Study On Safe And Efficient Recovery Of Footwall Orebody In Sublevel Caving

This study is carried out based on the needs of the project "Research on Caving Mining in West No.2 Mining Area",with the aim of solving the problems of the location of the lower wall ore body withdrawal and the layout of the lower wall roadway,and providing technical support for the safe and efficient recovery of the lower wall ore body in mines using the sublevel caving.This paper establishes an orthogonal combination of sublevel height and ore body dip angle based on the commonly used sublevel caving in domestic mines without sill pillars.Through theoretical analysis and numerical simulation,in-depth research has been conducted on the location of the footwall ore body withdrawal and the location of the associated roadway.Finally,a safe and efficient recovery technology for the footwall ore body under different sublevel heights has been proposed The layout problems of the withdrawal position of the footwall ore body and the position of the footwall combined roadway are solved.Firstly,in order to ensure the efficient recovery of the footwall ore body,under the premise of ensuring the maximum recovery rate of the ore,an economic model was established with the main goal of reducing the ore dilution rate and the secondary goal of improving the grade of the mined ore.Based on the production indicators such as the ore dilution rate of the mine being relied on,the reasonable withdrawal position of the footwall ore body in the orthogonal combination was searched for;The research shows that when the sublevel height is 20m and the dip angle of the ore body is 30°,50°,and 70°,the reasonable withdrawal positions of the footwall ore body are 14m,10m,and 7m,respectively;When the segment height is 15m and the dip angle of the ore body is 30°,50°,and 70°,the reasonable withdrawal positions of the footwall ore body are 12m,9m,and 6m,respectively;When the segment height is 20m and the dip angles of the ore bodies are 30°,50°,and 70°,the reasonable withdrawal positions for the footwall ore bodies are 11m,8m,and 5m,respectively.Secondly,in order to ensure the safe recovery of the lower wall ore body,under static response,according to the different combination of segmented height and ore body inclination obtained by the research,FLAC 3D is used for static response calculation.It can be concluded that when the segmented height is 20m and the ore body inclination is 30°,50°,and 70°,the safe distance between the retreating position and the lower wall connecting roadway is 9m,9m,and 8m;When the segmented height is 15m and the dip angle of the ore body is 30°,50°,and 70°,the safe distance from the mining position to the lower wall connecting roadway is 11m,10m,and 9m;When the segmented height is 12m and the dip angle of the ore body is 30°,50°,and 70°,the safe distance from the withdrawal position to the footwall connecting roadway is 11m,10m,and 9m.Finally,in view of this factor of blasting vibration,by combining theoretical analysis and numerical simulation,and referring to previous research results on blasting vibration,using the FLAC 3D dynamic analysis module,the safety distances from the footwall roadway to the withdrawal position under different segment heights are obtained.When the segment heights are 20m,15m,and 12m,the corresponding safety distances from the withdrawal position to the footwall roadway are 14m,12m,and 10m,respectively.The safety distance of the footwall roadway is obtained by combining the static and dynamic responses and fitting to obtain a mathematical expression for the safety distance from the footwall roadway to the withdrawal position based on the subsection height:S=5.024+0.452H.Applying the research conclusions of this article,based on the mine on which it is based,the location of the ore body in the lower wall of the mine site was optimized for hole filling.The ore quantity recovered from each row of additional blastholes was approximately 800 tons,significantly improving the ore recovery rate.At the same time,the rationality of the location of the lower wall roadway in the production process was evaluated,proving the rationality of the proposed expression.