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WO1996026165A1 - Procede de fabrication de brique de ciment portland - Google Patents

Procede de fabrication de brique de ciment portland Download PDF

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Publication number
WO1996026165A1
WO1996026165A1 PCT/DK1996/000077 DK9600077W WO9626165A1 WO 1996026165 A1 WO1996026165 A1 WO 1996026165A1 DK 9600077 W DK9600077 W DK 9600077W WO 9626165 A1 WO9626165 A1 WO 9626165A1
Authority
WO
WIPO (PCT)
Prior art keywords
clinker
cooler
calorific value
fuller
earth
Prior art date
Application number
PCT/DK1996/000077
Other languages
English (en)
Inventor
Jesper Sand Damtoft
Peter Lund
Original Assignee
Aalborg Portland 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 Aalborg Portland A/S filed Critical Aalborg Portland A/S
Publication of WO1996026165A1 publication Critical patent/WO1996026165A1/fr

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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
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/38—Preparing or treating the raw materials individually or as batches, e.g. mixing with fuel
    • C04B7/42—Active ingredients added before, or during, the burning process
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/44—Burning; Melting
    • C04B7/4407—Treatment or selection of the fuel therefor, e.g. use of hazardous waste as secondary fuel ; Use of particular energy sources, e.g. waste hot gases from other processes

Definitions

  • the present invention relates to a method for manufacturing Portland cement clinker, by which method raw meal is preheated and calcined prior to being burned into clinker, and where the clinker, subject to addition of a material, is cooled in a clinker cooler.
  • Portland cement clinker is manufactured on the basis of a raw mix which is for example composed of limestone, flyash, sand and pyrite ash. After the raw mix has been ground, preheated and calcined, it is burned in a rotary kiln at temperatures reaching a level of 1450-1500 ⁇ C in the burning zone of the kiln. During the burning process in the kiln, the raw materi- als will react with one another, whereby the clinker compo ⁇ nents, the so-called clinker minerals, are formed. As part of the process, the components are consolidated into nodules, the socalled clinker.
  • An important feature in the manufacture of cement is the cooling of the clinker.
  • the clinker temperature In order to avoid a deterioration of the properties of the finished cement, the clinker temperature must be rapidly reduced from a level around 1300-1400°C down to a level below approximately 200 ⁇ C. This is done in a clin- ker cooler.
  • a very common cooler type is the so-called grate cooler in which the hot clinker from the rotary kiln drops down onto a system of cooler grates.
  • the clinker bed is moved by the movement of the grates backwards in the cooler, while air is being injected through the bed so that the clinker is cooled.
  • Part of the heat which is removed from the clinker during the cooling-down phase is re-utilized in the burning process in that the heated air from the foremost part of the cooler is directed through the rotary kiln and possibly through the calciner, if the latter is incorporated in the plant, in which it is utilized as combustion air.
  • the cooling air from the rearmost and coldest part of the cooler is directed backwards to a discharge point to the surrounding environment. That part of the air which is directed from the cooler and through the rotary kiln is called secondary air, and that part of the air which is directed through a calciner, if any, is called tertiary air.
  • One possible method for utilizing difficult-to-handle secon ⁇ dary fuels is to add such fuels to the riser duct which con ⁇ nects the kiln to a preheater, if any, or to the precalciner or the calciner in the types of kiln equipped with such fea ⁇ tures.
  • Another option involves feeding of the difficult-to-handle fuels to the hot end of a clinker cooler, preferably a grate cooler.
  • a clinker cooler preferably a grate cooler.
  • the temperature of the secondary and tertiary air will be increased, so that the fuel feed rate through main burners and burners in precalciners or calciners can be redu- ced.
  • the point of introduction in the clinker cooler must be selec ⁇ ted so that the combustible material is totally burned out while falling through the cooler or when deposited on the clinker bed itself.
  • the material must, therefore, be fed to the hottest part of the cooler and it may be advantageous to introduce the material to the kiln hood or the connecting piece which constitutes the interface between the kiln and cooler.
  • By feeding the material to the hot part of the cooler it will also be possible to avoid the risk of gases which are not completely burned being directed backwards in the cooler and thus being released to the surrounding environment.
  • Feeding of a combustible material to the hot part of the clinker cooler is for instance known from DE Al 26 24 971.
  • waste andfit by-products are used as secondary fuels for example by production of cement clinker.
  • the primary object of the method according to this publication is to eliminate hazardous waste products, in a way where both ashes and a large part of the harzardous volatile components are bound in the clinker.
  • the secondary object is to utilize the available calorific value of the waste products and to make use of what the waste product might contain of raw ma ⁇ terials.
  • the objective of the invention to provide a method for manufacturing of Portland cement clinker by means of which a greater amount of material can be fed to the clin ⁇ ker cooler, while the secondary air temperature is simultane ⁇ ously controlled, without causing damage to the kiln outlet, and ensuring, at the same time, that the clinker produced is of a good quality.
  • This objective is achieved according to the invention by adjusting the caloric value of the material which is added to the clinker cooler by mixing of at least two different types of material, where at least one of the materials which is added to the clinker cooler has a calorific value which ex ⁇ ceeds the desired value and at least one other material has a calorific value which is lower than the desired value, and in that the total mixture has a certain water content.
  • a simple method by means of which a material with a given calorific value can be manufactured is to mix at least two different materials, of which at least one material has a calorific value which exceeds the desired value and where at least one other material has a calorific value which is lower than the desired value.
  • By regulating the ratio between the added materials with different calorific values it will also be possible to regulate continuously the temperature of the secondary air. At least one of the added materials must have a certain water content since the water has a cooling effect on the surroundings around the point of introduction.
  • Used Fuller's earth is a waste product which can be used for carrying out the method according to the invention.
  • used Fuller's earth has a relatively high calorific value and also has a mineral composition which, without problems, can be incorporated into the cement clinker manufacturing process.
  • Used Fuller's earth emerges as a by-product when manufacturing miscellaneous vegetable, animal and mineral oil products, e.g. rape-seed oil, margarine and diesel oil.
  • the oils contain a number of turbid features which, because of a very small particle size, cannot be removed by filtration in conventional filters. Therefore, the oil is mixed with Fuller's earth which is manufactured on the basis of naturally occurring clay minerals belonging to the smectite group. These clay types are also referred to as bentonite, montmorillonite and fuller's earth.
  • the Fuller's earth absorbs the turbid features where ⁇ after it is subjected to filtration in traditional filters, such as chamber filter presses. Hence a homogenous by-product, used Fuller's earth, is generated.
  • Used Fuller's earth typically has a calorific value of about 3.000 kcal/kg and it contains approximately 40% oil and 60% clay, which means that in connection with the manufacture of clinker it may serve both as a fuel and as a raw material which is used in partial substitution for clay, shale, sand and flyash.
  • Experience gained during the manufacturing process indicates that the used Fuller's earth is ignited and com ⁇ busted almost instantaneously when it is introduced to the hot end of the cooler. As a consequence hereof, the material is completely burned out when that part of the ash which is not entrained in the secondary airstream into the rotary kiln lands on the clinker bed on the cooler grate.
  • Used Fuller's earth is very sticky and conveying devices made up of, for example, screw conveyors, belt conveyors and elevator will be clogged, in a matter of minutes or a few hours, due to accumulations of the sticky Fuller's earth.
  • Another material which may be used for carrying out the method according to the invention is de-inking sludge derived from the paper manufacturing process.
  • Paper sludge from de-inking process emerges as a by-product in connection with the manufacture of recycled paper and its water content is typically 30-60%. On a dry basis, paper sludge typically contains 50% paper fibres, 25% clay of the kaolin type, and 25% chalk. The calorific value is around 500-1000 kcal/kg. De-inking sludge is produced in vast quanti ⁇ ties during the manufacture of recycled paper and, therefore, poses a serious environmental problem unless appropriate fields of applications for the sludge are identified.
  • De-inking sludge is non-sticky and can be transported by means of mecha ⁇ nical conveying devices such as screw conveyors, elevators or belt conveyors.
  • this property can be utilized also if it is desirable to use spent Fuller's earth at another stage of the process during the clinker manufac ⁇ turing process, for example through feeding to a calciner or a riser duct.
  • liquid substances such as oil, solvents, emulsions containing various combustible substances, slurry containing plastic etc.
  • pasty or solid substances such as coal, petcokes, shred- ded automobile tyres, used oil filters, plastic waste, oil sludge, de-inking sludge derived from the paper manufacturing process, used Fuller's earth, dewatered or dried sewage, house or town refuse etc.
  • the manufacture of mineralized clinker involves addition of mineralizers to the raw meal in small quantities, hence reducing the burning temperature while promoting the formation of alite, which is the most important strength-en ⁇ hancing and hydraulic component of the cement.
  • a combination of fluoride and sulphate, where the clinker contains at least 0.15% F and 1.5% S0 3 of the clinker weight has proven to be particularly suited as a mineralizer.
  • the temperature in the burning zone of the kiln is reduced by approximately 100 ⁇ C when using the described combination of mineralizers
  • the temperature of the clinker in the clinker cooler will also be lower than is the case during the manufacture of conventional Portland cement clinker. This is reflected in a lower temperature of the secondary air, leading to a corresponding reduction of the amount of heat which is transmitted from the clinker cooler to the burning zone.
  • Unsteady kiln operation during the manufacture of mineralized clinker due to a deterioration of the temperature transmission in the kiln and a reduction in the secondary air temperature may thus be prevented by adding combustible material to the hot end of the clinker cooler.
  • the addition of material will increase the temperature of the secondary air, improve the heat distribution in the burning zone of the rotary kiln, reduce the content of free lime in the clinker and limit the dust load.
  • Kiln operation will be stabilized and the fuel consumption of the main burner can be reduced.
  • a further aspect of the invention emerges if the material which is fed to the clinker cooler has a certain content of clay minerals, which, for example, is the case for Fuller's earth and de-inking sludge.
  • a content of clay minerals may be considered to be an extra addition of pozzolanic ma- terial.
  • literature see e.g. Mielenz R.C., Witte, L.P., and Glantz, O.J.: "Effect of calcination on natural pozzolana.” Symp.
  • clay minerals will obtain pozzolanic properties, i.e. they contribute to the strength development of the finished cement if heat-treated within a temperature range around 600-900"C in such a way that the crystal water of the minerals is liberated and the crystal structure is destroyed, without any recrystallization of the amorphous minerals.
  • This condition applies, for example, both for the manufacture of mineralized and for the manufacture of conventional Port ⁇ land cement clinker.
  • the added clay minerals will thus contri- bute towards developing the strength of the cement, hence leading to a reduction in the price of the cement through substitution of a corresponding quantity of clinker.
  • the influence of the temperature on the clay minerals which are fed to the clinker cooler must be controlled so that the clay minerals are exposed to temperatures of 600-900 ⁇ C during an appropriate time period in order to achieve the optimum degree of pozzolanicity.
  • This control action can be performed by varying the calorific value of the feed material, which may, for example, be a mixture of used Fuller's earth and de-inking sludge, where the calorific value is regulated by varying the mixing ratio.
  • Example 1 A mixture of used Fuller's earth and paper sludge was added to a semi-wet process during the manufacture of conventional Portland cement clinker.
  • the plant deployed comprised a rotary kiln with a two-stage cyclone preheater and SLC unit (Separate Line Calciner), and a grate cooler.
  • a mixture of used Fuller's earth and paper sludge was fed to the same plant as described in Example 1 during the manufac ⁇ ture of mineralized cement clinker.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

L'invention a trait à un procédé de fabrication de brique de ciment portland, selon lequel on doit d'abord ajouter une matière à un refroidisseur de brique de ciment, et qui consiste à préchauffer et à calciner la farine crue du ciment avant de procéder à la cuisson du clinker. Après quoi, le clinker est refroidi dans un refroidisseur de brique de ciment. On contrôle le pouvoir calorifique de la matière ajoutée au refroidisseur de clinker en mélangeant au moins deux différents types de matière, dont au moins une possède un pouvoir calorifique dépassant la valeur voulue et l'autre un pouvoir calorifique inférieur à la valeur voulue, de sorte que le mélange total puisse avoir une certaine teneur en eau.
PCT/DK1996/000077 1995-02-23 1996-02-21 Procede de fabrication de brique de ciment portland WO1996026165A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK19495 1995-02-23
DK0194/95 1995-02-23

Publications (1)

Publication Number Publication Date
WO1996026165A1 true WO1996026165A1 (fr) 1996-08-29

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Application Number Title Priority Date Filing Date
PCT/DK1996/000077 WO1996026165A1 (fr) 1995-02-23 1996-02-21 Procede de fabrication de brique de ciment portland

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WO (1) WO1996026165A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000006514A1 (fr) * 1997-04-10 2000-02-10 Lafarge Canada Inc. Procede de production de clinker par addition de cendre de charbon
US6391105B1 (en) 2001-02-16 2002-05-21 Lafarge Canada Inc. Enhancement of cement clinker yield
EP1180502A3 (fr) * 2000-08-14 2003-01-15 EIRO Rohstoffgesellschaft mbH Procédé pour contrôler des réactions chimiques endothermiques
WO2006016210A3 (fr) * 2004-08-05 2006-04-27 Cemex Trademarks Worldwide Ltd Procede de fabrication de clinker ciment portland et clinker ainsi obtenu

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3346901C2 (de) * 1983-12-21 1986-10-09 Mannesmann AG, 4000 Düsseldorf Verfahren zur rückstandsfreien energetischen Nutzung zellulosereicher Abfälle und Anlage

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3346901C2 (de) * 1983-12-21 1986-10-09 Mannesmann AG, 4000 Düsseldorf Verfahren zur rückstandsfreien energetischen Nutzung zellulosereicher Abfälle und Anlage

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000006514A1 (fr) * 1997-04-10 2000-02-10 Lafarge Canada Inc. Procede de production de clinker par addition de cendre de charbon
EP1180502A3 (fr) * 2000-08-14 2003-01-15 EIRO Rohstoffgesellschaft mbH Procédé pour contrôler des réactions chimiques endothermiques
US6391105B1 (en) 2001-02-16 2002-05-21 Lafarge Canada Inc. Enhancement of cement clinker yield
WO2006016210A3 (fr) * 2004-08-05 2006-04-27 Cemex Trademarks Worldwide Ltd Procede de fabrication de clinker ciment portland et clinker ainsi obtenu
GB2434147A (en) * 2004-08-05 2007-07-18 Cemex Trademarks Worldwide Ltd Process to produce portland cement clinker and obtained clinker
EA014136B1 (ru) * 2004-08-05 2010-10-29 Семекс Рисерч Груп Аг Способ получения портландцементного клинкера
US8021478B2 (en) 2004-08-05 2011-09-20 Cemex Trademarks Worldwide Ltd. Process to produce portland cement clinker and obtained clinker

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