Shrinking core models in hydrometallurgy: What students are not being told about the pseudo-steady approximation

Liddell, K.C.

doi:10.1016/j.hydromet.2003.07.011

Cited by 113 publications

(61 citation statements)

References 13 publications

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“…The economics of heap leaching were found to be strongly governed by the trade-off between the slow rate and limited extent of leaching from large particles and the cost of crushing finer (Schnell, 2013). It is known that leaching from large particles occurs only at the surface and in subsurface regions, which are accessible from the surface by cracks and pores (Ghorbani et al., 2013a;Liddell, 2005). The presence of micro-cracks plays a key role in the diffusion of reagents throughout particles during leaching and is significant for the further analysis of the effect of comminution method on downstream ore processing.…”

Section: Comminutionmentioning

confidence: 99%

“…Implicit in this is an assumption regarding the relative significance of particle scale phenomena, and which process (diffusion or reaction kinetics) is limiting at the particle scale. A conventional shrinking core approach would work only for ore particles of a particular size class that are homogeneously porous and have mineral grains well distributed throughout (Liddell, 2005;Velardo et al., 2002;Vegliò et al., 2001). Furthermore, the overall rate at which a mineral is dissolved from an ore particle is quite often the manifestation of a complex network of individual phenomena, each proceeding at its own intrinsic rate (Ghorbani et al 2013a(Ghorbani et al ,2013cvan Buuren, 2003).…”

Section: Heap Modelling and Controlmentioning

confidence: 99%

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Heap leaching technology – current state, innovations and future directions: A review

Ghorbani

Franzidis

Petersen

2015

Mineral Processing and Extractive Metallurgy Review

104

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Heap leaching is a well-established extractive metallurgical technology enabling the economical processing of various kinds of low-grade ores, which could not otherwise be exploited. However, despite much progress since it was first applied in recent times, the process remains limited by low recoveries and long extraction times. It is becoming increasingly clear that the choice of heap leaching as a suitable technology to process a particular mineral resource, which is both environmentally sound and economically viable, very much depends on having a comprehensive understanding of the underlying fundamental mechanisms of the processes and how they interact with the particular mineralogy of the ore body under consideration. This paper provides an introduction to the theoretical background of various heap leach processes, offers a scientific and

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Section: Comminutionmentioning

confidence: 99%

Section: Heap Modelling and Controlmentioning

confidence: 99%

Heap leaching technology – current state, innovations and future directions: A review

Ghorbani

Franzidis

Petersen

2015

Mineral Processing and Extractive Metallurgy Review

104

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“…This is the "pseudo-steady state" assumption, and is generally valid as long as β is small (Wen, 1968;Liddell, 2005). The partial differential equation then reduces to an implicit ordinary differential equation,…”

Section: Shrinking Core Modelsmentioning

confidence: 99%

Models for apparent reaction kinetics in heap leaching: A new semi-empirical approach and its comparison to shrinking core and other particle-scale models

et al. 2016

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Particle-scale effects are critically important to the performance of heap leaching operations. In a heap-scale simulation, the transport of fluid phases and reactive species external to the ore particles might be modelled with thousands of grid elements by the finite volume or finite element method. The inter-and intra-particle diffusions and reactions are usually parametrised by a deterministic model, such as the shrinking core model (SCM), that translates the external conditions into an effective product extraction rate. However, the rate equation takes the form of an implicit or partial differential equation for all but the simplest models and kinetic regimes, becoming expensive to solve on large grids. We instead propose an economical, easily calibrated semi-empirical approach in which the dependencies on external conditions and the current state of the ore are considered to be mathematically separable. We show that the standard SCM does not suffer greatly from this approximation even when there is a mixed control regime with nonlinear kinetics. The dependency on the state of the ore is derived empirically, inherently capturing heterogeneous features and cluster-scale effects. We demonstrate that this method scales correctly when fitted to data from physical column leaching experiments.

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“…This low leaching efficiency although leaching time for the heap pad reach to 73 days can be related to the large grain size of the ore. Recent experimental evidence suggests that in fact leaching from large particles occurs only at the surface and in subsurface regions, which are accessible from the surface by cracks and pores [6][7][8][9]. Another important process at the particle level is the transport of reactants to, and reaction products from, reaction sites within the particle.…”

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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Shrinking core models in hydrometallurgy: What students are not being told about the pseudo-steady approximation

Cited by 113 publications

References 13 publications

Heap leaching technology – current state, innovations and future directions: A review

Heap leaching technology – current state, innovations and future directions: A review

Models for apparent reaction kinetics in heap leaching: A new semi-empirical approach and its comparison to shrinking core and other particle-scale models

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

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