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The Middle Eocene lignite-mudstone deposits of the Kutch (Kachchh) Basin, western India, manifest a highly restricted marginal-marine depositional setting, in which an unusual preservation of Rosselia erecta can be observed within organic-carbonaceous-rich mudstone beds. It is the earliest Cenozoic record of the ichnospecies hitherto reported. Rosselia erecta occurs in a paucispecific R. erecta–Trichichnus isp. ichnofabric within thinly laminated mudstones that are intercalated with lignite seams and laminae. The burrows are primarily vertical, characterized by cone-in-cone structures that are penetrated by a centrally positioned cylindrical shaft with concentric or intermittently eccentric lining. The lining intermittently contains sulfide-mineralization, often with the framboidal pustules that probably formed as a result of anaerobiosis by chemautotrophic symbiotic bacteria. The cone opening at the bedding surface displays radial striae, indicating surface-detrital foraging behaviour. We propose that the burrow serves as a facultative multifunctional structure, with the tracemaker employing two distinct feeding mechanisms: (1) surface-detritus-feeding (fodinichnia) and (2) cultivating microbial colonies (agrichnia) of sulfate-reducing bacteria in a mutualistic symbiotic relationship. The well-preserved morphological features in the newly examined specimens facilitate a reassessment of the constructional mechanisms and functional implications of the ichnospecies R. erecta reminiscent of the recently established ethological category sequestrichnia. [ABSTRACT FROM AUTHOR]

In this study, we utilized spark emission spectroscopy to develop a fast analysis technique for identifying the concentration of metal components in airborne coal dust. Quantitative measurements of Al, Si, Fe, Ca, and Ti elements in lignite, bituminous coal, and anthracite were conducted. Calibration models were built under both variable concentration and fixed concentration conditions. The R2 values of all calibration curves were approximately 0.90. Except for Si in lignite, the limits of detection (LODs) of other measured elements were within 4 μg m−3, with a sampling time of 10 minutes. Comparative analysis with the reference method revealed normalized root mean square error (NRMSE) concentrations of 9.1%, 9.8%, 10.7%, 24%, and 8.2% for various elements in lignite. Additionally, principal component analysis (PCA) was employed to categorize coal samples, confirming the method's capability to distinguish coal dust types. This shows the effectiveness of spark emission spectroscopy in coal dust composition analysis, demonstrating high sensitivity and efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • An innovative demineralization activating strategy is established to simultaneously regulating the interfacial properties and microstructure of lignite-derived carbon. • Demineralization process exposes more interfacial oxygen-containing functional groups in lignite. • Demineralization process introduces numerous voids and defects, resulting in the formation of highly-disordered microstructure. • The electrode shows a high reversible capacity, superb rate performance and excellent cycling stability in SIBs Lignite, as one of the coal materials, has been considered a promising precursor for hard carbon anodes in sodium-ion batteries (SIBs) owing to its low cost and high carbon yield. Nevertheless, hard carbon directly derived from lignite pyrolysis typically exhibits highly ordered microstructure with narrow interlayer spacing and relatively unreactive interfacial properties, owing to the abundance of polycyclic aromatic hydrocarbons and inert aromatic rings within its molecular composition. Herein, an innovative demineralization activating strategy is established to simultaneously modulate the interfacial properties and the microstructure of lignite-derived carbon for the development of high-performance SIBs. Demineralization process not only creates numerous void spaces in the matrix of lignite precursor to assist aromatic hydrocarbon rearrangement, thereby reducing the ordering and expanding interlayer spacing, but also exposes more interfacial oxygen-containing functional groups to effectively increasing the sodium storage active sites. As a result, the optimal demineralized lignite-derived hard carbon (DLHC 1300) delivers a high reversible capacity of 335.6 mAh g−1 at 30 mA g−1, superior rate performance of 246.3 mAh g−1 at 6 A g−1 and nearly 100 % capacity retention after 1100 cycles at 1A g−1. Furthermore, the optimized DLHC 1300 material functions as an outstanding anode in sodium ion full cells. This work significantly advances the development of low-cost, high-performance commercial hard carbon anodes for SIBs. [ABSTRACT FROM AUTHOR]

When mining deep coal seams, the overlying mined-out area must be pumped and drained, and the remnant coal in the mining void area is vulnerable to spontaneous combustion via water immersion and air drying. To investigate the effect of soaking time on the spontaneous combustion characteristics of lignite, low-temperature N2 adsorption experiments and Fourier transform infrared spectroscopy (FTIR) experiments were used in this study to investigate the changes in pore structure and functional group content of coal samples by increasing the soaking time. Based on programmed warming experiments, macroscopic characteristic indicators of coal spontaneous combustion (CSC) oxidizability, such as the oxygen consumption rate and index gas, were derived. Results showed that the effect of soaking caused the total pore volume and specific surface area of lignite to increase to different degrees, which enhanced the adsorption capacity of coal to oxygen and improved the effective contact of oxygen with the active sites on the coal surface. However, there was no consistency in the effect of different soaking times on the content of reactive functional groups of the coal, with higher methyl and methine contents after 60 days of soaking (S60) and 120 days of soaking (S120) than in the raw coal (RC), and less in 90 days of soaking (S90). The propensity of coal to spontaneously combust is determined by both the pore structure and reactive functional groups, which shows the propensity of spontaneous combustion S60>S120>RC>S90. Results from this study are important in understanding the mechanism of CSC of water-soaked lignite in mined-out areas and can provide theoretical guidance to prevent CSC in mining areas. [ABSTRACT FROM AUTHOR]

Coal is considered to be one of the most significant energy sources in the world. Dewatering, upgrading, and reutilization of lignite is an essential way for the clean coal utilization. Numerical simulation is a practical method combined experimental data with fundamental theories. In this study, based on the Luikov irreversible thermodynamic model, numerical calculations were carried out using the finite volume method and total Hermite integration. The drying characteristics of lignite at different drying temperatures and airflow velocities were simulated employing the fluid computational software. Initially, in order to verify the reliability of the simulation model, the simulated results were compared and validated with the experimental data. The results indicated that the drying parameters obtained from the simulation were in good agreement with the experimental values, and the correlation coefficients were greater than 0.95. Furthermore, the influence of airflow velocity and temperature on the drying characteristics was analyzed based on the numerical results. The results revealed that the drying temperature had the greatest effect on the drying process, while the airflow velocity had a minor effect. The optimum drying conditions for lignite were in the range of 1.2–1.8 m/s for airflow velocity and in the range of 140–160°C for drying temperature. [ABSTRACT FROM AUTHOR]

This study aims to compare and analyze the coal tendency to undergo coal spontaneous combustion (CSC) oxidation, thereby providing theoretical guidance for predicting and controlling CSC in goafs. Experimental research was conducted to investigate the oxygen absorption characteristics during the pressure-increasing stage of 0–0.1 MPa and to examine the differences in macro- and microcharacteristic parameters during the oxidation process of coal with varying metamorphic degrees at temperatures ranging from 30 to 250 °C. The experimental data were comprehensively analyzed. The results of the experiments and analysis indicate that high-rank anthracite exhibits the highest physical oxygen absorption capacity. At 30 °C, the O2 adsorption (Qmax) maximum values of anthracite is 1.186 cm3 g−1 when the maximum equilibrium pressure (Pmax) is attained. Low-rank lignite, on the other hand, demonstrates high rates of oxygen consumption and gas generation, with the lowest crossing-point temperature (CPT) observed during the CSC oxidation process. The CPTs for lignite, bituminous coal, and anthracite are 138.2 °C, 167.9 °C, and 185.5 °C, respectively. Additionally, the linewidth (ΔH) and g-values for lignite surpass those of bituminous coal and anthracite. The free radical concentrations (Ng) of coal exhibit a significant increase with rising temperature, with high-rank anthracite demonstrating the highest Ng throughout the experimental oxidation process. However, the oxygen adsorption per unit specific surface area (QBET) is greatest, and the rate of increase in free radical concentration (ΔNg) for low-rank lignite is substantially higher than that of bituminous coal and anthracite. The active structure of lignite possesses a strong capacity to convert physiosorbed oxygen into chemisorbed oxygen, indicating that coal samples with a low degree of metamorphism exhibit a pronounced oxidation self-heating ability, which facilitates the initiation and acceleration of the free radical chain reaction. This study conducts a comprehensive analysis comparing the CSC oxidation capabilities of various types of coal. The findings provide relevant methodologies for assessing the spontaneous combustion characteristics of different metamorphic coals, which is significant for elucidating the mechanism of CSC and offering guidance for its prevention and control. [ABSTRACT FROM AUTHOR]

Thirty-two coal (lignite-bituminous in rank) and carbonaceous shale samples, ranging from immature to overmature, were collected from the various coal-bearing basins (Saurashtra Basin, Bikaner Nagaur Basin, Damodar Basin, Mahanadi Basin, and Foreland Basin) in India and characterized petrographically (vitrinite reflectance and maceral composition), geochemically (total organic carbon and total sulfur) and chemically (Fourier Transform Infrared spectroscopy, FTIR). This paper explores utilization of FTIR study on bulk non-demineralized carbonaceous shale and coal to examine the interference between mineral and organic matter visible on FTIR spectra and application of such techniques to assess organic matter chemistry based on FTIR signal. Mineral matter is considerably affecting the organic matter FTIR signal in the region between 1700–1350 and 900–700 cm−1, while the 3100–2800 cm−1 region is unaffected. The general trends of organic matter evolution with thermal maturity, i.e. a decrease of aliphatic and oxygen-bearing groups and increase in aromatic signal, are visible in bulk non-demineralized samples; however, the interpretation of the signal is problematic due to the dilution-related signal weakening and region-specific overlapping. The quality of the FTIR signal is lower than the signal from demineralized kerogens or targeted specific maceral grains via combination of FTIR with microscopy. The spectra can still be useful for more qualitative aspects of FTIR, like assessment of organic functional groups, study of coal impurities, or as a complementary method in conjunction with other analytical techniques such as X-ray for mineral matter characterization. [ABSTRACT FROM AUTHOR]

Peat mosses have been an important part of the lignite forming vegetation in the early Eocene of the Helmstedt Lignite Mining District. Three genera of Sphagnum-type spores can be distinguished: Tripunctisporis, Distancoraesporis and Sphagnumsporites. The distribution of these sphagnoid spores is traced through seven lignite seams including most of the known hyperthermal events from the PETM to the EECO. In general, Sphagnum-type spores increase in importance from base to top in each seam as a result of acidification and nutrient depletion during peat accumulation. The proportion of Tripunctisporis increases from Main Seam to Seam 6. The lower three seams are characterized by assemblages typical for coastal plain swamp forests including tree stumps and charcoal in distinct layers and lenses. The upper seams, in which Tripunctisporis is dominant and woody material is rare, are thin-bedded with charcoal in numerous thin drapes on bedding planes. The palynomorph assemblages here indicate a low growing mainly herbaceous vegetation typical of ombrogenous bogs. The change from topogenous swamp forests to open ombrogenous bogs takes place along with the hyperthermals of the early Eocene from the PETM to the EECO. The change from a swamp forest to a shrub forest in the middle of the Main Seam coincides with the isotope excursion of the PETM. Similar changes in other seams independent of thermal events indicate that thermal events merely amplify changes in vegetation, which are primarily imposed by edaphic constraints. It is rather the rapid accumulation of hyperthermals during the EECO that exerts sufficient environmental stress to fundamentally alter the peat forming vegetation. [ABSTRACT FROM AUTHOR]

The majority of Greek lignite fields and coal-fired power plants is accumulated in the centre of Western Macedonia in the Ptolemais-Amynteo region of Northern Greece (Ptolemaida basin). The corresponding environmental impact dominantly caused by the mining process itself but also due to the burning process of lignites needs to be considered. Therefore, this study aimed at assessing the potential of PAHs to trace the environmental impact of power plant and coal mining emissions on soil pollution in the Ptolemaida basin. Noteworthy, the study area exhibits some special features (e.g. geomorphological and meteorological conditions, well-defined emission sources) that allow to prove the suitability of PAHs as indicators for specific petrogenic contaminations. The different sets of PAH emission sources followed in this study (fly ashes, lignite dust, charred woody material) reflected the pollution as derived from the coal mining activities as well as agricultural measures. Different approaches from simple (total amount) to more complex fingerprinting (ring member classification; profiles of sulphur-/nitrogen- and oxygen-containing PACs) as well as the application of established specific PAH ratios revealed no significant correlation with the detected soil contamination or rather soil PAH profiles. However, the microscopic analyses contradicted this assumption, since relevant particle concentrations were evident for fly ash as well as lignite particles. Hence, a huge superimposition by a further PAH emission source is assumed, probably the exhaust fumes of car traffic. In general, the study demonstrated that the application of PAHs as source indicators in soil systems is very complex and needs a very thorough interpretation. Hence, the need of using additionally complementary parameters for an unambiguous emission source apportionment seems obvious. [ABSTRACT FROM AUTHOR]

The residual coal is prone to oxidation in different degrees after being immersed-dried in waterlogged goafs, but the reignition characteristics of water-immersion coal by low-temperature pre-oxidation remain unclear. Herein, lignite was pre-oxidized to 40 °C, 80 °C, 120 °C, 160 °C, 200 °C, and 230 °C after 60 days of immersion. Moreover, the microstructure changes of water-immersed lignite after oxidized were investigated using low-temperature nitrogen adsorption and infrared spectroscopy, and its spontaneous combustion characteristics were assessed employing thermogravimetry. The results displayed that the pore volume, specific surface area, and pore diameter increased and then decreased as the pre-oxidation temperature rose. Specifically, lower temperatures (below 80 °C) promoted the formation of micropores and mesopores, as well as the merger and transformation of pores into macropores, which facilitates the diffusion and adsorption of oxygen. However, higher temperature oxidation (> 200 °C) reduced both the number of pores and the content of reducing functional groups (–OH, –CH3, and –CH2). Comparatively, the lignite oxidized at 80 °C maintained a strong chemical reactivity owing to the high relative content of -CH2 and C = O. Furthermore, the pre-oxidation treatment mainly affected the thermal decomposition and gas-phase combustion of the water-immersed coals. Moreover, as the degree of oxidation rose, the characteristic temperatures (T2–T4) and the activation energy first decreased and then increased, while the comprehensive combustion index exhibited an opposite trend. Notably, the critical oxidation temperature of 80 °C is a turning point for the above change. Thus, the pre-oxidation at 80 °C heightens the risk of reignition in water-immersion coal owing to its developed pore structure and abundant active groups. It is imperative to avoid the critical temperature during low-temperature oxidation of water-immersed coals. [ABSTRACT FROM AUTHOR]

The floatability of low-rank coal is poor because of its low metamorphosis, and the oily bubble flotation is an effective means to collect coal particles. In this paper, adhesion angles and forces between watery/oily bubbles and coal surfaces were measured to analyze the influence of oil film on adhesion behavior between bubble and particle. The properties of watery/oily bubbles were analyzed by dynamic foam analyzer (DFA) to reveal the influence of oil film on the bubbles further. The results showed that in the dynamic environment, the maximum adhesion angle of the oily bubble was 36.55°, while the angle of the watery bubble was 31.29°, and the adhesion kinetic constant for oily bubble-particle and watery bubble-particle were 0.0295 and 0.0174, respectively. The measured maximum adhesion forces of the watery bubble and oily bubble were 19.2 μN and 86.8 μN, respectively, indicating that oily bubbles were more prone to attach to the coal surface and were beneficial to flotation. The calculated normalized contact line indicated that the oil film could squeeze a lot of water out from the coal surface, increasing the actual contact area and strengthening the attachment. The results of DFA showed that with the oil film, the oily bubbles could be more stable with a smaller size and lower liquid content than the watery bubbles. The results of the above study show that the oil film covering the watery bubble could improve the adhesion between bubble and particle and reduce the bubble size, which is conducive to promoting the sorting efficiency and thus enhancing the flotation of lignite. [ABSTRACT FROM AUTHOR]

Based on the common step of alkaline extraction-acid precipitation, lignite treatment techniques have been developed to improve extraction efficiency and yield of humic acid (HA). This study explored the combination of bacterium Paenibacillus mucilaginosus (P.m) LT1906 and fungus Penicillium pimiteouiense (P.p) LL2205 strains for pre- and post-treatment of lignite collected from eastern Inner Mongol to enhance HA and fulvic acid (FA) yield and plant growth-promoting activity. The lignite was subjected to P.m followed by HNO3 treatment, HNO3 followed by P.p treatment, and a combination of P.m, HNO3 and P.p treatments, then performed by alkaline extraction-acid precipitation technique. The results indicated that P.m pretreatment increased HA yield by 12.47 %, while P.p posttreatment significantly enhanced FA yield by 13.37 %. Combined bacterial and fungal treatments notably improved the total yields of HA and FA by 19.12 %. Structural analysis showed that P.m pretreatment caused the deformation on the lignite surface and the complete lignite oxidation and leaching reactions, thereby increasing the production of HA, yet had no impact on the elemental composition or chemical structure of HA. P.p posttreatment introduced oxygencontaining functional groups and reduced aromatic components through oxidative depolymerization of lignite, leading to increased FA production and HA seed germination-promoting activity. [Display omitted] • Bacterial-fungal treatment improves humic and fulvic acid extraction from lignite. • Paenibacillus mucilaginosus deforms lignite to facilitate subsequent reactions. • Penicillium pimiteouiense introduces oxygen groups to enhance bioactivity. • Improved bioactivity of humic acids confirmed by wheat seed germination tests. [ABSTRACT FROM AUTHOR]

Present review focuses on the most recent advances in a liquid‐phase nuclear magnetic resonance (NMR) of the coal‐derived products—coal tar pitches, asphaltenes, and humic and fulvic acids, covering exclusively the results in the liquid‐phase NMR studies leaving apart an overwhelming amount of publications dealing with the solid‐state NMR investigations in this field (which are comprehensively reviewed elsewhere). Owing to the complexity of the coal‐derived products, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of coal tar pitches, asphaltenes, and humic and fulvic acids by means of NMR over the past several decades revealed characteristic functional groups of those fractions together with spectral regions in which they resonate. Quantitative 1H and 13C NMR spectra characterize aromatic and saturated carbons spread over many structural moieties, which provides a solid guideline into molecular structure of the coal‐derived products. Nowadays, quantitative 13C NMR measurements yield information about a variety of structural parameters such as functional group distribution, aromaticity, degree of condensation of aromatic rings, and medium chain lengths together with many other more specific parameters. The structural NMR studies of coal and coal‐derived products are developing on a backdrop of a marked progress in computational NMR. At present, we are witnessing an unprecedentedly fast development of theoretical and computational methods in the field of NMR spectroscopy. Discussed in the present review are the most recent advances in the NMR studies of the processing products of peat, lignite or brown coal, anthracite or hard coal, and graphite in solution, like coal tar pitches, asphaltenes, and humic and fulvic acids. [ABSTRACT FROM AUTHOR]

Studies were carried out in order to verify the research hypothesis that "the introduction of organic matter in the form of high peat, brown coal, and wheat straw to the mineral soil contaminated with nickel will reduce the content of this metal in the lettuce", the main purpose of which was to determine the impact of various organic materials with varying degrees of decomposition on the content of nickel in lettuce leaves. The factors of the experiment were different types of organic material that were added to the mineral soil (loamy sand), such as high peat, brown coal, and wheat straw. The substrates in which lettuce was grown were contaminated with increasing doses of nickel: 0, 50, 75, and 100 mg Ni·dm−3 of the substrate. This research shows that the type of organic material introduced into the mineral soil as a source of soil organic meter has a significant impact on the content of nickel in lettuce leaves. [ABSTRACT FROM AUTHOR]

More than 41% of households and 2.8 billion people worldwide depend on solid fuels including coal. The available coal reserves in Indonesia are 31.7 billion tons and only enough for the next 65 years. This makes the government encourage the development of research on the utilization of biomass waste as alternative energy. Efforts are made to convert biomass waste in the form of rubber wood into alternative solid fuels through the pyrolysis process. Biochar is produced from biomass through pyrolysis, resulting in excellent combustion quality. Biochar from pyrolysis is combined with brown coal and molasses adhesive to create coal biobriquettes as an alternative solid fuel. The purpose of this study was to identify the optimal composition of brown coal and biochar in producing coal biobriquettes with the best quality. The pyrolysis process of rubber wood waste was carried out at a temperature of 350-400 °C for 2 hours. This study used variations in the composition of biochar (75%, 80%, 85%, 90%, and 95%) and brown coal (5%, 10%, 15%, 20%, and 25%) and 15 mL molasses adhesive. Testing the combustion quality of coal biobriquettes through proximate analysis and value. The results showed that the most optimal product was a sample with a composition of 85% biochar and 15% brown coal. [ABSTRACT FROM AUTHOR]

This research work presents an examination of the concentrations and modes of occurrence of environmentally sensitive elements within lignite deposits, located in Neyveli, within the Cauvery Basin of India. Coal is one of the most complex geologically formed materials, consisting of organic and inorganic matter. The inorganic mineral matter including the crystalline minerals, non-crystalline mineraloids, and elements with non-mineral associations. These lignite samples underwent complete analysis encompassing macroscopic, microscopic and geochemical assessments. The analysis reveals that the total mineral matter (MM) content, comprising significant proportions of sulphides, carbonate and argillaceous components. Geochemical characterization further elucidates the lignite's properties, with proximate analysis yielding values such as ash, volatile matter and fixed carbon and the Ultimate components analysis reveals the carbon, hydrogen, nitrogen, sulphur and oxygen. Inorganic mineral matters play a significant role in coal utilization, and also such modes of occurrence of elements provide useful geochemical information on coal formation and coal-bearing basin evolution. In this paper, we assess the associations of elements and minerals, as well as the associations of selected elements including environmentally-sensitive (e.g., S, As, U, and Hg), and some major elements (e.g., Ca, Mg, Fe, Al, and Ti) that have largely occurred in non-mineral forms in these low-rank coals. And also, comparative analysis is conducted between the concentrations of elements within the lignite samples and the values reported for World Clarke Brown Coals (WCBC). Particularly, some of these elements exhibit significantly high environmental sensitivity, demanding careful consideration in lignite extraction and utilization practices. [ABSTRACT FROM AUTHOR]

Microwave dehydration technology has been widely used in coal processing methods due to its unique advantages. Adding additives with high dielectric loss to coal can enhance the microwave absorption capacity of coal, so as to effectively improve the dehydration process. In order to understand the change and distribution of multi-fields in the microwave drying process of lignite under the action of different additives, verify the experiment and reduce the cost and number of experiments, this paper established a multi-field coupling model of electromagnetic field and heat and mass transfer of multiphase porous media based on COMSOL Multiphysics, so as to simulate the microwave drying process of lignite. The results show that the distribution areas of electromagnetic field, temperature field, and vapor in coal are basically the same, while the distribution of liquid water is just the opposite. With the enhancement of additive promotion effect, the parts with strong electromagnetic field strength increase, the hot spots of temperature field increase, the maximum temperature, and minimum temperature increase, and the water content in coal samples decreases. The promotion effect of additives on the microwave dehydration process of lignite is consistent with the experiment. [ABSTRACT FROM AUTHOR]

Although renewable energy-based technologies such as water electrolysis and biomass gasification for hydrogen production are cleaner than fossil energy-based routes, there are still prevailing challenges associated with the high cost and operational challenges in the scale-up of those technologies in the short term. Considering the abundance of coal as a current primary source of energy in Australia, the use of coal to produce hydrogen is not only in line with Australia's resource endowment but is also expected to become a supplement to the other hydrogen production pathways during the global energy transition period. This paper presents a comprehensive techno-economic assessment of low-emission hydrogen production from Australian coal gasification integrated with carbon capture and storage (CCS). The study explores four cases of hydrogen production, comparing Australian brown coal (Victorian brown coal) and black coal (Queensland black coal) gasification. Variations in gasifiers, gasification agents, and associated operating conditions contribute to differences in energy efficiency, costs, and CO 2 emissions among the cases. The findings reveal a levelized cost of hydrogen from coal gasification ranging between A$4.12–4.90 per kg of hydrogen. Notably, entrained flow gasification of Victorian brown coal in a mixture of oxygen and steam environment demonstrates advantages under the current market conditions. However, less mature technologies like dual fluidized bed gasifiers could emerge as viable alternatives if deployed on a commercial scale. The study also addresses direct carbon emissions from the process, indicating a CO 2 emission intensity range of 16.3–20.9 kg CO 2 /kg H 2 without CCS and 0.1–1.1 kg CO 2 /kg H 2 with CCS for the four cases. These insights contribute valuable information for decision-making in the pursuit of sustainable and economically feasible hydrogen production methods during the ongoing energy transition. • Coal is the primary source of energy in Australia and could still play a role in the transition to a low-carbon future. • Coal gasification integrated with CCS is a viable option for low-emission hydrogen production. • The Levelized cost of Hydrogen from Australian coal gasification is A$4.12–4.90/kg H 2. • EFR gasification of VBC in an O 2 /steam environment is the most economically viable option for hydrogen production. • The Direct CO 2 emission from coal-to-H 2 with CCS is 0.1–1.1 kgCO 2 /kgH 2. [ABSTRACT FROM AUTHOR]

The whiteflies (Hemiptera: Aleyrodidae) are small sternorrhynchan insects, which have the potential to cause significant economic damage to agricultural crops. There is a paucity of knowledge regarding the diversity, disparity, and evolutionary history of these insects, with classification based on the immatures, called puparia. The fossil record of whiteflies is sparse and incomplete, with the majority of fossils representing imaginal forms preserved as inclusions in fossilized resins. In this study, we present the first inclusion in succinite associated with the layers of Lower/Middle Miocene 2nd Lusatian Lignite Seam of Wanninchen in Brandenburg, Germany. The objective of the present study is to elaborate this fossil, and as a consequence, a new fossil genus and species, Pudrica christianottoi gen. et sp. nov., is described. This fossil is a representative of the subfamily Aleyrodinae, and it is the third fossil genus of this whitefly subfamily to be described. The discovery of the fossil inclusion in the succinite from the lignite deposits of Lower Lusatia challenges the current understanding of the character and conditions of formation and deposition of central and east European Paleogene fossil resins. Succinite is a fossil resin that occurs in the Eocene deposits of the Gulf of Gdańsk, belonging to the Prussian Formation, containing a glauconite-rich horizon known as the 'Blue Earth'. Similarly, glauconite-rich deposits are present in the Lublin area of Poland, where they are associated with the occurrence of succinite. Additionally, succinite has been found in deposits in the Rovno-Zhitomir area of Ukraine, which are alluvial deposits containing glauconite and lignite layers. Succinite was also identified in Eocene strata of Spitsbergen and in Axel Heiberg Island in the Canadian Arctic. Succinite has also been discovered in early Miocene deposits in Bitterfeld, Germany, where it occurs alongside lignite deposits (the deposit actually encompasses different fossil resins, so potentially originating from different source plants). Furthermore, it has been identified in younger (Pleistocene) deposits across Europe. The autochthonous (parautochthonous) character of the lignite deposits in Lower Lusatia raises questions regarding the time range of the succinite-producing gymnosperm trees and the autochthonous or allochthonous character of the lignite layers associated fossilized resins. [ABSTRACT FROM AUTHOR]

CO, H2, and other combustible gases will be produced during coal oxidation in coal mines, which will increase the risk of explosion when mixed with methane. Therefore, it is very important to understand the production characteristics of combustible gas during coal oxidation. In this paper, a programmed temperature gas test system is built to study the impact of lignite on the production of gases at different particle sizes and temperatures, and the release characteristics of gases are also analyzed. The result shows that the production of combustible gas is influenced by the coal particle size significantly when the temperature is above 200 °C, and it decreases as the particle size increases. CO is the main gas during the early stage of coal spontaneous combustion, and the release of CH4 and H2 increases after 300 °C. The fitted equations of gas generation and temperature are consistent with the experimental results. The research results are helpful in understanding the hazards of coal spontaneous combustion and have a certain guiding significance for coal mine monitoring and prevention of coal spontaneous combustion. [ABSTRACT FROM AUTHOR]

This paper presents the results of analytical studies of the combustion process of semi-coke, cedar sawdust, and their mixtures using the TGA method at three different heating rates with the determination of the main characteristics of heating: the presence of synergetic interaction between the components of the mixture affecting the maximum rate of combustion and kinetic parameters. Calculations of activation energy and pre-exponential multiplier of the Arrhenius equation by the Friedman and Ozawa–Flynn–Wall priori methods for initial combustibles and their mixtures have been carried out. Semi-coke was obtained by thermal treatment of brown coal at 700–900 °C to remove volatile substances, which makes it more environmentally friendly than the original coal. Semi-coke has a higher heat of combustion than biomass, and biomass has a higher reactivity than semi-coke. The combustion process of biomass occurs in a lower temperature range, and adding biomass to semi-coke shifts the combustion process to a lower temperature range than such for biomass. Adding at least 50% of biomass to semi-coke increases the combustion index by at least 1.1 times. Regardless of the heating rate of mixtures, synergetic interaction between the mixture's components increases the maximum combustion rate of coke residue by 20%. [ABSTRACT FROM AUTHOR]

The conversion of biomass-coal mixtures into energy using thermal conversion systems offers a more environmentally sustainable alternative to conventional coal consumption. A reactor with an internal compartment is proposed to improve the pyrolysis performance of lignite coal and mixtures of lignite coal with peanut shells. The study investigates lignite coal with varying moisture contents and peanut shell proportions (0%, 10%, 25%, and 50%) at a temperature of 500°C, using a heating rate of 0.1°C/s. The results indicated that dry mixtures demonstrated higher overall productivity compared to wet mixtures, particularly in terms of charcoal production. The weight of charcoal increased by 4.83%, 4.71%, 4.02%, and 2.61% across the mixtures. The total conversion rates for dry mixtures were 24.59%, 29.27%, 34.36%, and 40.44%, while for wet mixtures, the conversion rates were 29.42%, 33.98%, 38.38%, and 43.05%, respectively. The results revealed that moisture content during pyrolysis significantly influenced the productivity of lignite and lignite-peanut shell mixtures. The conversion rates in dry mixtures were lower compared to those in wet mixtures. The novelty of this work lies in its pioneering investigation of the impact of moisture on the slow pyrolysis of Turkish lignite mixed with peanut shells. It offers novel insights into optimizing the thermal conversion process for these materials by uniquely examining the effects of moisture on productivity and conversion rates. [ABSTRACT FROM AUTHOR]

To investigate the impact of hydrogen bonds on the removal mechanism of ether bonds and phenolic hydroxyl groups during the hydrothermal dewatering (HTD) process of lignite, we employed density functional theory at the B3LYP-D3/6–311 G (d, p) level to calculate the removal paths of these functional groups. The results revealed that the ether bonds in lignite underwent conversion to phenol hydroxyl and carbonyl groups through isomerization and rearrangement reactions, respectively. Specifically, the isomerization reaction (IR) exhibited a lower minimum energy barrier (339.09 kJ/mol) compared with the rearrangement reaction (RR) (376.24 kJ/mol). Regarding phenolic hydroxyl groups, paths involving H radicals facilitated removal more effectively than direct dehydroxylation. Upon the formation of hydrogen bonds with lignite and water molecules, the energy barrier of PHR1 decreased by approximately 27.5 kJ/mol. In contrast, the IR energy barrier experienced a slight decrease, whereas the RR increased marginally. Simultaneously, the rearrangement of ether bonds and direct dehydroxylation of phenolic hydroxyl groups became more challenging, indicating that hydrogen bonds render these removal processes more favorable through isomerization and H radical-assisted mechanisms. [ABSTRACT FROM AUTHOR]

This research presents the results of a comprehensive study of mineralogical and geochemical features of REE distribution in coals of Central Kazakhstan deposits—Karaganda coal basin and Shubarkol deposit, which have large hard coal reserves and are industrially important for the coal industry of Kazakhstan; the research is based on 205 samples of clayey interlayers and coal seams. It shows basic patterns of distribution and features of concentration for impurity elements, gives an estimate of the impurity elements concentration, including REE, defines conditions and factors of their accumulation, and studies features of their forms in coal and coal-bearing rocks, which allows estimating the mechanisms of their migration and conditions of accumulation. According to the results of geochemical indicators, the article establishes the factors of REE dislocation, reveals the composition of margin rocks that have influenced REE concentration in coal seams, and the presented latest data on mineralogy allowed to establish the ways of their transportation to the paleobasin during the syn- and epigenetic periods of formation of the coal deposits of Central Kazakhstan being researched. It was found that the coals are insignificantly enriched with heavy lanthanides from Ho to Lu. The distribution curves of UCC normalized REE values in the coals are similar and coincide, but they are less than the average value for world coal, and amount to only one-third of the UCC. It was found that the highest concentrations of all REE are characteristic of clayey interlayers and oxidized coals. The La/Yb ratio in this case increases upwards along the section, indicating mainly clastogenic mechanism of REE delivery to the coals. In coal and clay samples, the predominant mineral form of REE is light lanthanide phosphates. Identified particles of REE from minerals and their composition peculiarities suppose autigene nature of their formation. The formation of the bulk of autigene minerals occurred during the maturation of brown coals and their transformation into hard ones. [ABSTRACT FROM AUTHOR]

Traditional energy resource, i.e. coal, is converted to value-added electrode materials in electrochemical energy conversion systems. [Display omitted] • Traditional coal energy resource is converted to value-added electrode material for electrochemical energy conversion system. • The intrinsic N- and S-heteroatoms in coal effectively enhance the ORR performance. • The electrode exhibited excellent performance in Zn-air batteries with both liquid and solid electrolytes. Coal-based oxygen electrocatalysts hold immense promise for cost-effective applications in rechargeable Zn-air batteries (ZABs) and the value-added, clean utilization of traditional coal resources. Herein, an electrospun membrane electrode comprising coal-derived carbon nanosheets and directly grown carbon nanotubes (CNS/CMF@CNT) was successfully synthesized. The hierarchical porous structure of the electrode, composed of multiple components, significantly facilitates mass and ion transportation, resulting in exceptional electrochemical performance. Employing Fe as the catalyst for CNT growth, the CNS/CMF@CNT electrode exhibits a remarkable onset potential of 0.96 V and a half-wave potential of 0.87 V in the oxygen reduction reaction (ORR). In-situ surface-enhanced Raman spectroscopy reveals that hydroxyl radical desorption on the surface of CNS/CMF@CNT(Fe) is the rate-determining step of the ORR. Notably, the aqueous ZAB featuring the CNS/CMF@CNT(Fe) electrode achieved a peak power density of 216.0 mW cm−2 at a current density of 414 mA cm−2 and maintained a voltage efficiency of 65.1 % after 2000 charge/discharge cycles at 5 mA cm−2. Furthermore, the all-solid-state ZAB incorporating this electrode displayed an open-circuit voltage of 1.43 V, a peak power density of 70.1 mW cm−2 at a current density of 110 mA cm−2, and a voltage efficiency of 66.5 % after 150 charge/discharge cycles. The utilization of abundant coal as the raw material for electrode fabrication not only brings conceivable economic benefits in ZAB construction, but also commendably advances the effective application of traditional coal resources in a more sustainable manner. [ABSTRACT FROM AUTHOR]

This article deals with the development of the mobility sector in a very specific area in Germany. The Rhenish coal-mining area has to tackle an ongoing structural change. With the phase-out of lignite-based power generation, (infra-) structural changes and further resulting challenges will arise in the area between Aachen and Cologne in the coming years and decades. Within the framework of the field of action "Mobility" in the Rhenish coal-mining area, the DAZWISCHEN (In Between) ("As of March 17, 2023 the project listed on its website ") is investigating the current spatio-structural state as well as the possibilities for quantitative modelling of individual indicators up to the year 2040. In this article, "mobility" is understood as the spatial change in the location of people and households in daily life using different means of transport. Against this background, the modal share is considered as the central parameter. This describes the distribution of transport demand among different means of transport. Based on the status quo of the current mobility behaviour of the population in the Rhenish coal-mining area, future scenarios show which measures can be used to reduce CO2 emissions in transport in order to achieve the Paris climate targets. The results can show local decision-makers in the Rhenish coal-mining area which measures are necessary to achieve this. [ABSTRACT FROM AUTHOR]

The importance of energy in the economic development of countries in transition is almost vital, especially in countries with large coal mineral resources, such as our country, Kosovo. Quantification and accurate analysis of sulfur dioxide (SO2) emissions from lignite power plants are done to inform environmental stakeholders, improve regulatory compliance, protect public health, improve emission control technologies, and support environmental practices. sustainable energy. This study investigated the quantification and accurate analysis of SO2 emissions from lignite power plants to inform environmental stakeholders, improve regulatory compliance, protect public health, improve emission control technologies, and support sustainable energy practices. The laboratory analyses performed with standard methods have resulted in different values for the parameters: Moisture, ash, and sulfur content in lignite is up to 45%, 20%, and 1.2% during the year 2023, through these results we have calculated the SO2 emission that resulting in an average value of 777.4 kg/h. The realized correlation o between the SO2 emission and parameters such as Moisture, sulfur in lignite (total and organic), and High thermal, has increased the accuracy of SO2 emission estimates, the components that are active components during the coal combustion process. Better estimates facilitate a more accurate assessment of the environmental impact of organic SO2 emissions, such as their role in acid rain formation and ecosystem damage. This assessment reflects the poor state of current lignite combustion technologies and suggests their improvement in terms of controlling SO2 emissions. [ABSTRACT FROM AUTHOR]

The samples of humic acids (HAs), hymatomelanic acids (HmAs), humus acids (HuAs), and fulvic acids (FAs) and residual coals were obtained by extraction from brown coals of the Kansk-Achinsk and South Ural coal basins. The fractions of humic substances were studied using Fourier transform IR and 13C NMR (CPMAS) spectroscopy, technical analysis, and elemental analysis. It has been established that all fractions of humic substances had individual elemental and structural group compositions. [ABSTRACT FROM AUTHOR]

This article is about the chemical element germanium, which has become one of the most important materials today. Germanium, which is a trace element, was isolated mainly from the products of other mines and from ore rocks. Native germanium minerals are extremely rare and are mostly found in the form of micro dispersions in the main phases of the ore. In connection with the rapid development of technologies, the demand for germanium increased sharply, and intensive searches for sources of its production began. It turned out that fossil coal can be the main raw material source of germanium. The application of germanium in different industries is very diverse. Germanium is one of the most important materials that ensure the development of modern technology of semiconductor devices. Germanium begins to be used in biogeochemistry and medicine. Nuclear physics also uses germanium. Production of infrared optics and solar cells also increased. According to forecasts, by 2030, the demand for germanium will amount to 320–400 tons per year, and its production will grow almost one and a half times. The greatest growth is expected in infrared and fiber optics (5.6% per year). Ukrainian coal deposits, which are characterized by germanium metal content, are currently not working in full for their complex purpose. The consumption volumes of germanium in the domestic mineral and raw material complex are at the level of 2–4 tons every year, while in the past Ukraine was able to export several times more metal to the developed countries of Europe and Asia. The purpose of the work is to study the geochemical features of lignite in Transcarpathia, to analyze the existing methods of extracting germanium in the world, and to apply technologically possible and economically feasible methods of extracting germanium from lignite of this region. The work contains an analysis of previous studies on methods of extracting germanium from coal and lignite, in particular Transcarpathia. Materials used by domestic and foreign authors who studied this issue in different years, in particular, in relation to hard and brown coal deposits.

Modification reaction of lignite in subcritical H2O–CO system can significantly increase its caking index to more than 90. Separating and extracting the caking components from modified lignite, exploring the formation path of caking components, and establishing a kinetic model for the generation of these components are of significant importance for lignite hydrogenation reaction control. The lignite modified reaction was carried out in subcritical D2O–CO systems using the isotope tracer method. The formation path of caking components was defined by solvent extraction–IRMS–GPC combination technology. The results show that the soluble substances of tetrahydrofuran (TS) and benzene (BS) are the main caking components causing the structural transformation of lignite (A). The separation of n-hexane soluble (NS) also has an effect on the caking index of the modified coal. In the hydrogenation caking component formation stage, the lignite pyrolysis fragments combine with active hydrogen generated by water gas shift reaction to form caking substances, that is, A → TS + BS + NS. The formation activation energy of caking components is in the range of 0.39–58.24 kJ/mol. In the polycondensation caking component conversion stage, three soluble substances are converted in the order of TS → BS → NS, and the activation energy for the formation of caking components is 31.710–57.616 kJ/mol. [ABSTRACT FROM AUTHOR]

Rare earth elements are an essential critical raw material in the development of modern technologies and are highly sensitive to both supply chain disruptions and market turbulence. The presented study examines the characteristics of fuel, fly ash, and bottom ash from lignite combustion in power plant units. Also, we attempted to determine the amount of amorphous glass in the ashes and whether and to what extent the glass from the ash samples is bound to REY. The suitability of the ash was assessed as an alternative source of REY. The fuel and ash samples were acquired from power plants in Poland. The tests determined the fuel quality parameters, including the chemical and phase composition, of amorphous glass using ICP-MS and XRD methods, respectively. The study showed that all ash samples dissolved in 4% HF were enriched in REY. The efficiency of REY enrichment varied, and its presence in the residue samples was found to be in similar proportions compared to the raw sample. All ash residue samples were enriched in critical elements. The obtained values of the Coutl prospective coefficient allowed for the classification of some of the analyzed ashes and their residues after dissolution in 4% HF as prospective REY raw materials. [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) offers a promising path for greenhouse gas conversion, but industry usually relies on pressurization conditions, and the drawback of rapid carbon deposition leading to deactivation of conventional catalysts under pressurization has hindered its industrial development. In this study, a cost-effective N-doped Co-based DRM catalyst was developed by utilizing melamine to induce heteroatom doping defects on modified lignite to overcome the problem of deactivation due to rapid carbon deposition under pressurized conditions. The catalyst, Co/CN-40 (Impregnated with 40 wt% melamine), has the smallest metal particle size (3.13 nm), the largest specific surface area (376 m2/g), high defectivity (I D /I G ratio = 0.84), enhanced metal-support interactions and a relatively high pyridine N content (48%). The evaluation of DRM activity and stability at 780 °C and 0.5 MPa demonstrates that Co/CN-40 offers the highest catalytic efficiency. The highest conversion was quickly achieved by the catalyst during activity assessments, and maintain an efficient conversion with suppressed metal agglomeration over a 100-h stability test. These improvements are attributed to the increase in the number of defects which enhances electron transfer, improves metal anchoring and boosts the adsorption and activation of reactant molecules. [Display omitted] • Increased defectivity enhances metal anchoring and inhibits metal sintering. • Co/CN-40 shows the best catalytic performance and activation rate. • Co/CN-40 under pressure effectively inhibits carbon nanotube generation. • Stable catalyst operation relies on enhanced metal anchoring. [ABSTRACT FROM AUTHOR]

Coal is one of the important energy sources; however, the direct combustion of raw coals is discouraged due to their low calorific value and the production of harmful gases. Microbial transformation of coal is an eco-friendly method to convert raw coal into clean and cost-effective valuable products like humic, fulvic acids, and other complex organic compounds. In present study, out of 51 bacterial isolates, 05 isolates, designated as ANK-4, AN-25, ANK-30, BD4, and Mn-250 were selected based on their degradation/solubilization activity for lignite as well as bituminous coal samples. All the isolates showed ligninolytic activity as determined by Azure-B decolorization and Manganese oxidation assays as well as by Guaiacol and α-Naphthol tests. For the bio-treated lignite and bituminous coals, the Z-average size was 434.2 to 187.5 and 587.6 to 280.2 nm and zeta potential was −35.2 to −29.3 and −32.6 to −23.8 mV, respectively. Morphological and molecular studies showed that the isolated bacteria belong to genus Bacillus and Kocuria. The coal solubilization/degradation and ligninolytic activities as well as size and zeta potential studies indicated that the isolated bacteria could be potential candidates for development of green technologies for conversion of coal into valuable products for fuel and non-fuel applications. [ABSTRACT FROM AUTHOR]

Coal is an essential primary energy for the national economy and people's livelihood. In recent years, with the rapid growth of the consumption of high-quality coal resources, Lignite with a low degree of metamorphism has been extensively exploited and utilized. In this paper, desulfurization and ash reduction treatment of 6–0 mm fine-grade low-grade high-sulfur Lignite was carried out using a FGX dry separation bed (FGX FGX compound dry separation bed). The migration and distribution of differentiated density particles in the bed under the action of cascade air flow were mainly studied, and the influence of vibration intensity (amplitude and frequency) on the separation effect of fine-grade low-grade high-sulfur Lignite was explored. At the same time, the material distribution characteristics of each section in the direction of the discharge edge of the bed were systematically analyzed, the material distribution area of the bed was determined, the optimal operating parameters (A = 2.8 mm, f = 26 Hz, V = 2.29 m/s) were obtained, and the sorting test was carried out under the optimal parameter conditions. The test results show that when the vibration frequency f = 26 Hz, the sulfur segregation degree of bedding materials reaches the maximum Ss = 0.36, and the sulfur content of materials in I, II, and III regions is 0.85%, 5.47%, and 18.78%, respectively. The stratification effect of bedding materials is the best. When A = 2.8 mm, the material sulfur segregation reaches the minimum value of Ss = 0.28, and the average sulfur content of materials in I, II, and III regions is 0.78%, 5.46% and 18.27%, the material is stratified according to density. When the airflow rate is 2.55 m/s. The stratification effect of bed material is best according to density. The clean coal yield is 69.87%, and the sulfur content is 0.98%. The gangue yield is 30.13%, and the sulfur content is 18.66%. The Ep value of energy deviation is 0.11 g/cm3, which realizes high precision dry desulfurization and upgrading fine-grade, low-grade, and high sulfur lignite. [ABSTRACT FROM AUTHOR]

This case study investigates five fly ashes with high CaO and SO3 levels in their chemical composition and compares the apparent influence of the presence and absence of anhydrite on compressive strength. Another distinguishing feature of the above ashes is that they, more or less, naturally contain anhydrite. Two different series of mixed proportions were adopted. Series 1 is designed to understand the maximum possible replacement level of fly ash. Series 2 is designed to understand the effect of anhydrite on compressive strength development. The mineral composition and glass phase of fly ashes were determined by X-ray diffraction Rietveld analysis. As a result of this study, we have found that concrete containing anhydrite-rich fly ash exhibits a higher strength than concrete containing anhydrite-free fly ash at all ages. The compressive strength increases with an increasing fly ash replacement ratio when anhydrite-rich ash is used, but strength decreases when the replacement level exceeds a certain point. The optimal amount of anhydrite was 2 ± 0.5 kg/m3 of concrete, excluding the anhydrite contained in cement. [ABSTRACT FROM AUTHOR]

The growing use of local coal in Ethiopia has created challenges for cement factories due to inconsistencies in grade and quality. This paper presents the main areas rich in coal resource and potential sites for their development. Field studies have been conducted extensively in some areas to explore coal and analyze its compostion for potential use as major energy source in addressing the high energy demands for cement production across the country. Ethiopian coal beds vary in thickness from a few centimeters to 6 m and encompass a range of ranks from lignite to bituminous coal. Quality also varies widely, with ash content being a significant parameter of concern, as some studies indicate elevated levels. However, because of insufficient data, it is challenging to generalize other quality parameters accurately. Ethiopia's coal exploration dates back to the 1940s, with rough estimated deposits totaling 600 million tons nationwide. Currently, small‐scale producers satisfy 66% of the cement industries coal demand, which is the major consumers. Efficient coal mining enables the country to substitute significant amounts of imported coal, reducing large expenditures in foreign currency. Local coal production offers cost savings, job creation, streamlined transport, and reduced import reliance, thereby preserving hard‐earned foreign currency and granting the country a competitive edge. [ABSTRACT FROM AUTHOR]

The authors of this study focused on the energy and material assessment of processes for processing pellets from metal-bearing waste, specifically Fe concentrate. A mathematical model was created for process evaluation, with which thermotechnical calculations of parameters in the processing of metallized pellets were carried out. Thermodynamic calculations were performed to determine the enthalpy of the charge in individual devices (drying chamber, rotary kiln, cooler). For the reduction of Fe oxides, carbon from coke (with Fe oxide reductions of 50%, 61%, and 92%) and lignite (with Fe oxide reductions of 69% and 92%) were considered as part of the pellets. The degree of reduction of iron oxides was a determining parameter, and the consumption of the reducing agent corresponded to the direct reduction of Fe oxides by carbon with a coefficient of 1.5. Another determining parameter was the input and output temperature in individual devices. For a more precise description of the processes in individual devices, calculations were carried out zonally. The results of the calculations are analyses and recommendations for feasible alternatives for the reducing agent and associated processes. [ABSTRACT FROM AUTHOR]

The Pb, Cr, Cd, Ni, Zn, Cu, Co, As, Sr, Ba, and Zr content has been determined in the tested rock raw materials. The concentration of cadmium (Cd) was found to be elevated in all types of rock materials and was found on average to be: 1.39 mg/kg in limestones, 0.86 mg/kg—sandstones, 0.44 mg/kg—diatomites, 0.55 mg/kg—opoka rocks, 0.89 mg/kg—marls, 0.21 mg/kg—gaizes 0.42 mg/kg—kaolin clays, and 2.13 mg/kg—decalcified opoka rocks. Higher concentrations of arsenic (As) have also been recorded in sandstones and diatomites, as well as lead (Pb) in limestones and sandstones. The results obtained indicate that the anomalous level of elements is of natural origin and the results of identified secondary mineralisation processes that have affected the tested materials. Pyritization and sulfatization processes have been detected. Mineralogical research has shown that these processes can be associated with the activity of biochemical processes caused by the decomposition of the soft tissues of animal organisms and the organic substances of plant origin that fill the stylolites. It has been shown that the content of strontium (Sr) increases in geologically older Jurassic formations compared to younger Cretaceous formations, which can be used in the monitoring of building materials. [ABSTRACT FROM AUTHOR]

Boric acid is a dilute or mild acid derived from boron, and it is available in a water-soluble form as a white powder. Strong acids are generally preferred to remove ash and sulfur from coal. However, consumption of these strong acids harms the environment. Therefore, it is necessary to improve the leaching possibilities of weak acids. Also, a combination of beneficiation methods may need to be used to achieve the desired quality and environmental compatibility of coal. In this study, a combination of bioleaching and chemical experiments was employed to eliminate ash and sulfur from Sivas Kangal lignite coal. Initially, bioleaching experiments were conducted on lignites with high ash and sulfur contents by bioreactor with Acidithiobacillus ferrooxidans. Following this, in the second phase of experiments, boric acid leaching was employed to beneficiate Sivas/Turkey lignites through chemical methods. Additionally, the effect of glycerol on the leaching efficiency of boric acid, which is a weak acid, was investigated. Experimental findings have shown that combination methods provide better results in ash and sulfur removal from lignite coal. Finally, a clean coal product with 19.80% ash and 2.89% S content was obtained by combination methods to the lignite coal (46.60% ash and 4.99% S). [ABSTRACT FROM AUTHOR]

In order to obtain data on the effect of moisture content on the grindability of coals, experimental research was conducted. The experiment included six samples of coal from the Kolubara basin. The samples were selected based on experimentally obtained values of their Hardgrove grindability index (HGI), in order to cover the entire range of experimental HGI values. In addition to determining the HGI, proximate, and petrographic analyses were performed on all samples. Lignites are naturally tough, soft, and greasy when in a moist state. By reducing the moisture content, lignites become more brittle. For this reason, Hardgrove grindability index values have different values depending on the moisture content at which they are determined. The HGI has a non-linear dependence on the moisture content of the coal. All curves have two inflection points, one minimum and one maximum value of Hardgrove grindability index in the tested range. The minimum values of HGI are in the range of 15-22% of the mass fraction of total moisture in coal, while the maximum values of HGI are for a total moisture content of 5-13%. In the case of high moisture content in coal, the obtained high values of HGI may not reflect the true grindability of the coal. These values could be misleading and not necessarily indicative of the coal inherent characteristics. Instead, they could be a result of the imperfections in the Hardgrove method used to determine the grindability index of coal with high moisture content. [ABSTRACT FROM AUTHOR]

The goal of securing almost 100 % of electricity generation in Germany with renewable energies (RE) and green energy imports is analyzed. The annual continuous load lines of the ways of generating electricity with RE demonstrate the actual supply capacity of RE as a function of the installed capacity. The increasing volatility resulting from the expansion of RE has a negative impact on the effectiveness of electricity generation and leads to high residual loads. It is not possible to compensate for this by storing the surplus electricity with hydrogen and regenerating electricity and importing green energy sources. A globally feasible concept of the complementary decarbonization of electricity generation from RE and fossil fuels via natural gas pyrolysis and the material‐energetic use of lignite is proposed. [ABSTRACT FROM AUTHOR]

The particle sizes of main mineral compounds in the structure of lignite were determined using physical methods (SAXS, TEM, and XRD analysis) and chemical processes of selective dissolution. It has been shown that calcium and magnesium compounds in the structure of lignite were present in the form of small nanoparticles with sizes of about 10 nm. Particles consisting of aluminum and iron compounds had larger sizes of about 20–35 nm. Silica-containing particles in the structure of lignite had sizes of 100 nm or greater. [ABSTRACT FROM AUTHOR]

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4 +-N, 77.84% for NO3--N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives. [ABSTRACT FROM AUTHOR]

This paper analyses the discursive and material politics of energy transition, focusing on promotion of Australian industrial regions as 'green hydrogen hubs'. Regions are key spatial imaginaries in transition projects promoted by state-capitalist coalitions. First-to-market investments target regions with suitable infrastructures and workforces, anticipating future decarbonised energy markets. Yet, far from an orderly transition, such projects confront competing regional imaginaries and conflicts across governance scales, with hydrogen's troublesome material limitations precipitating hedging tactics among established energy-intensive firms. Scholars of decarbonisation, 'green capitalism' and energy transitions must pay closer attention to materiality and the complexity of regional contestations and asymmetries. [ABSTRACT FROM AUTHOR]

It is paramount that solutions to questions of energy security for a developing nation be addressed through its internal resources. India, endowed with 23.8 billion tons of deep un-minable lignite, faces the challenge of economically sustainable extraction. This study presents a comprehensive assessment of lignite's suitability for underground coal gasification (UCG) compared to bituminous coal. Employing a multi-dimensional approach, combining single-step and distributed activation energy model of pyrolysis kinetic modeling with extensive physicochemical analysis (proximate and ultimate analyses, FTIR, SEM–EDX, XRD), revealed that lignite has a lower activation energy making it suitable for UCG. This finding, highlighted by kinetic modeling, is substantiated by the lignite's structural properties as identified in physicochemical analysis. This study leverages machine learning for higher heating value prediction, finding long short-term memory as the most effective model compared to five other models based on the R2 score and error values. Additionally, an XGBoost algorithm-based model predicts syngas heating value and yield while showcasing the application of machine learning in enhancing energy prediction accuracy. The economic analysis, applied for a 50 MW power plant framework, determines the unit costs for syngas and electricity production to be 7.49 and 6.71 $/GJ and 53.68 and 59.93 $/MWh for the samples of lignite and bituminous coal, respectively. The sensitivity analysis revealed that the energy content in syngas is the most significant parameter. These comprehensive findings validate lignite's potential for energy production in India, offering insights for similar resource optimization in other developing countries. [ABSTRACT FROM AUTHOR]

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Excessive industrial release of trace elements may pose a great risk to the environment. Conventional remediation treatments have considerable limitations, making less expensive new technologies an important research area. Batch experiments were conducted at room temperature to investigate the use of two lignite‐derived humic products (nano‐humus and humic powder) and a cattle manure biochar as adsorbents in the removal of cadmium and zinc from laboratory synthesized water. Nano‐humus was most effective in adsorbing Cd(II), wherein 89% adsorption was rapidly achieved in 15 min. The adsorbed amount of Cd(II) and Zn(II) both increased with initial metal ion concentrations from 25 to 125 mg L−1. Despite being produced from the same sources, nano‐humus and humic powder showed different properties and adsorption behaviors. The adsorption mechanism of nano‐humus followed the Freundlich isotherm model and pseudo‐second‐order kinetic model, indicating multilayer chemisorption. Humic powder followed the pseudo‐second‐order kinetic model, although it had a low isotherm model fit, implying chemisorption‐dominated adsorption. Cattle manure biochar followed the Freundlich isotherm and pseudo‐first‐order kinetics model, suggesting diffusion‐dominated multilayer adsorption. Of the three adsorbents tested, nano‐humus had greatest potential as an effective and inexpensive material for metal remediation. [ABSTRACT FROM AUTHOR]

This study focuses on optimizing double stir casting process parameters to enhance the tensile strength of hybrid composites comprising aluminum alloy, brown pumice, and coal ash, intended for brake disc applications. Analytical techniques including X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were employed to characterize the composite constituents. The Taguchi method was utilized for experimental design and optimization to determine the optimal weight compositions of brown pumice and coal ash, as well as stir casting parameters (stirrer speed, pouring temperature, and stirring duration). Regression analysis was employed to develop a predictive mathematical model for the tensile strength of the hybrid composites and to assess the significance of process parameters. The optimized composite achieved a predicted tensile strength of 186.81 MPa and an experimental strength of 190.67 MPa using 7.5 vol% brown pumice, 2.5 vol% coal ash, a pouring temperature of 700 °C, stirrer speed of 500 rpm, and stirring duration of 10 min. This represents a 52.23% improvement over the as-cast aluminum alloy's tensile strength. Characterization results revealed that brown pumice and coal ash contain robust minerals (SiO2, Fe2O3, Al2O3) suitable for reinforcing metal matrices like aluminum, titanium, and magnesium. Thermogravimetric and differential thermal analyses demonstrated thermal stability up to 614.01 °C for the optimized composite, making it suitable for brake disc applications. [ABSTRACT FROM AUTHOR]

Conveyor belts are vital for material transportation in coal mines due to their cost-effectiveness and versatility. These belts endure significant wear from harsh operating conditions, risking substantial financial losses if they fail. This study develops five artificial neural network (ANN) models to predict conveyor belt damage using 11 parameters from the Belchatow brown coal mine in Poland. The models target five outputs: number of repairs and cable cuts, cumulative number of repairs and cable cuts, and their ages. Various optimizers (Adam, Nadam, RMSprop, Adamax, and stochastic gradient descent or SGD) and activation functions (ReLU, Swish, sigmoid, tanh, Leaky ReLU, and softmax) were tested to find the optimal configurations. The predictive performance was evaluated using three error indicators against actual mine data. Superior models can forecast belt behavior under specific conditions, aiding proactive maintenance. The study also advocates for the Diagbelt+ system over human inspections for failure detection. This modeling approach enhances proactive maintenance, preventing total system breakdowns due to belt wear. [ABSTRACT FROM AUTHOR]

This study was aimed at investigating the effects of adding sodium fluoride (NaF) and using the assistance of ultrasonic and microwave energy on the removal efficiency of ash content during the hydrochloric acid (HCl) chemical leaching process of lignite samples from Zhaotong, Yunnan, China. Chemical leaching was conducted on lignite samples from Zhaotong, Yunnan, China, under the experimental conditions of time (30–120 min), temperature (55–95 °C), microwave power (240–800 W), ultrasonic power (25–100%), and NaF addition concentration (0.2–1.2 M). The addition of NaF greatly improved the removal efficiency of ash content from lignite. Under optimized conditions, the addition of NaF increased the removal rate of ash content from lignite from 25% to 65.27%. The microwave-assisted deashing of lignite can significantly improve the deashing efficiency, with positive implications for the microstructure regulations of lignite. Ultrasonic-assisted deashing can lower the temperature for coal powder burnout and enhance the combustion performance of coal. [ABSTRACT FROM AUTHOR]