Spheroidizationprocessofceramsitesand.Intheprocess,thefreshwetceramsitesandandthecirculatingsieveresiduearemixedevenlyandusedasthefeedforthedrum.Atthefeedendofrotarydrum,therearetwowaystoincreasetheparticlesizeoffreshfeed,oneisthatthefreshpowdercladdingisontheexistingrecycledgranule,theotheristogeneratenewagglomerates.Iftheoperationisstable,mustmakethestabilityofthemassofthenewnucleargenerationrateandgrainsizemeettherequirementsofmassproductionratesareequal,infactit'sdifficulttoachievethebalanceofaccurate,becauseevenifthewetcontentintherawmaterialintheprocessofnodulizingandrawmaterialinputflowrateremainsthesame,intheprocessofmaterialcirculationwillalsochange(pulse).Intypicalindustrialoperations,thecycletimeisbetween8and12minutes,thematerialcyclevolumeis150%to300%ofthefeedflow,andthefluctuationrangeis20%oftheaverage. Becausetherotarycylinderdoesnothavethesameautomaticscreeningfunctionastheswashplate,thesizedistributionrangeofmaterialdischargedfromthecylinderisverywide.Therefore,thecirculardrumsuwawithaclosed-circuitwaytosiftleftovermaterialbacktothedrumentrance(ofcourse,ifthereisasieveonthethingshouldbebroken).Inaddition,aswiththeoriginalceramsitespheroidization,ifthedesiredparticlesizeisincreasedinonepass,thelengthoftherotarycylindermustbelarge.Therefore,itisnecessarytocirculatethematerialthroughtherotatingcylinderseveraltimes.Ifcyclicoperationisadopted,largespaceisrequiredandthesameauxiliarymachinesastheslantingplategranulatorarecommonlyused.Inaddition,controlproblemsexistinthespheroidizationprocessitself. CarterandWrightdescribethefluctuationsinthespheroidizationprocessofceramsitesand.Ifthereistoomuchfluctuationinoperation,itisprobablycausedbylowmoisturecontent.Thepelletizationratebegantodecreaseduetooperationalfluctuations,thematerialcirculationvolumeincreased,andthelumpcoregrowthratewasfurtherhinderedbecausemostofthefreshrawmaterialswereusedforthegranularitycoarseningoftherecycledmaterials.Duetothedecreaseofnucleargrowthrate,thespheroidizationprocesstendstobeinterrupted,thatis,thecoarseningofcircularballsizeactuallypreventstheformationofagglomeratesuntilthecircularballsizeislargeenoughtoberequired.Whenmostofthesystemmeetsthegranularityrequirementsandisspheroidized,thecorereforms.Thewholeprocessstartsalloveragain. Thus,theincreasednucleargrowthratecanobviouslyimprovethestabilityofsystemblowing.Thefillingofwaterbysprayintherotatingcylindercanreducetheamountofmaterialcirculationandreducethefluctuationoftheprocess.However,theformedlumpsmayhavelowstrengthandirregularshape,sowhenthematerialcirculationisrelativelylarge,fluctuationshouldbeavoidedandtheoperationshouldbestable,otherwisetheproductqualitymayhaveproblems.Therearemanywaystomaintainstability,themostimportantistofollowtheoperationalrequirementsofcarefuldesign.Becauseofthemoisturecontentofrawmaterials,inputrate,rotatingspeedandchangesintheinnersurfaceoftherotatingcylinderwillaffectthestabilityofoperation,sothedesignshouldbecareful. Theuseofmulti-systemcirculatoryequipmenthelpstomitigateoperationalfluctuations.Themaximumfluctuationsgeneratedbyonesystemcanbecompensatedforbytheminimumfluctuationsgeneratedbyanothersystem.Inordertomaintainstableoperation,adouble-rotatingbarrelprocesscanalsobeadoptedtoproperlycontroloperatingconditions.First,proportionalcoresaregeneratedinthefirstrotatingbarreltoformlumps,andthenmorerawmaterialsaretransferredtothesecondrotatingbarrel,inwhichseedsarecoarse-grainedintoqualifiedproductsbycladdingmethod.