Study On The Parameter Optimization Of Ball Mills Based On The Technology Of Distinct Element Method

Along with the energy issue become worse, the requirements that increase the production and develop less energy consumption in comminution devices is greater than before, especially in the high energy consumption industry, for example, cement, mining, electric generation and so on. Ball mill is the best rife and all-purpose comminution devices in these industries, because it has many advances: simple structure, steady-going capability, big comminution ratio, mighty adaptability, easy to achieve automatization, etc. Though there are some less energy consumption mills today, the ball mill which possess important place in mineral comminution and fine comminution will be hard to be replaced. In a long period of time in future, ball mill will bring into play its important function all the same. Many experts and scholars have gone along with the study of ball mill, and obtained some power formularies and mathematical models, made great contributions to grinding technology. But the comminution issue of mill is very complex, and it is not solved very well so far.Direct Element Method (DEM), which is based on the contact model, using the Newton's second law of motion, researching state of the particle system from the single granule, is discrete materiel analysis method. From DEM was brought forward, it develops very fast, and the using field enlarges: pharmacy, chemical medicine, disposal of mineral and material, oil and gas production, extractive industry, architecture industry, technique industry and so on. Along with the visualization of computer, DEM applications upgrade ceaselessly, it makes it possible that use computer to solve problem of a great deal of particles. Twenty years ago, some people studied the charge motion in ball mill with DEM, but the relation of breakage and impact energy was never solved, these large amounts of potentially useful information which DEM produces were not used adequately. So we need to research breakage and impact principle of ball mill, look for good method for DEM data analysis. And we can predict breakage and energy status via predicting charge motion with DEM, find solution for increase the production and develop less energy consumption of ball mill.When ball mill is operating, not all kinetic energy which medium have can be used to ore breakage, most of the energy loses in the form of sound energy, light energy, heat energy etc. Under a good mineral grinding status, the impact energy which decides the breakage of ore is more, the disposal quantity of mill in unit time is big. Morrison, Shi and Ryan (2006) reported on various approaches to modeling incremental damage. They found a satisfactory model for the probability of breakage, degree of breakage and likely progeny size distribution. The model could calculate the quantity of the energy which loses and never brings ore breakage. This enables us to research the comminution in ball mill in view of the relation of ore breakage and medium impact. The paper is using the model to guide the optimization of the parameters of ball mill aim at the most energy that could bring ore breakage. This dissertation takes the researches on the following points:(1) General conclude the development status of DEM and DEM application, introduce the basic principles of DEM and important contact models. Explain the background that DEM technology is applied to ball mill. Analyze the configuration and direction of the new DEM application—EDEM concisely. Referral the useful data that can gain from DEM, expound how to use the DEM outputs.(2) General conclude the structure and operation principles of ball mill, present the breakage theory of the ball mill, and analyze the motion and forces of the medium, design the project of the parameter optimization based on the method of experimentation optimization. Refer to correlation literature of incremental damage, make the most energy that could bring ore breakage as the optimization goal. Use the L₄ (2 ) orthogonal table to optimize.(3) Describe the parameters which effect grinding of ball mill, choose appropriate experiment factor level referring to correlation literature and based on prevenient experiences, buildup feasible examination point. Calculate the special data of the experiment factor level by the informed parameter of ball mill 5585. Apply EDEM to simulate the operation of ball mill at each examination point, plot the histogram of"collision-relative velocity". And simulate the startup process of the ball mill, obtain the torque line graph in startup process.(4) Select the 40mm granularity ore of copper mine as archetype, evaluate the least medium energy which could cause ore breakage. Use the theory and calculation methods of ore incremental damage to evaluate the impact energy which bring the ore breakage. Analyze the parameter's influence about the ore breakage impact energy, the energy is optimization goal. Deal with the experimental data by R-method, attain the best parameter match and PRI of each parameter.This paper use cumulate damage theory to impact characteristic analysis, use experimentation optimization method to design experiment process, and contact DEM and experimentation optimization to optimize the parameters of the ball mill. During the progress of the optimization, research how to use the outputs of the EDEM, create the calculation formula of the optimization target- the impact energy which cause the ore damage. Offer a reference to make use of the DEM data for the continuing DEM simulation of ball mill.