Estudo do modelo de contato para avaliar a dinâmica de corpos moedores em moinhos de bolas utilizando o método dos elementos discretos.

Abstract

Cominuation is a process widely used in the beneficiation of the ore, in order to reduce the size of the particles. In this sense, this work has as objective to study the movement of the load of a ball mill of the type cadente, from experimental test using a system of filming and of 2D computational simulation by means of the Method of the Discrete Elements (MED). The effect of process velocity, Coulomb friction coefficient and the Kelvin-Voig and Hertz-Mindlin contact models in the DemPACK software are evaluated. It was possible to observe, qualitatively, that the movement of the particles was even that observed experimentally regardless of the speed of the process used. An oscillatory movement was observed where a maximum is reached and afterwards a tendency to reach a stability condition, suffering small oscillations in relation to the equilibrium position. It was possible to perform the calibration of the model by comparing the images obtained by the simulation with those obtained from the experiments performed. For the contact models studied (Kelvin-Voigt and Hertz Mindlin), it was verified that both the process velocity and the Coulomb coefficient of friction influenced the behavior of the displacements (in the x and y directions) of the grinding bodies. For the Coulomb coefficient of friction μ = 0.1 there was no significant variation in the displacement of the grinding bodies independent of the contact theory, but when the coefficient of friction goes from μ = 0.51, the displacements for the non-linear contact model of Hertz-Mindlin were lower than those obtained using the Kelvin-Voigt linear model, for the same process speed. It was possible to observe the cataract and waterfall movements when simulating the mill load consisting of grinding and ore bodies.