• Tunnel and Underground Space
• /
• v.27 no.3
• /
• pp.161-171
• /
• 2017

Demand for high-grade limestone is increasing, but the production in the domestic mines has been limited due to the lack of systematic development plans and efforts to develop mining technology to improve the recovery ratio, transition to high-cost underground mining due to increasing social awareness of environmental protection, and the smallness of the domestic mining industry, etc. In this study in connection with this issue, an analysis on the recovery change by improvement of mining method was executed. 3D modeling technique was used to construct a 3D model. 3D model includes the geological structure, the limestone ore body and the underground pits and tunnels excavated at the Daepyeong District of Daesung MDI Donghae District. By using the 3D model, measured resources, reserves and ore recovery were evaluated from the results of pilot operation of the room and pillar hybrid mining method, which is a variant of room and pillar mining method. These results were compared with those obtained from the conventional mining method. The ore recovery obtained by hybrid mining method was found to be up to 71.6%, showing about 26%p. increase compared with the case of conventional mining method.

• Tunnel and Underground Space
• /
• v.26 no.1
• /
• pp.1-11
• /
• 2016

This study deals with the case that was the field application of the microseismic monitoring techniques for the stability monitoring in a domestic mine. The usefulness and limitations of the microseismic techniques were examined through analyzing the microseismic monitored data. The target limestone mine adopted a hybrid room-and-pillar mining method to improve the extraction ratio. The accelerometers were installed in each vertical pillar within the test bed which has the horizontal cross-section $50m{\times}50m$. The measured signals were divided into 4 types; blasting induced signal, drilling induced signal, damage induced signal, and electric noise. The stability analysis was performed based on the measured damage induced signals. After the blasting in the mining section close to the test bed, the damage of the pillar was increased and rockfall near the test bed could be estimated from monitored microseismic data. It was possible to assess the pillar stability from the changes of daily monitored data and the proposed safety criteria from the accumulated monitored data. However, there was a difficulty to determine the 3D microseismic source positions due to the 2D local sensor arrays. Also, it was needed to use real-time monitoring methods in domestic mines. By complementing the problems encountered in the mine application and comparing microseismic monitored data with mining operations, the microseismic monitoring technique can be used as a better safety method.