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

Raw material preparation.From the quarry to raw meal feedinginto the preheater.A company ofThyssenKruppTechnologiesPolysiustk

2Future-oriented raw material preparation solutionsmade by Polysius:Innovative – Individual – Ideal.The manufacturing of cement begins withthe 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 homogeneityassures the economicalproduction of high-qualitycements. This can only beachieved if the plant designershave precise knowledge of thematerials that will be used (rawmaterials and fuels). This isthe basis for purposive selectionof the production process,including the blending, storage,homogenisation, grinding andanalysis systems.Taking into account the determinedmaterial properties andthe customer-specific boundaryconditions, the requiredmachines and analysis equipmentis then selected, dimensionedand arranged. To obtainsufficient latitude for the creationof alternative design solutions,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 ensuresthat the optimum processtechnologicaland economicsolution is found for everyindividual project.As the first step, experiencedgeologists determine the availableraw material deposits.Next, the chemical, mineralogicaland physical laboratories ofthe Polysius Research Centreanalyse, evaluate and test theraw material samples. Thanksto the very extensive Polysiusdatabase, the materials arereliably classified even if a relativelysmall amount of data isavailable.Whether a given depositis a suitable supplier ofraw materials for thecement production processis decided on the basis ofprecise examination andanalysis data. As a firststep, geologists prospectthe deposit.

3From the PC to reality:because of the diversity ofraw material deposits, simplystringing standard individualprocesses or even just machinesone after the other is not enough.The desired success can only beachieved if a comprehensive view istaken, including the obtained rawmaterial data and the necessaryinvestment and operating costs.ISAR – a totally unique softwareprogram – allows quick creationand simulation of an optimum rawmaterial preparation concept.Starting materialOutputShear Test evaluation for moist materials – Polysius AG/Research and Development –1 2 3 4 5Client 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 17.5Normal stress g/cm 2 200 200 200 200 200Greatest consolidation stress g/cm 2 502 508 489 482 455Bulk material strength g/cm 2 92 184 262 271 227Effective angle of friction Degree 39 42 45 46 43Bulk material cohesion g/cm 2 24.5 52.1 80.8 86.3 71.7Flow functionffcffc < 1Hardenedffc < 2 Very cohesive 1.9 1.8Non-flowing2 < ffc < 4 Cohesive 2.8 2.04 < ffc < 10 Easy flowing 5.510 < ffc Free flowingAngle of wall friction St-37 Degree 27.0 24.5Angle of wall friction PVC Degree 23.9 19.8Angle of wall frictionDegreeHandling behaviour 0.21 1.73 5.65 6.60 4.05After the material-specific preparation of the representativematerial samples supplied by the geologists, laboratorytests determine the chemical and physical properties whichform the basis for evaluation and classification of theraw materials.Handling –characteristic factor642WE-10415 Claystone10 15 20Moisture content [%]– Handling property depending on the moisture content –The determinedmaterial properties arethe basis for theplant configuration.

4The process chainat 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.Crushersx Raw material analysis: the POLAB ® CNA online analyser provides the firstdata regarding the chemical contents and/or homogeneity of the raw material.POLAB ® CNAx Bulk material storage/blending/metered feeding: the raw materials arebuffer stored in stockpiles or homogenised in blending beds and then suppliedto the grinding process in the required flow rate and composition either directlyor via feed bins.Longitudinal stockpile/longitudinal blending bedCircular stockpile/circular blending bedFlow regulation binx 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 rollx 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 ® AMTx 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 systemsEverything 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.

High-performance analyser trio assures qualitythe vital factor.5While the raw materials andfuel grades are becoming moreand more complicated (primarilydue to the increasingly problematicraw material depositsand the use of secondarymaterials), the demands onclinker quality are increasing.This makes quality assurancewith highly effective analysissystems an absolutely indispensablecomponent 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 theright 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 downstreamof the raw material grindingsystem and POLAB ® AMT, thesample preparation and analysissystem in the central laboratory,Polysius offers high-performancesystems that provideinformation about the chemicalcomposition and homogeneityof the materials at quality-relevantpoints of the process andinitiate appropriate control interventions.The systems areequipped with an adaptivemixture control which calculatesthe raw meal mixture inadvance and thus reliablymaintains the setpoint value.KST95,094,594,093,593,092,592,091,591,090,5Silo – current valueDownstream of millThe 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.SetpointMeasurement time [2 days]Installed directly downstream of the rawmill, the POLAB ® AOT takes raw mealsamples at short intervals, fine-grindsthem, analyses them with its energy dispersiveX-ray fluorescence analyser andcontrols the raw material compositionand mill feeding.Use of the POLAB ® CNA analysis systemupstream of the blending bed ensuresthe earliest possible knowledge of thechemical content and homogeneity of theraw materials. The entire flow of gravelsizedraw material coming from the crusherpasses through the online analyser.POLAB ® AMT, the sample preparationand analysis system installed in thecentral laboratory, performs all qualityassurance functions for a completecement production line.The POLAB ® CNA determines the process-relevant oxide concentrationsof the entire stream of material (no matter whether it isan individual component like limestone, marl or clay, or mixturesof these) without requiring any pre-treatment. On the basis ofthe analysis results, the quality of the starting materials can becontrolled at an early stage, thus enabling optimum blendingbed stacking. Thanks to the modular design of the POLAB ® CNAit can be installed very quickly, even into an existing conveyingsystem.

6The right mixture is crucial.Requirement-oriented blending and storage configurations.Raw material preparation with integrated blending bedThe raw material preparationconcept with an integratedblending bed has establisheditself as the ideal solutionfor material components with»normal« and acceptable handlingproperties.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 chemicalvalues close to the setpoints.Upstream of the mill a precisionadjustment then takes place onthe basis of the raw meal analysisand the addition of correctivecomponents by the adaptivemixture control.The final homogenisation usuallytakes place in a tangentialblending silo.LimestoneClayRaw material preparation concept withintegrated blending bed – the ideal solutionfor material components with normaland acceptable handling properties.AdditivesFor efficient storageand homogenisation ofthe raw materials,Polysius offers a broadrange of blendingbed and storage technologyfor circular andlongitudinal installationswith harmonisedstacking and reclaimingmethods.

7Raw material preparationfor materials with extremehandling propertiesMore and more often, the materialsused have extreme handlingproperties (e.g. are verysticky or extremely moist), tendto segregate or are simply notsimultaneously available.In these cases the individualcomponents have to be speciallystored and prehomogenisedto suit their handling and homogeneityproperties. These componentsremain separate untiljust before they are fed into thegrinding plant. Particularly in thecase of materials that are difficultto handle, the best solutionis direct feeding from the storagefacility into the mill.In the case of longitudinal stockpilesthat are stacked discontinuously,the direct feeding systemcan consist of a combinationof 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 assuranceof a uniform flow of material.For this reason, the centralchute of the circular blendingbed’s bridge scraper is usedas a small buffer bin, whichparticularly compensates shortwavedischarge fluctuations.The compact Polysius blendingbed design, in which the chainof 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 automaticallyincreased, which raisesthe reclaiming capacity.The direct mill feeding systemcan also be used if the circularblending bed is located at agreat distance from the mill.Raw materialpreparation formaterials thatare extremelydifficult tohandle.LimestoneClayFeed bins for flow-regulated feeding ofthe raw grinding plant cannot always beavoided. Even if a direct mill feeding systemfrom 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 properoutflow 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 adirect millfeeding system.ClayAdditives

8Raw material grinding plants.The requirements determine the mill type.Polysius offers a comprehensiverange of grinding processes.However, the right choiceof grinding plant for the respectiveapplication is governed bynumerous criteria.Apart from the raw materialproperties and the requiredthroughput capacity, the capitalinvestment, operating costsand 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 consumptioncompared to othergrinding processes and lowmaterial drying capability.The POLYCOM ®high-pressuregrinding roll hasthe lowest energyrequirement and can be readilycombined with other grindingprocesses, to achieve greatincreases in output. However,the POLYCOM ® also has a limitedmaterial drying capability.In about 85 percent of all rawmaterial grinding applicationsthe roller mill is nowadays used.It offers the advantage of combiningthree work operations –grinding, drying and separating– in one compact unit. Thedesign of the DOROL ® doublerollermill, well-known fromover 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 outsidethe mill and are thus protectedagainst 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 requirement.For maintenance purposes,each pair of oppositegrinding rollers can be pivotedout of the mill housing. Thetwo roller units remaining inthe mill then take over the comminutionprocess, which is aprecondition for online operationwith an uninterrupted flow ofmaterial from the mill into thekiln.Good accessibility, easy maintenance andthe possibility to change over to partialloadoperation with 2 roller units withoutinterrupting operation complete the convincingQUADROPOL ® concept.

9The 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 higheris the energy saving compared to othersystems.The DOROL ® double-roller mill is thestandard roller mill for grinding a verybroad range of materials including coal,blast furnace slag and clinker. This milltype has been constantly refined andoptimised over the years, and has thusachieved an excellent level of efficiencyand reliability.Simple plant concept andlow capital costs are characteristicfor the air-swept tube mill.

10Silo 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 capabilitiesand range of functions. Investment constraintsalso affected the requirement profile by forcinga reduction in silo size.The raw meal silo performs two functions: onthe one hand it acts as a raw meal store, ensuringthat 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 precedingprocess sections or to raise it to the targethomogeneity, if this has not yet been reached.the principle of homogenisation is the storageof 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.The combination of the new systems‚POLAB ® AOT analyser and tangential blendingsilo, is one of the most innovative raw mealhomogenisation and storage configurationson the market.Tangential blending siloThe 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 conventionalblending 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 possiblefor the coarser grain sizefraction of the raw meal to permanentlyfall straight downonto the same point and forma pile of large-sized material.The special silo filling processthus already counteracts segregationof the raw meal.The new tangential blendingsilo has a unique aeration floorwhich covers almostthe entire ring areaat the bottom of thesilo and thusensures optimumaeration 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 aerationpanels with a large numberof outlets, it is possible togenerate discharge funnels thatgo through the entire chargeof raw meal, even if it is nonfreelyflowing 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 inthe mixingchamber alsoresults in aconstant dischargebehaviour,whichensures thatthe downstreamflowregulatingunits receivean optimumfeed flow ofmaterial.Silo aerationfloor.Blending and dischargebehaviour in the tangentialblending silo.

11Multi-cell siloThe multi-cell silo, which isa 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 responseto 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 segregationcan occur.An important difference tothe already known multicompartmentsilo systemsis that the simultaneouslydischarged material isdirectly fed to the preheaterand not first keptin storage silos (whereexperience shows thatsegregation can againtake place).The advantages of the multi-cell silo at a glance:Cone and outlet ofthe multi-cell silo.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 inspectedwithout affecting or evenstopping the system operation.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 proportionedinto the main flow.x If the capacity of the completeplant is increased, theraw meal capacity can beeasily and cost-effectivelyraised by adding on furthersmall silos.The individual cells of themulti-cell silo are filledone after the other butemptied simultaneously.