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Minerals
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Heap Leaching: The State-of-the-Art
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Heap Leaching: The State-of-the-Art

A special issue of Minerals (ISSN 2075-163X).

Deadline for manuscript submissions: closed (31 October 2017) | Viewed by 31072

Special Issue Editors

Mr. Petrus J. Van Staden

E-Mail Website
Guest Editor
Mintek, Randburg 2125, South Africa
Interests: heap leaching; bioleaching; sulphide oxidation; gold processing; hydrometallurgy of base metals and polymetallics
Prof. Dr. Jochen Petersen

E-Mail Website
Guest Editor
Department of Chemical Engineering, University of Cape Town, Cape Town 7701, South Africa
Interests: exploration of fundamental reaction and transport phenomena during the leaching of minerals, especially the (bio)leaching of sulphide minerals, and mathematical modelling, particularly of heap leach processes; copper, zinc and nickel sulphide bioleaching; chloride and ammoniua leaching; Au and PGM cyanide leaching; extraction of REEs from ion adsorption clays; evaluating extractive technologies in a broader socio-economic context, both locally and globally, in terms of commodity cycles, such as Cu and Zn production and metals recovery from e-waste in the local South African context
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Economically-significant quantities of gold, silver, copper, and uranium are currently extracted using heap leaching technology, and the technology is being explored also for nickel, zinc, PGMs, rare earths, as well as electronic circuit boards and nitrate minerals. Design of heap leach operations, to this day, relies more on experience-based approaches combined with empirical testing. At the same time, a substantial body of fundamental knowledge around the mechanisms of heap leaching has been developed, such as gas and solution flow, heat transport, particle-level reaction phenomena, microbial colonisation phenomena, etc.

Heap leach practice and fundamental knowledge have developed in parallel, sometimes informing each other, but, to a large extent, in isolation. True innovation in the field can much more readily flow from an open exchange of knowledg between theory and practice, and it is the intention of this Special Issue to foster this exchange.

Mr. Petrus J. van Staden
Prof. Dr. Jochen Petersen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • the impact of different blasting and crushing and ore handling methods on heap performance
  • agglomeration and curing phenomena
  • leaching kinetics
  • different commodities
  • different leaching chemistry
  • ore mineralogy and gangue chemistry
  • hydrology
  • geomechanics
  • microbiology
  • modelling studies
  • from laboratory data to engineering specifications
  • methods/devices for detection, monitoring and control

Published Papers (5 papers)

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Research

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16 pages, 5390 KiB  
Article
A Posteriori Analysis of Analytical Models for Heap Leaching Using Uncertainty and Global Sensitivity Analyses
by Mario E. Mellado, Luis A. Cisternas, Freddy A. Lucay, Edelmira D. Gálvez and Felipe D. Sepúlveda
Minerals 2018, 8(2), 44; https://doi.org/10.3390/min8020044 - 26 Jan 2018
Cited by 22 | Viewed by 3144
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Heap Leaching: The State-of-the-Art)
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20 pages, 6055 KiB  
Article
Heap Leaching: Modelling and Forecasting Using CFD Technology
by Diane McBride, James Gebhardt, Nick Croft and Mark Cross
Minerals 2018, 8(1), 9; https://doi.org/10.3390/min8010009 - 03 Jan 2018
Cited by 19 | Viewed by 8516
Abstract
Heap leach operations typically employ some form of modelling and forecasting tools to predict cash flow margins and project viability. However, these vary from simple spreadsheets to phenomenological models, with more complex models not commonly employed as they require the greatest amount of [...] Read more.
Heap leach operations typically employ some form of modelling and forecasting tools to predict cash flow margins and project viability. However, these vary from simple spreadsheets to phenomenological models, with more complex models not commonly employed as they require the greatest amount of time and effort. Yet, accurate production modelling and forecasting are essential for managing production and potentially critical for successful operation of a complex heap, time and effort spent in setting up modelling tools initially may increase profitability in the long term. A brief overview of various modelling approaches is presented, but this paper focuses on the capabilities of a computational fluid dynamics (CFD) model. Advances in computational capability allow for complex CFD models, coupled with leach kinetic models, to be applied to complex ore bodies. In this paper a comprehensive hydrodynamic CFD model is described and applied to chalcopyrite dissolution under heap operating conditions. The model is parameterized against experimental data and validated against a range of experimental leach tests under different thermal conditions. A three-dimensional ‘virtual’ heap, under fluctuating meteorological conditions, is simulated. Continuous and intermittent irrigation is investigated, showing copper recovery per unit volume of applied leach solution to be slightly increased for pulse irrigation. Full article
(This article belongs to the Special Issue Heap Leaching: The State-of-the-Art)
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2609 KiB  
Article
Effect of Pretreatment on Leaching Primary Copper Sulfide in Acid-Chloride Media
by Cecilia P. Cerda, María E. Taboada, Nathalie E. Jamett, Yousef Ghorbani and Pía C. Hernández
Minerals 2018, 8(1), 1; https://doi.org/10.3390/min8010001 - 21 Dec 2017
Cited by 31 | Viewed by 5336
Abstract
The aim of this study was to improve the dissolution of copper sulfide ore composed mainly of chalcopyrite (1.21 wt %) and bornite (0.54 wt %) using a pretreatment before leaching. The effect of the pretreatment on copper sulfide dissolution was investigated using [...] Read more.
The aim of this study was to improve the dissolution of copper sulfide ore composed mainly of chalcopyrite (1.21 wt %) and bornite (0.54 wt %) using a pretreatment before leaching. The effect of the pretreatment on copper sulfide dissolution was investigated using different types of leaching. Three sets of experimental tests were performed (flask, reactor and mini-column). Using experimental design, three operational variables in the ore pretreatment were evaluated: chloride concentration (20, 50 and 90 kg/t), repose time (7, 20 and 40 days) and repose temperature (20 and 50 °C). A maximum of 93% copper dissolution was obtained when the ore was treated with 90 kg Cl−/t ore, 40 d of repose time and 50 °C in flask leaching. Without any ore pretreatment, 53% copper dissolution was achieved. Using reactor leaching, an 85% copper dissolution was obtained using pretreatment stage. Without this pretreatment, only 55% copper dissolution was obtained. The final test, which involved leaching a pretreated ore in a mini-column at room temperature, yielded 49% copper dissolution. The data showed that repose time and temperature were the most important variables affecting copper extraction in the pretreatment stage. This study indicates that pretreatment has a positive effect on copper dissolution from primary copper sulfide ore in an acid-chloride medium. It also provides a feasible alternative for treating primary copper sulfide ores at the industrial level. Full article
(This article belongs to the Special Issue Heap Leaching: The State-of-the-Art)
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3999 KiB  
Article
Heap Leaching of Caliche Ore. Modeling of a Multicomponent System with Particle Size Distribution
by Javier I. Ordóñez, Alicia Condori, Luis Moreno and Luis A. Cisternas
Minerals 2017, 7(10), 180; https://doi.org/10.3390/min7100180 - 26 Sep 2017
Cited by 11 | Viewed by 6231
Abstract
Caliche is a mineral exploited in northern Chile, from which iodine and Nitrate salts (saltpeter) are obtained. This ore is the most important source of iodine in the world and is processed mainly by heap leaching using water as a leaching agent. Heap [...] Read more.
Caliche is a mineral exploited in northern Chile, from which iodine and Nitrate salts (saltpeter) are obtained. This ore is the most important source of iodine in the world and is processed mainly by heap leaching using water as a leaching agent. Heap leaching of caliche ore is carried out by the stacking of ROM (Run-Of-Mine) material, where the particle size distribution covers a wide range, from a few millimeters up to several decimeters, even diameters about 1 m. During the leaching, the multiple soluble species of caliche, which can reach total fractions larger than 40%, are dissolved at different rates, mainly controlled by their solubilities. When it occurs and unlike most other leachable ores, the particle size diminishes. The leaching modeling of several soluble species of caliche has been recently addressed; however, one of the main assumptions is the idealization that the heap is composed of particles of the same size. The present work aims to complement the previously formulated phenomenological models for caliche ore leaching, through a model that considers the simultaneous dissolution of two species from caliche with three different particle sizes. These two water-soluble species have different solubilities and dissolution rates and the conceptual model considers that both species are dissolved at the particle surface. When the most soluble species is being depleted, the particle collapses, leaving a remaining fraction of the less soluble species together with insoluble material. The less soluble species is now being dissolved from the collapsed material. This article also includes the experimental verification of the conceptual model using data obtained from column leaching tests conducted for this purpose, focusing on the dissolution of two soluble species: Nitrate and Magnesium. Full article
(This article belongs to the Special Issue Heap Leaching: The State-of-the-Art)
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Review

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11 pages, 588 KiB  
Review
Acid-Gangue Interactions in Heap Leach Operations: A Review of the Role of Mineralogy for Predicting Ore Behaviour
by Deshenthree Chetty
Minerals 2018, 8(2), 47; https://doi.org/10.3390/min8020047 - 29 Jan 2018
Cited by 26 | Viewed by 6706
Abstract
Heap leaching accounts for a fifth of global copper production, sourced primarily from porphyry ores, yet metal recoveries are often not optimal. Gangue, and its interaction with acid, plays an important role in such processes. Thus, a proper understanding of gangue minerals present [...] Read more.
Heap leaching accounts for a fifth of global copper production, sourced primarily from porphyry ores, yet metal recoveries are often not optimal. Gangue, and its interaction with acid, plays an important role in such processes. Thus, a proper understanding of gangue minerals present in the ore, their textural relationships relative to particle size distribution, reactivity with acid under different conditions, and relationship to lithotypes and geological alteration in the orebody, is necessary to predict ore behaviour in the comminution, agglomeration, curing and heap leach unit operations. Mineralogical tools available for characterisation are routine X-ray diffraction, optical microscopy, automated scanning electron microscopy, and electron probe microanalysis, accompanied by more recent advancements in hyperspectral infrared imaging and X-ray computed tomography. Integrated use of these techniques allows mineral abundance, textural relationships and mineral chemistry to be addressed over the range of particle and agglomerate sizes. Additionally, diagnostic leach results can be better interpreted when calibrated against robust mineralogical data. The linkage of ore attributes, metallurgical behaviour and their distribution in the orebody forms an integral part of a geometallurgical approach to predicting, and addressing, changes during the heap leaching process. Further investigation should address the fundamentals of gangue reaction with strong acid, and concomitant structural breakdown during curing and agglomeration processes, and how this differs from gangue-acid reactivity under weaker acid conditions, combined with temperature and fluid flow effects of heap leaching. Pre- and post- characterisation is necessary to understand and quantify the effects of variables for gangue-acid reactivity in these various operations. The characterisation outcomes should lead to a refinement of the hierarchy of gangue mineral reactivity under different conditions of comminution and leaching, and how these in turn relate to identified ore types that are mined. Full article
(This article belongs to the Special Issue Heap Leaching: The State-of-the-Art)
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