Performance Analysis And Electromechanical Coupling Dynamics Of Ball Mill Based On Discrete Element Method

The tumbling ball mill is the main grinding equipment of the concentrator plant.Its performance and reliability have a great influence on the efficiency and safety of the concentrator plant.Supported by the National High Technology Research and Development Program(863 Program)‘Large Open-pit Minerals Mining Technology and Equipment'(No.2012AA062002),the research of electromechanical coupling dynamic of the tumbling ball mill based on discrete element method(DEM)is carried out,which provides theoretical basis of the design of large and efficient energy-saving ball mill.Firstly,the research situation of DEM dynamics and electromechanical coupling dynamics of the large ball mill are introduced.Based on the classical theory of ball mill,the barrel force situation of throwing off and slip condition is analyzed.The DEM model of a ball mill barrel is established.The particle area ratio is defined as the index of particle movement.The reliability of the DEM model is examined by the experimental validation.The torque change process of the ball mill start situation is simulated by the DEM model,the relationship of particle movement and load torque during the starting process is established.The effects of liner heights and numbers on ball mill particles movement,torque and power are studied.Simulation results show that the ball mill torque is positively correlated with the liner height when the ball mill rotation rate is less than 60% critical speed,and the torque and liner height are negatively correlated when the ball mill rotation rate is greater than 90% critical speed;the ball mill torque generally increases with the number of liners increase,but the growth rate gradually decreased and finally stabilized.Based on the DEM dynamic model of ball mill,the characteristic equation of air clutch and the dynamic model of induction motor,the electromechanical coupling model of ball mill,clutch and motor system is established.Aiming at the typical working conditions,the electromechanical coupling simulation and the physical prototype experiment of the ball mill are carried out.The results show that the simulation and the experiment are in good agreement,which verifies the correctness of the established electromechanical coupling model of the ball mill.Starting process is analyzed based on the ball mill electromechanical model.The impact extent,sliding power,and motor protection are proposed as evaluation indexes for the starting process of ball mill.For a large ball mill,the starting process is simulated.Differrnt conditions of driving motor full voltage starting,rotor series resistor starting,and air clutch start are analyzed.The influence of the different inflation time of the clutch on the strarting process is compared and analyzed,and the method for determing the reasonble inflation time of the clutch is proposed.In this paper,the electromechanical coupling dynamic model of ball mill based on DEM is established,and the correctness of the model is verified by the physical prototype experiment.The influence of different working parameters and liner parameters on the performance of ball mill is studied.The selection of motor and the method for determining the reasonable starting parameters are proposed.The research work of this paper is of great significance to the improvement of the development level of the large ball mill in China.