Optimal Design Theory Of Ball Mill Based On Discrete Element Method

Comminution is an important process in industrial production. Ball mills are key equipments that are widely used in mining, chemical engineering, cement, metallurgy, building, thermal power and any other industry, which consume huge energy with low efficiency. The action mechanisms among grinding media and mineral are complicated, which made it hard to study grinding process of ball mills by traditional methods. The discrete element method offers an important way to the mechanisms with the development of numerical simulation.Four-equation discrete element method has been made to study grinding mechanisms of ball mills, with the formation of particle breakage criterion parameter optimization design of ball mills has been formed. The contents are as follows:(1) Discrete element method based on superquadrics was used to study particles with different kinds of shapes, both simulations and experiments of particle filling and particle movement in a rotating drum were made. Comparing the results of both simulations and experiments demonstrates the veracity of the discrete element method.(2) Grinding process was studied and particle breakage criterion obtained by studying particle breakage base on energy. The criterion can be used to analyze whether a collision was useful or useless to particle breakage. Thus the efficiency and useful power was obtained.(3) Simulations with orthogonal design were made at four factors that contain fill rate and size of grinding media, ball mill rotation speeds and quantity of mineral. Three different values were studied in each of these factors. Extreme differences analysis was used to study the effects of parameters on ball mill efficiency and available power, which formed the optimal design method of ball mills that based on discrete element method.(4) Axial segregation of binary mixed particles in a horizontal cylindrical drum was studied aim at channeling of ball mills and new axial band patterns were found, which announced the basic law of axial segregation.The discrete element model made in this study can simulate the interaction among grinding media and mineral accurately, which is an effective research method to analyze ball milling process. Thus it offers technology supports on the optimal design of ball mills and any other crushing and grinding equipments.