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Global map of the location, age, deposit type and principal metals of major porphyry copper deposits (Sillitoe, 2010).
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... are typically very large (Keeney, Walters and Kojovic, 2011) and can have over a billion tonnes of ore (McMillan and Panteleyev, 1980), with copper grades running typically around 0.2 to two per cent. Sillitoe (2010) provides an excellent global overview of porphyry deposits (Figure 1). ...
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... Dome ore is generally well liberated, following a nominal target P 80 of 120 µm, whereas West Dome ore is significantly different, with copper minerals tending to have a smaller grain size and be present as rimming around or veining through pyrite. The resultant lower liberation of West Dome ore can be seen in Figure 10. A regrind circuit was installed for the West Dome ore in response to this, with laboratory testing indicating the P 80 of the regrind feed and discharge to be substantially smaller, at approximately 40 and 20 µm respectively. ...
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... higher amount of magnesium in the -20 µm fraction is thought to have resulted in a surface coating on the copper minerals, reducing the overall copper recovery to the flotation concentrate across all size fractions. Figure 11 shows an example of a chalcopyrite grain, and a grain with fine particulates on the surface. A higher proportion of calcite in the LSN may contribute further by aggravating the surface coating with additional Ca-ions. ...
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... supergene regions that have developed locally can result in pyrite becoming included in covellite-chalcocite, which will typically be recovered during flotation, reducing grade (McMillan, 1991). Seaman et al (2012a) report this challenge at Telfer, where West Dome ore has copper sulfide inclusions found in pyrite hosts (Figure 12), and Czehura (2007) reports that at Butte (Montana) pyrite in the Continental pit has been extensively replaced by chalcocite veins. Waldner, Smith and Will (1976);McMillan et al (1976); Barra et al (2003) and Leichliter et al (2011) describe a range of deposits with strong chalcopyrite-pyrite association. ...
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... were intended to reject the non-sulfide gangue, allowing the recovery of slower floating valuable minerals (both liberated fines and composites), and to replace the NSG being recovered with gold-bearing pyrite. Figure 13 shows the success of this in reducing the unwanted recovery of NSG. ...
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Citations
... As the transition from secondary copper mineralogy (covellite, chalcocite, malachite, etc.) to a primary-one (chalcopyrite, bornite) occurs throughout the exploitation of most copper porphyries, an increase of hardness is expected along with it. This transition also changes the gangue mineral association (Goodall and Bradshaw, 2013), often entailing the mining of harder rocks due to the higher contents of quartz, feldspars and other mechanically resistant minerals. Since copper porphyries are the main source and reserve of copper in the world (Singer, 2017), it is important to study these deposits and develop good practices regarding comminution and energy consumption to face the challenges to come (Garrido et al., 2019). ...
... In the first protocol as grain form, one seeks to keep the largest possible particle size while maintaining the final subsample mass reasonable (≤ 15 g, hence 15 PS at 1 g/PS). This is useful for mineralogical quantification which provides relevant information about the ideal particle-size to reach given the concentration process considered (Cropp et al., 2013;Pease et al., 2006;Petruk, 2000;Wills and Finch, 2015). The second protocol brings the first subsample to fine particle sizes corresponding to liberation meshes typically encountered in mill. ...
In the mining industry, mineralogical characterization using automated mineralogical devices (scanning electron microscope and reflected optical microscope) has become inescapable, especially for geometallurgical purposes. Mineralogical characterization using these techniques requires correct sampling of the material to obtain representative polished sections. This technical note proposes a method to decide the appropriate number of polished sections which need to be prepared according to the size class considered to achieve enough representability. To illustrate this method, two sampling protocols (at grain form for textural purposes and powder form) of a theoretical typical sulfide ore including a sizing preparation, are presented with the computation method of the variance of the fundamental error related to sampling. The sampling protocols are an adaptation of safety lines derived from the sampling theory of Pierre Gy and need to be adjusted according to the intrinsic properties’ knowledge of the material considered. The method can be very useful to better anticipate the lack of representativity of mineralogical data provided by automated mineralogical devices linked to the sampling preparation.
... Tangible ore characteristics, such as mineralogy, metal deportment and microfabric constrain the efficiency of mineral processing operations and, therefore, are important factors to consider during the exploration and evaluation stages of a mining project (Core et al., 2006;Cropp et al., 2013;Gregory et al., 2013;Kesler et al., 2002). Modern analytical techniques, such as scanning electron microscope-based automated mineralogy systems (e.g. ...
Scanning electron microscope-based automated mineralogy studies are readily associated with quantitative results, providing one of the foundations of geometallurgical studies. Despite the importance of quantitative data for such studies, and efforts to reduce statistical errors, the reporting of uncertainties is rare. This contribution illustrates how bootstrap resampling can be used to provide robust estimates of statistical uncertainties for the modal mineralogy, metal deportment and all relevant textural attributes of a sample or a series of samples. Based on a case study of the Bolcana Au-Cu porphyry deposit in the South Apuseni Mountains, Romania, the impact of insufficient sampling statistics on quantitative mineralogical studies is illustrated. Quantitative analyses of the mineralogy and microfabric of milled ore samples from seven 40 m drill core intervals from the Bolcana Prospect were conducted using a Mineral Liberation Analyser (MLA), complemented by electron probe micro-analysis. Bootstrap resampling was then applied to assess how many grain mount surfaces should be analysed to achieve statistically robust results for both Cu and Au mineralogy, deportment and textural attributes. Despite variable mineralogy, grades and mineralisation styles, estimated statistical uncertainties on Cu deportment are consistently low. In contrast, uncertainties for Au deportment are so high that most reported values for important characteristics are statistically meaningless. This is mainly attributed to the pronounced nugget effect for Au mineralisation, exacerbated by the small sample size analysed by MLA. An unfeasible number of measurements would be necessary to provide robust figures for the deportment of minor/trace elements and minerals, along with other tangible mineralogical properties, such as mineral associations. The results of this case study demonstrate that statistical uncertainties need to be carefully incorporated when considering the results of automated mineralogical studies and their impact on geometallurgical models. This is particularly relevant for studies of precious metal ores.
... Complex ore textures on the top and ore modification types after initial formation at the bottom[59] Cropp et al. reported that ore texture could directly affect flotation regarding the optimum feed size, degree of liberation, phase-specific surface area, quantities of fine particles, amount of composite particles, and their types[60]. ...
... The most fundamental aspect of process mineralogy is trying to achieve a grade and recovery as close to the theoretical grade-recovery curve as possible. The theoretical curve can only be attained if an exact ore (one with the same grade as analysed to generate the theoretical curve) is passing through the circuit (the circuit must also be achieving complete recoveries), void of unexpected impurities (Chauhan et al., 2013;Cropp et al., 2013). The mining plant in question has achieved erratic economic metal grades/recoveries in the past. ...
... Mineralogy and microfabric relationships play a significant role in the extraction of copper and gold from porphyry ores, and must therefore be considered during geometallurgical studies, for effective ore body management, optimisation and sustainable development of future mine and plant operations (e.g. Birtel et al. 2013;Cropp et al. 2013). ...
The maiden resource estimate for the Bolcana gold-copper porphyry defines 381 Mt at 0.53 g/t gold and 0.18% copper. The early stage of exploration provides the perfect opportunity for the application of geometallurgical studies, to enable optimisation of future mine and plant operations. Quantitative mineralogy and microfabric characterisation of crushed material and thin sections from seven 40 m drill core intervals were accomplished by Scanning Electron Microscopy based Mineral Liberation Analysis, complemented by X-ray Powder Diffraction. The mineralogy of the studied samples is highly variable, depending on lithology, mineralisation and alteration. The main Cu-bearing mineral is chalcopyrite, predominantly occurring in B and C veins. At shallow depths, secondary bornite and covellite form rims around chalcopyrite. Primary bornite occurs at greater depths in the system. Native gold grains are typically <10 μm and hosted by chalcopyrite or, to a lesser extent, pyrite. Electron Probe Microanalysis on four samples determined that gold concentrations in solid solution in selected sulphide minerals are <100 ppm. Copper and associated gold should be recoverable by flotation of chalcopyrite. The recovery of free gold and gold associated with pyrite may require additional processing steps.
... However, with more complex and refractory ore bodies being exploited, there is an increasing emphasis on risk management and cost efficiency. The geometallurgical approach directly addresses this by using 3D block models that display the distribution of key metallurgical parameters through the orebody [41]. An effective geometallurgical model integrates the important geological information, including geological, geotechnical, geochemical, and mineralogical data, with metallurgical test work results. ...
Mining wastes, particularly in the form of waste rocks and tailings, can have major social and environmental impacts. There is a need for comprehensive long-term strategies for transforming the mining industry to move toward zero environmental footprint. “How can the mining industry create new economic value, minimise its social and environmental impacts and diminish liability from mining waste?” This would require cross-disciplinary skills, across the social, environmental, technical, legal, regulatory, and economic domains, to produce innovative solutions. The aim of this paper is to review the current knowledge across these domains and integrate them in a new approach for exploiting or “re-thinking” mining wastes. This approach includes five key areas of social dimensions, geoenvironmental aspects, geometallurgy specifications, economic drivers and legal implications for improved environmental outcomes, and circular economy aspirations, which are aligned with the 10 principles of the International Council on Mining and Metals (ICMM). Applying circular economy thinking to mining waste presents a major opportunity to reduce the liability and increase the value of waste materials arising from mining and processing operations.
... Historically, the most profitable copper mines have been the giant porphyry deposits that supply up to 60% of the world's copper [1]. The majority of the existing copper mines, as well as new discoveries, are increasingly operating under stricter operational, financial and environmental regulations, in more remote areas, on deeper, harder and more mineralogically complex ores [2,3]. ...
... Process mineralogy has been used to solve and understand problems that occur throughout the mining cycle [16][17][18][19]. Cropp et al. [1] discuss examples of porphyry copper deposits where process mineralogy has been used to evaluate the effect textural variations and gangue mineralogy have on copper recovery by flotation. An investigation by Bradshaw et al. [20] showed how process mineralogy was used to identify the cause of low Chalcopyrite recoveries at the Kennecott Utah Copper Concentrator [20]. ...
In this project the aim is the characterization and mineralogical studies of ROM ore by the XRF-XRD Technique for identification of minerals under polarizes microscope the study of ore minerals like Chalcopyrite, Pyrite, Hematite, Mica, etc., has been identified, the studies show that about 5% are opaque minerals. Mineralogical studies show that the major gangue minerals are such as Siderite, Quartz and Pyrite. Pyrite could be observed in the forms of dark mineral in polished specimens that include 10% of mineral, by counting it. Liberation studies indicate that +75 microns is the optimum liberation size and thus, recommended for flotation unit of the Rangin Flez plant.
... On the other hand, the recovery of coarse particles is due to the poor degree of liberation of this size fraction, being composite with the floatable valuable minerals. As mentioned by Cropp et al. (2013), rejecting this size fraction resulted in increasing the grade of the concentrate but losing the target grains of the valuable minerals thereby reducing overall recovery. oxidising conditions (i.e. the Eh +200 and +400 mV SHE). ...
... oxidising conditions (i.e. the Eh +200 and +400 mV SHE). Cropp et al. (2013) mentioned that the main causes for the recovery of middle size gangue to the concentrate is recovery by activation. As the middle size fraction is typically considered to be fully liberated it is expected to show a high recovery of valuable minerals and low recovery of gangue minerals ( Figure 14). ...
The global demand for the copper metal is continuously increasing however, the high-grade copper ore deposits are constantly depleting. As a result, ore bodies with complex mineralogy characteristics and rich in arsenic-copper bearing minerals are increasingly processed. Arsenic-copper sulphides such as enargite can represent a significant amount of arsenic in concentrate, which causes high financial penalties by smelters. On the other hand, arsenic (As) is a highly toxic inorganic pollutant, which causes human health and environmental problems. Recent research studies have demonstrated promising results showing the possibility of separating arsenic-copper sulphides from copper sulphides using controlled pulp potential (Eh) flotation at laboratory scale. However, the selective removal of arsenic-copper minerals in real ore systems is not well understood. Two ore samples were selected from the Tampakan copper-gold deposit located in the Philippines named the HAS (high arsenic sample) and the LAS (low arsenic sample) samples and the mineralogical analyses were performed on both samples. The floatability of enargite in a batch flotation system under controlled pulp potential conditions was investigated for the HAS and the LAS samples. It was observed that it is possible to selectively separate enargite from other copper minerals after reducing the pulp potential to about -200 mV SHE at pH 11 in the LAS sample. However, no separation between enargite and other copper minerals was observed at a reducing potential for the HAS sample. Mineralogical analyses and surface chemistry studies were undertaken for both samples to find out the reasons for different observations. This study focused on the non-sulphide gangue mineralogy and their effects on the enargite floatability and selectivity from other copper sulphide minerals.
... It is widely accepted that textures are critical mineralogical characteristics which strongly govern the ore behaviour in mineral processes Bonnici 2012;Cropp et al. 2013;Tungpalan et al. 2015;Dey et al. 2017;Pérez-Barnuevo et al. 2018). The problem relies on how to describe textures and how to use that information to forecast the ore behaviour during processing (Bonnici et al. 2008;Lund et al. 2015). ...
... In mineral processing and metallurgy, the term texture (also referred to as micro-structure) is applied to describe the size and shape of particles (broken fragments of rocks) and then extended to the description of quantity and types of mineral components that make up the particle (Bonnici 2012 and references therein). In these fields, the classification of ore grain textures is intended to associate grains to processing characteristics, i.e. attributes that are likely to influence the processes of liberation, flotation and ultimately the recovery of the valuable mineral phase (Cropp et al. 2013;Bonnici 2012 and references therein). Thus, a particle can be classified based on the number of mineral phases it comprises. ...
Lithium represents one of the strategic elements for the rest of the 21 st century due to its increasing demand in technological applications. Therefore, new efforts should be focused on the optimization of mineral characterization processes, which link the ore properties with its behaviour during downstream processes. These efforts should result in reducing operational risks and increasing resources utilization. The methodology presented in this study is based on the application of several classification techniques, aiming the mineral and textural characterization of two spodumene pegmatite deposits within the Keliber Lithium Project. Twelve textural classes have been proposed for the textual classification of the ore, which have been defined through the recognition of the main mineral features at macro-and micro-scale. The textural classification was performed through the application of drill core logging and scanning electron microscopy. Six classes are proposed to describe the characteristics of the spodumene ore. Six additional classes describe the main properties of the rocks surrounding the ore zone. Image analysis was implemented for the generation of mineral maps and the subsequent quantification of spodumene and Li2O within the analysed drill core images. The image segmentation process was executed in Fiji-ImageJ and is based on eight mineral classes and a set of seven feature extraction procedures. Thus, quantification of spodumene and Li2O is estimated by textural class. Hyperspectral images were used as a reference for assessing the estimations made through images analysis. A machine learning model in Weka allowed forecasting the behaviour of the twelve textural classes during spodumene flotation. This model is fed by metallurgical data from previous flotation tests and uses Random Forest classifier. The proposed methodology serves as an inexpensive but powerful approach for the complete textural characterization of the ore at Keliber Lithium Project. It provides information about: (1) mineral features at different scales, (2) spatial distribution of textures within the pegmatite body, (3) quantification of spodumene and Li2O within the drill cores and (4) processing response of each textural class. However, its application requires wide knowledge and expertise in the mineralogy of the studied deposits.
