POLYCOM® high-pressure grinding roll for the minerals industry.

POLYCOM ® high-pressure grinding rollfor the minerals industry.A companyof ThyssenKruppTechnologiesPolysiustk

POLYCOM ® high-pressure grinding roll.The economic andgentle processing solution.The high-pressure grinding roll has provedextremely effective for the grinding of mineralraw materials. With more than 250 POLYCOM ®installations in different industrial sectors,Polysius is the worldwide market leader for thistechnology.60 % of the high-pressure grinding rollsinstalled in the minerals industry are fromPolysius: the POLYCOM ® operates convincinglyall around the world, comminuting x copper orex gold ore x iron ore x diamond ore x platinumore x coal x granulated blast furnace slag x limestonex cement clinker and x other mineral rawmaterials.This type of mill offers the minerals industrynumerous benefits:Low operating expenses: in comparison toother systems, both the power consumption andthe costs for wear parts are significantly lower.High throughput rates: a high-pressure grindingroll can replace several reduction crushers.Metallurgical advantages in the downstreamprocess stages.Shorter delivery and commissioning timesthan can be achieved with other systems.Maximum feed size [mm]807060504030201001.0 1.5 2.0 2.5Feed sizein relation toroll diameter.Compared to thecrusher product (left-handpicture) the POLYCOM ®product is extensivelycracked.Spec. throughput = 250Spec. throughput = 225Spec. throughput = 200Roll diameter [m]POLYCOM ® units are designedfor throughput rates in excessof 3,000 tph. The mill feed materialcan be dry or moist andwith particle sizes ranging frombelow 1 mm to more than 75mm. If required, the materialcan be dried in screens or airseparators in a closed circuitgrinding system.The new low-maintenancewear protection systems for rollsurfaces permit even the mostabrasive materials to be efficientlyground. Because ofthe short material dwell time in the mill, thesettings of the machine can be altered withina very short time by the touch of a button,making the process easy to control and permittingquick compensation for fluctuationsin the properties of the feed ore.Modern, user-friendly regulating, monitoringand control devices, combined with advancedprocess technology, ensure reliable and effectiveoperation of the plant and an efficient processcycle.

The grinding elements of thehigh-pressure grinding roll aretwo counter-rotating rolls, onefixed and the other floating,between which the material iscrushed.The required comminutionpressure is transmitted by ahydraulic system via the floatingroll.The following features distinguishthe POLYCOM ® highpressuregrinding roll fromother grinding systems:x The drive system can beequipped with variable speedmotors in order to compensatefor throughput variations in theupstream and downstreamprocess.Whereas the grinding action ofa tube mill involves a mixture ofcompressive and shear forces,the POLYCOM ® imposes virtuallypure compressive force onthe layer of material betweenthe rolls. The compressionstress thus caused in a particleof material is more than fivetimes higher than shear stresswould be.Comminution in the POLYCOM ®results in a product that has afar higher percentage of finesthan can be achieved with thecrusher method. Moreover, thecoarser particles show extensivecracking which reduces theamount of grinding work to beperformed in the downstreammills and improves the liberationof metal from the ore.The benefits are particularly noticeablein the heap leachingprocess, where the POLYCOM ®product demonstrably increasesthe yield and thus the operatingeconomy of the facility.x A hydropneumatic springsystem builds up a pressure ofup to 250 Mpa. During operationof the machine it is possibleto alter the pressure andthus change the product fineness.x Highly wear-resistant rollsurfaces achieve service livesof 4,000 to 10,000 hourswhen grinding abrasive hardrock. When softer materialsare involved, the servicelife can even exceed 20,000hours.x The feeding device ensuresthat the machine permanentlyruns with the optimum fillinglevel - the precondition forefficient operation and a highservice life of the rolls.Material passing screen [%]100908070605040302010Productof highpressuregrinding rollProductof crusherPOLYCOM ® particlesize distribution.Feedmaterial00.01 0.1 1 10 100Particle size [µm]

4Innovative POLYCOM ® design.The guarantee for high availability andeconomical continuous operation.In order to fulfil the expectations placed on the high-pressuregrinding roll, such as x high roll surface lifetimes x optimum feedmaterial pull-in capability for maximum throughput rates, evenof moist materials x straightforward replacement of worn out rollbodies, the POLYCOM ® rolls have a length to diameter ratio of0.3 to 0.7.This provides the following advantages:x large roll diameters allow the feeding of lumpy oresx minimised wear costs,x thick roll tyres permit refurbishment of the roll bodies (a furtherwear-cost-reducing aspect),x self-aligning roller bearings dimensioned for a safe and reliableoperation,x quick and safe mounting and dismounting of the gear unitduring roll changes because it is only bolted onto the shaft.The grinding force is transmittedto the floating roll by 4hydraulic cylinders.A hydropneumatic spring systemallows the setting of differentpressure characteristicsand different control methodsto enable optimum applicationof the grinding pressure in theroll gap and to protect the machineagainst possible overloading.The floating roll automaticallyaccommodateschanges in feed material characteristicsby moving outwardsor inwards. Spacers preventthe rolls from touching.Self-aligning roller bearingscompensate skewing of the floating roll.The fixed and floating rollsare both mounted in bearingblocks. The self-aligning rollerbearings, which compensatefor skewing of the rolls, have amultiple seal system to preventdust penetration and greaseloss. The bearing blocks of thefixed roll are bolted onto themachine frame, while thoseof the floating rolls travel in alongitudinal slideway. Thefixed and floating rolls are ofidentical construction and cantherefore be interchanged.Frame designvariant enablingsimpleand quickroll change.The roll drive system consistsof: x constant or variable-speedelectric motors x V-belt connectionto the gear units up to adrive power of 300 kW permotor x cardan shaft connectionto the gear units > 300 kWx mechanical overload couplingfor protecting the gear unit andx planetary gear unit.The feed chute is an importantcomponent for the assurance ofreliable and optimum operationof a high-pressure grinding roll.x For moist and sticky feedmaterials (such as iron oreconcentrates), Polysius installsvertical feed chutes with straightwalls.x For lumpy feed materials,chutes that assure mass floware installed.In order to ensure uniform distributionof the drive power tothe two drive motors, the verticalfeed chute can be equippedwith infeed guide plates to adjustthe distribution of materialflowing through the mill. If thisfeeding device is installed, thematerial filling level is monitoredby means of load cells.

5Since the introduction of the POLYCOM ® ,the wear protection concept has beenconstantly refined and adapted to therequirements of the different industries.Polysius offers:x forged, hardfaced roll bodies,x chill cast alloy tyres made of bainite,x roll bodies made of compound castingandx roll bodies with hard metal studs.Principle of feed shaftadjustment.Autogenous wearprotection: groundmaterial accumulatesbetween the hardmetal studs and thusminimises roll surfacewear.For abrasive materials, roll bodies with surfacesprotected against wear by hard metalstuds are generally used.This version ensures a long service lifeand therefore high plant availability and thelowest maintenance requirement. It alsoenables moist and sticky materials to beground.The design of the hard metal studs(geometry, hardness and metallurgicalcomposition) and their arrangement onthe roll surface are selected to suit theoperating conditions and feed materials.Nowadays, the achieved roll service livesare 4,000 to 10,000 h for hard rock, 6,000to 12,000 h for diamond and iron ore and12,000 to 30,000 h for iron ore concentrate.Depending on the operating parameters,higher values are also possible.

6Application examples.High-pressure grinding rollsin preparation plants …Compared to crushers, the POLYCOM ® produces a significantlyhigher percentage of fines. Moreover, the comminutedparticles have a large number of micro cracks. These productfeatures provide enormous economic and process technologicalbenefits for the various preparation industries...Groundplatinum ore.From mineral resource to finished productThe first step onthe way to goldjewellery is theliberation of goldparticles.From the naturalrock via liberatedcopper ore to thecopper coin...

… for gold, platinum and copper ore.7Comparison: gold yieldrate of a crusher and of aPOLYCOM ® .For new plants the POLYCOM ®is an economically superiorconcept compared to conventionalsystems, such as reductioncrushers or SAG mills.The prospect of achievingmaximum increases in thethroughput of existing grindingplants also make the POLYCOM ®a popular machine for plantextensions. Thanks to its lowspace requirement and highcapacity in relation to machinesize, the POLYCOM ® can beeasily incorporated into existingplant configurations. Used as aprimary grinding unit upstreamof ball mills, the POLYCOM ® canboost the throughput by 20 to30 %.The POLYCOM ® also bringssubstantial benefits to the heapleaching process. The yield ofvaluable substance and thusthe operating economy of thefacility are significantly raised.The ground material can eitherbe conveyed directly to the heapor first go through an agglomerationstage. If finer qualitiesare required, the POLYCOM ®product is first screened.Gold yield [%]Gold yield [%]10080604020001008060402010 20 30 40 50 60 70Yield period [days]0+10M -10+20M -20+48M -48+100M -100+200M -200MPOLYCOM ®CrusherCopper ore grinding in Peru: four POLYCOM ® units (2,500 kW drive and 2.4 m rolldiameter) perform the primary grinding. Four wet process ball mills (7.3 m diameter and12 MW ring motor drive) are used for final grinding – throughput 108,000 (!) tonnes ofrock per day. Energy-saving and low-wear technology.FLOTATION

8… for diamond ore.Breaking the diamond-bearing rock in ahigh-pressure grinding roll is a gentle methodof liberating the diamonds.The surrounding rock is broken while the harddiamond remains undamaged and is recoveredin a downstream process stage.POLYCOM ® fordiamond oreliberation inSouth Africa.POLYCOM ® and scrubberfrom Polysius: core processtechnological components ofa diamond ore processingplant.For scientists they may be just the materialwith hardness value 10, but for theancient Greeks they were the »tears ofthe gods«. Today we know that everydiamond was created billions of yearsago by enormous underground forces.They only see the light of day if the lavaof erupting volcanoes carries them tothe earth’s surface.

… for iron ore.The iron ore industry usesthe POLYCOM ® as a reductioncrusher for lump ore.Its high throughput rates, combinedwith the production of ahigh percentage of fines, bringclear operating and capital costbenefits: one POLYCOM ® canreplace several crushers.This also significantly reducesthe maintenance expenses ofthe plant.The main field of POLYCOM ®application is the production ofpellet feed: the high-pressuregrinding roll, usually installeddownstream of the ball mill andfiltering stage, grinds the filterproduct.The POLYCOM ® product isthe basis for manufacturinghigh-quality iron ore pellets.POLYCOM ® foriron ore grindingin Brazil.PELLETISATIONFrom iron orevia the moltonmetal to thefinished product.

10One solution for allapplications …To determine theoperating expensesand maintenancerequirement of ahigh-pressuregrinding roll, thenecessary characteristicdata for theservice life of theroll surfaces areprovided by ATWAL(a small HPGR).… must remain a dream. But Polysius has theknowhow and the equipment (the Polysius researchcentre with its ultramodern machines is one ofthe world’s leading development establishmentsfor basic material technology) to provide a suitableplant concept for the individual properties of therespective ore.From laboratory-scale toindustrial reality:Preliminary testseries, which providefundamentalinformation regardingthe comminutionbehaviour ofdifferent materialsamples, are performedin the highpressuregrindingroll LABWAL.The Polysius researchcentre is equipped withPOLYCOM ® units of differentsizes for grinding tests inopen circuit or closed circuitgrinding systems.The data concerning granulometricdistribution, powerconsumption and requiredgrinding forces that areneeded for dimensioningthe POLYCOM ® are determinedwith the aid of thesemi-industrial high-pressuregrinding roll REGRO.Following the material analysis,the ores are compared withthe comprehensive Polysiusmaterial database to quicklyand reliably obtain the data regardingtheir grindability, hardness,abrasiveness and agglomerationbehaviour that areneeded for designing the plantconfiguration.High-performance simulationprograms support the selectionof machines and systems andforecast the energy requirements,mill circuit materialbalances, wear rates etc.,thus assuring future-oriented,custom-tailored plant solutionswith the lowest possible operatingexpenses – no matterwhether a new plant or theupgrading of existing facilitiesis concerned.If the high-pressure grinding rollis to be used in a new field of application,it is good policy to grind alarge quantity of test material or toincorporate a high-pressure grindingroll into an existing plant. TheMAGRO, a mobile, semi-industrialPOLYCOM ® is available for thispurpose. With its throughput rangeof 50 to 100 tph it realisticallysimulates industrial processes.

Technical data.11L2HXZYBL1Construction size01245Type9/711/7 11/814/7 14/815/10 15/11 17/1017/12 17/14Roll diameter[mm]9501,1001,4001,520 1,520 1,7001,700Roll width[mm]650650 800650 800950 1,100 1,0001,200 1,400Grinding force[kN]2,7003,4004,3007,0008,600Max. motor power[kW]2 x 2202 x 4502 x 5002 x 8002 x 1,600L1[mm]1,1501,3001,6001,720 1,720 1,9001,900 1,900L2[mm]2,7853,1903,7354,305 4,305 4,4904,870 4,870B[mm]1,8602,1502,1643,030 3,030 3,0303,000 3,500H[mm]1,3711,6851,8952,095 2,095 2,2202,390 2,370Y[mm]3,6204,4304,4975,316 5,316 5,2306,273 6,523X[mm]4,5505,5005,6006,900 6,900 6,8007,800 8,300Construction size6789Type19/15 20/1520/1522/16 24/1726/18Roll diameter[mm]1,850 2,0002,0002,200 2,4002,600Roll width[mm]1,5001,5001,550 1,6501,750Grinding force[kN]11,00013,50017,00020,000Max. motor power[kW]2 x 1,8502 x 2,5002 x 2,8002 x 3,400L1[mm]2,050 2,2002,2002,400 2,6002,800L2[mm]5,220 5,3655,8056,370 6,5757,215BHYX[mm][mm][mm][mm]3,310 3,4602,635 2,8556,757 6,7278,400 8,5003,6102,7957,3369,2003,820 3,8203,160 3,1807,401 7,4019,300 9,3004,1503,5107,5509,600– the stated dimensionsare subject toalteration in the courseof technical advancements–