The Establishment Of Limestone Discrete Element Model And Research On The Characteristics Of Impact Crushing

Vertical shaft impact crusher act as a key equipment of crushing and screening,is an important factor of ensuring the quality of man-made sand product line.Researches about the broken process and factors that affect the crushing of material particles have a great importance of optimizing the structural parameters of the rotor and the quality of production in a crusher.The theoretical analysis,comparison of experiments and discrete element simulation were combined to study the crushing properties in a crusher.The physical property parameters and contact parameters which will be used in discrete element simulation were gained by experiments and simulations.A cohesive particles ball model which contains inner structural planes and cracks was built and verified from discrete element method.The impact crushing properties of limestone were studied by the combination of experiments and discrete element simulation.The main results of this research are listed below:(1)Experiments were designed to gain materiel particles physical parameters.The uniaxial compression test was conducted to gain rock shear elasticity.The drop test of limestone from a crusher feed was conducted to gain collision coefficient of restitution.The sliding plate test and stacking angle test were conducted on devices designed by myself to gain static friction coefficient.Ultimately,two stacking angle tests were compared with the experiments to confirm the physical property parameters and contact parameters of limestone discrete element model.(2)A cohesive particles ball model which contains inner structural planes and cracks was built based on the discrete element model and the basic mechanism of rock dynamic crushing and crushing effects in production and experiments.Design and manufacture experiment device which can shoot out particles based on pneumatic principle.Simulation model were built which conforms to impact crushing process to realize the simulation of single particle impact crushing process.Compare impact crushing process with experiments in different working conditions to verify the validity of the particle model.(3)Experiments of different particle diameter,impact velocity,impact angel were conducted by using the signal particle impact crushing experiment device.At the same time,simulation of the signal particle impact crushing was conducted in the same conditions by using the discrete element particle model.Compared with the results from simulations and experiments to analysis various factors that influence the crushing effects like ratio of crushing,particle size distribution,sand rate etc.This paper contributes to initiative impact crushing theory and further study of the structure parameters of the vertical shaft impact crusher,it is of preferably theoretical research value and practical value.