Evaluating Unsaturated Flow of Heap Leach Materials in Large Diameter Column Tests

Abstract

Two large columns (1.3 m diameter by 2 m tall) were filled with crushed and run-of-mine heap leach ore respectively. These columns were instrumented to measure water content and matric suction; the instruments were sourced from two different manufacturers. Water was applied on the top of each column at a range of calibrated flow rates and outflows were measured using tipping bucket rain gauges. A data logger collected all the instrument data from where it was transferred to a computer. This paper describes the grain size, saturated hydraulic conductivity and unsaturated flow parameters of the heap leach materials as well as the column experimental set-up and results. The observed results are discussed as they relate to the flux application rate, drain down and relative values of water content and matric suction. The results of this study provide important insights in the unsaturated flow behaviour in heap leach facilities.