Study On Filling Mining Scheme And Reasonable Size Of Isolation Pillar In Long Dong Security Mine Of Daye Iron Mine

In order to fully recover the residual ore resources,Daye Iron Mine plans to use the filling method to recover the Longdong security pillar.During the mining of Longdong security pillars from the same level of caving method to filling method,a reasonable vertical isolation pillar at the junction of the two mining methods and a reasonable security pillar mining scheme must be designed to ensure the safety of security pillar mining and the safety of adjacent first phase auxiliary shaft.In this paper,the theoretical analysis,numerical simulation,and similar tests are used to study the reasonable size of the isolation pillar and the safe mining scheme to provide theoretical guidance for mine production.(1)Based on the analysis of the stress on the isolation pillar in the transition zone of the horizontal filling method to caving method of Longdong mining area,the isolation pillar is simplified as a fixed beam with variable moment of inertia,and its stress analysis is carried out.The width of the upper end of the trapezoidal isolation pillar is preliminarily determined to be 16 m.Based on the initial width of the upper end of the trapezoid isolation,the settlement of the roof surrounding rock and the deformation of the auxiliary shaft are calculated by using the numerical simulation method under the synergistic action of different width and different filling cement-sand ratio.When the security pillar is mined safely,the width of the upper end of the trapezoid isolation matched with the filling body of 1:4,1:6,1:8,1:10 and 1:12 is 25 m,28m,32 m,36m and 41 m respectively.The mining profit of security pillar is calculated when the different cement-sand ratio and the width of the upper end of the trapezoidal isolation pillar are matched.When the cement-sand ratio is 1:6,the profit of the security pillar is the largest.(2)According to the optimal matching parameters of the width of the upper end of the trapezoidal isolation pillar and the cement-sand ratio of the backfill body,numerical simulation methods were used to study the stope structure parameters and the mining sequence under the first-stage and second-stage backfill mining of the security pillar.During the first-stage mining of the security pillar,the optimal mining structure parameters of the room and the pillar are both 10 m.The optimal mining sequence of the mine is: mining from west to east,first mining 2 rooms,then mining the remaining 3 rooms,the optimal mining order of the pillar is mining from east to west.Two pillars are mined first,and the remaining two pillars are mined.In the second-stage mining of the security pillar,the optimal stope structure parameters are 20 m for the room and 15 m for the pillar.The security pillar is mined from the bottom to the top,first mining stage I and then mining stage II.The mining sequence of stage I is: Mining 3 rooms first,then mining the remaining 2 pillars;the mining sequence of stage II is: Mining 3 rooms first,then mining the remaining 2 pillars.(3)The typical geological profile of Longdong security pillar in Daye iron mine was selected to establish a similar physical model of mining in Longdong security pillar.The first-stage mining scheme of security pillar in the numerical research scheme was verified,and the strain deformation of isolation pillar and auxiliary shaft was monitored and analyzed.The results show that when the width of the upper end of the trapezoidal isolation column is 28 m,the cement-sand ratio of the filling body is 1: 6,and the size of the mine pillar is 10 m.During the first-stage backfill mining,the strain distribution and deformation of the auxiliary shaft isolation pillar are basically consistent with the numerical simulation results.