WO2012076861A2 - Sintered lightweight aggregates - Google Patents

Sintered lightweight aggregates Download PDF

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Publication number
WO2012076861A2
WO2012076861A2 PCT/GB2011/052236 GB2011052236W WO2012076861A2 WO 2012076861 A2 WO2012076861 A2 WO 2012076861A2 GB 2011052236 W GB2011052236 W GB 2011052236W WO 2012076861 A2 WO2012076861 A2 WO 2012076861A2
Authority
WO
WIPO (PCT)
Prior art keywords
ash
pelletiser
ground
furnace ash
grinding
Prior art date
Application number
PCT/GB2011/052236
Other languages
French (fr)
Other versions
WO2012076861A3 (en
Inventor
Andrew Doel
Original Assignee
Lytag Limited
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 Lytag Limited filed Critical Lytag Limited
Priority to EP11787935.3A priority Critical patent/EP2648835A2/en
Publication of WO2012076861A2 publication Critical patent/WO2012076861A2/en
Publication of WO2012076861A3 publication Critical patent/WO2012076861A3/en

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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
    • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B18/02—Agglomerated materials, e.g. artificial aggregates
    • C04B18/027—Lightweight materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/14—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic in rotating dishes or pans
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • This invention relates to lightweight aggregates produced by sintering furnace ash.
  • the apparatus comprises a screw-conveyor for delivering controlled quantities of the pulverised fly ash to a mixer unit, where it is mixed with a certain amount of water.
  • the mixture is then fed by a conveyor at a controlled speed into a pelletiser, which rotates around an inclined axis such that the mixture is formed into pellets which are eventually discharged from the pelletiser by continued rotation thereof.
  • the pellets are then conveyed to a sintering device, such as a sinter strand, where they are formed into a bed on top of a movable grate or mesh.
  • a sintering device such as a sinter strand
  • the bed of material which contains carbon, is then is ignited from above and moved away from the ignition source over a downdraft, which causes the ignition to propagate downwardly through the bed of material in a controlled manner to fully combust the material.
  • the resultant sintered material is both strong and lightweight and thereby lends itself to use as an aggregate for the building industry.
  • Such apparatus is only suitable for processing fine ash recovered from the exhaust gases of certain coal fired furnaces.
  • a travelling gate boiler both fine ash and clinker is removed from the boiler either by sluicing or by using drag chain. Ash recovered from such boilers is unsuitable for use with the apparatus disclosed in International Patent Application WO2010/100468 due to the presence of the clinker in the ash.
  • an apparatus for producing a lightweight aggregate from furnace ash comprising means for grinding the furnace ash to be processed, a pelletiser for receiving the ground furnace ash and for forming pellets thereof and means for sintering the pellets to form the lightweight aggregates.
  • the provision of the grinding means prior to the pelletiser allows the output from travelling grate boilers to be processed since the coarser clinker contained therein is ground to a suitable consistency for feeding to the pelletiser.
  • the provision of the grinding means prior to the pelletiser also allows for the processing of furnace ash recovered from landfill sites by grinding the clumps and other matter to a suitable consistency for feeding to the pelletiser.
  • the matter received by the grinding means can be of varying degrees wetness and as a result the ground furnace ash output from the grinding means has a corresponding water content. Since the degree of wetness of the material in the pelletiser is crucial to the formation of pellets, means are preferably provided for drying the ground furnace ash and for mixing the dried furnace ash with water prior to the pelletiser. The initial drying of the ground ash then allows a controlled amount of water to be added to produce material suitable for reliable pelletisation.
  • Preferably means are provided between the drying means and the pelletiser for diverting the output of the drying means away from the pelletiser if the output contains particles over a certain size.
  • the apparatus comprises an input for re-introducing the diverted output of the drying means back into the grinding means.
  • a problem of producing surplus furnace ash is that it has to be stored in a location where some will blow away and contaminate the surrounding environment. Hitherto, this problem has been solved by adding water to the ash to allow for stockpiling. Preferably are provided for mixing conditioned ash with the output from the grinding means. The production of matter of a suitable wetness for pelletisation can thus be achieved by appropriate blending of the ground and conditioned ash.
  • a method of producing a lightweight aggregate from furnace ash comprising grinding the furnace ash, feeding the ground ash to a pelletiser and sintering the pellets produced by the pelletiser.
  • the furnace ash is ground in a wet condition.
  • the ground ash is dried prior to feeding it to the pelletiser.
  • Preferably water is added to the dried ash prior to or during the pelletisation step.
  • ground ash is mixed or blended with conditioned ash prior to the pelletisation step.
  • Figure 1 is a block diagram of a first embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate
  • Figure 2 is a block diagram of a second embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate
  • Figure 3 is a block diagram of a third embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate.
  • FIG. 1 of the drawings there is shown an apparatus in accordance with the present invention for producing a lightweight aggregate from either furnace ash A recovered from a landfill site and/or conditioned furnace ash B.
  • the apparatus comprises a grinding device 10 for receiving the recovered furnace ash A.
  • the grinding device 10 grinds any clumps or other particles in the ash to a suitable consistency for processing.
  • the output of the grinding device 10 is fed to a blender or mixer 1 1 where the ground is mixed to the desired consistency with the ash B.
  • the output of the blender or mixer 1 1 is fed to apparatus of the kind disclosed in International Patent Application WO2010/100468, which basically comprises a pan pelletiser 12 and a sintering device 13 for igniting the pellets to produce a lightweight aggregate.
  • the provision of the grinding means 10 prior to the pelletiser 12 allows for the processing of furnace ash recovered from landfill sites by grinding the clumps and other matter to a suitable consistency for feeding to the pelletiser 12.
  • FIG. 2 of the drawings there is shown an apparatus in accordance with the present invention for producing a lightweight aggregate from furnace ash C output from a travelling grate boiler.
  • the apparatus comprises a grinding device 10 for receiving the furnace ash A.
  • the grinding device 10 grinds the larger clinker particles in the ash to a suitable consistency for processing.
  • the output of the grinding device 10 is fed to a dryer 14 where the ground ash is dried.
  • the dryer may use heat recovered from a sintering device 13 of the apparatus.
  • the output of the drier 14 is fed to apparatus of the kind disclosed in International Patent Application WO2010/100468, which comprises a mixer which mixes a weighed quantity of the ground ash with water.
  • the output of the mixer is fed at a controlled rate into a pan pelletiser 12.
  • a sintering device 13 ignites the pellets produced by the pelletiser to produce a lightweight aggregate.
  • FIG. 3of the drawings there is shown another embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate from furnace ash C output from a travelling grate boiler.
  • the apparatus is similar to the apparatus of Figure 2 and like parts are given like reference numerals.
  • the output from the grinding device 10 is fed to a sorting device 15 arranged to only allow particles above a certain size to progress towards the pelletiser 12. Larger particles are fed back to the grinding device 10 for further grinding.
  • the provision of the grinding means 10 allows the output from travelling grate boilers to be processed since the coarser clinker contained therein is ground to a suitable consistency for feeding to the pelletiser 12.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Civil Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

An apparatus for producing a lightweight aggregate from furnace ash comprises a grinder (10) for grinding the furnace ash A to be processed, a pelletiser (12) for receiving the ground furnace ash and for forming pellets thereof and a sintering device (13). The provision of the grinder (10) prior to the pelletiser (12) allows ash from travelling grate boilers to be processed, since the coarser clinker contained therein is ground to a suitable consistency for feeding to the pelletiser. The provision of the grinding means prior to the pelletiser also allows for the processing of furnace ash recovered from landfill sites by grinding the clumps and other matter to a suitable consistency for feeding to the pelletiser. Conditioned fly ash B may also be blended with the furnace ash A after it leaves the grinder (10).

Description

SINTERED LIGHTWEIGHT AGGREGATES
This invention relates to lightweight aggregates produced by sintering furnace ash.
Our co-pending International Patent Application WO2010/100468 discloses a method and apparatus for producing a lightweight aggregate for the construction industry from fly ash, which is a fine residue recovered from the gasses of burning coal during the production of electricity.
The apparatus comprises a screw-conveyor for delivering controlled quantities of the pulverised fly ash to a mixer unit, where it is mixed with a certain amount of water. The mixture is then fed by a conveyor at a controlled speed into a pelletiser, which rotates around an inclined axis such that the mixture is formed into pellets which are eventually discharged from the pelletiser by continued rotation thereof.
The pellets are then conveyed to a sintering device, such as a sinter strand, where they are formed into a bed on top of a movable grate or mesh. The bed of material, which contains carbon, is then is ignited from above and moved away from the ignition source over a downdraft, which causes the ignition to propagate downwardly through the bed of material in a controlled manner to fully combust the material. The resultant sintered material is both strong and lightweight and thereby lends itself to use as an aggregate for the building industry.
Such apparatus is only suitable for processing fine ash recovered from the exhaust gases of certain coal fired furnaces. In a travelling gate boiler, both fine ash and clinker is removed from the boiler either by sluicing or by using drag chain. Ash recovered from such boilers is unsuitable for use with the apparatus disclosed in International Patent Application WO2010/100468 due to the presence of the clinker in the ash.
The practice of disposing of fly or other furnace ash in landfill sites is widespread in some countries and this has the undesirable effect of contaminating the surrounding environment. We have realised that the recovery of fly or other furnace ash from landfill sites for conversion into lightweight aggregates can have both economic and environmental benefits. However a problem of using such ash is that it forms into wet clumps in landfill sites when exposed to water and can contain other particulate matter or solids. We have now devised an apparatus for producing lightweight aggregate which alleviates the above-mentioned problems.
In accordance with the present invention, there is provided an apparatus for producing a lightweight aggregate from furnace ash, the apparatus comprising means for grinding the furnace ash to be processed, a pelletiser for receiving the ground furnace ash and for forming pellets thereof and means for sintering the pellets to form the lightweight aggregates.
The provision of the grinding means prior to the pelletiser allows the output from travelling grate boilers to be processed since the coarser clinker contained therein is ground to a suitable consistency for feeding to the pelletiser. The provision of the grinding means prior to the pelletiser also allows for the processing of furnace ash recovered from landfill sites by grinding the clumps and other matter to a suitable consistency for feeding to the pelletiser.
The matter received by the grinding means can be of varying degrees wetness and as a result the ground furnace ash output from the grinding means has a corresponding water content. Since the degree of wetness of the material in the pelletiser is crucial to the formation of pellets, means are preferably provided for drying the ground furnace ash and for mixing the dried furnace ash with water prior to the pelletiser. The initial drying of the ground ash then allows a controlled amount of water to be added to produce material suitable for reliable pelletisation.
Preferably means are provided between the drying means and the pelletiser for diverting the output of the drying means away from the pelletiser if the output contains particles over a certain size.
Preferably the apparatus comprises an input for re-introducing the diverted output of the drying means back into the grinding means.
A problem of producing surplus furnace ash is that it has to be stored in a location where some will blow away and contaminate the surrounding environment. Hitherto, this problem has been solved by adding water to the ash to allow for stockpiling. Preferably are provided for mixing conditioned ash with the output from the grinding means. The production of matter of a suitable wetness for pelletisation can thus be achieved by appropriate blending of the ground and conditioned ash.
Also in accordance with the present invention there is provided a method of producing a lightweight aggregate from furnace ash, the method comprising grinding the furnace ash, feeding the ground ash to a pelletiser and sintering the pellets produced by the pelletiser.
Preferably the furnace ash is ground in a wet condition.
Preferably the ground ash is dried prior to feeding it to the pelletiser.
Preferably water is added to the dried ash prior to or during the pelletisation step.
Preferably the ground ash is mixed or blended with conditioned ash prior to the pelletisation step.
Embodiment of the present invention will now be described by way of examples only and with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a first embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate;
Figure 2 is a block diagram of a second embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate; and
Figure 3 is a block diagram of a third embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate.
Referring to Figure 1 of the drawings, there is shown an apparatus in accordance with the present invention for producing a lightweight aggregate from either furnace ash A recovered from a landfill site and/or conditioned furnace ash B. The apparatus comprises a grinding device 10 for receiving the recovered furnace ash A. The grinding device 10 grinds any clumps or other particles in the ash to a suitable consistency for processing. The output of the grinding device 10 is fed to a blender or mixer 1 1 where the ground is mixed to the desired consistency with the ash B.
The output of the blender or mixer 1 1 is fed to apparatus of the kind disclosed in International Patent Application WO2010/100468, which basically comprises a pan pelletiser 12 and a sintering device 13 for igniting the pellets to produce a lightweight aggregate.
The provision of the grinding means 10 prior to the pelletiser 12 allows for the processing of furnace ash recovered from landfill sites by grinding the clumps and other matter to a suitable consistency for feeding to the pelletiser 12.
Referring to Figure 2 of the drawings, there is shown an apparatus in accordance with the present invention for producing a lightweight aggregate from furnace ash C output from a travelling grate boiler. The apparatus comprises a grinding device 10 for receiving the furnace ash A. The grinding device 10 grinds the larger clinker particles in the ash to a suitable consistency for processing. The output of the grinding device 10 is fed to a dryer 14 where the ground ash is dried. The dryer may use heat recovered from a sintering device 13 of the apparatus.
The output of the drier 14 is fed to apparatus of the kind disclosed in International Patent Application WO2010/100468, which comprises a mixer which mixes a weighed quantity of the ground ash with water. The output of the mixer is fed at a controlled rate into a pan pelletiser 12. A sintering device 13 ignites the pellets produced by the pelletiser to produce a lightweight aggregate.
Referring to Figure 3of the drawings, there is shown another embodiment of apparatus in accordance with the present invention for producing a lightweight aggregate from furnace ash C output from a travelling grate boiler. The apparatus is similar to the apparatus of Figure 2 and like parts are given like reference numerals. In this embodiment the output from the grinding device 10 is fed to a sorting device 15 arranged to only allow particles above a certain size to progress towards the pelletiser 12. Larger particles are fed back to the grinding device 10 for further grinding. The provision of the grinding means 10 allows the output from travelling grate boilers to be processed since the coarser clinker contained therein is ground to a suitable consistency for feeding to the pelletiser 12.

Claims

1 . An apparatus for producing a lightweight aggregate from furnace ash, the apparatus comprising means for grinding the furnace ash to be processed, a pelletiser for receiving the ground furnace ash and for forming pellets thereof and means for sintering the pellets to form the lightweight aggregates.
2. An apparatus as claimed in claim 1 , comprising means for drying the ground furnace ash and for mixing the dried furnace ash with water prior to the pelletiser.
3. An apparatus as claimed in claim 2, comprising means disposed between the drying means and the pelletiser for diverting the output of the drying means away from the pelletiser if the output contains particles over a certain size.
4. An apparatus as claimed in claim 3, comprising an input for re-introducing the diverted output of the drying means back into the grinding means.
5. An apparatus as claimed in any preceding claim 1 , comprising means for mixing conditioned ash with the output from the grinding means.
6. A method of producing a lightweight aggregate from furnace ash, the method comprising grinding the furnace ash, feeding the ground ash to a pelletiser and sintering the pellets produced by the pelletiser.
7. A method as claimed in claim 6, in which the furnace ash is ground in a wet condition.
8. A method as claimed in claim 6 or 7, in which the ground ash is dried prior to feeding it to the pelletiser.
9. A method as claimed in any of claims 6 to 8, in which water is added to the dried ash prior to or during the pelletisation step.
10. A method as claimed in any of claims 6 to 9, in which the ground ash is mixed or blended with conditioned ash prior to the pelletisation step.
PCT/GB2011/052236 2010-12-06 2011-11-16 Sintered lightweight aggregates WO2012076861A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP11787935.3A EP2648835A2 (en) 2010-12-06 2011-11-16 Sintered lightweight aggregates

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB201020613A GB201020613D0 (en) 2010-12-06 2010-12-06 Sintered lightweight aggregates
GB1020613.4 2010-12-06

Publications (2)

Publication Number Publication Date
WO2012076861A2 true WO2012076861A2 (en) 2012-06-14
WO2012076861A3 WO2012076861A3 (en) 2012-09-20

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EP (1) EP2648835A2 (en)
GB (1) GB201020613D0 (en)
WO (1) WO2012076861A2 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010100468A2 (en) 2009-03-06 2010-09-10 Lytag Limited Sintered lightweight aggregates

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI397511B (en) * 2005-01-14 2013-06-01 Alkemy Ltd Synthetic aggregates comprising sewage sludge and other waste materials and methods for producing such aggregates
EP1853531A2 (en) * 2005-01-14 2007-11-14 Alkemy Ltd. Pyroprocessed aggregates comprising iba and low calcium silicoaluminous materials and methods for producing such aggregates
KR100799238B1 (en) * 2006-04-28 2008-01-29 (주)쎄라그린 Method for Manufacturing an Artificial Lightweight Aggregate Containing Bottom Ash

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010100468A2 (en) 2009-03-06 2010-09-10 Lytag Limited Sintered lightweight aggregates

Also Published As

Publication number Publication date
WO2012076861A3 (en) 2012-09-20
EP2648835A2 (en) 2013-10-16
GB201020613D0 (en) 2011-01-19

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