Study On The Migration Law Of Granular Ore-rock Under Draw By Caving Method

Ore-drawing loss and dilution have become the prominent problem in caving method.However,because of the limitation of the theory and the bad adaptability of software,the traditional continuum mechanics ore-drawing theory and the current computer simulation of ore-drawing technology cannot meet the need of the development of the ore-drawing technology.In order to explore the migration law of ore-rock during ore-drawing and improve the theory of ore-drawing furtherly,the physical experiments,mathematical modeling,theoretical analysis,numerical simulations and industrial control methods were carried out in this work.A preliminary study was performed with the migration law of ore-rock and optimization of ore-drawing parameters.The work could be summarized as follows.(1)Experiments on free-surface chute particle flow with respect to different particle size.The equivalent viscosity test device of free-surface chute particle flow was designed.The yield stress,the structure of flow layer,the distribution of mass and velocity of the particle flow were investigated.The constitutive model of non-Newtonian fluid was deduced based on the assumption of the continuous medium.(2)Establishment and solution of the LBM-DEM coupled frame theory model.The unified relationship between LBM macroscopic and microscopic variables was analyzed based on Chapman-Enskog expansion.The method of solving the LBM density distribution function under different boundary conditions was deduced.Moreover,the Bingham-FPFM model was introduced into the LBM-DEM coupling frame and the accuracy and stability of LBM-DEM coupling program were verified by classical examples.(3)Numerical simulations of ore-drawing in caving method mine were carried out based on LBM-DEM coupling frame.The percolation law of waste fine particles was explored and the microscopic effect of the rock mass and water content on the morphology of single funnel was analyzed.In addition,the distribution of velocity and stress in the ore field was discussed.(4)Series of three-dimensional and two-dimensional ore-drawing experiments by caving method were carried out.The development regularity of the isolated extraction zone(IEZ)and the isolated movement zone(IMZ)during the process of single drawbell ore-drawing was explored according to the experiments of single drawbell ore-drawing under overburden condition.Furthermore,the law of uniform ore drawing and slag ore drawing under the condition of multi-drawbells was explored.(5)Establishment of Bergmark-Roos ore release theory correction model.The Bergmark-Roos equation was modified based on the basic principle of Bergmark-Roos equation and the simulation results of LBM-DEM coupled ore-drawing.The mathematical model of the migration of granular media ore-rock was established according to the theory of mechanics,and the mathematical ore-drawing model of plasticity and kinetic was established.(6)Optimization of caving method mine ore-drawing control technology and ore-drawing parameters.Combined with the production parameters of Tongkuangyu copper mine,the numerical simulations of ore-drawing by caving method were performed based on the derivation of the modified model of Bergmark-Roos ore-drawing theory.Besides,the unequal average ore-drawing model was validated according to the principle of minimum ore contact surface.