MR imaging of ore for heap bioleaching studies using pure phase encode acquisition methods

Fagan, Marijke A.; Sederman, Andrew J.; Johns, Michael L.

doi:10.1016/j.jmr.2012.01.010

Cited by 11 publications

(12 citation statements)

References 22 publications

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“…Approximately 1 kg was packed on top of a layer of 10 mm glass ballotini placed on top of the drainage plate to provide a liquid disengagement region below the ore which prevented upwards wicking of any liquid. The cell was irrigated at a flow rate of 10 mL/h (approximately equivalent to 1 L/m 2 .h) with deionised water that had been doped with 0.8 g/L of GdCl 3 .6H 2 O in accordance with the MRI signal requirements (Fagan et al, 2012). Multiple ore samples were tested in order to examine the reproducibility of the results.…”

Section: Mri Cellmentioning

confidence: 99%

“…A standard SESPI sequence was used as described in Fagan et al (2012). The field of view was 80 mm × 80 mm in the x and y directions and 160 mm in the z (along the bore length) and the nominal resolution in all three directions was 2.5 mm.…”

Section: Mri Cellmentioning

confidence: 99%

“…In the first instance, a specialist magnetic resonance imaging (MRI) method which is insensitive to the metal content of the ore (Fagan et al, 2013;Fagan et al, 2012) is used to examine the liquid flow in the immediate vicinity of the irrigation point where the signal in an MRI acquisition is directly proportional to the liquid volume. The liquid distribution is subsequently monitored using gravimetric techniques in a long-term bioleach of a 132 kg "slice" of agglomerated ore, the results of which are related to the microbial colonisation and mineral recovery in the heap.…”

Section: Introductionmentioning

confidence: 99%

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MRI and gravimetric studies of hydrology in drip irrigated heaps and its effect on the propagation of bioleaching micro-organisms

et al. 2014

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Heap bioleaching performance is dependent on the contacting of the leach solution with the ore bed, hence on the system hydrodynamics. In this study two experimental setups were used to examine hydrodynamics associated with irrigation from a single drip emitter, one of the most common methods of heap irrigation. A specialist magnetic resonance imaging (MRI) method which is insensitive to the metal content of the ore was used to examine the liquid flow into an ore bed in the immediate vicinity of an irrigation point. The distribution of liquid in, microbial colonisation of and mineral recovery from a bioleach of a large scale 132 kg "ore slice" were subsequently monitored using sample ports positioned along the breadth and height of the reactor. In both systems the lateral movement of the liquid increased with bed depth, though preferential flow was evident. The majority of the liquid flow was in the region directly below the irrigation point and almost no liquid exchange occurred in the areas of lowest liquid content at the upper corners of the bed in which fluid exchange was driven by capillary action. The MRI studies revealed that the liquid distribution was unchanging following an initial settling of the ore bed and that, at steady state, the majority (~60%) of the liquid flowed directly into established large channels. The limited lateral movement of the liquid had a significant impact on the local leaching efficiencies and microbial colonisation of the ore with cell concentrations in the regions of lowest liquid content lying below the detection limit. Hence poor lateral liquid distribution with drip irrigation, and the associated impact on colonisation was identified as a significant disadvantage of this irrigation approach. Further, the need to optimise fluid exchange throughout the ore bed was identified as key for optimisation of leaching performance.

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Section: Mri Cellmentioning

confidence: 99%

Section: Mri Cellmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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MRI and gravimetric studies of hydrology in drip irrigated heaps and its effect on the propagation of bioleaching micro-organisms

et al. 2014

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“…It has been found that such image distortions can be minimised through the use of Spin Echo Single Point Imaging (SESPI), a specialist MRI acquisition sequence (Ouriadov et al, 2004). In a previous study we have shown via direct, unambiguous comparison with X-ray CT images of saturated ore beds that the SESPI technique is compatible with the ore material used and is able to provide accurate and hence quantitative images (Fagan et al, 2012). This compatibility with the ore is largely because the spatial dependence of the signal is phase encoded during SESPI and thus measurement of the time evolution of the signal (as is the case for conventional MRI pulse sequences) is avoided.…”

Section: Introductionmentioning

confidence: 99%

Phase distribution identification in the column leaching of low grade ores using MRI

Fagan

Sederman

Harrison

et al. 2013

Minerals Engineering

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Heap bioleaching is gaining importance as an approach for the recovery of valuable metals (e.g. Cu 2+ ) from low grade ores. In this process iron and/or sulfur oxidising microorganisms are used to aid the oxidation of base metal sulfides in the ore, thereby liberating the metal ions into solution. Leach performance is strongly influenced by the contacting of the leach solution and the ore particles. In order to better understand the distribution of the leaching solution on the pore scale in these heaps, MagneticResonance Imaging (MRI) was used to acquire images non-invasively of a section of an irrigated ore bed. This was made possible by the use of specialist MRI acquisition sequences suited to the magnetically heterogeneous environment as presented by the ore material. From the images we were able to determine the pore-occupancy of the liquid and gas phases and to provide novel measurement of the interfacial area between air, leach solution and ore.

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“…We have shown in a previous study that maps of the liquid distribution in representative leaching systems can be acquired using a specialist magnetic resonance imaging (MRI) technique called spin echo single point imaging (SESPI) which is immune to the detrimental influence of para-and ferromagnetic species in the ore (Fagan et al, 2013;Fagan et al, 2012) and is able to detect liquid both external and internal to the ore. This technique may be used to determine the liquid distribution and position relative to the solid ore and through analysis of temporal changes in signal magnitude, changes in the flow patterns in the bed may be projected.…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance imaging characterisation of the influence of flowrate on liquid distribution in drip irrigated heap leaching

Fagan-Endres

Harrison

Johns³

et al. 2015

Hydrometallurgy

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Liquid irrigation is one of the key process control parameters following the construction of an ore leaching heap. This study uses 3D magnetic resonance imaging (MRI) to examine noninvasively the effect of liquid flowrate changes on heap hydrology when drip irrigation is used. Experimental results from a vertical column show that the increase in flowrate causes an increase in the number of rivulets in the ore bed. The new rivulets were found to be thicker, and their development caused an increase in liquid-solid contacting area which is considered advantageous for metal ion recovery. Experiments performed on larger samples showed that the effects of flowrate changes were limited to the region directly below the drip emitter because the increase in flowrate caused an increase in macro-pore flow and not capillary retention of liquid. Therefore the increase in flowrate was not found to perturb liquid distribution patterns in a way that would be substantially advantageous to heap leaching recoveries.

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MR imaging of ore for heap bioleaching studies using pure phase encode acquisition methods

Cited by 11 publications

References 22 publications

MRI and gravimetric studies of hydrology in drip irrigated heaps and its effect on the propagation of bioleaching micro-organisms

MRI and gravimetric studies of hydrology in drip irrigated heaps and its effect on the propagation of bioleaching micro-organisms

Phase distribution identification in the column leaching of low grade ores using MRI

Magnetic resonance imaging characterisation of the influence of flowrate on liquid distribution in drip irrigated heap leaching

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