Experimental Study On The Formation Of Compound Overburden From Open-pit Transferring To Underground Mining In Miaogou Iron Mine

Because of the strict requirements of national environmental protection,Miaogou Iron Mine,which is in the transition period from open-pit transferring to underground mining and adopts pillarless sublevel caving for underground mining,now it is urgent to solve the potential safety hazards such as open-pit,tailings pond and waste dump left on the surface,especially the problem of mine waste(waste rock and tailings)stockpiled.Therefore,it is of great significance to make full use of the open-pit to study stockpiled technology and discharging the mine waste to form the composite overburden under the condition of ensuring the production capacity connection and underground operation safety of Miaogou Iron Mine.Based on the previous studies,this paper combined with the actual situation of Miaogou Iron Mine,using Miaogou Iron tailings as the main raw material,and adding the self-made binder "W" to preper the tailing stockpiled sample in accordance with the stockpiled requirements at room temperature,and then,the relevant similar ore drawing model test is carried out to determine the formation process of the compound overburden from open-pit transferring to underground mining in Miaogou Iron Mine.The main work of this paper is as follows:(1)Mastering and Familiar preliminarily the current mining situation of the mine by on-site investigation,including on-site open-pit stockpiled volume,physical and mechanical parameters of ore and rock,formation mode of overburden,etc.,and the formation process scheme of composite overburden is proposed;then,testing and analyzing the basic physical and mechanical properties of tailings to provide theoretical parameters for the next preparation of tailings stockpiled by on-site sampling.(2)In order to determining the the optimal ratio scheme and the main performance index of "W" stockpiled sample,the preparation test of tailing stockpiled sample and comparative analysis of relevant properties were carried out by using self-made binder "W" and slag Portland cement as binder respectively.(3)The similar ore drawing model test of overburden is based on ore drawing technology,loose ellipsoid theory and actual situation of Miaogou Iron Mine.Firstly,verifing and determining the initial thickness of covering layer and the range of water content of the mortar by simulating the iron tailings stockpiled sample with different water content.Secondly,analyzing the rule of tailings and water leakage by the characteristics of ore drawing simulation process of iron tailings with different water content.Thirdly,determining the initial cover height,single stockpiled thickness and cycle by the simulation of different single stockpiled thickness and different age of the w-stockpiled.Lastly,proposing the relevant anti-seepage measures by the simulation of rainstorm conditions.(4)This paper obtained the formation process parameters of composite overburden by the feasibility analysis and similar test research;and combined with the actual situation of Miaogou Iron Mine to propose the industrial test scheme of the north side wall and the potential safety control measures of related open pit,which will provide experience and methods for similar mines.