Feasibility evaluation of utilizing mine tailings as a paste backfill material for mine filling

There are totally 5,396 mines located in South Korea, and 2,033 mines are presently closed or abandoned. According to the current status of mine hazard by mine damage type (2017) of the Korea Mine Rehabilitation and mineral Resources Corporation, mine hazard could be caused by tailings loss in 237 mines. Mining stream/void inside the mines are inevitably formed during resource development, and therefore the appropriate management for the mine stability is continuously needed. Mining filling is regarded as one of the best options since the filling mass acts as a secondary support material that can ensure the stability of the mine void and increase the yielding rate of mining. This study evaluated the suitability of harmless tailings, generated from mine development, as a paste backfill material to secure the stability of mine. The particle size of tailings collected at the tungsten mine used in the study was suitable to be used as a paste backfill materials. The strength of cement solidified using test materials was affected by the content of cement and curing duration of the backfill materials sample. It turned out that above 3.5% the cement content and curing for two weeks were an optimal condition to produce the safe cement. In the Environment Ministry's water pollutant emission acceptance standards (South Korea), the tested backfill materials passed all domestic standards for As, Cd, Cr⁺⁶, Pb, Cu, and Hg. The environmental/physical properties of tailings obtained from the results demonstrated that the use the tailings as a paste backfill material to fill the inner space of mines could be considered as a promising option. This evaluation results will contribute to the stabilization of mining enemies and restoration of mine damage in abandoned mine areas through economical and efficient treatment of tailings.