Dense medium cyclone(DMC)is the working horse in coal industry.In practice,it is usually operated under constant pressure and the operational conditions(mainly medium-to-coal(M:C)ratio and oper-ational pressure)need to be adjusted according to coal washability data(mainly coal particle size and density distributions).Nonetheless,until now it is still not well understood how the M:C ratio would affect the performance of DMCs especially under the practical conditions.In this work,the effect of M:C ratio is for the first time numerically studied under conditions similar to plant operation by using both tra-ditional and coarse-grained(CG)combined approach of computational fluid dynamics(CFD)and discrete element method(DEM),called as traditional CFD-DEM and CG CFD-DEM,in which the flow of coal par-ticles is modelled by DEM or CG DEM which applies Newton's laws of motion to individual particles and that of medium flow by the conventional CFD which solves the local-averaged Navier-Stokes equations,allowing consideration of particle-fluid mutual interaction and particle-particle collisions.Moreover,impulse and momentum connection law is used to achieve energy conservation between traditional CFD-DEM and CG CFD-DEM.It is found that under constant pressure,the M:C ratio affects DMC perfor-mance significantly.The specific effect depends on coal washability or coal type.Under extremely low M:C ratio,the phenomenon that high-quality coal product is misplaced to reject is successfully repro-duced,which has been observed in plants in Australian coal industry and called as"low-density tail".Moreover,strategies are proposed to mitigate the"low-density tail"phenomenon based on the model.

Zhaoyang Li;Kaiwei Chu;Zongqing Zhou;Yixiong Feng;Aimin Wang

School of Mechanical Engineering,Zhejiang University,Hangzhou 310027,China;Shandong Iron and Steel Group Co.,Ltd.,Jinan 250101,China;JITRI Institute for Process Modelling and Optimization,Suzhou 215123,China;School of Qilu Transportation,Shandong University,Jinan 250002,China;State Key Lab Fluid Power&Mechatron Syst,Zhejiang University,Hangzhou 310027,China;Hengda Fuji Elevator Co.,Ltd.,Huzhou 313009,China

颗粒学报（英文版）

[1]Zhaoyang Li;Kaiwei Chu;Zongqing Zhou;Yixiong Feng;Aimin Wang-.Prediction of medium-to-coal ratio effect in a dense medium cyclone by using both traditional and coarse-grained CFD-DEM models)[J].颗粒学报（英文版）,2022(09):44-56

DMCs,misplaced

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