Theory And Test Study On Seepage Reinforement By Stress Wave In Heap Leaching

Mineral resources are the backbone of economic advance in China, and solution mining is an effective method to exploit the intractable ore resources or those with low grade. But the application and generalization of the method is restricted badly due to the low permeability of heap. Thus, it is very significant to investigate on the theory and applied technology of seepage reinforced in heap leaching.Based on the National Nature Science Fund Project The Study on the Mechanism of Flow in Granular Media of Heap under Stress Wave (No.50574099), and support by the National Science Fund for Distinguished Young Scholars of China The Study on Dynamics of Multilevel Seepage and Mass Transfer in Multiphase Granular Medium (No.50325415), the classification of ore leachability and the mechanism of seepage reinforced by stress wave in heap leaching were studied in this thesis.Combining the methods of indoor test, theoretical analysis, and numerical simulation, the importance of permeability of heap to ore leachability was analyzed against the heap with low permeability. Then, taking stress wave as technical measure to improve the permeability of heap, the law of stress wave propagation in heap, the mechanism of action to the mesh of granular media, and influencing law to seepage were studied. Taking the heap leaching plant in De-xing Copper Mine as an engineering example, the application technology of seepage enforced by stress wave was researched in this thesis.The main works completed are as follow:(1) The factors influencing ore leachability were studied systematically. They were classified as three grades according to their impact degree, deterministic factors, controlling factors and general factors. An evaluation model, taking ore leachability index LI as basis, was established, which enriches solution mining theory.(2) The modified Carman-Kozeny equation was introduced into the analysis of the seepage mechanism in heap leaching process. Based on it, the impact factors to the permeability of leaching heap were studied widely and systematically, which make the research results be more practical and useful for instructing heap construction. Furthermore, the numerical model describing the influence of fine particles precipitation and filtration on the permeability of leaching heap was established firstly, which disclosed the influencing rules of fine particles precipitation on leaching heap's permeability.(3) The shock tube was introduced into the seepage experiment during heap leaching initially. Based on seepage mechanics, the action rules of stress wave on the pore structure of granular medium and seepage were studied. The results indicate that stress wave can loose the granular medium and increase seepage coefficient from 3.8 to 10 times, as a result the seepage can be reinforced and presents certain secular properties.(4) Based on the dynamic mechanics of granular media, the double effective stress model was built with structure effective stress and effective stress among particles, and it could reveal the mechanism of triplicate action by stress waves on the structure of granular media in heap leaching process.(5) Based on the Biot theory, the coupled controlling equations of flow and stress under stress wave during heap leaching were set up in the condition of nonlinear flux. With numerical simulation, the coupling model of seepage-stress was verified. The effects of stress wave on seepage during heap leaching were investigated and the feasibility and availability of reinforcing seepage by stress wave were illuminated.(6) The application technology of seepage reinforcement by stress wave was researched. Take blasting wave as stress wave, and employ loosing controlling blast technology to reinforce fluid flow in heap leaching, the loosing blasting technology in heap leaching and the blasting parameters optimization were studied systematically. Moreover, take the dump leaching in Dexing Copper Mine as an example, a commercial test of dump loosing by loosing controlling blast was carried out, which proved the availability of reinforcing seepage in heap leaching by stress wave.