via a duct 11 a.
The volume of the extracted calcined alumina is adjusted according to the volume and the desired calcination degree of the filter dust by means of the splitter gate 13, preferably so that the temperature in the processing unit 11 is maintained at a level of minimum 310 -C.
From the processing unit 11 , the blended product is extracted in suspension via a duct 11 b and is introduced into the secondary cooler 7 in which it is subjected to cooling in conjunction with the finished product from the plant. Attention is drawn to the fact that this invention is not limited to the manufacture of alumina, but it can also be used for other calcination processes, such as e.g. the manufacture of burnt lime (CaO) and similar products.

Claims

Claims
1. Method for manufacturing alumina (AI2O3) from raw materials containing aluminium hydroxide (AI(OH)3), by which method the raw materials are preheated in a cyclone preheater (1 ), calcined in a furnace (3), cooled in a cyclone cooler (5), with dust filtration of process gases being effected in a filter (9), characterized in that a portion of the calcined, not completely cooled alumina is extracted from the plant, and that this portion is introduced into a separate processing unit (11 ) in which it is blended with filter dust which is fed to the processing unit (11 ) from the filter (9).
2. Method according to claim 1 , characterized in that the blending is done in a processing unit (11 ) comprising a fluidized bed.
3. Method according to claim 1 , characterized in that the volume of the extracted, calcined alumina is adjusted according to the volume and the desired degree of calcination of the filter dust.
4. Method according to claim 1 , characterized in that the temperature in the processing unit (11 ) is maintained at a level of minimum 310 -C.
5. Method according to claim 1 , characterized in that the blended product is extracted from the processing unit, preferably in suspension, and subject to subsequent cooling.
6. Method according to claim 5, characterized in that the blended product is cooled in conjunction with the final cooling of the finished product in a cooler (7) with a fluidized bed.
7. Plant for carrying out the method according to claim 1 , comprising a cyclone preheater (1 ), a furnace (3), a cyclone cooler (5) and a filter (9), characterized in that it comprises means (13) for extracting a portion of the calcined, not completely cooled alumina from the plant, a separate processing unit (11 ) for blending the extracted alumina with filter dust, and means (15, 17) for introducing the extracted alumina and filter dust, respectively, into the processing unit (11 ).
8. Plant according to claim 7, characterized in that the means (13) for extracting a portion of the calcined, not completely cooled alumina from the plant comprise a splitter gate (13).
9. Plant according to claim 7, characterized in that the separate processing unit (11 ) for blending the extracted alumina with filter dust is made up of a reactor (11 ) with a fluidized bed.
PCT/IB2006/050788 2005-04-06 2006-03-14 Method and plant for manufacturing of alumina WO2006106443A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200500476 2005-04-06
DKPA200500476 2005-04-06

Publications (2)

Publication Number Publication Date
WO2006106443A2 true WO2006106443A2 (en) 2006-10-12
WO2006106443A3 WO2006106443A3 (en) 2006-11-30

Family

ID=37073834

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2006/050788 WO2006106443A2 (en) 2005-04-06 2006-03-14 Method and plant for manufacturing of alumina

Country Status (1)

Country Link
WO (1) WO2006106443A2 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007014435A1 (en) 2007-03-22 2008-09-25 Outokumpu Technology Oyj Process and plant for the production of metal oxide from metal salts
DE102013103080A1 (en) 2013-03-26 2014-06-12 Outotec Oyj Method for removing fine solid material particles from fluidized bed in e.g. cement manufacturing plant, involves indirectly cooling additional gas flow into initiated fluidized bed chamber above fluidized bed
CN104556167A (en) * 2014-12-19 2015-04-29 贵州天合国润高新材料科技有限公司 Method for preparing flaky alumina powder
CN112174176A (en) * 2020-09-28 2021-01-05 沈阳鑫博工业技术股份有限公司 Device and method for preparing alpha-alumina by using aluminum hydroxide

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3529356A (en) * 1967-10-06 1970-09-22 Kloeckner Humboldt Deutz Ag Method of continuously dehydrating aluminum oxide hydrates
WO1996036563A1 (en) * 1995-05-17 1996-11-21 Aluchem, Inc. Method and apparatus for making high-grade alumina from low-grade aluminum oxide fines
DE10331364B3 (en) * 2003-07-11 2005-01-27 Outokumpu Oyj Process and plant for the production of metal oxide from metal hydroxide
US20050238571A1 (en) * 2004-04-26 2005-10-27 Raahauge Benny E Process and apparatus for the production of alumina

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3529356A (en) * 1967-10-06 1970-09-22 Kloeckner Humboldt Deutz Ag Method of continuously dehydrating aluminum oxide hydrates
WO1996036563A1 (en) * 1995-05-17 1996-11-21 Aluchem, Inc. Method and apparatus for making high-grade alumina from low-grade aluminum oxide fines
DE10331364B3 (en) * 2003-07-11 2005-01-27 Outokumpu Oyj Process and plant for the production of metal oxide from metal hydroxide
US20050238571A1 (en) * 2004-04-26 2005-10-27 Raahauge Benny E Process and apparatus for the production of alumina

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007014435A1 (en) 2007-03-22 2008-09-25 Outokumpu Technology Oyj Process and plant for the production of metal oxide from metal salts
DE102013103080A1 (en) 2013-03-26 2014-06-12 Outotec Oyj Method for removing fine solid material particles from fluidized bed in e.g. cement manufacturing plant, involves indirectly cooling additional gas flow into initiated fluidized bed chamber above fluidized bed
CN104556167A (en) * 2014-12-19 2015-04-29 贵州天合国润高新材料科技有限公司 Method for preparing flaky alumina powder
CN112174176A (en) * 2020-09-28 2021-01-05 沈阳鑫博工业技术股份有限公司 Device and method for preparing alpha-alumina by using aluminum hydroxide
CN112174176B (en) * 2020-09-28 2022-11-15 沈阳鑫博工业技术股份有限公司 Device and method for preparing alpha-alumina by using aluminum hydroxide

Also Published As

Publication number Publication date
WO2006106443A3 (en) 2006-11-30

Similar Documents

Publication Publication Date Title
EP2018353B1 (en) Method and plant for manufacturing cement clinker
AU728011B2 (en) Fluidized bed process for producing alumina from aluminum hydroxide
CN102317202B (en) Process and plant for producing metal oxide from metal salts
AU2010206320B2 (en) Process and plant for producing metal oxide from metal salts
CA2835488C (en) Decarbonation process
US4585645A (en) Alpha alumina production in a steam-fluidized reactor
WO2006106443A2 (en) Method and plant for manufacturing of alumina
EP0603998B1 (en) Method for the calcination of limestone
Fish Alumina calcination in the fluid-flash calciner
US4555388A (en) Method and apparatus for calcining raw phosphate material
CN111892832B (en) Method for preparing multistage calcined kaolin by suspension calcination of coal-series kaolin
JPS5962336A (en) Method and apparatus for calcinating powdery stock material
CA1161073A (en) Process of producing cement clinker
US4616575A (en) Method and apparatus for the heat treatment of fine-grained material
DK167004B1 (en) METHOD AND PLANT FOR HEAT TREATMENT OF POWDER-SHAPED MATERIAL
WO2022256925A1 (en) Production of calcined material with separate calcination of exhaust dust
US4511543A (en) Method for beneficiation of phosphate rock
JPS6036359A (en) Lime-rich binder, particularly method and apparatus for manufacturing cement
AU2016269697B2 (en) Process and system for thermal treatment of granular solids
US3293330A (en) Fluidized process for calcining particulate limestone
US4605370A (en) Method and apparatus for burning away organic components in raw phosphate
JPS5988348A (en) Manufacture and equipments for belite type cement
OA18775A (en) Process and system for thermal treatment of granular solids.
IL34473A (en) Process for compacting fines produced by the decrepitation of limestone
JPS58194766A (en) Cement raw material baking apparatus

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Country of ref document: DE

NENP Non-entry into the national phase

Ref country code: RU

WWW Wipo information: withdrawn in national office

Country of ref document: RU

122 Ep: pct application non-entry in european phase

Ref document number: 06727664

Country of ref document: EP

Kind code of ref document: A2

WWW Wipo information: withdrawn in national office

Ref document number: 6727664

Country of ref document: EP