عنوان مقاله [English]
In a copper heap leaching process in a heap, copper oxide soils are leached by sulfuric acid. The acid dissolves the copper and drains off the bottom of the heap through a drainage system consisting of slotted polyethylene pipes and some granular soil layers. Permeability coefficient of a granular soil affects the performance of the drainage system significantly. This coefficient, based on which the thickness of the draining layer is designed, is usually measured in the laboratory according to ASTM-2423 using water. But, in heap leaching structures, the fluid is a pregnant leach solution (PLS) of different the density and viscosity of which are different from those of water. In this study, three granular soil samples and one sample of a PLS were taken to the laboratory from heap leaching structure No.2 of Sarcheshmeh copper project, Kerman. The density, PH pH and viscosity of the acid and water, and the soil samples’ particle size distribution were determined at a temperature of c before starting the permeability tests. The samples were then poured into three separate cells and their permeability coefficients were measured against water and PLS at the same temperature. (a comparison of the Rresults showeds that the coefficients are were not the same for the three soil samples). Next, the permeability coefficients of the samples were determined theoretically and the outcomes were compared with those of the experiments. It is, therefore, recommended that, when designing the drainage system of a heap leaching structure, the permeability coefficient of the soil be measured using the PLS. On the basis of this research, the drainage system of a real case (Sarcheshmeh heap leaching structure No. 4) has been designed and presented in this paper.