This paper presents a summary of field and laboratory studies conducted to determine the need and extent of rinsing requirements for a spent oxide gold heap. The testwork utilized the Gold Acres Heap in Nevada. Monitoring data was reviewed to examine the geochemical processes occurring within the heap and predict the chemistry of future heap solutions for the Gold Acres Heap as well as the other heap facilities. In conjunction with this field study, column rinsing tests involving freshwater and recycled process water were conducted using representative spent oxide ore from the Gold Acres Heap in order to simulate heap conditions observed during field rinsing. A comparison between the column test results and the monitoring data collected during field scale recirculation indicates rinsing oxide ore recirculated barren solution does not decrease solute loadings. The column test indicates applying multiple freshwater rinses to the heap will only exacerbate the release of constituents by changing the pH-redox conditions of the heap. Consequently, this study indicates rinsing heap material with recirculation barren solution will produce no significant change (i.e., improvement) in the heap solution chemistry with respect to environmental release. Rinsing with freshwater will result in a higher risk for potential environmental degradation than not rinsing at all.
