Quantitative Evaluation Of Materials Research Articles

Revealing Microstructure and Enduring Properties of Settled Barite Extracted from an Offshore Well Two Decades Later: Well Abandonment and Slot Recovery

Summary Barite settling in the annulus behind the casing is an undesired yet common occurrence during the life of a well. Over time, the drilling fluid left in the annulus settles, leaving behind solidified barite that can hinder slot recovery and plug and abandonment (P&A) operations by impeding the cut and pull process. During a P&A operation, Equinor acquired settled barite samples from a North Sea well where the casing was held back by these weighting agents, introducing overpull and prolonging the cut and pull operation. A laboratory analysis program that included determination of the particle-size distribution (PSD), electrokinetic potential of particles (zeta potential), crystallography [X-ray diffraction (XRD)], chemical composition [X-ray fluorescence (XRF)], thermogravimetric analysis (TGA), and microstructure [scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and quantitative evaluation of materials by scanning electron microscopy (QEMSCAN)] was carried out on these settled barite samples to understand their properties. The results of this study provided valuable insights into the composition and characteristics of the settled material in the annulus. The solidified barite within the annular space exhibited no signs of chemical reactions. XRD analysis confirmed the barite to be the sole predominant solid in the solidified material, aligning with expectations. However, additional analytical techniques, including XRF, QEMSCAN, and EDS, detected interconnections between barite particles, primarily facilitated by iron or quartz particles. Additionally, trace amounts of calcite, iron oxide, and mixed compositions involving Si, S, Fe, Ba, O, and Cl were identified within the solidified material. SEM results indicated that the particles exhibited strong compaction characteristics but lacked cementation, retaining some porosity. Notably, the absence of bentonite or other clays was consistently observed in all analyses. This study highlights the process of solidification observed in settled barite, suggesting that factors other than chemical reactions may be responsible for this phenomenon. The potential mechanisms contributing to solidification include physical aggregation, compaction, and alterations in surface charge under downhole conditions. This enhanced understanding of the solidification process will contribute to the development of solutions for efficient casing removal and even the usage of settled barite as a barrier material.

Novel approach evaluating powdered raw and hydrothermally treated syenite as stonemeal for tropical environments: Potential effects on groundwater quality and agricultural suitability

Soluble fertilizers, particularly potash, are often prohibitively expensive or unavailable in Africa. Consequently, alternatives such as powdered silicate rocks, both raw and hydrothermally treated, are being explored as potential solutions, especially for acidic tropical soils. This study investigates the possible impacts of these rocks (syenite) on groundwater quality, which is a critical factor for agricultural activities. The powdered raw material underwent chemical and mineralogical characterization, including X-ray fluorescence and X-ray diffraction, followed by quantitative evaluation of materials by scanning electron microscopy. Both raw and 46 hydrothermally treated materials were subjected to sequential leaching cycles (1, 24, and 192 h) using deionized water, and the resulting leachates were analyzed by inductively coupled plasma atomic emission spectroscopy. Parameters such as electrical conductivity, total dissolved solids, soluble sodium percentage, sodium adsorption ratio, magnesium hazard, Kelly's ratio, and permeability index were also evaluated. Results from the 47 leachates indicated that 64 % of the samples exhibited excellent to acceptable water quality for irrigation purposes across all parameters. Conversely, 6 % to 13 % fell into the doubtful category, and 2 % to 24 % were classified as unsuitable. Consistency index and ratios of approximately 0.07 and 0.042, respectively, were determined using multi-criteria decision analysis (analytic hierarchy process: AHP), confirming the coherence of the decision and pairwise comparison matrix. The weighted coefficients for each criterion ranged from 0.06 to 0.2. Consequently, the optimal sample (Treatment 23) was identified, showing a hydrothermal temperature of 176 °C, a time of 3.9 h, a normality of 4.62, and a liquid-solid ratio of 0.24. This treatment met all high-water quality standards, including low salinity and sodium hazard, as corroborated by the US salinity laboratory and Wilcox diagrams. Furthermore, due to their nutrient release, low concentration of toxic elements, and effective buffering capacity (pH ∼ 10.6), these powdered syenites are suitable for application in acidic soils.

Thorium speciation in ilmenite concentrates from the Mandena deposit, Madagascar: Implications for environmental remediation and thorium beneficiation

Placer ilmenite deposits are important sources for titanium dioxide production but are often radioactive due to elevated thorium and uranium contents, posing significant challenges to their upgrading and downstream commercial applications. In this contribution, we have investigated ilmenite concentrates containing 133 ppm Th and 12.8 ppm U from the Mandena deposit, Madagascar, using a wide range of analytical techniques: powder X-ray diffraction, electron microprobe analysis, quantitative evaluation of materials by scanning electron microscopy, inductively coupled plasma mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, synchrotron X-ray absorption spectroscopy, microbeam synchrotron X-ray fluorescence mapping, and microbeam synchrotron Laue X-ray diffraction analysis. Our data show that monazite-(Ce), mainly as discrete grains, accounts for ∼55% of Th in the Mandena ilmenite concentrates. Thorianite hosting the remaining Th at ∼45% is revealed by synchrotron Th LIII edge X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses and is correlated with the degree of ilmenite alteration. These results suggest that thorianite probably formed from the alteration of ilmenite and precipitated on the surface of altered ilmenite. The presence of monazite-(Ce) and thorianite in the Mandena ilmenite concentrates is further supported by principal component analysis of trace elements. Our results suggest that combined magnetic separation and acid leaching are effective for reducing the Th (and U) abundances in the Mandena ilmenite concentrates, via the removal of Th-bearing minerals. These findings have important implications for both Th remediation and beneficiation. Moreover, the precipitation of thorianite on the surface of altered ilmenite is an effective method for attenuating the common radionuclide Th in surficial environments.

102 Application of Quantitative Mineralogy to Determine Sources of Airborne Particles at a European Copper Smelter

Abstract To ensure that regulatory compliance is maintained at mineral processing operations, worker exposure is regularly monitored. Determining the quantity and type of airborne particles permits the operation to identify the sources of dust, implement proper dust suppressant strategies, and ultimately, limit worker exposure. Conventional methods of analysis, such as chemical assay, are unable to rigorously differentiate between phases containing the same elements and may result in ambiguity related to identifying the source of airborne dust. A combination of Quantitative Evaluation of Materials by Scanning Electron Microscope (QEMSCAN) and chemical characterization has been used to evaluate personally taken size selective aerosol samples at key locations throughout a Cu smelter in Europe. Surface samples were also examined using higher resolution measurements. The Cu phases present in the workplace air samples are reflective of the activities performed at specific locations. Near the anode and electric furnace, the majority of Cu in the airborne dust is carried in metals and oxide phases (60-70%), and in the batch preparation area where Cu concentrate is received, significant amounts of Cu are carried in sulfide minerals (chalcocite, chalcopyrite/bornite, >40%). The results of the analysis will aid in the identification of the origin of emissions specific to location and activity, assist personnel in developing the appropriate mitigation strategies to limit workers exposure, and further understanding of the health risks associated with exposure. Additional metals of concern (e.g, Pb, As, and Cd) are also considered throughout this program. Speaker Biography Michelle Kelvin is a geoscientist and environmental mineralogist. She specializes in characterizing dust emissions that originate from industrial operations using modern geochemical methods and X-ray beam technologies.

Application of quantitative mineralogy to determine sources of airborne particles at a European copper smelter

Copper processing operations, such as smelters and refineries, can produce airborne particles that may impact the health of workers. At these operations, worker exposure to chemicals are regularly monitored to ensure that regulatory compliance with occupational exposure limit values (OELVs) are maintained. Determining the type of airborne particles present is important for characterizing the composition of dust exposures and better understanding the relationship between worker exposure and health. Routine methods of analysis (e.g., chemical assay) are unable to differentiate between phases containing the same elements and may result in ambiguity. A novel approach of a combination of Quantitative Evaluation of Materials by Scanning Electron Microscope (QEMSCAN) and chemical characterization was used here to evaluate airborne and settled dust collected at key locations throughout a copper smelter in Europe. The copper (Cu) phases present in the airborne dust are indicative of the activities performed at specific locations. In the batch preparation area where Cu concentrate is received, significant amounts of Cu were carried in sulfidic minerals (chalcocite, chalcopyrite/bornite, >40%), whereas near the anode and electric furnace, the majority of Cu in dust was carried in metallic and oxidic phases (60–70%). Particle size analysis of the settled dust indicates that the sulfidic and oxidic Cu minerals are more likely to become airborne over metallic Cu. Furthermore, overall Cu concentrations decreased with particle size where metallic and oxidic Cu dominate, which suggests that differences in the proportion of Cu forms present in the dust will impact how much Cu ends up in the respirable fraction. These results highlight the need to understand the characterization of Cu in dust in order to set better OELVs.

Piezoelectric energy harvesters: A critical assessment and a standardized reporting of power-producing vibrational harvesters

Energy harvesting devices have emerged as an auspicious sustainable energy source for low-power electronics, where delivering electricity using conventional means is not feasible nor desirable. This clear technological impact has drawn huge attention and driven research into energy harvesting materials and devices. Reports are often published, even in high-caliber journals claiming high-efficiency devices. However, these are typically based on poorly defined or even undefined metrics and lack the details needed for re-evaluation and comparing different devices for peer assessment. The enthusiasm to publish is pushing the field towards qualitative rather than quantitative research. Here, after introducing the basic concepts of energy harvesting, randomly selected research papers on piezoelectric energy harvesting devices published over the last two decades, have been assessed. It is shown that essential parameters which are needed for a quantitative evaluation of materials and devices are missing from nearly 90% of the reviewed papers, thus rendering them less reproducible (or even irreproducible) for peer assessment. Such a frequent occurrence of improper data reporting damages the credibility and reliability of the energy harvesting field. To enhance reproducibility and facilitate progress, we herein suggest a measurement and data reporting protocol that should be followed when reporting energy harvesting devices and concomitant performances. The standardized protocol can be further adapted for other vibrational harvesters based on other mechanisms such as triboelectricity.

High-Grade Copper and Gold Deposited During Postpotassic Chlorite-White Mica-Albite Stage in the Far Southeast Porphyry Deposit, Philippines

Abstract Ninety-eight underground diamond holes (~102 km) drilled by Far Southeast Gold Resources Inc. at the Far Southeast porphyry Cu-Au deposit, Philippines, from 2011 to mid-2013, provide a three-dimensional exposure of the deposit between 700- and –750-m elevation, with surface at ~1,400-m elevation. Far Southeast contains an inferred resource of 891.7 million tonnes (Mt) averaging 0.7 g/t Au and 0.5 wt % Cu, equivalent to 19.8 Moz Au and 4.5 Mt Cu. This contribution reports the spatial and temporal distribution of alteration and mineralization at Far Southeast, notably a white-mica–chlorite-albite assemblage that formed after early secondary biotite and before late quartz–white-mica–pyrite alteration and that is associated with the highest copper and gold grades. Alteration assemblages were determined by drill core logging, short-wavelength infrared (SWIR) spectral analysis, petrographic examination, and a quantitative evaluation of materials by scanning electron microscopy (QEMSCAN) study. Alteration is limited around sparse veins or pervasive where vein density is high and the alteration halos coalesce. The alteration and mineralization zones with increasing depth are as follows: (1) the lithocap of quartz-alunite–dominated advanced argillic-silicic alteration that hosts part of the Lepanto high-sulfidation Cu-Au epithermal deposit (mostly above ~700-m elevation), (2) an aluminosilicate-dominated zone with coexisting pyrophyllite-diaspore ± kandite ± alunite and white mica (~700- to ~100-m elevation), (3) porphyry-style assemblages characterized by stockwork veins (below ~500-m elevation), (4) the 1 wt % Cu equivalent ore shell (~400- to –300-m elevation), and (5) an underlying subeconomic zone (about –300- to –750-m elevation, the base of drilling). The ore shells have a typical bell shape centered on a dioritic intrusive complex. The paragenetic sequence of the porphyry deposit includes stage 1 granular gray to white quartz-rich (± anhydrite ± magnetite ± biotite) veins with biotite-magnetite alteration. These were cut by stage 2 lavender-colored euhedral quartz-rich (± anhydrite ± sulfides) veins, with halos of greenish white-mica–chlorite-albite alteration. The white mica is largely illite, with an average 2,203-nm Al-OH wavelength position. The albite may reflect the mafic nature of the diorite magmatism. The quartz veins of this stage are associated with the bulk of copper deposited as chalcopyrite and bornite, as well as gold. Thin Cu sulfide (chalcopyrite, minor bornite) veins with minor quartz and/or anhydrite (paint veins), with or without a white-mica halo, also occur. These veins were followed by stage 3 anhydrite-rich pyrite-quartz veins with white-mica (avg 2,197 nm, illite)–pyrite alteration halos. Combined with previous studies, we conclude that this porphyry system, including the Far Southeast porphyry and Lepanto high-sulfidation Cu-Au deposits, evolved over a period of 0.1–0.2 m.y. Three diorite porphyry stocks were emplaced, and by ~1.4 Ma biotite-magnetite–style alteration formed with quartz-anhydrite veins and deposition of ≤0.5% Cu and ≤0.5 g/t Au (stage 1); coupled with this alteration style, a barren lithocap of residual quartz with quartz-alunite halo plus kandite ± pyrophyllite and/or diaspore formed at shallower depth (>700-m elevation). Subsequently, lavender quartz and anhydrite veins with bornite and chalcopyrite (high-grade stage, avg ~1 wt % Cu and ~1 g/t Au) and white-mica–chlorite-albite halos formed below ~400-m elevation (stage 2). They were accompanied by local pyrite replacement, the formation of hydrothermal breccias and Cu sulfide (paint) veins. Stage 2 was followed at ~1.3 Ma by the formation of igneous breccias largely along the margins of the high-grade zones and stage 3 pyrite-quartz-anhydrite ± chalcopyrite veins with white-mica (mostly illitic) halos. At shallower depths in the transition to the base of the lithocap, cooling led to the formation of aluminosilicate minerals (mainly pyrophyllite ± diaspore ± dickite) with anhydrite plus high-sulfidation-state sulfides and pyrite veinlets. Consistent with previous studies, it is likely that the lithocap-hosted enargite-Au mineralization formed during this later period.

Feasibility of reprocessing gold tailings: Integrated management approach for the control of contaminated neutral mine drainage

Sulfide ore processing generates finely ground mine tailings that often contain sulfide minerals such as pyrite, pyrrhotite, arsenopyrite, and gersdorffite. These minerals can generate acid mine drainage or contaminated neutral drainage (CND) due to weathering (aqueous oxidation by oxygen, and bacterial activity). Contaminated neutral mine drainage affects the surrounding environment by contaminant release (e.g., As, Ni, Fe, Cu, and Zn), which is one of the most challenging environmental issues for the mining industry. This paper examines the feasibility of desulfurization by flotation at the laboratory scale as a sustainable tailings management approach to prevent CND generation from tailings produced by the Amaruq mine (Nunavut, Canada). The flotation tests were conducted using a five-level statistical experimental design (DOE) using five parameters that include: collector dosage (PAX), activator dosage (CuSO4), frother dosage (MIBC), pH, and solid content (Cs). The response surface methodology (RSM) was used to predict sulfur recovery and to choose the optimal conditions of flotation. The mineralogical properties of the samples before and after reprocessing were investigated by combining optical microscopy, X-ray diffraction spectroscopy (XRD), and the quantitative evaluation of materials by scanning electron microscopy (QEMSCAN®). The trace element (As, Co, Ni, etc.) microanalysis of the identified minerals was quantified using electron probe micro-analyser (EPMA), and the bulk chemical composition was analyzed using induction furnace, X-ray fluorescence, and ICP-AES/MS. Finally, the geochemical behavior of the initial (WTT) and desulfurized (DWT) tailings was evaluated using kinetic weathering cells. The main results demonstrated that sulfur recovery can reach up to 97 % using the following optimal conditions: pH of 11.5, PAX dosage of 158 g/t, CuSO4 dosage of 300 g/t, MIBC dosage of 55 g/t, and Cs of 29.3 %. Moreover, the residual sulfides within the desulfurized tailings were completely locked within the non-sulfide gangue minerals as analyzed by QEMSCAN® and optical microscopy. Kinetic testing was performed on WTT and DWT to assess their contaminant release rates (especially As, Ni, Cu, Fe, and Zn).The desulfurized material did not cause any significant risk of contaminated mine drainage generation. All released contaminants were below the limits of Quebec provincial legislation.

Characterization of Particulate Matter Generated at a Nickel Smelter Using Quantitative Mineralogy

Activities performed at mineral processing operations are capable of producing significant quantities of dust. To ensure that regulatory compliance is maintained throughout operation, dust levels are monitored by routine analysis of air filter samples. Determining the quantity and type of particulate matter present in dust allows for the operation to identify the sources of dust and where warranted, implement a dust suppressant strategy. Conventional methods of analysis, such as chemical assay, are unable to rigorously differentiate between phases containing the same elements and may result in ambiguity related to the identification of dust sources. By incorporating Quantitative Evaluation of Materials by Scanning Electron Microscope (QEMSCAN) into their routine monitoring programs, the Sudbury INO smelter has greatly improved characterization of the Ni and Co dust emissions generated at the operation. To determine specific activities responsible for emissions, bulk particulate matter was sampled from several key locations at the smelter that regularly produce dust. QEMSCAN was able to distinguish between critical subspecies of Ni and Co and mineralogical, and chemical signatures in the dust that are representative of locational activity were established. An apportionment of elements contributed by each source was calculated based on this information. The results of the characterization study assisted personnel in developing strategies to mitigate dust emissions that originate from the Smelter operations, and have general implications to occupational hygiene and environmental risk assessment.

Probing cleaner production opportunities of the Lac Tio pyrite-enriched tailings generated to alleviate sulfur dioxide emissions

Sulfur dioxide (SO2) emissions following mineral roasting of sulfide bearing ore should be maintained as low as possible to avoid adverse air pollution and to fulfill the government pledge. The hematite–ilmenite deposit near Havre-Saint-Pierre in Quebec, Canada, mined by Rio Tinto Iron and Titanium encompasses naturally occurring high cut-off grades of hemo-ilmenite. The ore is directly sent to mineral roasting to recover titanium oxide used as feedstock for further processing. To mitigate sulfur dioxide emissions, magnetic separation preceding mineral roasting was explored to retrieve sulfides from the ore. This upstream solution is constrained by several challenges linked to the concentrate quality, the operating costs and the environmental risk of the generated solid waste (tailings). Scoping surveys of the magnetic separation revealed that Rare-Earth roll magnetic separation technology (RERMS) yields encouraging trade-offs among the feasibility driving factors. This technology allowed the removal of 23% of the initial sulfur mass and recovered 97.74% of the initial mass of hemo-ilmenite in the concentrate product. It was also selected owing to its technical and economical assets. Tailings generated upon the magnetic separation underwent detailed physico-chemical and mineralogical characterization to highlight its inherent environmental risk. Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN) was conducted to identify the potential contaminants that could be released in water during the oxidation of sulfides. Results revealed that 50% of pyrite grains, the sole sulfide detected, encompass Ni grades higher than 0.2%. Accordingly, batch sorption tests were performed to identify the sorption properties of the gangue minerals in the presence of 30 mg/L of Ni. Using a liquid to solid ratio 3:1, only 1% of the initial concentration is detected in the liquid phase after 6 h. Accordingly, the Lac Tio tailings could effectively attenuate the Ni leaching even with up to 30 mg/L of Ni. In addition to acid-base accounting, kinetic modeling was performed to unravel the pH buffering capacity associated to the gangue minerals. Results revealed that the mineral assemblage of the tailings produced by the magnetic separation exhibits a neutralization potential that could offset acidity generated by pyrite oxidation. However, long-term kinetic tests are required to validate that the magnetic separation offers cleaner production opportunity for both the atmosphere and the mine drainage.

A Digital Rock Physics-Based Multiscale Multicomponent Model Construction of Hot-Dry Rocks and Microscopic Analysis of Acoustic Properties under High-Temperature Conditions

Summary The development of hot-dry rock (HDR) resources relies on the accurate evaluation of acoustic properties. The acoustic properties are usually measured by rock physical experiments. However, the high-temperature heating experiment is difficult because of high costs, long time-consumption, and complex operations. Hence, digital rock physics (DRP), a less time-consuming and more economical way, is used to analyze the acoustic properties. Here, multiple scanning experiments, including X-ray computed tomography (X-ray CT) for reconstructing 3D model, quantitative evaluation of materials by scanning electron microscopy (QEMSCAN), and modular automated processing system (MAPS), are conducted, and a fusion method of multiple scanning images is proposed to solve the contradiction between image resolution and the sample size caused by small pore size and complex mineral distribution and to generate the multiscale multicomponent digital rock. Then, the acoustic numerical modeling at high temperatures is conducted, where the essential idea is to derive the theoretical correlation between the elastic moduli of the minerals and the temperatures to obtain the elastic moduli of minerals at different temperatures. Finally, the acoustic properties of the digital rock are calculated, and the microscopic mechanism at high temperatures is studied in detail. The simulating results demonstrate that bulk modulus, shear modulus, Poisson’s ratio, Young’s modulus, P-wave velocity, and S-wave velocity decrease as the temperature rises. More importantly, the thermal cracking behavior of HDR is represented, and fractal Brown motion is utilized to generate the fractured digital rock. The simulation results of fractured digital rock illustrate that it is the fracture to cause rapid decline of acoustic properties after 250℃. Overall, this pore-scale work accurately illustrates the acoustic properties of HDR and provides a new idea to study the rock physics properties at high temperatures and a microscopic interpretation for geothermal fracturing development.

Integrated Approach Toward Diagnosing Microbiologically Influenced Corrosion in the Petroleum Industry

Summary The microbiologically influenced-corrosion (MIC) -related problems encountered in the water-injection wells of the Rijn Oil Field, offshore the Netherlands, were assessed from multiple perspectives to determine the root cause of the corrosion and the declining injection performance. Various classical petroleum-engineering methods were combined with full-bore electromagnetic inspection and 3D laser scanning of tubing sections to analyze the injectivity and integrity problems on both well and reservoir scales. Quantitative evaluation of materials by scanning electron microscopy (QEMSCAN), a novel technique for quantitative analysis of minerals, was used to identify chemical components in the corrosion products and allowed us to reconstruct the electrochemical processes that had taken place on a micrometer scale. Molecular microbiological methods (MMMs) such as quantitative polymerase chain reaction (QPCR) and 16S next-generation sequencing (NGS) were applied to identify the entire microbial population in various samples. Petroleum engineering, corrosion engineering, and microbiology were thus combined in a multiscale and multidisciplinary approach. This approach was followed successfully during the diagnostic process, resulting in verifiable hypotheses about the fundamental corrosion and plugging mechanisms in these water-injection wells. The results confirmed that the dominant corrosion process was MIC. Also, the presence of chloride contributed significantly to the corrosion process, possibly in combination with underdeposit corrosion (UDC). The full suite of analyses shed light on possible causes of the declining injectivity in the wells: There appeared to be a link between the formation of deposits and corrosion, strongly influenced by microbes. In this paper we demonstrate the importance of an integrated approach, which can lead to reliable diagnostics and successful mitigation against future corrosion and the declining performance of wells and pipes.

Transformation of the carbonaceous matter in double refractory gold ore by crude lignin peroxidase released from the white-rot fungus

Sulfides and carbonaceous matter in double refractory gold ore (DRGO) were bio-treated sequentially using an iron-oxidizing archaeon Acidianus brierleyi followed by lignin peroxidase-dominating crude enzymes released from the white-rot fungus Phanerochaete chrysosporium to significantly improve gold recovery from 24% to 92%. Transformation of the carbonaceous matter in the sequential bio-treatment was interpreted with Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN), Raman spectroscopy and three-dimensional fluorescence spectrometry. Firstly, microbiological sulfide oxidation did not affect carbonaceous matter but decreased the arsenic content in the solid residue, facilitating the following enzymatic reaction. Next, the crude enzymes predominantly decomposed the defect-bearing graphitic carbon into humic-like substances. The humic-like substances were not completely soluble under pH 4 but were instead retained in the solid residue as a part of a newly formed carbonaceous aluminosilicate (C–Si–Al) phase. Due to a wide pKa range of humic-like substances, it is proposed that at pH 4, electrostatic interaction between humic substances and illite, with and without heavy metals, might have enabled the agglomeration of fine aluminosilicate particles. Some gold grains trapped in C–Si–Al agglomerates were released by the dissolution of humic-like substances in 1 M NaOH, resulting in a further increase in gold recovery of approximately 15%.

Comparison of the Mineralogy of Iron Ore Sinters Using a Range of Techniques

Many different approaches have been used in the past to characterise iron ore sinter mineralogy to predict sinter quality and elucidate the impacts of iron ore characteristics and process variables on the mechanisms of sintering. This paper compares the mineralogy of three sinter samples with binary basicities (mass ratio of CaO/SiO2) between 1.7 and 2.0. The measurement techniques used were optical image analysis and point counting (PC), quantitative X-ray diffraction (QXRD) and two different scanning electron microscopy systems, namely, Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN) and TESCAN Integrated Mineral Analyser (TIMA). Each technique has its advantages and disadvantages depending on the objectives of the measurement, with the quantification of crystalline phases, textural relationships between minerals and chemical compositions of the phases covered by the combined results. Some key differences were found between QXRD and the microscopy techniques. QXRD results imply that not all of the silico-ferrite of calcium and aluminium (SFCA types) are being identified on the basis of morphology in the microscopy results. The amorphous concentration determined by QXRD was higher than the glass content identified in the microscopy results, whereas the magnetite and total SFCA concentration was lower. The scanning electron microscopy techniques were able to provide chemical analysis of the phases; however, exact correspondence with textural types was not always possible and future work is required in this area, particularly for differentiation of SFCA and SFCA-I phases. The results from the various techniques are compared and the relationships between the measurement results are discussed.

Synchrotron Computer Tomography as a Characterization Method for Engineering Materials

X-ray tomography is a non-destructive imaging technique enabling a three-dimensional representation of the irradiated volume, its internal architecture and subsequently a qualitative and quantitative evaluation of materials. It is thus an attractive method for examinations in the field of materials science, where the correlation between macroscopic properties and microstructure often is of major interest. In particular, tomography using high-energy synchrotron radiation is well suited for the examination of metallic materials due to its high penetrationdepth. In addition to absorption contrast, the (partial) coherence of a synchrotron beam also allows the utilization of phase contrast for imaging techniques [1]. The achievable spatial resolution using synchrotron beams may also be higher than that of conventional laboratory(-based) X-ray tomography using focusing optics [2].There are about fifty synchrotrons worldwide. The high brilliance achieved by third-generation facilities, such as ESRF in Grenoble, France [3] and Petra III/DESY in Hamburg, Germany [4] enables experiments in real time with recording times of up to a few MHz frame rates at selected beamlines [5]. Another benefit is the adjustability of the monochromatic beam to suitable energies for specific experiments/materials or for absorption edge tomography as well as the possible combination with other experimental methods directly at the beamline, e. g. diffraction. It is extremely difficult to give an up-to-date overview of the available energy ranges, achievable minimum voxel sizes and scanning times on synchrotron beamlines with tomographic setups suitable for 3D imaging of metallic structures due to the highly dynamic method development; orientational overviews can be found in [2, 6]. This paper will provide a summary of current methods and applications of synchrotron tomography and practical examples taken from current research topics covered by the authors.

Selectivity potential of ionic liquids for metal extraction from slags containing rare earth elements

The recycling of rare earth elements and base metals from recycling slag powders of nickel metal hydride (NiMH) batteries by ionic liquid leaching was studied. Leaching tests were conducted by using the ionic liquid 1-methylimidazolium hydrogen sulfate (HmimHSO4) selected after some preliminary leaching tests on slag powders. The HmimHSO4 concentration of aqueous ionic liquid solution was 30% (v/v) in all tests. The slag powders were ground and sieved to obtain two different particle-size fractions namely 63–90μm and 90–125μm in order to evaluate the leaching behavior and the kinetics. The most important metals present in the initial slag powders are iron (35.70% w/w), aluminum (9.95% w/w), manganese (3.45% w/w) and rare earth elements (REEs) such as lanthanum, cerium, neodymium and yttrium (totally 22.50% w/w). In the leaching experiments three parameters were studied: temperature, particle size and time. The average dissolution ratios of 63–90μm particle size slag powder were 100% for iron, manganese and yttrium after 2h at a temperature of 80°C. However, the maximum leaching efficiencies were about 15% for lanthanide and cerium and 20% for neodymium under the same conditions. As an explanation for the low recovery rates, a phase analysis with QEMSCAN (Quantitative Evaluation of Materials by SCANning electron microscopy) indicated decomposition in the initial REE phases but a precipitation as sulfates. The kinetic study of Fe and Mn dissolutions showed that the leaching process follows the shrinking core model with an unchanged particle size controlling diffusion through the product layer.

Indicator mineral-based exploration for carbonatites and related specialty metal deposits — A QEMSCAN® orientation survey, British Columbia, Canada

This orientation survey indicates that Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN®) is a viable alternative to traditional indicator mineral exploration approaches which involve complex processing followed by visual indicator mineral hand-picking with a binocular microscope. Representative polished smear sections of the 125–250μm fraction (dry sieved and otherwise unprocessed) and corresponding Mozley C800 table concentrates from the drainages of three carbonatites (Aley, Lonnie, and Wicheeda) in the British Columbia Alkaline Province of the Canadian Cordillera were studied. Polished smear sections (26×46mm slide size) contained an average of 20,000 exposed particles. A single section can be analyzed in detail using the Particle Mineral Analysis routine in approximately 3.5–4.5h. If only mineral identification and mineral concentrations are required, the Bulk Mineral Analysis routine reduces the analytical time to 30min.The most useful carbonatite indicator minerals are niobates (pyrochlore and columbite), REE-fluorocarbonates, monazite, and apatite. Niobate minerals were identified in the 125–250μm fraction of stream sediment samples more than 11km downstream from the Aley carbonatite (their source) without the need for pre-concentration. With minimal processing by Mozley C800, carbonatite indicator minerals were detected downstream of the Lonnie and Wicheeda carbonatites. The main advantages of QEMSCAN® over the traditional indicator mineral exploration techniques are its ability to: 1) analyze very small minerals, 2) quickly determine quantitative sediment composition and mineralogy by both weight percent and mineral count, 3) establish mineral size distribution within the analyzed size fraction, and 4) determine the proportions of monomineralic (liberated) grains to compound grains and statistically assess mineral associations in compound grains. One of the key advantages is that this method permits the use of indicator minerals based on their chemical properties. This is impossible to accomplish using visual identification.

Mössbauer quantification of pyrrhotite in relation to self-heating

Pyrrhotite (Po) is widely considered the most significant mineral in the self-heating of sulphide ores and concentrates. It is therefore desirable to determine the amount of Po in a sample. This is commonly accomplished through X-ray diffraction (XRD) or quantitative evaluation of materials by scanning electron microscopy (QEM–SEM), neither of which are suited to oxidizing samples such as Po. The sample preparation for these methods often requires heating and drying, which may alter the composition. This paper introduces another quantitative method based on Mössbauer analysis, whose sample preparation is limited, and not as likely to alter the sample. The technique is tested using binary and ternary mixtures containing pyrrhotite with pentlandite (Pn), pyrite (Py) and sphalerite (Sp). A detection limit of 2 wt.% Po is easily obtained in the Po–Pn binary mixtures. The Po is also successfully measured in Pn–Po–Py and Sp–Po–Py mixtures; however, the presence of sphalerite increases the time required for an accurate measurement. The time required to measure Po in complex samples may be optimized through future work.

Use of the QEM∗SEM analysis in flotation testwork on a phosphate ore containing monazite

The flotation behaviour of monazite in Australian Mt Weld phosphate ore was studied by QEM∗SEM (Quantitative Evaluation of Materials by Scanning Electron Microscopy). The flotation products of two batch tests AF5 and AF27 were analysed. In both tests, fatty acid was used as collector and the flotation pH was adjusted to 9.8. Sodium silicate was used in test AF5 but not in test AF27. It was found that sodium silicate depressed the flotation of all the iron minerals to a greater extent than the phosphate minerals and remarkable differences in floatabilities between the iron and phosphate minerals resulted. In test AF5, apatite floated faster than monazite in the rougher stage while monazite floated faster than hematite in the scavenger stage. Apatite in the concentrates was mostly liberated from the other minerals. The degree of liberation of apatite in the tailing and the other minerals in all the flotation products was low. Monazite was mainly associated with the iron minerals especially ilmenite. On the basis of the QEM∗SEM analyses of the floatabilities and the intergrowth and association characteristics of the major minerals, a flotation flowsheet was suggested to recover monazite from the phosphate ore as a by-product.

A QEM∗SEM study of the flotation of composite particles

The floatability of composite particles in a phosphate ore was studied by QEM∗SEM (Quantitative Evaluation of Materials by Scanning Electron Microscopy). The particles were classified according to their calcium phosphate content. The flotation recovery values for each class of composite particles were obtained both experimentally and theoretically. By using the weighted linear regression analysis, the correlation between the experimental and theoretical recovery values is close to linear and supports the proposition that the floatability of a composite particle is the average of the floatabilities of its component minerals weighted by the volume fraction of each mineral.