Ore detection and grade estimation in the Sudbury mines using thermal infrared reflectance spectroscopy

This pilot study investigated the usefulness of thermal infrared reflectance (TIR) spectroscopy to estimate ore grade in an underground environment and to separate ore‐bearing samples from their host rocks. Work was carried out under laboratory conditions to test the initial concept; all samples had naturally broken faces to mimic the situation in a freshly blasted underground opening. A total of 26 samples, including massive and disseminated ores, were collected from eight mines around the Sudbury basin in Ontario. Rock surfaces were measured wet and dry to address environmental conditions encountered underground. To separate barren rocks from ores and for ore‐grade estimation, an important finding of this research is that, in the region of [Formula: see text], most known silicate minerals converge to a common reflectance minima (<1.5%), but massive and disseminated sulfides have distinctly higher reflectance. Individual sulfide minerals (chalcopyrite, pyrrhotite, pentlandite), however, do not reveal diagnostic features in this spectral region. When sulfides are disseminated in the host rock, the average reflectance of the rock increases but the correlation with abundance is not systematic. However, sulfide concentration as a function of continuum‐removed reflectance (CRR) is systematic. The empirical correlation between CRR at [Formula: see text] versus the total sulfide concentration, estimated via thin‐section point counts, gives a coefficient of determination value [Formula: see text] of 0.93 for measurement of dry and wet surfaces when averaged. Similar results are observed when dry and wet locations are analyzed separately. The relationship demonstrates the feasibility to estimate total sulfide concentration from TIR reflectance data even when samples are wet.

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Quantifying total sulfide content of cores and cut-rock surfaces using thermal infrared reflectance

Geophysics ◽

10.1190/1.2195990 ◽

2006 ◽

Vol 71 (3) ◽

pp. M1-M9 ◽

Cited By ~ 3

Author(s):

Jilu Feng ◽

Benoit Rivard ◽

E. Ann Gallie ◽

Arturo Sanchez

Keyword(s):

Quantitative Estimation ◽

Thermal Infrared ◽

Calibration Data ◽

Infrared Reflectance ◽

Data Set ◽

Thin Sections ◽

Core Logging ◽

Total Sulfide ◽

Sulfide Content ◽

Text Model

In this study, core samples of sulfide-rich zones were delineated from their host rock and a quantitative estimation of sulfide content on cut-rock faces was made using thermal infrared reflectance (TIR; [Formula: see text] region) spectroscopy. Core sections and rocks were collected from mines in the Sudbury basin, Ontario, Canada. The TSC% (areal percentage of total sulfide content) of each sample was then estimated by summing the modal abundance of all sulfide minerals (chalcopyrite, pyrrhotite, and pentlandite). TIR at [Formula: see text] [Formula: see text] is linearly related to TSC%. The average of the spectral ratios [Formula: see text] and [Formula: see text] [Formula: see text] is related exponentially to TSC%. The coefficients of determination [Formula: see text] based on a calibration data set are 0.90 and 0.87, respectively. Two models were tested, the [Formula: see text] model and the [Formula: see text] model; the latter combines [Formula: see text] and [Formula: see text]. The value for [Formula: see text] for predicted TSC% versus observed TSC% (from thin sections) is 0.98 and 0.97, respectively, with little or no bias. The standard deviation of the residuals is 3.1 and 3.5 TSC%, respectively. The [Formula: see text] model is preferred over the [Formula: see text] model because it is linear and therefore does not have the problem with insensitivity at low TSC% that the exponential [Formula: see text] model has. In addition, from the viewpoint of developing an instrument for automated core logging, the [Formula: see text] model requires measurements at only one wavelength rather than three and hence requires a less expensive instrument.

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The influence of distance weight on the inverse distance weighted method for ore-grade estimation

Scientific Reports ◽

10.1038/s41598-021-82227-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Zhan-Ning Liu ◽

Xiao-Yan Yu ◽

Li-Feng Jia ◽

Yuan-Sheng Wang ◽

Yu-Chen Song ◽

...

Keyword(s):

Estimation Accuracy ◽

Block Model ◽

Minkowski Distance ◽

Inverse Distance Weighted ◽

Grade Estimation ◽

M 10 ◽

Weight Calculation ◽

Distance Weighted ◽

Inverse Distance ◽

Ore Grade

AbstractIn order to study the influence of distance weight on ore-grade estimation, the inverse distance weighted (IDW) is used to estimate the Ni grade and MgO grade of serpentinite ore based on a three-dimensional ore body model and related block models. Manhattan distance, Euclidean distance, Chebyshev distance, and multiple forms of the Minkowski distance are used to calculate distance weight of IDW. Results show that using the Minkowski distance for the distance weight calculation is feasible. The law of the estimated results along with the distance weight is given. The study expands the distance weight calculation method in the IDW method, and a new method for improving estimation accuracy is given. Researchers can choose different weight calculation methods according to their needs. In this study, the estimated effect is best when the power of the Minkowski distance is 3 for a 10 m × 10 m × 10 m block model. For a 20 m × 20 m × 20 m block model, the estimated effect is best when the power of the Minkowski distance is 9.

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Mineral Physicochemistry Underlying Feature-Based Extraction of Mineral Abundance and Composition from Shortwave, Mid and Thermal Infrared Reflectance Spectra

Minerals ◽

10.3390/min11040347 ◽

2021 ◽

Vol 11 (4) ◽

pp. 347

Author(s):

Carsten Laukamp ◽

Andrew Rodger ◽

Monica LeGras ◽

Heta Lampinen ◽

Ian C. Lau ◽

...

Keyword(s):

Mineral Exploration ◽

Relevant Information ◽

Ore Deposits ◽

Reflectance Spectra ◽

Full Potential ◽

Infrared Reflectance ◽

Vibrational Modes ◽

Diagnostic Features ◽

Wide Range ◽

Mineral Assemblages

Reflectance spectroscopy allows cost-effective and rapid mineral characterisation, addressing mineral exploration and mining challenges. Shortwave (SWIR), mid (MIR) and thermal (TIR) infrared reflectance spectra are collected in a wide range of environments and scales, with instrumentation ranging from spaceborne, airborne, field and drill core sensors to IR microscopy. However, interpretation of reflectance spectra is, due to the abundance of potential vibrational modes in mineral assemblages, non-trivial and requires a thorough understanding of the potential factors contributing to the reflectance spectra. In order to close the gap between understanding mineral-diagnostic absorption features and efficient interpretation of reflectance spectra, an up-to-date overview of major vibrational modes of rock-forming minerals in the SWIR, MIR and TIR is provided. A series of scripts are proposed that allow the extraction of the relative intensity or wavelength position of single absorption and other mineral-diagnostic features. Binary discrimination diagrams can assist in rapidly evaluating mineral assemblages, and relative abundance and chemical composition of key vector minerals, in hydrothermal ore deposits. The aim of this contribution is to make geologically relevant information more easily extractable from reflectance spectra, enabling the mineral resources and geoscience communities to realise the full potential of hyperspectral sensing technologies.

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Relevance vector machines using weighted expected squared distance for ore grade estimation with incomplete data

International Journal of Machine Learning and Cybernetics ◽

10.1007/s13042-016-0535-x ◽

2016 ◽

Vol 8 (5) ◽

pp. 1655-1666 ◽

Cited By ~ 1

Author(s):

Yukui Zhang ◽

Shiji Song ◽

Keyou You ◽

Xunan Zhang ◽

Cheng Wu

Keyword(s):

Incomplete Data ◽

Grade Estimation ◽

Relevance Vector Machines ◽

Vector Machines ◽

Ore Grade

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Reappraisal of H2S/sulfide concentration in vertebrate blood and its potential significance in ischemic preconditioning and vascular signaling

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00025.2008 ◽

2008 ◽

Vol 294 (6) ◽

pp. R1930-R1937 ◽

Cited By ~ 226

Author(s):

Nathan L. Whitfield ◽

Edward L. Kreimier ◽

Francys C. Verdial ◽

Nini Skovgaard ◽

Kenneth R. Olson

Keyword(s):

Ischemic Preconditioning ◽

Baseline Level ◽

Venous Blood ◽

Sulfide Concentration ◽

Potential Significance ◽

Aortic Blood ◽

Total Sulfide ◽

Series Of Experiments

Hydrogen sulfide (H2S) is rapidly emerging as a biologically significant signaling molecule. Studies published before 2000 report low or undetectable H2S (usually as total sulfide) levels in blood or plasma, whereas recent work has reported sulfide concentrations between 10 and 300 μM, suggesting it acts as a circulating signal. In the first series of experiments, we used a recently developed polarographic sensor to measure the baseline level of endogenous H2S gas and turnover of exogenous H2S gas in real time in blood from numerous animals, including lamprey, trout, mouse, rat, pig, and cow. We found that, contrary to recent reports, H2S gas was essentially undetectable (<100 nM total sulfide) in all animals. Furthermore, exogenous sulfide was rapidly removed from blood, plasma, or 5% bovine serum albumin in vitro and from intact trout in vivo. To determine if blood H2S could transiently increase, we measured oxygen-dependent H2S production by trout hearts in vitro and in vivo. H2S has been shown to mediate ischemic preconditioning (IPC) in mammals. IPC is present in trout and, unlike mammals, the trout myocardium obtains its oxygen from relatively hypoxic systemic venous blood. In vitro, myocardial H2S production was inversely related to Po2, whereas we failed to detect H2S in ventral aortic blood from either normoxic or hypoxic fish in vivo. These results provide an autocrine or paracrine mechanism for myocardial coupling of hypoxia to H2S in IPC, i.e., oxygen sensing, but they fail to provide any evidence that H2S signaling is mediated by the circulation.

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