Evaluation of the Effect of Chemical Degradation of Copper Leaching Solution on Permeability of Rock Mass Using DFN-DEM Modeling (Case Study: DAREZAR Mine-Kerman)

Evaluating the effects of sulfuric acid solution used in leaching of copper metal on hydro- mechanical behavior of rock mass، and also understanding of chemo- hydro- mechanical coupling processes related to this phenomenon are the main objectives of this research work. Biotechnology is regarded as one of the most promising and certainly the most revolutionary solution to the defects of pyrometallurgy. It holds the promise of dramatically reducing the capital cost of the projects. It also offers the opportunity to reduce the environmental pollution. A set of laboratory experiments were implemented for evaluating the influences of sulfuric acid with different pH values; 1، 3 and 5 on the properties of three types of Andesite rock joints in heap leaching site of DAREZAR copper mine. Joint roughness coefficient، joint shear stiffness، joint aperture، and shear strength of degraded rock joints in different sulfuric acid concentrations were measured. Using a Discrete Fracture Network-Distinct Element Method (DFN-DEM) approach، the effect of chemical solution on permeability of the fractured rock mass is evaluated. The numerical modeling results show that with decreasing pH value of copper metal leaching solution، the coefficients of equivalent permeability tensor increases. The effect of ratio of horizontal to vertical stresses (k0) on hydraulic properties of Andesite rock mess is also negligible.