Study On Open-pit To Underground Mining Of Baiyun Iron Mine

Steel is an important pillar industry of the national economy.At present,the amount of ore mined in China's underground iron ore accounts for less than 20%of the total,and more than 90%of the open pit mine has entered the stage of deep concave mining.With the increase of mining depth and the shrinking of mining space and the lengthening of the transportation distance of ore and rock,the amount of Rock-Peeling?Discharged Rock?has increased sharply,and the limited land resources of the mine have been destroyed or occupied.The mining cost has increased year by year,which seriously affects the survival and development of the mine.The conversion of deep open pit into underground mining and backfilling technology has become one of the hotspots in the mining industry.It has important significance for resource recycling and the extension of mine production life and environmental protection.However,during this period,the influence of ground stress on the stability of roadway and stope continues to increase,and factors that are difficult to determine are also increasing.Baiyun Iron Mine is the largest comprehensive polymetallic symbiotic mine in the country,and open pit mining in the east is facing the pressure of closed pit production.Retrieving deep iron ore and protecting the country's strategic rare earth resources,which account for more than 41%of the world's proven reserves,has become a comprehensive problem for the mine.This paper starts from the open-pit mining mode of the dolomite ore,and studies the key issues such as the mining method and the structural parameters of the stope.The filling technology of the rare earth tailings after the large-diameter deep hole drilling stage is proposed for the first time.During the research,the influencing factors of the open-pit mining method were analyzed.Based on the principle of protecting rare earth resources,a multi-objective decision-making index system optimized for dolomite mining methods was established.In order to form a more objective evaluation method of mining method,the quantitative index and qualitative index membership matrix are calculated by using the standard deviation method and the priority relationship binary comparison ranking method.FAHP was used to determine the filling method after the discharge of the large-diameter deep hole rock drilling stage as the preferred mining method.A tailings filling scheme using rare earth resources is proposed.Using FLAC^3D numerical simulation,the maximum principal stress,vertical displacement of the roof and plastic zone distribution of the stope of 9 different ore parameters were analyzed.Based on this,4 schemes with better stability of the stope were selected.The effective index is extracted to establish the evaluation index system of the stope structure parameters,and the TOPSIS is used to optimize the structural parameters of the stope.Therefore,under the protection of rare earth,dolomite can be safely and efficiently mined in the open air.This paper solves the problem of optimum selection of mining methods in the transition from open pit to underground mining of symbiotic ore bodies.The optimization of stope structural parameters in deep mining is solved.The research ideas and achievements have important reference value for similar problems.