Material Transport Study into a SAG Mill by DEM Impact on the Inclination of Lifter
This research studies the application of the discrete element method in the kinematics and dynamics of the flux of material and milling methods occurring inside a SAG mill of 40′ × 26′, working on normal operation conditions with a capacity of 120.000 ton
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Abstract This research studies the application of the discrete element method in the kinematics and dynamics of the flux of material and milling methods occurring inside a SAG mill of 40′ × 26′, working on normal operation conditions with a capacity of 120.000 ton/day. It is used a feeding granularity F80 of 150 mm at a critical speed rate of 72 %. Also, the study works with a DEM contact model between bodies which contains elastic and shock-absorber elements, the last ones have been varied to consider the presence of liquid inside the mill that changes the impact coefficients between the different surfaces to consider. The study begins with straight-line lifters, as they are used nowadays in the concentrators of the world. Then, there are proposed 4 cases which consider inclined lifters of 10, 15, 20, 25, 30 and 45°. The flux behavior will be studied, determining the exit flux and the wear produced on each case. With these results obtained it is possible to conclude whether it’s feasible to add inclined lifters or not.
1 The Problem SAG mills in these days are the most used equipment in the milling process, their high processing capacities, alongside their capacity to reduce material sizes, makes them attractive. The mill, in essence, it’s a cylinder that spins around a horizontal axis, provided, in one side, with a material feeding and milling methods (steel balls). In its inner central walls, there are lifters attached which increase the material and steel balls displacement, and then an exit for, when the material reaches a determined size, it can leave the mill. This milling process uses mainly three reduction mechanisms, the first one is the impact that generates the milling means when they are lifted by the lifters and then fall to the material cape. The second mechanism stands for the rubbing as a result from the relative movement between the different intern A. Gutiérrez (&) F. Lillo S. Ugalde Departamento de Ingeniería Mecánica, Universidad de Santiago de Chile, Alameda 3363, Estación Central, Santiago de Chile, Chile e-mail: [email protected] © Springer Science+Business Media Singapore 2017 X. Li et al. (eds.), Proceedings of the 7th International Conference on Discrete Element Methods, Springer Proceedings in Physics 188, DOI 10.1007/978-981-10-1926-5_133
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components. The last mechanism is the attrition process, generated by the weakening of the mineral when they are shocked or crushed. These mechanisms can be simulated with the usage of the Discrete Elements Method, because if the impact energy threshold is defined, it is possible to evaluate the impact; if the velocity field of each body is known, it is possible to determine relative velocities and therefor, the wear using a method like Archard’s one [1]. In the case of the attrition, it can be quantified from the number of impacts that don’t produce an immediate fracture on the mineral, in the other hand, it is possible to calculate the total force acting in each body, this allows to quantify the pressure ov
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