Study On Mining Method Of Transition Region From Caving To Filling Method In West-wing Of Chengchao Iron Mine

There is a wide range of surface subsidence, because the Chengchao Iron Mine ismined by caving method. the subsided area becomes larger with the increase of miningdepth. Chengchao Iron Mine will transform caving method into filling method to minethe ore of west-wing. The filling method can reduce the influence to the enviroment ofmining area. The transition region is reserved between the caving mining area and thefilling mining area for the successful transition of these two methods. The transitionregion has a large number of ore, the mining method of transition region is researchedby theory analysis and numerical simulation to mine ores in transition region safety andadequately. The practicability of the mining method is verified by the production in testmining area of Chengchao Iron Mine.(1) Mining sequence of transition region is determined based on the miningcondition. The transition region is divided into mining area with filling and safety pillarwhich consists of horizontal safety pillar and vertical safety pillar. The mining sequenceof transition region is mining area with filling, horizontal safety pillar, vertical safetypillar.(2) According to the mining condition, putting forward a mining method whichcalled caving-filling combined mining method to exploit transition region. The miningmethod of horizontal safety pillar is sublevel caving method. The mining method ofvertical safety pillar is upward drift stoping with cemented backfilling. Mining area withfilling have three alternative mining methods, they are upward horizontal slicing andfilling, upward drift stoping with cemented backfilling and Sublevel open stoppingsubsequent filling. There are8factors which are selected as evaluation index fromeconomic and technology. Sublevel open stopping subsequent filling is selected as theoptimal mining method by deviation degree grey relational analysis(DD-GRA).(3) The safety pillar size of transition region is determined by stability analysis.The stability evaluation model of horizontal safety pillar is established by dimensionalanalysis. The stability of horizontal safety pillar is analyzed by numerical simulation.The numerical simulation results are applied to evaluation model to determine thehorizontal safety pillar size. The horizontal safety pillar size for Chengchao Iron Mine is17.5m. The relationship of vertical safety pillars top width and its stability is analyzedby numerical simulation. The vertical safety pillars top width for Chengchao Iron Mineis25m. (4) The mining method of transition region is applied to test at5-1mining area inChengchao Iron Mine. The test results show that the safety pillars of transition regionare stable, and the ore of transition region is recovered fully.