Research On Media Optimization Of Vertical Coaxial Centrifugal Ball Mill Based On Discrete Element Method

With the development of mineral processing and building materials industry,the development trend of metal ore and non-metal ore grinding has become the fine grinding,ultra-fine grinding and rapid grinding of ore,conventional ball mill,self-grinding machine and rod mill and other equipment can not meet the development needs of these industries.Therefore,it is a hot topic to study the new grinding equipment which has new theoretical support and novel structure and can realize fine grinding,ultra-fine grinding and fast grinding in the range of conventional grinding cost.Vertical coaxial centrifugal mill is a new type of mill suitable for fine grinding of ore.The working principle of the mill is that the ore medium flow guiding mechanism fixed in the vertical rotary cylinder body can change the centrifugal movement state and the movement track of the medium and the material to generate strong acting force of the medium and the material,wherein the strong acting force comprises impact force,shearing force and grinding and stripping force,and the strong acting force can effectively crush and grind the material.The guide mechanism is composed of discontinuous spiral blades,and the structure not only disturbs the flow of ore medium but also promotes the flow of ore medium in the grinding process.Discrete element method(DEM)is a method for the analysis of granular discrete materials based on the principle of molecular dynamics.Discrete element method is applied to solve practical problems in mineral processing engineering,chemical engineering and geophysics.In this paper,the vertical coaxial centrifugal mill is taken as the research object,and the three-dimensional discrete element simulation software EDEM is used to simulate the working state of the mill under different rotating speed,medium filling rate and medium grading conditions.Taking the weighted sum of the five indexes of the collision times,the average normal force,the average tangential force,the total kinetic energy of the medium ball and the energy utilization rate as the evaluation indexes,the single factor experiment and the orthogonal experiment with three factors and three levels were carried out.Based on the analysis of simulation testdata by range analysis method and variance analysis method,the optimum parameters of mill operation are obtained: rotation speed 350 rpm,filling rate 45 %,mass ratio of ball to ball 33.3: 33.3: 33.4;The influence of the three factors on the comprehensive index from the main to the second order is speed,steel ball ratio,filling rate;The influence of rotation speed,filling rate and steel ball ratio on the comprehensive index was significant at the level of ?=0.05.The research results have certain reference significance for the optimization of operating parameters of vertical coaxial centrifugal mill.