Application of geophysical methods to determine subsurface acid saturated zones of heap No. 3 at Sarcheshmeh copper mine, Iran

Sarcheshmeh copper mine, located in Kerman Province, is the first mine in Iran utilizing heap leaching technology to extract low grade ores. In order to assure proper performance of a heap leaching pad, monitoring of the PLS within the heap is essential. In this study, application of geophysical techniques to solve heap leaching problems was investigated for the first time in Iran. Geophysical measurements, including electrical resistivity, IP and GPR methods, were used over a part of heap No. 3 at Sarcheshmeh copper mine to determine acid saturated zones. To do this, acid sprinkling on pad No. 903 of heap No. 3 was stopped for ten days. Geophysical measurements were then carried out along five parallel profiles on the heap surface. Due to the small area of pad No. 903, spreading of the electrodes for resistivity and IP measurements was limited so that the maximum depth of 20m was obtained. The interpreted electrical resistivity sections showed that the resistivity of the heap varies in the range of 2-13Ωm. With the help of the results obtained from laboratory measurements of electrical resistivity on the samples taken from heap No. 3, low moisture zones and acid saturated areas were determined. GPR data were collected using the 50MHz LOZA GPR system with the antenna length of 3m. Acid saturated zones were also determined in GPR sections. GPR depth of investigation was decreased to about 30m as a result of radar wave attenuation in high conductive material within the heap.