Experimental Study And DEM Simulation On The Effect Of Lifters On The Behavior Of Tumbling Ball Mill

This article is based on the National High-Tech Research and Development Program ofChina(863 Plan)(No.2012AA062002),the effect of lifters on behavior of ball mill is studied by discrete element method simulation(DEM)and experimental research.The effect of mill speed,lifter height and lifter number on particle behavior,torque and power of ball mill are studied in this article.In addition,the power of ball mill obtained by five empirical formulas are validated by DEM simulation and a series of experiments.Moreover,the liner wear is researched in qualitative way.Furthermore,lifter(including lifter height and lifter number)and particle area ratio are defined to explain the changing rule of torque and power of ball mills when design or operation parameters are changed.Based on the relevant domestic and foreign literatures,the effect of lifter parameters on the behavior of ball mills,the influence of the liner wear on the efficiency of ball mills and the experimental study on ball mills are summarized.In addition,the process to determine working parameters,the calculation method of critical speed and net power of ball mills are also given in this article.A new type of ball mill experimental device is designed and manufactured after studying on the ball mill experimental setups used by many domestic and foreign scholars.The structure of the experimental device is simple,innovative and multifunctional.For the convenience of replacement,lifters are machined independently and fixed with the cylinder shell in the form of bolt connection.Therefore,it can be used to study the effect of lifter number and height on ball mill behavior effectively.The front end-wall consists of two pieces of transparent semicircular perspex.The behavior of the particles in the drum can be observed clearly through the perspex.The structure of the front end-wall also makes the process of loading,unloading of particles and lifter-changing easily,which makes the experimental device convenient in studying of ball mills.Both DEM simulation and experimental research are used when studying the effect ofmill speed on the behavior of ball mill.First of all,the particle behavior is validated both qualitatively and quantitatively,and the DEM model used in this article is verified in the same time.Then,the change of torque and power with mill speed is researched both by DEM simulation and experimental study,which also verifies the correctness of the DEM model.In addition,the power results obtained from five empirical formulas are validated with DEM and experimental results and the validating result shows that the accuracy of specific empirical formula changes when the rotation rate varies.In the present study,the effect of lifter height and number on the particle behavior,torque,and power consumption of ball mills,respectively,are analyzed quantitatively by DEM.In addition,the torque of liners and baffles is also examined when the operating parameters of ball mills are changed,which provides a reference for energy-saving optimization of ball mills.The changes in the torque and power consumption of ball mills can be effectively explained using two important parameters: lifters and particle area ratio.Furthermore,the lifter is a decisive factor when a ball mill works at a relatively low speed;a high lifter height causes a large liner torque.By contrast,the particle area ratio is the main factor when a ball mill works at a relatively high speed;an increased particle area ratio causes a small liner torque.The results of the effect of mill speed,lifter parameters on mill behavior can be used to properly choose mill speed,lifter height and number.The optimization of liner and lifter structure can be carried out base on the study of liner wear.Moreover,the changes in the torque and power consumption of a ball mill can be effectively predicted using two important factors: lifter and particle area ratio.