Assessing surface and underground cooling methods, coupled to efficient ventilation systems to improve the climatic conditions in deep and hot mines
AuthorBandeira Teixeira, Marcelo
Mining and Metallurgical Engineering
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Exposure to elevated levels of heat and humidity can significantly affect health & safety, and productivity in underground mines. Cold air is primarily achieved by ventilation up to a critical depth from where further cooling must be provided by cooling systems, which can either be located on the surface or underground. Three major strategies that can be applied when it comes to cooling the air: centralized cooling (surface and underground), spot cooling, and micro-cooling. Selecting the most suitable strategy is achieved by assessing the mines’ site-specific characteristics such as auto-compression, geothermal gradient, depth, and others. Evaluation of each heat source contribution to the mines’ heat load profile is crucial to select an optimized cooling system for an underground mine. In order to help with the selection of the most effective cooling method & system a workflow that takes into account the mines’ site-specific characteristics was developed. The workflow can also determine whether ventilation alone would be sufficient to provide adequate work conditions, or a cooling system is needed. Many times, the climatic conditions in the production areas can be improved by simply redesigning the auxiliary ventilation system. Ventilation simulations show that by changing the fan arrangement from forcing to exhausting, appropriate climatic conditions can be achieved in the production area and along the access drift. The through-flow ventilation arrangement was the most attractive auxiliary ventilation system. In addition, the assessment of the thermal flywheel effect was performed at a particular mine site. Renewable-energy based systems such as storing cold energy during winter in glycol tanks and extracting heat from strata by means of organic rankine cycle (ORC) systems are being investigated as future alternatives.