Study On The Theory Of Drawing And Stope Structure Parameters In Sublevel Caving Method Without Sill Pillar For Steeply Inclined Medium-Thick Orebody

When the steeply inclined medium-thick inclined ore body is mined by the sublevel caving method without sill pillar,a mining approach is generally arranged along the strike of the ore body in each sublevel.The upper and lower sublevel drawing bodies cannot form a diamond,which can easily cause ore loss and dilution.At this time,if the design of stope structure parameters is unreasonable,the ore loss and dilution index will be further improved.In order to reduce the loss and dilution index of caving method in steeply inclined medium-thick ore body,the flow law of ore-rock bulk and the design of stope structure parameters of caving method in steeply inclined medium-thick ore body were systematically studied by means of laboratory test,theoretical analysis and numerical simulation.The similar simulation test of ore drawing in a single mining roadway at the end of steeply inclined medium-thick ore body was carried out.The marked particles were recovered by the hole-reach method to draw the profile shape of the drawing body,and the shape expansion law of the drawing body under the steeply inclined boundary condition was analyzed.When the height of the release body does not reach the inclined wall of the hanging wall,the shape of the release body is a symmetrical regular ellipsoid.When the top of the release body is close to the inclined wall of the hanging wall,the release body begins to deflect to the side of the footwall,and then the’finger shape’expands upward along the inclined wall of the hanging wall,and the smaller the dip angle of the ore body,the greater the deflection of the release body,and the thinner the release body.Based on the Bergmark-Roos equation ore drawing theory,the ellipsoid arrangement model of the end drawing of the steeply inclined medium-thick ore body is constructed,and the calculation method of the theoretical loss rate and dilution rate of the end drawing is deduced.Based on the analysis of ore loss and waste rock mixing mode in different mining approach layout of steeply inclined medium-thick ore body,the quantitative relationship between ore loss and waste rock mixing amount and ore body dip angle,thickness,bulk flow parameters,segmentation height and mining approach position is constructed,and the ore loss and dilution index is predicted according to ore body conditions and stope structure parameters.Based on Python language,the formula of theoretical loss dilution index is derived,and the optimization software of stope structure parameters of non-pillar sublevel caving method for steeply inclined medium-thick ore body is developed.After inputting the dip angle,thickness and flow parameters of ore body,the function of automatically calculating the stope structure parameters of caving method for steeply inclined medium-thick ore body and predicting the corresponding loss and dilution indexes is realized.Combined with the actual situation of an iron mine,the PFC^2D ore drawing model was constructed by using the stope structure parameters calculated by the optimization software to carry out the numerical simulation ore drawing test,and the accuracy of the calculation results of the stope structure parameters optimization software was verified.The research reveals the law of granular flow under the steeply inclined boundary condition,constructs the quantitative relationship between the loss and dilution index of ore drawing and the structural parameters of stope,develops the optimization software of stope structural parameters of caving method for steeply inclined medium-thick ore body,realizes the automatic design of stope structural parameters according to the ore body conditions,and provides a new method for the design and optimization of stope structural parameters.