Computational fluid dynamics simulation of coal ash filling in underground mine cavity

Coal fly ash waste from thermal power plants has recently been considered as a fill material for abandoned coal mine voids in Korea. A volume of fluid method, used in computational fluid dynamics, was adopted to simulate the process of coal ash injection into mine cavities. The difference in the filling efficiency of coal ash versus water using both upper and lower injection points was also investigated. Results show that use of a lower injection point more stably packed the cavity and provided a higher density of fill than use of an upper injection point. Thus, it would be better to place the nozzle of the injection pipe near the bottom of the mine cavity, below the groundwater level.