HUA Qingyi¹，WEI Guangchao²，DAN Jiayun³，WANG Xiaoyi³，CUI Jiaxin¹，E Dianyu^1，3

1. Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems，Jiangxi University of Science and Technology， Nanchang 330013， China；2. School of Transportation and Vehicle Engineering， Shandong University of Technology， Zibo 255000， China；3. Hunan Valin Xiangtan Iron and Steel Co. ， Ltd. ， Xiangtan 411101， China

Abstract

Objective Stable operation and energy consumption control of the blast furnace are subject to the complex physical and chemical behavior within the raceway. However， there is still a lack of research on the gas-solid flow characteristics and interaction mechanisms of non-spherical particles in the raceway. Fundamental dynamical problems， such as elucidating the motion mechanism of non-spherical particles and assessing the effect of the mixing ratio of various multi-shape particles on raceway evolution，remain largely unaddressed. This study systematically investigates the effects of four different mixed non-spherical particle volume fractions on raceway evolution morphology and microstructure. The developed model provides fundamental insights into the complex transport phenomena in the raceway zone to achieve better understanding and optimization in operation.

Methods The study began by addressing the fluid flow using the Navier-Stokes equations， alongside particle motion modeled via the Discrete Element Method （DEM）， which includes both translation and rotation equations governed by Newton's second law.To couple the gas and solid phases， the well-established Di Felice model for drag force was employed. The drag coefficient for non-spherical particles was calculated using the Holzer-Sommerfeld approach. Validation of the developed model was conducted by examining the particle flow patterns in a bubbling fluidized bed， which were moving at 2 m/s comprising disc-shaped particles ，and by analyzing the bed pressure drop under different gas flow rates. Furthermore， the study explored the effects of different non-spherical particle volume fractions on the evolution process and microstructure of the raceway.

Conclusion This study investigated the effects of non-spherical particles volume fraction on the evolution process and microstructure of the raceway. Through kinetics analysis，it was observed that increasing the volume fraction of mixed non-spherical particles from 0 to 9% yielded a 96% increase in the raceway width， a 67% increase in height， and a 3. 53-fold increase in rotational energy. Furthermore， considering the microstructure， the drag force on particles increased as the volume fraction of non-spherical particles in the mixture increased. Additionally， the probability density function distribution of the normal contact forces between particles shifted leftward， accompanied by a decrease in peak magnitude. Moreover， the peak of the coordination probability density function distribution diminished when non-spherical particles were mixed， compared to the condition with only spherical particles.

Keywords：computational fluid dynamics； discrete element method； raceway of blast furnace；multi-shape particles； numerical simulation