3D quantification of mineral components and porosity distribution in Westphalian C sandstone by microfocus X-ray computed tomography

Long, Haili; Swennen, Rudy; Foubert, Anneleen; Dierick, Manuel; Jacobs, Patric

doi:10.1016/j.sedgeo.2009.07.003

Cited by 61 publications

(46 citation statements)

References 42 publications

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“…Also, since only single energy level radiography is used, materials with similar attenuation coefficients will not be distinguishable from one another. For those materials, multiple energy radiography will be needed (Lin et al, 2013;Long et al, 2009). Also, the methodology is bounded to the mineralogy presented by the SEM analysis so it can't distinguish minerals that have not been identified in the SEM analysis.…”

Section: Simplified 3d Mineralogical Mapmentioning

confidence: 99%

Calibrated X-ray micro-tomography for mineral ore quantification

Reyes

Lin

Udoudo

et al. 2017

Minerals Engineering

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Scanning Electron Microscopy (SEM) based assessments are the most widely used and trusted imaging technique for mineral ore quantification. X-ray micro tomography (XMT) is a more recent to the mineralogy toolbox, but with the potential to extend the measurement capabilities into the three dimensional (3D) assessment of properties such as mineral liberation, grain size and textural characteristics. In addition, unlike SEM based assessments which require the samples to be sectioned, XMT is non-invasive and non-destructive manner. The disadvantage of XMT, though is that the mineralogy must be inferred from the X-Ray attenuation measurements, which can make it hard to distinguish from one another, whereas SEM when coupled with Energy-Dispersive X-ray Spectroscopy (EDX) provides elemental compositions and thus a more direct method for distinguishing different minerals. A new methodology that combines both methods at the mineral grain level is presented. The rock particles used to test the method were initially imaged in 3D using XMT followed by sectioning and the 2D imaging of the slices using SEM-EDX. An algorithm was developed that allowed the mineral grains in the 2D slice to be matched with their 3D equivalents in the XMT based images. As the mineralogy of the grains from the SEM images can be matched to a range of X-Ray attenuations, this allows minerals which have similar attenuations to one another to be distinguished, with the level of uncertainty in the classification quantified. In addition, the methodology allowed for the estimation of the level of uncertainty in the quantification of grain size by XMT, the assessment of stereological effects in SEM 2D images and ultimately to obtain a simplified 3D mineral map from low energy XMT images. Copper sulphide ore fragments, with chalcopyrite and pyrite as the main sulphide minerals, were used to demonstrate the effectiveness of this procedure.

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Section: Simplified 3d Mineralogical Mapmentioning

confidence: 99%

Calibrated X-ray micro-tomography for mineral ore quantification

Reyes

Lin

Udoudo

et al. 2017

Minerals Engineering

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“…Over the past two decades, X-ray computed tomography (xCT) has become a valuable tool for 3D visualization and characterization of geological specimens [1][2][3][4][5][6][7][8][9], including fracture geometries [10][11][12][13][14][15][16][17][18][19][20][21], pore networks [22][23][24][25][26][27][28][29][30][31], crystal sizes [32,33], and mineral phases [3,[34][35][36][37][38][39]. xCT imaging is indispensable for non-destructive observation of geometry of fractures, which is important because fractures provide preferential flow conduits and often dominate mass transfer in geological materials.…”

Section: Introductionmentioning

confidence: 99%

Quantifying fracture geometry with X-ray tomography: Technique of Iterative Local Thresholding (TILT) for 3D image segmentation

2016

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This paper presents a new method-the Technique of Iterative Local Thresholding (TILT)-for processing 3D X-ray computed tomography (xCT) images for visualization and quantification of rock fractures. The TILT method includes the following advancements. First, custom masks are generated by a fracture-dilation procedure, which significantly amplifies the fracture signal on the intensity histogram used for local thresholding. Second, TILT is particularly well suited for fracture characterization in granular rocks because the multi-scale Hessian fracture (MHF) filter has been incorporated to distinguish fractures from pores in the rock matrix. Third, TILT wraps the thresholding and fracture isolation steps in an optimized iterative routine for binary segmentation, minimizing human intervention and enabling automated processing of large 3D datasets. As an illustrative example, we applied TILT to 3D xCT images of reacted and unreacted fractured limestone cores. Other segmentation methods were also applied to provide insights regarding variability in image processing. The results show that TILT significantly enhanced separability of grayscale intensities, outperformed the other methods in automation, and was successful in isolating fractures from the porous rock matrix. Because the other methods are more likely to misclassify fracture edges as void and/or have limited capacity in distinguishing fractures from pores, those methods estimated larger fracture volumes (up to 80 %), surface areas (up to 60 %), and roughness (up to a factor of 2). These differences in fracture geometry would lead to significant disparities in hydraulic permeability predictions, as determined by 2D flow simulations.

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“…The absorption coefficient is a function of the material's density and atomic number and the initial X-ray intensity for the measurement [11]. If absorption coefficients differ substantially between phases, image analysis can be used to isolate the different phases in space.…”

Section: Introductionmentioning

confidence: 99%