Raw material preparation.From the quarry to raw meal feeding into the preheater.

PolysiusA company ofThyssenKrupp

Technologies

tk

2 Future-oriented raw material preparation solutionsmade by Polysius: Innovative – Individual – Ideal.

The manufacturing of cement begins with the extraction and preparation of raw material– a process covering the stages from rawmaterial quarrying to feeding the raw mealinto the preheater.

The purpose of optimum rawmaterial preparation for thecement manufacturing processis to supply the downstreamburning process with a rawmeal whose quality and homo-geneity assures the economi-cal production of high-qualitycements. This can only beachieved if the plant designershave precise knowledge of thematerials that will be used (rawmaterials and fuels). This is the basis for purposive selec-tion of the production process,including the blending, storage,homogenisation, grinding andanalysis systems.

As the first step, experiencedgeologists determine the avail-able raw material deposits.Next, the chemical, mineralogi-cal and physical laboratories ofthe Polysius Research Centreanalyse, evaluate and test theraw material samples. Thanksto the very extensive Polysiusdatabase, the materials arereliably classified even if a rela-tively small amount of data isavailable.

Taking into account the deter-mined material properties andthe customer-specific bound-ary conditions, the requiredmachines and analysis equip-ment is then selected, dimen-sioned and arranged. To obtainsufficient latitude for the cre-ation of alternative design solu-

tions, Polysius uses ISAR. This database-linked softwareprogram allows the very fastsimulation of different plantand process configurations ona PC, including the resultingdevelopment of raw materialhomogeneity. This ensures that the optimum process-technological and economicsolution is found for everyindividual project.

Whether a given deposit is a suitable supplier of

raw materials for thecement production process

is decided on the basis ofprecise examination andanalysis data. As a first

step, geologists prospectthe deposit.

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From the PC to reality: because of the diversity of

raw material deposits, simply stringing standard individual

processes or even just machines one after the other is not enough. The desired success can only be

achieved if a comprehensive view istaken, including the obtained raw material data and the necessary investment and operating costs. ISAR – a totally unique software program – allows quick creation

and simulation of an optimum rawmaterial preparation concept.

After the material-specific preparation of the representative material samples supplied by the geologists, laboratory tests determine the chemical and physical properties which form the basis for evaluation and classification of the raw materials.

The determined material properties are

the basis for the plant configuration.

Starting material Output

Shear Test evaluation for moist materials – Polysius AG/Research and Development –

1 2 3 4 5

Client Singfa Singfa Singfa Singfa SingfaMaterial Claystone Claystone Claystone Claystone ClaystoneWE-No. 10415 10415 10415 10415 10415Test-No. 0415C05 0415C10 0415C15 0415C16 0415C175Moisture content 5.0 10.0 15.0 16.0 17.5

Normal stress g/cm2 200 200 200 200 200Greatest consolidation stress g/cm2 502 508 489 482 455Bulk material strength g/cm2 92 184 262 271 227Effective angle of friction Degree 39 42 45 46 43Bulk material cohesion g/cm2 24.5 52.1 80.8 86.3 71.7

Flow function ffcffc < 1 Hardenedffc < 2 Very cohesive 1.9 1.8

Non-flowing2 < ffc < 4 Cohesive 2.8 2.04 < ffc < 10 Easy flowing 5.510 < ffc Free flowing

Angle of wall friction St-37 Degree 27.0 24.5Angle of wall friction PVC Degree 23.9 19.8Angle of wall friction Degree

Handling behaviour 0.21 1.73 5.65 6.60 4.05

6

4

2

10 15 20

Moisture content [%]

WE-10415 Claystone

– Handling property depending on the moisture content –

Han

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g –

char

acte

rist

ic f

acto

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4 The process chain at a glance.

x Crushing: crushers break up the raw material delivered from the quarry andprovide the raw mill with the feed size range it requires.

Crushers

x Raw material analysis: the POLAB® CNA online analyser provides the first data regarding the chemical contents and/or homogeneity of the raw material.

POLAB® CNA

x Bulk material storage/blending/metered feeding: the raw materials are buffer stored in stockpiles or homogenised in blending beds and then supplied to the grinding process in the required flow rate and composition either directly or via feed bins.

Longitudinal stockpile/longitudinal blending bedCircular stockpile/circular blending bedFlow regulation bin

x Grinding/drying: the raw material is ground in the raw mill to the finenessrequired by the downstream clinker burning process and dried.

QUADROPOL® roller millDOROL® roller millAir-swept tube millPOLYCOM® high-pressure grinding roll

x Raw meal analysis: the raw meal samples are analysed at short intervals andthe analysis data are used as the basis for controlling the raw material compositionand mill feeding.

POLAB® AOTPOLAB® AMT

x Final raw meal homogenisation/storage: the raw meal is homogenised andstored in silos and then supplied at a regulated flow rate to the preheater.

Multi-cell siloTangential blending siloFilter dust handlingDosing and conveying systems

Everything starts with theraw material quarrying.

Depending on its characteristics, the rawmaterial needed for the cement productionprocess is quarried by blasting, hydraulicexcavators or ripping. A wide range ofcrushing plants – depending on thematerial’s properties and type of extraction– can be used for breaking the extractedraw material to the size required by theraw mill. Polysius always installs crushersfrom renowned manufacturers.

5High-performance analyser trio assures quality the vital factor.

The POLAB® AOT raw mealanalyser, whose footprint of only2.2 m (!) means that it can alsobe retrofitted without any problem,performs one control cycle every10 minutes; i.e. every 10 minutesa raw meal analysis is performedand the weighbelt setting of theraw mill feed system is correctedby the adaptive mixture control.

Setpoint

Measurement time [2 days]

Silo – current value

Downstream of mill

KST

95,0

94,5

94,0

93,5

93,0

92,5

92,0

91,5

91,0

90,5

Installed directly downstream of the rawmill, the POLAB® AOT takes raw mealsamples at short intervals, fine-grindsthem, analyses them with its energy dis-persive X-ray fluorescence analyser andcontrols the raw material composition and mill feeding.

Use of the POLAB® CNA analysis systemupstream of the blending bed ensures the earliest possible knowledge of thechemical content and homogeneity of theraw materials. The entire flow of gravel-sized raw material coming from the crush-er passes through the online analyser.

POLAB® AMT, the sample preparation and analysis system installed in the

central laboratory, performs all qualityassurance functions for a complete

cement production line.

The POLAB® CNA determines the process-relevant oxide concen-trations of the entire stream of material (no matter whether it is an individual component like limestone, marl or clay, or mixtures of these) without requiring any pre-treatment. On the basis of the analysis results, the quality of the starting materials can becontrolled at an early stage, thus enabling optimum blending bed stacking. Thanks to the modular design of the POLAB® CNA it can be installed very quickly, even into an existing conveyingsystem.

While the raw materials andfuel grades are becoming moreand more complicated (primari-ly due to the increasingly prob-lematic raw material depositsand the use of secondarymaterials), the demands onclinker quality are increasing.This makes quality assurancewith highly effective analysissystems an absolutely indis-pensable component of the rawmaterial preparation process.

No generally valid concept canbe applied, but it is clear thatthe more complex the rawmaterials and fuels the moredifficult it is to determine the

right quality assurance conceptfor the particular applicationinvolved.

With the POLAB® CNA for onlineanalysis of the raw materialupstream of the blending bed,POLAB® AOT for online analysisof the raw meal downstream of the raw material grindingsystem and POLAB® AMT, thesample preparation and analy-sis system in the central labor-atory, Polysius offers high-per-formance systems that provideinformation about the chemicalcomposition and homogeneityof the materials at quality-rele-vant points of the process andinitiate appropriate control in-terventions. The systems areequipped with an adaptive mixture control which calcu-lates the raw meal mixture inadvance and thus reliablymaintains the setpoint value.

6 The right mixture is crucial. Requirement-oriented blending and storage configurations.

The raw material preparationconcept with an integratedblending bed has establisheditself as the ideal solution for material components with»normal« and acceptable han-dling properties.

The composition of the blendingbed is controlled by the onlineanalyser POLAB® CNA, whichregulates the supply of differentcomponents to the crusher orbefore the blending bed andthereby keeps the chemical values close to the setpoints.Upstream of the mill a precisionadjustment then takes place on

the basis of the raw meal analy-sis and the addition of correctivecomponents by the adaptivemixture control.

The final homogenisation usu-ally takes place in a tangentialblending silo.

Limestone

Clay

Additives

Raw material preparation with integrated blending bed

Raw material preparation concept withintegrated blending bed – the ideal solu-tion for material components with normal

and acceptable handling properties.

For efficient storageand homogenisation of

the raw materials,Polysius offers a broad

range of blending bed and storage tech-nology for circular and

longitudinal installa-tions with harmonisedstacking and reclaim-

ing methods.

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Raw material preparation for materials with extremehandling properties

More and more often, the mater-ials used have extreme han-dling properties (e.g. are verysticky or extremely moist), tendto segregate or are simply notsimultaneously available.

In these cases the individualcomponents have to be special-ly stored and prehomogenisedto suit their handling and homo-geneity properties. These com-ponents remain separate untiljust before they are fed into thegrinding plant. Particularly in thecase of materials that are diffi-cult to handle, the best solutionis direct feeding from the stor-age facility into the mill.

In the case of longitudinal stock-piles that are stacked discontin-uously, the direct feeding sys-tem can consist of a combina-tion of several reclaimers. Forcircular blending beds, speciallydesigned discharge systems aregenerally used. With a direct millfeeding system there is no needto convey the critical materialinto an additional feed bin,which eliminates the otherwisenecessary investment cost forthe feed bin and associateddischarge regulation system. A POLAB® AOT online raw mealanalyser performs the mixturecontrolling.

An important precondition fordirect mill feeding from theblending bed is the assurance of a uniform flow of material.For this reason, the centralchute of the circular blendingbed’s bridge scraper is used as a small buffer bin, whichparticularly compensates short-wave discharge fluctuations.The compact Polysius blendingbed design, in which the chain

of the bridge scraper passesthrough the central column,ensures that the material fallsinto the centre of the chute anddoes not adhere to its walls.

The filling level of the centralchute is captured with a fillinglevel measuring device. If thefilling level falls, the travel speedof the bridge scraper is auto-matically increased, which rais-es the reclaiming capacity.

The direct mill feeding systemcan also be used if the circularblending bed is located at agreat distance from the mill.

Limestone

Clay Clay

Additives

Feed bins for flow-regulated feeding of the raw grinding plant cannot always beavoided. Even if a direct mill feeding sys-tem from the blending bed is installed,additives may have to be metered into thestream of material. These feed bins haveto be correctly dimensioned to provide therequired buffer size and material flow andhandling characteristics. Only then is prop-er outflow and metering of the materialcomponents permanently assured. Thanksto material investigation and classification,as well as the performance of shear testsif necessary, Polysius also offers reliablefeed bin solutions.

Principle of a direct mill

feeding system.

Raw materialpreparation formaterials thatare extremely

difficult to handle.

8 Raw material grinding plants. The requirements determine the mill type.

Polysius offers a comprehen-sive range of grinding process-es. However, the right choice of grinding plant for the respec-tive application is governed bynumerous criteria.

Apart from the raw materialproperties and the requiredthroughput capacity, the capitalinvestment, operating costs and availability are particularlyimportant factors.

The tube mill is a proven, simpleand easy to maintain machine,which also involves the lowestcapital cost.

Its main disadvantages aresignificantly higher energy con-sumption compared to othergrinding processes and lowmaterial drying capability.

The POLYCOM®

high-pressuregrinding roll hasthe lowest energy

requirement and can be readilycombined with other grindingprocesses, to achieve greatincreases in output. However,the POLYCOM® also has a limit-ed material drying capability.

In about 85 percent of all rawmaterial grinding applicationsthe roller mill is nowadays used.It offers the advantage of com-bining three work operations –grinding, drying and separating– in one compact unit. Thedesign of the DOROL® double-roller mill, well-known from over 250 installations all aroundthe world, has been advanced.The result is the QUADROPOL®,which offers high throughputrates, low construction size andhigh availability. The QUADRO-POL® has four grinding rollers,whose bearings are located out-side the mill and are thus pro-

tected against dust and hightemperature. The mill can beautomatically switched overfrom 4 to 2 roller operation,which provides great flexibilityand the ability to adapt tochanges in raw meal require-ment. For maintenance pur-poses, each pair of oppositegrinding rollers can be pivotedout of the mill housing. The two roller units remaining in the mill then take over the com-minution process, which is aprecondition for online operationwith an uninterrupted flow ofmaterial from the mill into thekiln.

Good accessibility, easy maintenance and the possibility to change over to partial-load operation with 2 roller units without interrupting operation complete the convincingQUADROPOL® concept.

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The POLYCOM® can be used as a primarymill, or in combination with, for instance,tube mills or as an autonomous finishingmill. The more grinding work is shifted tothe high-pressure grinding roll, the higher

is the energy saving compared to othersystems.

The DOROL® double-roller mill is thestandard roller mill for grinding a very

broad range of materials including coal,blast furnace slag and clinker. This mill

type has been constantly refined andoptimised over the years, and has thusachieved an excellent level of efficiency

and reliability.

Simple plant concept and low capital costs are characteristic

for the air-swept tube mill.

10 Silo systems from Polysiusfor an uncompromising final homogenisation.

In the case of raw meal silos, the trend towardsmore complex raw materials demanded anincrease in their homogenisation capabilities and range of functions. Investment constraintsalso affected the requirement profile by forcing a reduction in silo size.

The raw meal silo performs two functions: on the one hand it acts as a raw meal store, ensur-ing that the kiln is supplied with raw meal evenduring raw mill stoppages. On the other hand, it has the task of homogenising the raw mealproduced by the raw mill to an extent whichensures that the kiln can produce a consistentlyhigh clinker quality. The silo has to maintain thedegree of homogeneity achieved in the preced-ing process sections or to raise it to the targethomogeneity, if this has not yet been reached.the principle of homogenisation is the storage of horizontal layers which each have differentquality characteristics, followed by the verticalblending of these layers when discharging thesilo.

Having thoroughly reengineered the standardblending silo, Polysius offers the tangentialblending silo and the multi-cell silo as solutionsfor the new requirements.

Tangential blending silo

The tangential blending siloconsists of the silo shell, thedistributing system, the innercone, the aeration surface withthe discharge systems, thecentral mixing chamber, theaeration system and the dustcollection filter.

The raw meal is fed into thesilo through the distributingsystem. Compared to the con-ventional blending silo, thenumber of feeding arms hasbeen increased and a centralinfeeding point has beeninstalled. As the feeding armsare alternately activated by acontrol system, it is not possi-ble for the coarser grain sizefraction of the raw meal to per-manently fall straight downonto the same point and forma pile of large-sized material.The special silo filling processthus already counteracts segre-gation of the raw meal.

The new tangential blendingsilo has a unique aeration floorwhich covers almostthe entire ring areaat the bottom of thesilo and thusensures optimum

aeration of the raw meal. Thematerial can be fluidised andextracted at all points of thesilo floor. The aeration floor isof modular and compactdesign and can therefore besimply, efficiently and thuscost-effectively installed.

The main process technologicaladvantage of this type of silo isderived from the new mode ofoperation of the central mixingchamber with constant fillinglevel. Due to the silo floor beingcompletely covered with aera-tion panels with a large numberof outlets, it is possible togenerate discharge funnels thatgo through the entire charge of raw meal, even if it is non-freely flowing or otherwiseproblematic. The discharge andfilling times for the material inthe mixing chamber that iswithdrawn from one segmentof the silo can be individuallyadapted to the size of the siloand mixing chamber, as well asthe properties of the material.The constant filling level in

the mixingchamber alsoresults in aconstant dis-charge be-haviour, whichensures thatthe down-stream flowregulatingunits receivean optimumfeed flow ofmaterial.

The combination of the new systems‚ POLAB® AOT analyser and tangential blendingsilo, is one of the most innovative raw mealhomogenisation and storage configurations on the market.

Silo aeration floor.

Blending and dischargebehaviour in the tangentialblending silo.

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Multi-cell silo

The multi-cell silo, which is a combination of small silos, is particularly used in caseswhere the raw meal has astrong tendency to segregate (in response to the trendtowards complex raw materials)and/or in processes demandingthe homogenisation of smallstorage volumes (in response to the requirement for smallerraw meal silo capacities).

The small individual membersilos of the multi-cell silo arefilled one after the other butdischarged simultaneously. The product is then fed directlyto the preheater. In this way, a reliable blending effect isachieved. The silos are sodesigned that mass flow isensured and no segregation can occur.

The advantages of the multi-cell silo at a glance:

x A defined minimum blendingeffect is ensured, even in thecase of very complex rawmaterials.

x The size of the individualsilos ensures a constantmass flow.

x For maintenance purposesone silo can be taken out ofthe combination and inspect-ed without affecting or evenstopping the system opera-tion.

x Any raw meal tonnages thatdiffer greatly in quality (firstcut of a blending bed, filterdust in mill bypass operation)can be filled into one siloand subsequently slowly pro-portioned into the main flow.

x If the capacity of the com-plete plant is increased, theraw meal capacity can beeasily and cost-effectivelyraised by adding on furthersmall silos.

An important difference tothe already known multi-

compartment silo systemsis that the simultaneously

discharged material isdirectly fed to the pre-

heater and not first kept in storage silos (whereexperience shows thatsegregation can again

take place).

Cone and outlet of the multi-cell silo.

The individual cells of themulti-cell silo are filledone after the other but

emptied simultaneously.