Optimization of Energy Utilization for dewatering system in Bogala Graphite Mine, Aruggammana, Sri Lanka

Mining sustainability implies the idea of extracting non-renewable resources from the Earth at maximum extent and minimum environmental impact. Any mine has a certain economic mining depth beyond which the production cost for ton of product will be greater than the income generated due to increasing operational costs. Considerable contribution to operational cost is generated by the energy consumption for dewatering, ventilation and man & material hoisting. Dewatering cost is often considered among the most critical and governing factors that decide the economic mining depth of an underground mine, especially if it is located in a wet climatic zone. Reduction of energy expenditure and cost for dewatering leads to increase of economic mining depth, consequently expanding the resource extraction and ensuring the growing sustainability of the mining industry.  This study focuses on the dewatering system in Bogala graphite mine, a medium-depth underground mine located in the wet region of Sri Lanka. The methodological approach proposed in this work aims to optimize the energy utilization for dewatering and can be adapted to any general underground mine dewatering system. An Energy System Analysis targeted the critical elements of the dewatering system identified during the literature survey and verified by field studies carried out onsite. The main objective of a dewatering system is to drive up the water which accumulates underground to the surface with the use of combination of pumps. Selecting a more effective combination together with the application of more efficient pumps is one potential option for optimizing the dewatering energy consumption. Another option is to control underground water accumulation by suppressing the origin of underground water in the particular mine; however, the economical viability of implementing control measures to suppress water origin and accumulation should be carefully analysed since the cost of such implementation would sometimes be unrecoverable throughout the mine’s life.     This report evaluates several possible engineering applications to control the root-causes of underground water accumulation & recirculation while improving energy efficiency of water conveyance taking into consideration the viability under technical, financial and environmental constraints in order to optimize the energy utilization of the dewatering system in Bogala mines