The Research On The Ore Crushing With High Pressure Grinding Rolls Based On Discrete Element Method

In recent years, the demand of all kinds of mineral raw materials and building materials is increasing with the rapid development of the domestic economy. High Pressure Grinding Rolls is a new type of material crushing equipment, which is a kind of "more crushing and less grinding". It has become the focus of the mining enterprises and the design institutes concerned. The ore crushing process with High Pressure Grinding Rolls is mainly studied by researchers via experimental method and finite element method. However, due to the discontinuity of the ore, there are many obstacles and difficulties to study the ore crushing problem via the experimental method and the finite element method. The discrete element method based on non-continuum mechanics has a natural advantage to deal with the interaction between neighbor elements. It is considered to be an effective method to simulate granular materials and the fracture process, namely the transformation from continuum to non-continuum. Therefore, it is advisable to use the discrete element method to simulate the ore crushing process with High Pressure Grinding Rolls. The thesis is briefly described as follows:Firstly, the background and the ore crushing process with High Pressure Grinding Rolls were introduced briefly. A literature survey was presented on the experiment methods and the numerical simulation of the ore crushing process with High Pressure Grinding Rolls. The research contents and the significance of this paper was discussed.Afterward, the parameters of the Hertz-Mindlin with bonding model used in the ore crushing simulations are verified via uniaxial compression test, three-point bending test and Brazilian disc split test. The macroscopic mechanical properties of the model are consistent with those of the actual ore.Following that, the replacement program in the designated area was written by using the discrete element commercial software EDEM with API. The appropriate time step is set and the ore crushing model of High Pressure Grinding Rolls was established.Finally, the effects of the roller speed, the gap between the rollers and the static friction coefficient between ore and the rollers on the crushing efficiency and effectiveness are researched by orthogonal test and single factor test. The results of the orthogonal test indicate that the gap between rollers and roller speed have a significant effect on production efficiency, while the gap between roller has a significant effect on crushing percentage. The results of the single factor experiment indicate that production efficiency increases with the increase of speed firstly, when the speed reaches a certain value, production efficiency tends to be stable. With the increasing gap between the rollers, crushing percentage decreases and production efficiency increases.