InChinamorethantwo-thirdsofavailablecoalreservesareinaridareas,where,tobeneficiatetherun-of-minecoal,thereisnotenoughwaterresourcerequiredbyconventionalprocessing.DevelopingefficientdrybeneficiationtechnologyisofgreatsignificanceforefficientcoalutilizationinChina,notablythecleancoaltechnology(CCT).Thedrycoalbeneficiationtechnologywithair-densemediumfluidizedbedutilizesair-solidsuspensionasbeneficiatingmediumwhosedensityisconsistentforbeneflciation,similarinprincipletothewetdensemediumbeneficiationusingliquid-solidsuspensionasseparatingmedium.Theheavyportioninfeedstockwhosedensityishigherthanthedensityofthefluidizedbedwillsink,whereasthelighterportionwillfloat,thusstratifyingthefeedmaterialsaccordingtotheirdensity.Inordertoobtainefficientdryseparationinair-densemediumfluidizedbed,stablefluidizationwithwelldispersedmicro-bubblesmustbeachievedtoensurelowviscosityandhighfluidity.Thepurebuoyancyofbeneficiationmaterialsplaysamainroleinfluidizedbed,andthedisplaceddistributioneffectshouldberestrained.Thedisplaceddistributioneffectsincludeviscositydisplaceddistributioneffectandmovementdisplaceddistributioneffect.Theformeriscausedbyviscosityofthefluidizedbed.Itdecreaseswithincreasingairflowvelocity.Movementdisplaceddistributioneffectwillbelargewhenairflowrateistoolowortoohigh.Ifmediumparticlesizedistributionandairflowarewellcontrolled,bothdisplaceddistributioneffectscouldbecontrolledeffectively.Abeneficiationdisplaceddistributionmodelmaybeusedtooptimizebeneficiationoffeedstockwithawideparticlesizedistributionandmultiplecomponentsinthefluidizedbed.Therheologicalcharacteristicsoffluidizedbedswerestudiedusingthefallingspheremethod.ExperimentalresultsindicatedthatthefluidizedbedbehavesasaBinghamfluid.Theplasticviscosityandyieldstresscanbe
