Research On Mined-out Areas Stability Assessment And Mining Method Optimization Of A Gold Mine In The Altai City

A gold mine in Altai city locates at hilly grasslands, its green mining and safety production would have a very important meaning to the social and economical developments of that district.Based on the mining technical conditions and the need of enlarging mining capacity at lower levels of the mine, in this thesis, by using methods of field work, theoretical study, numerical simulation and so on. a number of systematic research work on the key technical problems related with safe and efficient mining has been done, and the main achievments are as follows:The engineering geology and hydrogeology of the mine was carefully investigated and analyzed, and according to orebody hosting conditions some physical and mechanical parameters of ore and rockmass were tested. Meanwhile, rockmass rating was studied by using the CSIR method, and a conclusion that the main rockmass and orebody was rated as the third class, that is, a general rockmass, was given out.In order to get the data of the tailings of this mine, the density, mineral component, elements of tailings, particle size of composition were tested in the labarotary. Moreover, the strength characteristics and lithological property were analyzed and tested respectively.Based on the current mining situation and vein orebody hosting conditions of the mine, by using FLAC numerical modeling, mine surface subsidence was simulated with mining process, and the simulation results shown that at about 410m level the surface subsidence would become serious if those mined-out areas were not properly treated.The data of mined-out areas of the mine were sorted and analyzed. Based on the complex system theory, a stability assessment model of mined voids was set up. A fuzzy analytic hierarchy process (fuzzy AHP) method and a catastrophe theory modeling method was used to evaluate the stability of typical 12 mined-out areas, and the results proved that 8 of them are at unstable or possibly unstable. Hence, backfilling of those mined-out areas was proposed, and a diagram of backfill system was disgned.An optimization model of stoping methods was set up based on the value engineering method, and an optimized stoping method of the mine was put forward, that is, a sublevel open stoping with delayed backfill method was selected. Design of the optimized mining method was done. It is believed that by using the optimized method in lower levels of the mine, the mining capacity and productivity would be enlarged, the whole mine stability and the underground stope stability would be maintained, and also the tailings discharged into tailings dam would be largely reduced, which would be helpful for mine environment protection.In theory, the research achievements of this thesis should have an innovation meaning, and in practice, would be helpful for safe and efficient mining operation of the mine.