Analysis Of Coal Ash Research Articles

Preliminary XRF Analysis of Coal Ash from Jurassic and Carboniferous Coals at Five Kazakh Mines: Industrial and Environmental Comparisons

This study analyzes 105 coal ash samples from Jurassic and Carboniferous coals from five mines in Kazakhstan, Lenin, Saradyr, Bogatyr, Maikuben, and Shubarkol, focusing on the inorganic elemental compositions, their occurrence, and industrial and environmental implications. Methods include coal ash yield and volatile matter analysis, mineralogical characterization via low-temperature ash X-ray diffraction (LTA-XRD), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). High-temperature ash (HTA) was analyzed using energy-dispersive X-ray fluorescence (EDXRF), highlighting XRF’s potential for rapid multi-elemental analysis. Nine major elements (Al, Si, P, S, Fe, K, Ca, and Ti) and eleven trace elements (As, Cu, Cr, Zn, Pb, V, Ga, Mn, Ni, Y, Yb, and Zr) were identified in HTA samples through EDXRF. SEM and dendrogram analysis confirm their co-occurrence with quartz, kaolinite, pyrite, and accessory minerals such as chalcopyrite, zircon, rutile, and REE-bearing apatite. The elemental content of samples enhances industrial suitability by reducing emissions. Only Yb shows slight enrichment for economic benefits, along with La, Ce, and Nd, while concentrations of potentially toxic elements indicate minimal environmental risk. EDXRF demonstrates its efficiency for large-scale investigations, with all samples analyzed in a few days using automated overnight measurements. This approach shows promise for future studies focusing on trace elements, including REE.

Analysis of Lignite Character in Inner Mongolia China

The character of indigenous lignite was measured by proximate analysis, ultimate analysis, coal ash analysis, coal true relative density, specific area.et al. The results showed that the internal moisture content is 8-9%, volat ile matter content is more than 45%, the oxygen content is above 20% while the sulphur content less than 0.5%.The main ash content is SiO2 and Al2O3, ash fusion point is above 1200 degree centigrade. The calorific value is between 12∼19MJ/kg. Macropore and mesopore is the pattern in the lignite.

Rapid analysis of heavy metals in the coal ash with laser-induced breakdown spectroscopy

In this study, laser-induced breakdown spectroscopy (LIBS) was applied for the qualitative elemental analysis of coal ash. The spectrum of the ordinary coal ash indicated that coal ash contains elements of Al, Fe, Cu, Ca, Mn, Ti and so on. Sulfates produced by the reaction of metal oxides in coal ash with the acid gases in the atmosphere are the main causes of haze-fog formation. To simulate the haze, eight solutions with different Pb concentrations were prepared and coal ash samples were soaked in solutions and then dried thoroughly. The spectra were obtained from these contaminated coal ash samples with the LIBS technique. To accurately identify the spectral lines of Pb in the spectrum, the spectrum of pure Pb were selected as a reference and the spectral lines of Pb were determined. At the same time, an internal standard method was used to quantitatively analyze the value of the component of Pb/Al with a calibration curve that had a linear correlation coefficient (R2) of 0.98648, which indicates rough estimation of Pb content can be achieved by the intensity of Pb in the spectrum. The results of the experiments show that LIBS technique can be employed for the rapid detection and analysis of metal elements in coal ash and provide a brand-new method for the detection of atmospheric environment based on the content of Pb.

Thermal analysis of coal ash

Carbon materials are widely used in metallurgy and in the power industry as fuels and reducing agents. Coal, although inexpensive, is difficult to use, on account of its high ash content. In the operation of industrial systems, the ash might melt, with the subsequent formation of buildup. In addition, coal ash must be stored in tailings. Therefore, fuel oil and natural gas are more commonly used. Ash tailings pose a significant environmental problem in Russia. Various methods are known for the use of ash in construction. However, their adoption has been slow, on account of the complications caused by the variability in ash composition and properties. The industrial applicability of ash may be assessed by studying the physicochemical processes that accompany ash heating and determining the relation between the properties and mineral composition of ash. An important property of ash is its fusibility, which may vary widely on account of its nonuniform mineral composition. Traditionally, the fusibility of ash is determined on the basis of State Standard GOST 32978–2014 (ISO 540:2008). As in any visual method, the results are highly inaccurate. Existing theoretical analyses employ fusibility values obtained on the basis of the international standard. In this context, there is a pressing need to develop and test new methods of determining the melting point of ash.

Composition, mineral matter characteristics and ash fusion behavior of some Indian coals

The present study aims to evaluate the chemical and mineralogical compositions of coal samples collected from three different seams of a particular borehole of Samaleswari Block, Ib river coalfield, Odisha, India. Different experimental and theoretical studies were conducted to predict and correlate the chemical and mineral composition of coal ash to ash fusion temperatures. The experimental techniques used include proximate analysis, ultimate analysis, gross calorific value determination and chemical analysis of coal ash for quantification of major oxides such as SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O, SO3 and TiO2. In addition, X-ray diffraction (XRD) and electron probe micro analysis (EPMA) techniques were used to identify the mineral phases present in coal and ash samples. Finally, FactSage Thermodynamics Model (FactSage 6.3) was used to understand the ash fusion behavior and to predict the phase transformations that occur during the process of coal combustion.

Investigation on characterization and liquefaction of coals from Tavan tolgoi deposit

On the basis of proximate, ultimate, petrographic and IR analysis results have been confirmed that the Tavan tolgoi coal is a high-rank G mark stone coal. The results of X-ray fluorescence analysis of coal ash show that the Tavan tolgoi coal is a subbituminous coal. The ash of Tavan tolgoi coal has an acidic character. The results of pyrolysis of Tavan tolgoi coal at different heating temperatures show that a maximum yield - 5.0% of liquid product can be obtained at 700°C. The results of thermal dissolution of Tavan tolgoi coal in tetralin with constant mass ratio between coal and tetralin (1:1.8) at 450°C show that 50.0% of liquid product can be obtained after thermal decomposition of the COM (coal organic matter). DOI: http://dx.doi.org/10.5564/mjc.v14i0.191 Mongolian Journal of Chemistry 14 (40), 2013, p12-19

Modeling trace element partitioning during coal combustion

A model to predict the partitioning of semi-volatile TEs such as arsenic, antimony and selenium, during coal combustion has been developed. Because the initial mode of occurrence of a trace element (TE) impacts its partitioning after coal combustion, the model uses computer controlled scanning electron microscopy data sets of the target coal's ash analysis to determine the mineral inclusion, mineral exclusion, and organically associated TE content, which are then modeled using a semi-random mineral placement approach. Previously developed mathematical approaches, in conjunction with pyritic mineral transformation mechanisms, exclusion fragmentation and recently determined experimental speciation details, were employed to predict TE partitioning during combustion and TE spatial evolution.Initial validation of the model was performed using a subbituminous coal. The residence time dependent particle temperature histories resulting from the combustion of this coal in a lab-scale down-fired combustor were generated using computational fluid dynamic simulations which were then used to predict the size-dependent TE evolution. A reasonable agreement with previously published measurements of the fractions of TEs vaporized was obtained. Of the original arsenic, antimony or selenium introduced in the simulated coal environment, 38%, 32% and 94% respectively were predicted to be released from pyritic family mineral inclusions. For excluded particles of similar size and temperature histories, a larger fraction (81%) of the initial selenium contained in pyritic family mineral exclusions was released than the fractions of either arsenic or antimony (33% and 26%, respectively). Fragmentation, which is associated with an increase in surface area, increased the TE release rates by 7–8%.

Distribution and origin of minerals in high-rank coals of the South Walker Creek area, Bowen Basin, Australia

The coals of the South Walker Creek area in the northern Bowen Basin, with a vitrinite reflectance (Rvmax) of 1.7 to 1.95%, are among the highest rank coals currently mined in Australia. X-ray diffraction studies have identified an unusual mineral variation through the vertical sequence, with kaolinite-rich assemblages typical of other Australian coals at the top and bottom of the seam section and an illite–chlorite assemblage resembling a metamorphic association in the middle. Calcite and ankerite are also abundant in parts of the vertical sequence. Diaspore is abundant in the middle section of the seam in some areas, and paragonite, dickite or nacrite occurs in some locations as well.The distribution of the non-carbonate mineral assemblages cross-cuts the seam stratigraphy, and appears to be primarily controlled by faults and other structural features. Integration of the mineral distribution with optical and electron microscope data on the coal and non-coal bands, chemical data from coal ash analysis, and information from X-ray micro-tomography, suggests that the illite–chlorite and diaspore-bearing assemblages resulted from hydrothermal effects associated with fluid migration through the middle part of the coal seam. This is further confirmed by the development of metamorphic textures in a tonstein band, also altered to illite and chlorite, in the illite-rich part of the seam section, in contrast to a tonstein with more normal sedimentary textures and a kaolinite composition in the kaolinite-rich upper part of the seam.Detailed studies of cleat mineralisation suggest that fluids rich in Ca, Mg and Al were introduced relatively early in the seam's post-depositional history, associated with heat flow sufficient to alter the minerals in the coal and tonstein in the affected part of the seam section. The relatively uniform vitrinite reflectance profile observed through the seam section may indicate that the coal was already of high rank before the fluids were introduced, or that any localised heat effects on the organic matter associated with the changes in clay mineralogy were overprinted by subsequent wider-ranging rank advance processes.

The physicochemical properties of different biomass ashes at different ashing temperature

There are no specific standards for biomass ash analysis in China, so the standards for coal ash analysis are usually used to determine the property of biomass ash. Three kinds of biomass including rice straw, pine sawdust and Chinese Parasol Tree leaf burned at 815 °C, 600 °C and 500 °C respectively corresponding to the temperature required in the standard of GB and ASTM. The ash content and composition were analyzed. Based on the ash composition results, the volatilization of alkali oxides in biomass ash and slagging/fouling problems related to biomass thermochemical conversion were investigated. The alkali metals were relatively more volatile with the increasing of ashing temperature. The crystalline phase composition and surface morphology characteristics of the ash particles were investigated by XRD and SEM analysis. The increasing ashing temperature resulted in the decreasing of the diffraction intensities of metal salts and the increasing of the diffraction intensities of silicon compound. Ash fusion temperatures were measured by 5E-AFII Ash Fusion Analyzer. The results indicated that the ash content, composition, crystalline phases composition, surface morphology and ash fusibility were all closely related to ashing temperatures. The analysis at 600 °C ashing temperature was regarded as the optimal for an exact determination of ash properties.

Analysis of Coal Ash for Trace Elements and their Geo-environmental Implications

This study determined the content of trace elements in coal ash collected from a coal-fired thermal power plant using local coal from Sawarak, Malaysia. This is crucial for the potential impact on the geoenvironment from its disposal and utilization; as coal ash has recently been produced locally in substantial amounts and very limited data is available. The trace elements concentrations presents in coal ashes are compared with the reported coal ash concentrations and the risk for the local wet tropical geoenvironment from the perspective of its vulnerability to these is studied for an indication of potential environmental implications on the wet tropics. The trace elements were found to be in concentrations that, if applied or inadvertently released into the environmental media, present a potential hazard and further necessary research in this regard is indicated.

Acid generating potential of waste rock and coal ash in New Zealand coal mines

Acid producing potential static tests have been undertaken on sample lithologies from New Zealand coal mines, to rank the lithologies into acid producing waste rock and stable non-acid producing waste rock. Results indicated that the main acid producing waste rocks in the Waikato Coal Region are the marine Whaingaroa siltstone and the Glen Massey formations and the main alkaline producing lithologies were the Tauranga group volcanic-derived sediments (A&D) and the Mesozoic basement. Coal ash analysis of 28 samples from 28 mines has also been analysed for reactive sulphur percentage and their base potential has been quantified by the chemical index of alteration (CIA). The results provide mine management in the Waikato Coal Region with a classification of problematic and stable waste rock types. New Zealand coal ash has the potential to be a problematic acid generator if the CIA value is above 20, CNK proportion in an A–CNK–FM ternary plot is between 30% and 56%, reactive sulphur per tonne of coal is >0.5 kg and dry ash weight percent in the coal is >5%. XRF and CIA values determined from wash drill cuttings would provide a method of determining waste rock volumes and magnitude of palaeoweathering underground.

Thermomechanical Analysis of Coal Ash: The Influence of the Material for the Sample Assembly

Concerns over the characterization of the thermal properties of coal ash using thermomechanical analysis (TMA) in carbon assemblies (crucible and penetrating ram) has led to a study which critically examines the effect of sample assembly materials on thermomechanical analysis measurements. This study quantifies the influence of the sample assembly material on the TMA traces. For temperatures up to 1600 °C and in inert conditions, ash chemistries were identified where the slag reacts with a range of sample assembly materials [molybdenum (Mo), platinum (Pt), carbon (C), zirconia (ZrO2), alumina (Al2O3), and boron nitride (BN)]. Only ZrO2 and Pt sample assemblies were found to be unreactive to ash samples during the tests. Iron-containing ashes were found to react with C assemblies, so that previous TMA data published for such assemblies and inert gases is not characteristic of ash fusibility alone. The implications of the reactions to the interpretation of this TMA data are outlined. For ashes that contain iron, TMA results in graphite sample assemblies may be considered to have been obtained under stronger reducing conditions than those used in the standard AFT test.

96/02273 Study of analytical method. Trace analysis of coal ash by atomic absorption spectrometry

96/02273 Study of analytical method. Trace analysis of coal ash by atomic absorption spectrometry

Methodological contribution to geochemical subdivision of coal seams

The statistical analysis of geochemical data collected at Zasavje coal basin offered the possibility to use distribution characteristics of geochemical factors and clusters for subdivision and genetic interpretation of coal seams. In accordance to sampling scheme for variance analysis the interval samples of coal and bearing rocks brought data on ultimate, proximate and atomic emission spectrometric analysis, and silicate analysis of coal ash. Variability of all measured variables was studied on regional, vertical, sampling and analytical level. After factor analysis of 23 selected variables terrigenous (K, Cu, V, Cr, ash, Zn, Be, Co, Al2O3, SiO2), carbonate (Mn, CO2, Fe2O3, Ni), sulphide-sulphate (sulphide and sulphate sulphur, Fe2O3), nitrogen-hydrogen (O, N, H) and typomorphic factor (Sr, Ca, organic sulphur, C, Ba) have been determined. Five synthetic variables (factors) explain 79% of the total variance. Yet on the basis of the first three factor values the samples can be arranged by use of cluster analysis into sample groups (clusters), which represent various geochemical segments of coal seams. By using above presented methodological guidelines which are based on crosssections of individual coal-bearing basins structural units, the future multidisciplinary research can lead to genetic model of Slovenian coal basins. Presented article is a contribution to look after best possible geochemical methodology which purpose is to reach this aim.

Sources of error in low temperature plasma ashing procedures for quantitative mineral analysis of coal ash

Using low temperature ashing in an oxygen plasma, the mineral matter in coals can be isolated and studied. A quantitative X-ray diffraction (XRD) technique has been developed, using accepted procedures, for the analysis of minerals (illite, gypsum, kaolinite, quartz, ankerite and pyrite) in low temperature coal ash (LTA). This XRD method should theoretically produce mineral totals approaching 100%, unless non-crystalline material is present. However, working with material ashed to constant weight gave mineral totals of between 50% and 80%; totals generally being lowest when the ash content of the coal was low. Further work showed that this shortfall was due to residual organic matter that can be removed by repeated fine-grinding and ashing.

Elemental analysis of coal ash using energy‐dispersive X‐ray fluorescence

AbstractAn energy‐dispersive X‐ray fluorescence spectrometer was used to analyse about 100 samples of coal ash. The elemental concentrations were determined using the standardless method and fundamental parameter approach. It was found that the Fe concentration was as high as nearly 30% in some samples. The results suggest that S, Ca, Ti and Fe are the major components that require corrections to be applied owing to X‐ray fluorescence in the back‐scattering techniques used for the determination of the ash fraction in coal.

Multi-element analysis of solutions of coal ash using inductively coupled plasma optical-emission spectrometry

A rapid dissolution method and analysis of coal ash using inductively coupled plasma optical-emission spectrometry is described. The calibration and analysis of “unknowns” involved the use of nickel as an internal standard. The most acceptable calibration was obtained using solutions of standard ash and slag materials. The precision for the determination of 11 elements expressed as their oxides is assessed by the analysis of ten replicate digestions of the same coal ash. The results compare favourably with the British Standards Institution (BSI) criteria. Using the procedure described, a five-fold increase in sample throughput is obtained compared with the current BSI method. All the elements are digested completely in 20 min and only sulphur is unstable if digestion periods in excess of 2 h are used. The method is ideally suited to cover the normal concentration levels for the major and minor elements present in coal or coke ash. It should also be adaptable for the determination of trace elements (except nickel) in coal ashes.

Separated Isotopes as Internal Standards in Spark Source Mass Spectrometry

Abstract The use of separated stable isotopes as internal standards in spark source mass spectrometry is described. This method is useful for solution samples and complements the more classical isotope dilution technique. For powdered or insoluble samples, the isotopes are dried onto a conducting matrix material-usually high purity silver powder-followed by homogenization of the sample with this «spiked’ matrix. The resulting mixture can then be pressed into solid electrodes and analyzed by spark source mass spectrometry. This technique has proven useful for the determination of mononuclidic elements such as Co, As, and Mn in a variety of samples, and for multielement analysis of coal ash and fly ash, with a minimum of sample handling and resultant contamination. Use of an isotope which has a mass near to that of the element being measured gives more precise and accurate analyses than the common technique of using one internal standard.

Coal Ash Analysis with an Argon Plasma Emission Excitation Source

Knowledge of the composition of coal ash and related materials has become important today in the investigation of air and water pollution, coal miners' pneumoconiosis, and strip mine reclamation as well as in the traditional investigation of clinkering and slagging problems in industrial use. Simplified procedures are needed to analyze these materials. In 1962, Gibson and Ode published a rapid method for analyzing coal ash based on colorimetric, flame photometric, and chelatometric titration techniques. This procedure, although faster and more direct than classical wet chemical procedures, requires two dissolutions per sample plus numerous reagents and dilutions. A more desirable route to the analysis of coal ash would involve the preparation of a single solution that could be analyzed directly.

The comprehensive analysis of coal ash and silicate rocks by atomic-absorption spectrophotometry by a fusion technique

A simple rapid fusion technique, in which lithium metaborate is used as the fluxing medium, has been developed for the analysis of mineral silicates, coal ash, furnace deposits and other related materials. A single fusion, followed by dissolution in dilute nitric acid, allows the major constituents of the samples to be determined by atomic-absorption spectrophotometry within the following ranges: SiO2 5 to 80 per cent., Al2O3 2 to 60 per cent., TiO2 0·5 to 5 per cent., Fe2O3 2 to 60 per cent., CaO 1 to 40 per cent., MgO 1 to 40 per cent., Na2O 0·5 to 20 per cent. and K2O 0·1 to 10 per cent., with a precision comparable with that of conventional methods used for silicate analysis.