Research And Application Of Key Technology For Fine Mining Of Steep Thin Orebody In High Altitude Area

In the mining of deposits at high altitude,the medium and deep hole mining method with low labor intensity and high mining efficiency is the primary choice.However,there are some problems in medium and deep hole mining of steeply inclined thin ore body,such as complex in-situ stress,large blasting vibration,difficult to control the minimum mining amplitude,high loss dilution rate,and easy caving when the surrounding rock is not stable,resulting in increased ore dilution.How to effectively reduce the degree of ore poverty and loss in the mining process through reasonable technical means and methods has extremely important theoretical and engineering significance for promoting the popularization and application of medium and deep hole mining method in steeply inclined thin ore body and solving the bottleneck problem of low mining efficiency in high-altitude areas.Taking goluolongwa gold mine of Qinghai Shanjin Mining Co.,Ltd.as the engineering background,through data statistical analysis,indoor experiment,mathematical modeling,numerical simulation analysis and field industrial practice,this paper systematically studies the medium and deep hole mining technology of high-altitude steeply inclined thin ore body,which is summarized as follows:(1)With the help of Surpac 3D mining software,the ore body model construction,ore body morphological characteristics analysis,ore grade and reserve estimation are carried out;The physical and mechanical properties of main ore rocks are studied through laboratory experiments,and the stability classification of surrounding rock is carried out based on the statistical investigation of joints and fissures.(2)Considering the technical feasibility of mining methods,economic benefits of mines,recycling degree of mineral resources,labor production efficiency,safety degree of mining face and environmental protection degree,a multi attribute decision-making evaluation index system for mining method optimization of underground metal mines in high-altitude areas is constructed,Based on the variable weight theory,a reasonable state vector function is constructed to dynamically adjust the constant weight.On this basis,the ranking method close to the ideal solution is used for multi-attribute decision-making optimization of mining method optimization.(3)The propagation law of detonation wave in the process of explosive explosion is analyzed,the blasting seismic wave equation is deduced,the calculation model of blasting dynamic load and the action time history function of blasting dynamic load are introduced,the functional equations of blasting stress wave field and in-situ stress field are constructed,and the coupled total stress field function model of in-situ stress field and blasting stress field is established,The temporal evolution characteristics and spatial distribution law of total stress field are expounded,and the action mechanism of medium and deep hole blasting is revealed.(4)According to the spatial distribution law of ore body shape,the numerical model of medium and deep hole blasting is established by using the finite element LS-DYNA software,and the reliability of the model is verified and analyzed combined with the theoretical derivation results.The medium and deep hole blasting is simulated by explicit dynamic analysis method,and the effects of hole arrangement,decoupling coefficient and millisecond time on blasting effect are deeply studied.At the same time,the blasting parameters are optimized and the minimum mining width of 0.8m is determined.(5)The calculation method of modified stability coefficient and the span range of roof along the strike are studied.The stable length of goaf along the strike of ore body is calculated by Matthews stability diagram method;Through 3DEC numerical simulation software,a three-dimensional numerical model which can reflect the actual joint and fissure distribution on site is established,and the stability state of narrow and long goaf with different angles and mining widths is analyzed;A new goaf stability evaluation index "tension shear degree" is defined to make the evaluation results more in line with the actual situation of the mine.(6)Aiming at the high dilution problem of mining steeply inclined thin ore body by medium and deep hole sublevel and subsequent waste rock filling method,a set of fine mining technology and methods are formed,including fine geological logging,fine measurement,fine modeling,fine design and fine construction,and industrial tests are carried out;In the promotion and application stage,the minimum mining width is accurately controlled through blasting parameter optimization and construction improvement,so as to further reduce the loss and dilution of ore,and finally control the dilution rate to 15?30%,realizing the successful application of medium and deep hole sublevel filling and low dilution mining in steeply inclined thin ore body.