Numerical Model to Assess the State and Increase of Temperatures in Underground Mine Galleries: A Tool to Support Heat Recovery Projects

Abstract

Underground mining is facing growing challenges related to the need to mine deeper and at higher temperatures, to operational expenditures associated with energy consumption, lower grade ores, environmental constraints, and social pressures. In this scenario, a new numerical model is proposed to estimate temperature increase inside mining galleries to provide specific criteria for heat recovery projects, which may consider heat extraction from abandoned mines using closed-loop geothermal systems or from operating mines using the exhaust ventilation air. This model couples different approaches from previous models and include key parameters unemployed until this moment, such as wall roughness and velocity profile modeling, what would allow for a more realistic estimation of convective heat transfer phenomena, which is critical to predicting heat exchange in ventilation air due to the turbulent nature of the airflow. The model also includes other heat sources that could be present inside galleries and should be accounted for, such as machinery, once the heat dissipated to the environment might be substantial depending on the equipment and gallery geometry. The general intention of this project is to account for every heat source that may contribute to increasing the temperature inside the gallery, so it becomes tangible to harness as much heat energy as possible, preventing energetic losses and stimulating an increase of thermodynamic efficiency in underground mining operations. The model is not validated yet with real temperature data, but preliminary results agree with the ones from previous models.