A Posteriori Analysis of Analytical Models for Heap Leaching Using Uncertainty and Global Sensitivity Analyses

Mario Mellado,Felipe Sepúlveda,Edelmira Gálvez,Luis Cisternas,Freddy Lucay

doi:10.3390/min8020044

Mario Mellado, Felipe Sepúlveda + Show 3 more

Open Access

https://doi.org/10.3390/min8020044

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Abstract

The heap leaching of minerals is one of the more commonly used processes in the mining industry. This process has been modeled by many authors. However, the validation, verification, and implementation of these models are difficult since there is uncertainty about the operating conditions and the leaching model parameters. This work uses the uncertainty quantification, based on uncertainty and sensitivity analysis, for studying the model strength against uncertainties in heap leaching. The uncertainty analysis (UA) is used to quantify the effect of the magnitude of the uncertainties of the input variables on the recovery of heap leaching. Global sensitivity analysis (GSA) is used to study the nature of connections between the recovery and input variables of the leaching model. In addition, GSA facilitates the detection of whether a leaching model is over-parameterized. The information obtained allows studying some applications of the kinetic model. The Mellado et al. kinetic model is used as an example. The UA results indicate that the kinetic model can estimate the recovery behavior considering the full range of uncertainties of input variables. The GSA indicates that the kinetic model is over-parameterized on the uncertainties range considered; this conclusion contradicts the results when the local sensitivity analysis is used. However, the model shows a good correlation between the results of GSA and the kinetic behavior of heap leaching. In addition, the kinetic model presents versatility because it allows the determination of operating regions for heap leaching.

Highlights

The hydrometallurgical process of heap leaching is one of the most commonly used processes in the mining industry
The test QQ-plot indicates that when the leaching time is equal to 100 days, the recovery moves away from normal behavior. These results show that the kinetic model can estimate the recovery of away from normal behavior. These results show that the kinetic model can estimate the recovery of heap leaching considering the full range of uncertainties of input variables
Indicates that when the leaching time is equal to 100 days, the recovery moves away from normal behavior

Summary

Introduction

The hydrometallurgical process of heap leaching is one of the most commonly used processes in the mining industry. Heap leaching allows the processing of low-grade metallic minerals (for example, less than 1% copper) [1,2]; nonmetallic minerals [3,4], and potentially yttrium and heavy rare earth elements [5]. Heap leaching is often the preferred method for extracting metal from low-grade ore deposits as it provides a low capital cost compared to other methods [6]. This low cost is due to the fact that energy-intensive comminution is not required. This is contrasted with often slow and inefficient recovery [7,8].

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