Kinematical Analysis&Parameters Optimization Of Large Tumbling Ball Mill’ Media Based On The Discrete Element Method

Lots of advantages in grinding of material make tumbling ball mill widely used inmetallurgy, cement and mining industries since its appearance. Particularly with theexpanding of mining in recent years, how to largely increase the processing functions,reduce the production costs and fundamental investments, as well as shorten theprocess configuration become numerous companies’ target which makes the largescalization for tumbling ball mill as technology development trends. In this condition,the optimization of configuration parameters and working parameters for largetumbling ball mill is necessary. Material grinding processes are caused by theinteraction between the material and the balls, and the reasonable movement of dampmill media benefits the grinding of the materials, yet there are obviouslycorresponding relationships between effective power and grinding efficiency. In orderto improve the grinding efficiency of the ball mill, the trajectory of the media and thegrinding efficiency should be analyzed together.Firstly build the large tumbling ball mill(6080)’s discrete element model based onthe discrete element software EDEM, then analyze the effects of the liner shapes(including rectangle、trapezoidal and waveform liner) on the media motion state andthe different liner shape’s influcence on ball mill’s rotative speed respectly. The studyshows that the liner shape has a great impact on cataracting trajectories of the media,while the waveform liner has an apparent influence on the falling height and numberof media. Take the effective power as the objective function, then calculate the optimalrotation speed rate under different circumstances, lastly discuss the collision energydistribution. The results indicate that rectangle liner can only lift the inner layeredmediums, the trapezoidal liner can lift the inner and outer layered media, though thetrapezoidal liner has more throwing mediums，yet the height difference of the innerlayered medium is lower. The results verify the feasibility of the discrete elementmethod. Analysis the connection between packing fraction and rotation speed, thenrespectively determine the critical rotation rate and the appropriate rotation rate inwhich circumstances the mediums can be restricted to a certain range. Analyze theinfluence of the media sizes on media motion state、effective power and collisionenergy distribution in the same filling ratio, and the results show that when the mediasize changes,the outer layered media trajectories are similar, while the inner layeredmedia trajectories have large differences. Size differences of the media have smalleffect on effective power, while have a large influence on distribution of the collisionenergy.Considering the influence of mill’s operating parameters and configurationparameters on the medium movements, take the specific power as testing target, thenoptimize the main parameters that affect the grinding efficiency based on orthogonalexperimental design method, finally acquiring the primary and pecondary factor andthe optimal parameter combination of all the experimental factors.The research of this article can provide scientific data for choosing liner shapesand operating parameters, as well as the design of the waveform liner, which haveimportant significances to improving grinding efficiency.