Mineralogical Composition Data Research Articles

Evaluating CO2 sequestration through Technosol constructed from coal mining waste

This paper proposes enhancing CO2 sequestration and recovering degraded areas using Technosols constructed with coal waste and strategic materials. The evaluation of carbon capture considered four methods: (i) plant dry mass produced by Megathyrsus Maximus cv. Mombasa (ii) carbon incorporation via biochar, (iii) microbial biomass carbon, and (iv) mineral sequestration by lime. Local soil from the mine site was used as a control. Results show soil fertility parameters of the Technosols according to Brazilian guidelines. Plant growth increased with biochar incorporation but was still lower than in control soil. The pH, chemical, and mineralogical composition data were combined with geochemical reactions, showing the interaction of coal waste compounds, mainly pyrite with lime. Regarding calculating the CO2 capture potential, biochar and mineral carbonation were the most relevant means for the designed system. The best performance obtained can capture approximately 65 t CO2eq ha−1, about four times greater than the systems traditionally used to recover waste disposal areas. The study demonstrates the feasibility of incorporating mining site recovery, waste disposal, and emissions mitigation in a closed system, providing sustainable options for the coal mining industry.

Bucchero Ware from the Etruscan Town of Tarquinia (Italy): A Study of the Production Site and Technology through Spectroscopic Techniques and Multivariate Data Analysis

Bucchero is a well-known class of Etruscan ceramics, characterized by being entirely black both on the surface and in the body. In the present investigation, a representative set of bucchero sherds from the excavations of the Etruscan town of Tarquinia (Viterbo, Italy) was analyzed through flame atomic absorption spectroscopy (FAAS), Fourier-transform infrared spectroscopy (FTIR) and near-infrared (NIR) reflection spectroscopy. Both elemental and mineralogical composition data were treated with methods of multivariate analysis. It was thus possible to discriminate between local and imported production, to estimate the firing temperature and to verify the origin of the grey-black color in this peculiar ceramic class. Furthermore, a virtual reconstruction of a bucchero vase starting from fragments was also attempted on the basis of chemical analysis data.

Evaluation of the Relationship between the Milling Breakage Parameters and Mineralogical Data: A Case Study of Three Copper Ores from a Multi-Mineralised Deposit

The study evaluated the milling kinetics of three copper ores, from a multi-mineralised deposit, which were identified as sulphide 1 (with bornite as a dominant copper mineral), sulphide 2 (mainly composed of chalcopyrite) and oxide (with malachite as a dominant copper mineral) and related the breakage parameters to the mineral composition data. Five mono-size fractions between 1000 µm and 212 µm were dry milled for short grinding times in the laboratory ball mill in order to obtain data for predicting breakage rate parameters. The analytical and mineralogical characterisation of the ores were performed using X-ray fluorescence (XRF) analysis, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, optical microscopy analysis and X-ray diffractometer (XRD). The mineralogy data showed that quartz was the abundant gangue mineral (average for each ore was above 60% (w/w)), followed by K-feldspar minerals (orthoclase and microcline) which constituted between 4% (w/w) and 6% (w/w) and the remainder are the minor calcite and dolomite minerals which are also in the host rock. The experimental milling kinetics parameters and mineralogical data were used to assess the robustness of the heterogeneous (two-component) and homogeneous (single-component) first-order rate breakage models. The mineral composition data were used for setting up the predictions of breakage parameters in the two-component and single-component first-order breakage models. The experimental data fitted better on the two-component breakage model than the single-component breakage model. These results highlighted the influence of two groups of minerals (generally classed as valuable and gangue minerals). The breakage data showed that the selection function for the hard component (the gangue minerals) has a dominant contribution to the overall selection function of the ores, with SiA correlating fairly well with experimental Si. The parameter a in the Austin empirical breakage model was relatively similar (approximately 1) for all three ores, which confirms similar milling conditions to which the ores were subjected to. The data suggests that there is a relationship between breakage parameter α (material-specific parameter) in the Austin empirical breakage model and brittleness index βi (calculated from the mineralogical composition of the gangue phase). No clear trends could be deduced from the cumulative breakage distributions of the three ores. This highlights the complexity of developing relationships between the mineralogical composition data and breakage distributions of the ores which are extracted from the same deposit and with comparable gangue composition.

Rock-physics modeling by using particle swarm optimization algorithm

Rock physics modeling is an important method used to study reservoir characteristics in the seismic method. Optimum rock physics modeling must consider the research area and the theory of the effective medium used. Rock physics modeling in real cases requires mineralogical composition data from XRD data and mineral elastic modulus values which are generally taken from the literature. However, XRD data is not continuous in every depth, as well as mineral's elastic modulus information which has different characteristics in each research area, so using literature data can cause inaccuracies. This study aims to estimate rock physics parameters such as elastic modulus of minerals and rock pore shape using the Particle Swarm Optimization (PSO) to solve this problem. In this study, Kuster-Toksöz's effective medium theory and Gassmann's relation were used to produce the effective moduli of saturated rock. There are five forward and inverse modeling scenarios in this experiment. The first scenario is a combination of Kuster-Toksöz and Gassmann's relation. The second and third scenario utilizes the Kuster-Toksöz equation with penny cracks and sphere inclusion. The fourth scenario is carried out only using the Gassmann relation, and the fifth scenario is cross modeling with different forward and inverse algorithms. The results of this study show good fitting of saturated rock's elastic moduli. The Kuster-Toksöz scenario with single inclusion best estimates rock physics parameters.

New constraints on the palaeo-environmental conditions of the Eastern Paratethys: Implications from the Miocene Diatom Suite (Azerbaijan)

The Miocene Diatom Suite sediments of the Eastern Paratethys Sea, Azerbaijan, provide significant information to establish how Middle Miocene climate influenced erosion, sedimentation and deposition in the marine environments and continental source areas of Western Asia. Discriminant function analyses, ratios of Ti/Al, Si/Ca and Sr/Ca as well as mineralogical composition data indicate the Karaganian-Konkian sediments from the Pereküşkül-Diatom section were derived largely from the Greater Caucasus with a recognizable input from the Russian Platform during earliest Konkian. The chemical index of alteration and detrital clay mineral content document a change in climatic conditions from humid to relatively arid conditions occurred in the Greater Caucasus and Russian Platform area during the Karaganian-Konkian. The distribution of redox-sensitive elements across the Miocene Diatom Suite indicates oxic conditions prevailed in the Eastern Paratethys Sea Basin during the deposition of the Karaganian-Konkian sediments. Geochemical proxies suggest that, despite the Cenozoic been a period of global cooling, eastern Azerbaijan mainly characterised by a moderately humid to arid climate during this time. This indicates that warm climatic conditions, as seen during the mid-Miocene Climatic Optimum, were notably prolonged in the region of the Eastern Paratethys Sea basins and adjacent source areas, possibly reflecting palaeo-geographic changes in ocean and wind circulation patterns and/or local climate forcing associated with regional volcanic methane emissions.

Pore-fluid-dependent controls of matrix and bulk thermal conductivity of mineralogically heterogeneous sandstones

For a variety of geothermal engineering applications, the only indirectly determinable matrix thermal conductivity (λm) is frequently used to convert the measured bulk rock thermal conductivity (λb) of air-saturated sandstones to water-saturated conditions. However, the necessary assumption that the absolute value of λm remains constant irrespective of the pore fluid present turns out to be not valid in practice and the explicit control factors on λm have not been demonstrated yet for different pore fluids. A pore fluid-controlled change in the λm value also questions the transferability of empirical proxy models for the estimation of water-saturated λb when they were calibrated on air-saturated samples. This study applies a multiple regression analysis to quantitative mineralogical composition data and porosity (Φ) to identify the controls of the λm for different types of pore fluids (water- vs. air-saturation). In addition, the differences in the calculated λm values resulting from different calculation methods or input data (theoretical geometric mean model or mineralogical composition data) are examined. We further test the suitability of different sandstone properties as potential proxies for the estimation of the λb, with respect to the pore fluid type. Differences in the absolute value of λm of sandstones from different measurement conditions (air- or water-saturated) are most probably related to the formation of authigenic kaolinite in the pore space, originating from the alteration of alkali feldspar. In addition, the thermal properties of the rock matrix are mainly controlled by the volume fractions of the high thermally conductive mineral fractions quartz and dolomite. Empirical models that have solely Φ or P-wave velocity (vp) as variables are not suitable for the prediction of water-saturated λb of sandstones. Instead, quantitative mineralogical data of high thermally conductive mineral phases such as quartz and dolomite have to be included. The easily measureable vp is proposed as a promising proxy for both pore fluid types tested: combined with the total quartz volume/porosity ratio for air-saturated sandstones, and combined with the quartz plus dolomite volume fractions for water-saturated sandstones.

Thermal–physical properties of selected geomaterials: coal, sandstone and concrete based on basic series and parallel models

Thermal diffusivity and thermal conductivity of three types of selected geomaterials: coking coal, sandstone and foamed concrete, are presented in this paper via water absorbability and thermal–physical property measurements. Experimental results show that the relationships among different thermal–physical properties of composite–porous geomaterials are consistent with the theoretical prediction and the previous experimental data. Based on the hypotheses of basic series and parallel heat propagation patterns, the harmonic approach between series and parallel thermal resistance models is performed. Under the combination of water-saturated and oven-drying conditions, this hypothetical model can be used to inversely calculate the effective/equivalent thermal conductivity (ETC) of the solid matrix with the acceptable accuracy compared with five other ETC prediction models based on mixing laws, especially for saturated samples. In addition, the rationality of the respective proportions of series and parallel heat propagation forms is also examined due to the acceptable accuracy of solid matrix inversely calculated ETC. Further validation on solid skeleton ETC of selected geomaterials indicates that the difference between two solid matrix ETC computational methods: namely the forward calculation using the XRD mineralogical composition data and inverse computation using the block sample ETC experimental results, is significant. Compared with the inverse calculation (overall relative uncertainty of 4.26%), the forward calculation results obtained using XRD data are not accurate enough (relative uncertainty is approximately 7.6–11.4%), which requires a large database for validation and further researches.

Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization.

In the framework of two national research projects (ORGANOSOL and CN-linkAIR), fine particulate matter (PM2.5) was sampled for 17months at an urban location in the Western European Coast. The PM2.5 samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), major water-soluble inorganic ions, mineralogical, and for the first time in this region, strontium isotope (87Sr/86Sr) composition. Organic matter dominates the identifiable urban PM2.5 mass, followed by secondary inorganic aerosols. The acquired data resulted also in a seasonal overview of the carbonaceous and inorganic aerosol composition, with an important contribution from primary biomass burning and secondary formation processes in colder and warmer periods, respectively. The fossil-related primary EC seems to be continually present throughout the sampling period. The 87Sr/86Sr ratios were measured on both the labile and residual PM2.5 fractions as well as on the bulk PM2.5 samples. Regardless of the air mass origin, the residual fractions are more radiogenic (representative of a natural crustal dust source) than the labile fractions, whose 87Sr/86Sr ratios are comparable to that of seawater. The 87Sr/86Sr ratios and the mineralogical composition data further suggest that sea salt and mineral dust are important primary natural sources of fine aerosols throughout the sampling period.

Spent limestone sorbent from calcium looping cycle as a raw material for the cement industry

It has been found that a spent limestone sorbent, coming from a pilot-scale calcium looping fluidized bed (CaL-FB) plant and purged after 60 cycles of calcination and carbonation, can be successfully employed in the Portland cement clinker manufacture in place of natural limestone. Laboratory measurements showed that the burnability index for a clinker-generating raw mixture consisting of commercial clay and the exhausted sorbent was better than that of a reference mixture containing the same clay and fresh limestone. The results of the burnability test were confirmed by (i) the mineralogical composition data on the synthetic clinkers obtained from both raw mixtures at 1500°C and (ii) the hydration rate of the related Portland cements, evaluated by means of X-ray diffraction analysis and simultaneous differential thermal-thermogravimetric analysis, respectively. Preliminary and novel results reported in this communication show that the utilization of the spent limestone sorbent as a raw material for making cement can have a very favorable effect not only on the economics of the CaL-FB process, but also on the cement manufacture in terms of (i) reduced generation of carbon dioxide and pollutants, (ii) saving of raw materials and fuel, (iii) decreased flow rate of gaseous emissions.

MINERALOGY OF SELECTED LIGNITIC COAL OVERBURDENS OF THE WILCOX GROUP IN EAST TEXAS

Lignite overburden core samples obtained in the premining stage were size-fractionated and analyzed by x-ray diffraction and chemical methods to determine their mineralogical composition. Although we found a broad similarity in crystalline mineral assemblage in these fluvial sediments from east Texas, we also observed wide variations in the distribution of smectite, kaolinite, mica, vermiculite, and chlorite, with sample location and depth. Electron microscopic investigations indicated that localized concentrations of siderite were probably authigenic in origin. The physicochemical properties and mineralogical composition data obtained in these investigations suggest that segregation of existing low-fertility surface soils for top-dressing may be unnecessary provided that pyrite-rich spoil material and clayey substrata are not deposited in the upper soil zone. 15 references, 6 figures, 3 tables.