Determination of parameters of the underground inclined coal seam mining in Quang Ninh basin under protected objects on the surface
- Institute of Mining Science and Technology – Vinacomin
Based on analysis of mining and geological conditions of natural occurrence of coal seams at Quang Ninh basin it has been determined that more than 37 % of deposit reserves are located under the protected surface objects. To justify the possible variants of technological schemes for development of these coal seams situated under protected surface objects there has been a methodology for evaluation of displacement parameters of undermined layer during underground mining operations. The article shows the possibility to perform calculations for this methodology that originally were developed for coal deposits in Russia and to use calculated coefficients for Bulanashskoe deposit (Ural), because its mining and geological conditions of natural occurrence for coal seams are similar to the conditions of occurrence at Quang Ninh basin. It also presents the research results for possibility to apply the development systems to mine the reserves located under protected surface objects using the technological schemes with roof control, with complete caving, full backfilling and pillar roof support. It has been identified that with a system of roof support using complete caving the deformation of surface exceed the critical values required for preservation of surface objects. In case of using the development technology with full backfilling there have been defined a minimal admissible coefficient of backfilling, as well as requirements to filling materials. For coal deposit mining technology using the method of pillar roof support there have been defined parameters for pillars and chambers, identified maximum admissible extraction ratio ensuring protection and safety of objects located on the surface. It also presents the algorithm for selection of technological mining scheme for development of coal seams of Quang Ninh basin.