Study On The Solution Seepage Rule In Low-grade Copper Ore Leaching Process Under Stress Wave

Permeability is the key factor that affects the leaching efficiency of low-grade copper ore in the heap leaching. Gradation, degree of compaction and granular structure are the main factors of permeability. The successful application of air shock in the orepass and ore bin blockage makes it is possible that stress wave could improve the permeability of granular medium.Based on the National Nature Science Fund Project (No 50574099), 973 Program—National Basic Research Program of China (No 2004CB619205) and National Science Fund for Distinguished Young Scholars of China (No 50325415), thesis focuses on the permeability improvement of ore granular particles in the heap leaching, and the main achievements are as follows:(1) Structure, gradation, permeability and deformation of bulk ores were analyzed, and permeability influence of particle shape, distribution range of particle size, heap and compaction degree are researched.(2) By studying the different nonuniform coefficient C_u and different curvature coefficient C_c, impacting rules to permeability of granular medium were obtained, as well as mathematical model. We can know that permeability positive correlate to both nonuniform coefficient and curvature coefficient.(3) Influence mechanisms of permeability of granular medium by nonuniform and curvature coefficient were known from experiment results. Particle sizes of granular medium with low nonuninform coefficient are uniform, and difference of aggregate and filling is not evident. There is no skeleton structure of heap, and heap will be breaked gradually. In contrast, when nonuniform coefficient is high, interspace of skeleton structure is large. Fine particles are free in the interspace, and will be washed away during heap leaching, lead to failure by piping.(4) Influence of permeability by compaction degree was studied. The results showed that permeability positive correlate to void ratio and negative correlate to compaction degree.(5) Tube wave test have been done to discover the influence of permeability by stress wave. Effective porosity increase by the effect of tube wave, and permeability coefficient run up. We can draw a conclusion that stress wave can improve permeability of heap effectively.(6) Structure deformation and aggregate deformation are the two kinds of granular medium deformation. Structure deformation of granular medium is the permanent plastic deformation and nonreversible. Aggregate deformation is the deformation of particles and is a reversible process. The saturated granular medium has different mechanics property from solid, and is a multiphase body with solid and liquid. It has structure stress and aggregate stress at the same time.(7) Based on Darcy's law, conservation of mass and basic equations of granular medium, interaction of stress field and seepage field was considered, and initial conditions and boundary conditions were analyzed. The mathematical model of coupled stress and fluid flow of granular medium was built.(8) According to governing equation of coupled stress, numerical simulation of coupled stress and fluid flow was done using software COMSOL Multiphysics. The simulation results showed that stress field, displacement field and seepage field had obvious change, and they were benefit to permeability of heap.