USING TRANSIENT ELECTRICAL RESISTIVITY TO CHARACTERIZE AN ACTIVE HEAP LEACH SITE

Transient electrical resistivity surveys were performed at Cortez Gold Acres Facility, a heap-leach mine site in northeastern Nevada. This research tested the ability of electrical resistivity to detect fluid flow through unsaturated, heterogeneous crushed gold ore piles. The resistivity data were also compared to geochemical data and lysimeter data concurrently collected by collaborators at the University of Nevada, Reno. Surveys were conducted along the surface of the heap and repeated at daily intervals for 9 days from initial solution application on the dry heap.

It was determined that electrical resistivity methods can be successfully employed to image an active heap. Areas with preferential flow paths and uneven wetting were identified. Interpreted wetting front progression from the resistivity data correlated with observed lysimeter flow times. The transient electrical resistivity data revealed that resistivity increased and decreased through time, rather than a constantly decreasing trend as was expected. While wetting and preferential flow were depicted, eliminating all potential causes of transient resistivity variability was not possible.