Abstract

Mud rushes are defined as the entry of large volumes of a mixture of water and fine granular material to underground mining operations, in a sudden and violent way. Mudflow and mudrush are one of the five main operational risks to which is exposed Mining Block/Panel Caving currently, claiming lot of lives in the operation, in addition to countless losses mineable reserves, temporary closures of mining operations and lengthy delays that adversely affect the industry. The Block/Panel caving mining operations are inherently susceptible to internal mud rushes. Mud rushes are caused by the combination of two factors: 1) the interaction of fine-grained particles – induced by secondary comminution – and water, driven by percolation through broken muck pile; 2) disturbances triggered by production activities and discharge points. In this sense, finding an alternative solution for mud rush problems is an urgent matter in mining. Hence, solve this problem not only will allow the exploitation of mineral saturated, but also it will minimize the personnel exposures and damages of vulnerable elements in mining operations. According to the latter, the purpose of this numerical research is to obtain a solution for this issue by proposing a methodology for determining the water flow expected at drawpoints as water is the mobilizing force for the mud rush phenomenon. Thus, we have implemented the equations of fluid mechanics in COMSOL Multiphysics, particularly the Darcy's law and the Brinkman's equation, which describe the motion of a fluid (water) through a granular medium. The problem parameters considered in the numerical simulations are the initial fluid velocity (vi), particle diameter (dp), extraction area (s) and dimensionless density (ρ). The parameter is simulated with different values in a numerical matrix for three draw strategies (uniform draw, dome and panel caving). The results allow to deduce that strategies control or delays the groundwater flow in function of cave back geometry. We have found that the draw uniform allows to avoid the premature entry of water to the drawpoints.