Large particle effects in chemical/biochemical heap leach processes – A review

Ghorbani, Yousef; Becker, Megan; Mainza, A.N.; Franzidis, J.-P.; Petersen, Jochen

doi:10.1016/j.mineng.2011.04.002

Cited by 110 publications

(67 citation statements)

References 68 publications

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“…Mineral grain size should be considered, however, with regard to accessibility of the mineral surface to the acid; this is a function of the mineral exposure in the particle, which in turn, is related to the particle size distribution. Studies typically consider this from the perspective of the copper-bearing ore minerals [26,27], but not from the gangue mineral perspective. Given the heterogeneity that can be expected in the mineralogy of large particles (top size 25 mm), together with porosity distribution, a shrinking core approach to particle reactivity [28] is likely to be an oversimplification.…”

Section: Other Factors Affecting Mineral-acid Interactionsmentioning

confidence: 99%

“…The types of comminution used for crushing have been shown to have an effect on PSD and crack generation, the latter of which is desirable in large particles to facilitate access to the ore minerals for leachability [26,27,30]. Of course, the presence of cracks and pores increases reaction by diffusion, and so is also applicable in the context of gangue-acid reactivity.…”

Section: Other Factors Affecting Mineral-acid Interactionsmentioning

confidence: 99%

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Acid-Gangue Interactions in Heap Leach Operations: A Review of the Role of Mineralogy for Predicting Ore Behaviour

Chetty

2018

Minerals

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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 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.

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Section: Other Factors Affecting Mineral-acid Interactionsmentioning

confidence: 99%

Section: Other Factors Affecting Mineral-acid Interactionsmentioning

confidence: 99%

Acid-Gangue Interactions in Heap Leach Operations: A Review of the Role of Mineralogy for Predicting Ore Behaviour

Chetty

2018

Minerals

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“…Besides, in heap leaching the relatively coarse size of the left tailings can help in minimizing dusting and wind erosion problems but recent experimental evidence suggests that in fact leaching from large particles occurs only at the surface and hence low recovery were considered increasing amounts of uranium that have been released to the environment [4].…”

Section: Introductionmentioning

confidence: 99%

Processing of Gattar Pilot Plants Tailing Piles for Removing Residual Uranium, Eastern Desert, Egypt

A¹,

S²

2017

J Anal Bioanal Tech

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Gattar uranium mineralization in eastern desert is of comparatively low grade containing about 300 ppm uranium. A pilot plant for leaching of uranium and produce commercial yellow cake was set up in 2000. A huge amount, of residues resulted during leaching process with uranium assay about 85 ppm uranium. The present study was performed mainly to leach of uranium from the already present residues resulted from previous uranium vat leaching from gattar uranium mineralization. Vat leaching, is a static process in which the mineralized granite is crushed, disposed in vats and irrigated with a sulfuric acid solution with proper concentration to leach the uranium. The flowsheet adopted is of sulfuric acid leach-ion exchange process, the leaching was optimized to leach uranium with low acid concentration. Uranium is finally recovered by precipitation with sodium hydroxide. The uranium leaching from the residues (tailings) were examined by re-crashed coarse size via a batch experiments as a function of contact time, grind size, L/S ratio and lixiviant concentration at ambient temperature. To verifying the feasibility of uranium leaching in large-scale applications, column leaching of uranium was carried out. The results indicate the feasibility of treating the residue of the vat leaching through dynamic leaching. recovery of about 83% of uranium in the residue was obtained using a 1.5%w/w consumption of acid, grain size is ˂10 mm and total liquidsolid ratio is 0.8 m 3 /t.

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“…In the case of the production of iodine and nitrates from caliche, depending on the grade and granulometry of the ore, the leaching process takes place in vats or heaps. The heap leaching has gained great importance due to the decreasing ore grades and the increment of processing costs (Ghorbani et al, 2011). Caliche heaps are frequently constructed by accumulation of 600 to 900 thousand tons of ROM caliche, which means that a wide spectrum of particle sizes composes the heaps.…”

Section: Introductionmentioning

confidence: 99%

“…The last one has an important effect on the leaching since the magnitude of the radius has a direct relation with the resistance to mass transfer within the solid matrix and with the surface area of contact between leachant and solid (Ghorbani et al, 2011). In previous works (Ordóñez et al, 2013;Ordóñez et al, 2014), column leaching experiments on a pilot scale using fine material were performed and a phenomenological model based on mass balance was fitted with acceptable accuracy for the dissolution of the highly soluble species.…”

Section: Introductionmentioning

confidence: 99%

Leaching of Coarse Caliche Ore. Experiment and Modelling

Valdez

Ordóñez

Cisternas

et al. 2016

Braz. J. Chem. Eng.

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-Heap leaching of caliche ores is frequently performed with run-of-mine (ROM) material, which includes rocks of very different sizes; however, most of the experimental data are obtained using small particles. To contribute to the understanding of caliche leaching, an experiment using coarse particles was carried out. The recoveries obtained from this experiment were compared with those observed in the leaching of fine particles and, as expected, a larger volume of leachant was required for leaching coarse particles to reach the same recovery. For the highly soluble species nitrate, the recovery was modelled using a previously developed model, obtaining good agreement without any fitting by using only the mass transfer coefficient obtained, by fitting, from fine particle leaching data in previous works. Physical properties such as permeability and capillarity were determined, showing that capillary forces are large, but that the permeability is very small, implying that flow through caliche particles should be very small.

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Large particle effects in chemical/biochemical heap leach processes – A review

Cited by 110 publications

References 68 publications

Acid-Gangue Interactions in Heap Leach Operations: A Review of the Role of Mineralogy for Predicting Ore Behaviour

Acid-Gangue Interactions in Heap Leach Operations: A Review of the Role of Mineralogy for Predicting Ore Behaviour

Processing of Gattar Pilot Plants Tailing Piles for Removing Residual Uranium, Eastern Desert, Egypt

Leaching of Coarse Caliche Ore. Experiment and Modelling

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