Field investigation to support the closure design of the Yankee Heap

摘要

A field investigation and laboratory-testing program was developed to aid in the closure design of the gold heap leach pad at the Yankee Mine near Ely, Nevada. The field investigation included rotosonic drilling of three boreholes through the heap to develop material and moisture profiles through the heap, assess the physical properties of the heap leached ore, and estimate the fluid inventory at closure to aid in the development of a solution disposal plan. In addition, local soils were sampled and tested for use in the design of the reclamation soil cover for the heap. The field- and laboratory-testing program included: in-situ density, in-situ moisture content, grain size distribution, saturated permeability, and the determination of the soil water characteristic curves. The data obtained through the testing program were used to estimate the residual solution inventory that would have to be handled at closure and was used to establish boundary conditions in finite element modeling of the proposed reclamation soil cover. The results of the field and laboratory investigation showed the heap to be very well drained, which led to a reduction in the overall design and cost of the solution disposal facilities at the site.