Computational fluid dynamics model for controlling dust and methane in underground coalmines

Abstract

Airborne dust and methane are common problems in the underground coalmines. They pose health and safety risk to mining personnel, and a safety risk to mining equipment as well. In order to prevent these risks air borne dust and methane concentrations must be reduced to within the acceptable levels. In South Africa, the dust and methane concentration in coalmines should not exceed 2.0 mg/m³ and 0.5% per volume, respectively. Mine ventilation is one of the popular ways of controlling both dust and methane. Different ventilation systems have been designed since the history of underground coal mining. Unfortunately, none provides ultimate solution to the dust and methane problem, especially in the most critical areas of the underground coalmine, like blind-end of the heading and last through road. By changing airflow patterns and air velocity, it is possible to obtain an optimum ventilation design that can keep dust and methane within the acceptable levels. Since it is very difficult to conduct experiments in the underground coalmine due to harsh environmental conditions and tight production schedules, the designer made use of the Computational Fluid Dynamics (CFD) modelling technique. The models were then experimentally verified and validated using a scaled down model at University of Pretoria. After verification further numerical analysis was done to in order to device a method for determining optimum fan positions for different heading dimensions. This study proves that CFD can be used to model ventilation system of a scaled down coalmine model. Therefore chances that this might be true for the actual mine are very high but it needs to be investigated. If this is found to be true then CFD modelling will be a very useful tool in coalmine ventilation system research and development.