The Effect of Hydro-Jex Operation on the Stability of Heap Leach Pads: a Case Study of a Heap Leach Operation in Central
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The Effect of Hydro-Jex Operation on the Stability of Heap Leach Pads: a Case Study of a Heap Leach Operation in Central Mexico Behrooz Abbasi 1
&
Babak Azarfar 1 & Seyedsaeid Ahmadvand 1 & Thom Seal 1 & Bryan Ulrich 2
Received: 2 January 2019 / Accepted: 16 June 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract Hydro-Jex® is a new enhanced method for heap leach treatment with significantly higher mineral recovery. In this case study at the Los Filos Mine in Mexico, the Hydro-Jex operation is evaluated for heap leach stability. This is pursued by numerical modeling of the heap leach pad stability and well monitoring of the phreatic surface before and after the Hydro-Jex operation. Experimental and numerical results both indicate an improvement in mineral processing under the influence of Hydro-Jex. Numerical results show an insignificant decrease and a significant increase in stability during and after Hydro-Jex injection application, respectively. The integrity of the liner is maintained in both cases. The zonal injection pressure, operationally below the overburden pressure, is found to be negligible compared with the dimensionality of the heap, and stability of the structure is not exposed to any significant risk, even up to 25% above overburden pressure. Furthermore, heap leach factor of safety increases after Hydro-Jex application. This is attributed to breakdown of the water solution build-up and thus a decrease in the phreatic surface depth below the top of the pad. It is suggested that injection wells be drilled, based on thorough geophysical data, in locations where overcompaction of heap material results in water solution build-up and pore pressure enhancement. Compared with traditional heap leaching, the Hydro-Jex technique not only expedites mineral processing by increasing chemical kinetics extraction but also increases the stability of the heap by unclogging drains. Keywords Hydro-Jex . Stability analysis . Numerical modeling . Heap leach pad
1 Introduction Heap leaching is a well-developed and widely used operation in the mining industry. It is used to process low-grade ore minerals while minimizing environmental impacts [1, 2]; however, a catastrophic heap leach pad failure has significant financial and environmental consequences, e.g., Summitville [3], Cieneguita [4], and Pará mines [4]. In recent decades, there have not been any major failures of heap leach pad structures; however, unfortunately, there have been several failures of similar structures, such as landfills and tailing dams [5, 6]. One of the important stages of leach pad design is the stability analysis with respect to the leaching method. Sliding of material along the slope, tensile tearing of the
* Behrooz Abbasi [email protected] 1
Department of Mining and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557, USA
2
Mine Site Infrastructure, Stantec, Edmonton, Canada
geomembrane, and failure of the geomembrane anchorage are three main instability factors [5, 6]. Critical surface failure d
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