Influence Mechanism Of Region-character Of Media Motion On Grinding Efficiency Of Particles In Ball Milling

Ball milling process,which is a mechanical crushing process for large-scale preparation of powder,is crucial to the basic industries such as metallurgy,mining,building materials,chemical industry,food processing,medicinal material production and so on.However,during the process of ball mill grinding,it needs high power and steel consumption.Moreworse,the grinding efficiency is extremely low.There are many factors affecting the grinding efficiency of ball milling process,such as the liner structures,the charge filling,and rotation speed.Many researches reference on the influence factors in the ball milling process have been published nowadays.But theses researches,which focus on the influence mechanism and influence process of influencing factors,are not sufficient.Because of the research on the influence mechanism of the effect on the region-character of media motion on the particles crushing efficiency is relatively inadequate.The final optimization solutions for various factors can only be conducted or verified by ball milling experiments.Nevertheless,the environment of ball milling experiment is rather harsh,which increases the workload and wastes more time.And the experimental method cannot study the effect process of the factors from the influence mechanism either.In order to explore the influence mechanism of the effect of region-character of media motion in different factors on the ground particles in the ball milling process,a mesh generation method based on the EDEM had been proposed.And the models of the regional distribution of the media motion in various factors had been built,for which the change of collision characteristics of the media group in the grinding cylinder had been studied.By dividing the cross section of the mill cylinder into many micro regions,the motion characters of the media group in each micro region could be obtained.Based on the mesh generation method,the region-character models of the motion velocity vector of the media group and their collision characteristics had been set up.For the different factors of influence,such as the liner structures and the mill movement mode,the numerical simulation and the grinding experiment had been carried out respectively.For the liner structure,took the spiral-angular liner as an example,the region-distribution models of the media motion velocity vector and the collision characteristics models had been set up in different structures of the liner.Then the effect of the liner structural changed on the regional distributions had been analyzed.Combined with the ground particles in the milling experiment in the same condition with the simulation,relationship function of the rate of optimal collision energy in total collision energy and finer particles production had been gained.This function is related with the property of ground particles,but nothing with the milling condition.For the movement mode,took a coupled flutter motion as an example,in the same way,the region-character of media motion in different flutter parameters and particle breakage rate,finer production in the corresponding conditions had been analyzed.Combining the particle breakage rate and the motion regional distribution of media group and characteristics of collision motion,the relationship equation of production of finer particles and collision energy of media had been established as well as the equation of particle breakage rate and average contact force of media group.According to the linear relationship between the breakage rate of finer particles and collision energy of media group in flutter mill experiment,on the basis of EDEM numerical simulation model,took both the model of media motion and ball mill experiment results into consideration,the mechanism of influence of media distribution and collision characteristics on particle breakage during ball milling was revealed,had the guiding significance to study the structural parameters,kinematic parameters optimization energy saving and consumption reduction of the cylinder liner in the process of ball milling.Comprehensive analysis on the relationship of the change trend of region-character of media group and grinding efficiency in different factors,the relative function between them had been summarized.The optimized model that could explain the influence mechanism,how the influence factor works on region-character of media motion,then imposed the effect on ground particles,had been constructed.In this paper,an optimized process method based on the region-characters of media motion had been proposed to study the influence factors in ball milling.The changes of the micro-region of media motion had revealed the influence mechanism and process for different factors in ball-milling from a microscopic point of view.These will provide the theoretical foundation for predicting the grinding rate and finer particles outcome,optimizing the parameters of liner structures and mill movement,and designing the ball-mill devices.