Study On Mining Model Of Mengku Iron Mine In Transition Period From Open-pit To Underground

According to relevant data,about 90% of open-pit iron mines in China have been converted to deep-pit open-pit mining,and many deep-pit open-pit mines are gradually or have been converted to deep underground mining,and in the transitional period of opencast mining to underground mining,Due to the insufficient prediction of underground large-scale mining,the research on the transitional mining mode of open-pit to underground mining at the same time is insufficient.Therefore,in the transition period from open-pit mining to underground mining,there are widespread problems of poor production safety conditions and simultaneous open-pit and underground mining interaction,resulting in a reduction in production or a stoppage transition during the transitional period,It seriously affects the smooth operation of the working procedure after mining enterprises.Due to the different mining technology conditions in China,the existing research results can not fundamentally solve the specific problems existing in the transition period from open pit to underground mining.The transition phenomenon of production reduction is widespread in most mines.Therefore,based on the engineering background of Mengku Iron Mine,the mining mode of transition period from open pit to underground in Mengku Iron Mine is studied by means of laboratory rock mechanics test,numerical simulation and theoretical analysis,which can provide reference for the smooth transition from open pit to underground in similar The main research results of this paper are as follows:(1)After on-site exploration of hydrogeology and engineering geology of Mengku Iron Mine,through the combination of indoor rock mechanics experiment and numerical simulation,it is found that hanging-wall orebody mining will have a greater impact on the slope and surface.With the continuous mining of hanging-wall orebody,subsequent disturbance and destruction of the hanging-wall slope will occur in a larger range and collapse on the surface.(2)Based on the analysis of the influence of hanging-wall mining on slope,in order to ensure that the production scale does not decrease sharply during the transition period from open-pit to underground mining in Mengku Iron Mine,the simultaneous mining of hanging-wall mining in 938 m stage and 884 m stage is simulated,and a 20-meter thick security pillar is preset between the two stages.The numerical simulation shows that the stress concentration of pillar is not high and there is no large position.According to the calculation results,it is suggested that the size of the security pillar in multi-stage mining room should not be less than 20 meters.(3)The formation method and thickness of overburden in Mengku Iron Mine are theoretically analyzed and demonstrated.Based on the theoretical analysis results,the formation of overburden is systematically studied by analogy method similar to mine experience.(4)Demonstration of the completion time of the 884 m horizontal infrastructure,the descending speed of the mining and mining body and the formation time of the open pit bottom layer,the completion time of the three space projects in one system is collected at one time point,that is,at the end of 2022.This time point just meets the conditions for simultaneous mining of the 972 m segment of the 938 phase and the 920 m segment of the 884 m phase.It can guarantee the smooth transition of the Mengku iron mine to the ground.Through the study of rock mass displacement of the transitional slope,the method of overburden formation,and the study of safety and reliability of multi-stage mining at the same time in the transition period,The study on the production organization model of multi-stage mining makes the output of Mengku iron mine transition from open pit to underground mining stable.On the one hand,it provides suggestions on production organization for the transition period from open-pit to underground mining of Mengku Iron Mine,on the other hand,it will help to strengthen the research progress in this respect and provide reference for other similar mining enterprises.