Simulation-based verification of stope heat loads in deep-level mines

Abstract

As gold mines continually increase their mining depths and distances from shafts, the difficulty of providing effective cooling also increases. This increases the need for effective planning, which requires accurate knowledge of the contributions of different areas to the mine's total heat load, especially the production areas (stopes). Few heat load quantification methods isolate the heat of production areas. A simulation-based approach can be used, but such a method's accuracy must be validated. The systematic literature review process revealed a gap in the literature which is if simulations as a predictive tool can be used to determine stope heat loads and whether it can be used to compare with heat loads determined by industry accepted methods. Therefore, this study focuses on validating whether the simulation method can be used to compare calculations done on stope heat loads. In this study, the heat loads of three stopes of an operational mine were quantified by considering their energy balances. Focus was placed on the main heat sinks - ventilation air and service water. Thermo hydraulic simulations were set up to duplicate the real-world setting as closely as possible. Certain simulation parameters were fixed based on real-world knowledge, while unknown parameters were adjusted to match real-world measurements as best as possible. The simulated heat loads were compared to the energy balance method. The Van der Walt's method was determined and also compared to the simulation method. The entire process was repeated for two case studies from literature.For the in-field measured stopes, the total stope heat generated was approximately 700 kW at a depth of approximately 3.6 km. The heat removed by the ventilation air and service water was 254 kW and 441 kW, respectively. Overall (including both the in-field measured stopes and case studies), the mean absolute errors produced by the simulation and Van der Walt's method were 10.9% and 29.6%, respectively. The simulation method was validated by applying the method to external case studies. Overall, it was demonstrated that the simulation method can be used to make predictions about expected stope heats and can compare with industry methods.