Anthracite Research Articles

Study on the Influence Mechanism of Hot Flue Gas Injection Pressure on the Wettability of Anthracite Coal: From the Perspective of Molecular Dynamics

Study on the Influence Mechanism of Hot Flue Gas Injection Pressure on the Wettability of Anthracite Coal: From the Perspective of Molecular Dynamics

Modelling the properties of aerated concrete on the basis of raw materials and ash-and-slag wastes using machine learning paradigm

The thermal power industry, as a major consumer of hard coal, significantly contributes to harmful emissions, affecting both air quality and soil health during the operation and transportation of ash and slag waste. This study presents the modeling of aerated concrete using local raw materials and ash-and-slag waste in seismic areas through machine learning techniques. A comprehensive literature review and comparative analysis of normative documentation underscore the relevance and feasibility of employing non-autoclaved aerated concrete blocks in such regions. Machine learning methods are particularly effective for disjointed datasets, with neural networks demonstrating superior performance in modeling complex relationships for predicting concrete strength and density. The results reveal that neural networks, especially those with Bayesian Regularisation, consistently outperformed decision trees, achieving higher regression values (Rstrength = 0.9587 and Rdensity = 0.91997) and lower error metrics (MSE, RMSE, RIE, MAE). This indicates their advanced capability to capture intricate non-linear patterns. The study concludes that artificial neural networks are a robust tool for predicting concrete properties, crucial for producing non-autoclaved curing wall blocks suitable for earthquake-resistant construction. Future research should focus on optimizing the balance between density and strength of blocks by enhancing the properties of aerated concrete and utilizing reliable models.

Investigation of the sorption activity of native coals to air oxygen

The influence of the gaseous medium during sample preparation, the granulometric composition, the duration of contact with air and the stage of metamorphism on the process of oxygen sorption from the air was established. It is shown that conducting sample preparation in an air atmosphere leads to primary oxidation of the outer surface of the coals, which introduces an error in determining the oxygen sorption rate constant. Fine coal fractions (0-0.2 mm) with a more developed outer surface have increased oxygen absorption activity. The rate of oxygen sorption is maximal at the initial moment of the interaction of active carbons with air and decreases with the duration of contact. The least metamorphosed hard coals of the D brand with a high content of reactive functional groups and a developed porous structure are characterized by the greatest chemisorption activity.

Geochemistry and Mineralogy of Upper Paleozoic Coal in the Renjiazhuang Mining District, Northwest Ordos Basin, China: Evidence for Sediment Sources, Depositional Environment, and Elemental Occurrence

This study aims to investigate the depositional environment, sediment sources, and elemental occurrence of Upper Paleozoic coal in the Renjiazhuang Mining District, Western Ordos Basin. Furthermore, SEM-EDX, optical microscope (OM), ICP-AES, ICP-MS, and AAS were used. Compared with hard coal of the world, M3 coals were enriched in Ga, Li, Zr, Be, Ta, Hf, Nb, Pb, and Th, M5 coals were enriched in Li (CC = 10.21), Ta (CC = 6.96), Nb (CC = 6.95), Be, Sc, Ga, Hf, Th, Pb, Zr, In, and REY, while M9 coals were enriched in Li (CC = 14.79), Ta (CC = 5.41), Ga, W, Hf, Nb, Zr, Pb, and Th. In addition, minerals were mainly composed of kaolinite, dolomite, pyrite, feldspar, calcite, and quartz, locally visible minor amounts of monazite, zircon, clausthalite, chalcopyrite, iron dolomite, albite, fluorite, siderite, galena, barite, boehmite, and rutile. In addition, maceral compositions of M3 coals and M9 coals were dominated by vitrinite (up to 78.50%), while M5 coals were the main inertite (up to 76.26%), and minor amounts of liptinite. REY distribution patterns of all samples exhibited light REY enrichment and negative Eu anomalies. The geochemistry of samples (TiO2 and Al2O3, Nb/Y and Zr × 0.0001/TiO2 ratios, and REY enrichment types) indicates that the sediment sources of samples originated from felsic igneous rocks. Indicator parameters (TPI, GI, VI, GWI, V/I, Sr/Ba, Th/U, and CeN/CeN*) suggest that these coals were formed in different paleopeat swamp environments: M3 coal was formed in a lower delta plain and terrestrial (lacustrine) facies with weak oxidation and reduction, and M5 coal was formed in a terrestrial and dry forest swamp environment with weak oxidation–oxidation, while M9 coal was formed in a seawater environment of humid forest swamps and the transition from the lower delta plain to continental sedimentation with weak oxidation and reduction. Statistical methods were used to study the elemental occurrence. Moreover, Li, Ta, Hf, Nb, Zr, Pb, and Th elements were associated with aluminosilicates, and Ga occurred as silicate.

Comparative Analysis of Domestic Production and Import of Hard Coal in Poland: Conclusions for Energy Policy and Competitiveness

In many energy policies, including Poland’s, environmental priorities clash with the issue of energy security. With these contradictions in mind, the main objective of the article is a comparative analysis of domestic production and imports of hard coal in Poland and the formulation of conclusions for energy policy and competitiveness. The analysis covers the years 2018–2023 and concerns three issues: the volume and directions of coal imports to Poland, the qualitative and price competitiveness of coal, and the possibility of substituting imported coal with domestic coal. The research used statistical analysis. Indicators of structure and dynamics as well as comparative analysis were also used. The analysis shows that the structure of coal importers to Poland is quite diverse and includes many geographic directions. However, until 2021, it was dominated by Russia, followed by Colombia, indicating a fairly homogeneous supply market and a continuing tendency to depend on a single importer. Analysis of qualitative competitiveness confirms the existence of balance and industrial resources whose quality parameters (sulfur content, ash content, and calorific value) are comparable to and better than those of imported coal. Polish hard coal can also compete with imported coal in terms of price. From 2021 to 2023, it was clearly cheaper than foreign coal. In the above circumstances, it is quite difficult to unequivocally assess the reasons for importing coal to Poland and to justify dependence on external suppliers. This is especially relevant since domestic mining in 2020–2023 remains stable (periodically even increasing), which does not indicate a decisive shift away from coal as an energy resource.

Influence of the Depth of Shallow Workings on the Probability of Sinkhole Formation and Determination of the Contribution of Mines to the Resulting Risk

AbstractThis paper presents a broad spectrum of factors that have an impact on the environment once underground mines have been closed, with particular emphasis on hard coal mines. Based on the review of scientific literature and own experience, several types of environmental impacts of closed mines were specified. In the author’s opinion, sinkholes pose the most serious hazard to post-mining areas. A high degree of urbanisation of the Upper Silesian Coal Basin and a wide range of mining operations conducted in the past necessitate the post-mining areas development for construction purposes. However, investing in these areas cannot carry risks and pose a threat to public safety. Therefore, a simplified method of determining the probability of sinkhole formation depending on the depth of a shallow void (excavation) in the rock mass was proposed. An algorithm has also been proposed for determining the contribution of individual mining companies to causing sinkhole hazard, which is of great importance in legal proceedings.

Comparative analysis of cotton oil and fuel oil as collectors in hard coal flotation: Toward sustainable mining practices

ABSTRACT This study investigates cotton oil as an environmentally friendly alternative to fuel oil in the flotation of hard coal from the Zonguldak Kozlu Region, Türkiye. We compared their performance across various operational parameters using a Denver-type flotation machine. Results showed that cotton oil achieved superior combustible recovery in most scenarios. At 1000 g/t, cotton oil achieved 97% combustible recovery compared to fuel oil’s 90% at 2000 g/t. Cotton oil maintained high recovery (94–95%) over a broader pH range (2–10) compared to fuel oil’s stable 90% from pH 2–8. However, fuel oil demonstrated better ash rejection, achieving 50% rejection at 2% solids compared to cotton oil’s 36%. Both oils performed optimally at pH 8.25 and 10% solid ratio. Cotton oil maintained 93% recovery at 1050 rpm compared to fuel oil’s 89% and exhibited less sensitivity to frother concentration. FTIR and zeta potential analyses revealed distinct interaction mechanisms, with cotton oil showing stronger adsorption on coal surfaces. This research contributes to developing sustainable practices in coal beneficiation, highlighting the trade-offs between combustible recovery and ash rejection when choosing between these collectors for industrial applications.

Analysis of the ecological footprint of mining machines in the phase of material extraction and processing in LCA

Sustainability in the mining industry continues to be a challenge. Although there is research in this area, there are still no solutions supporting the assessment of environmental impact in this sector. Therefore, it is important to look for and conduct various types of analyses that will be useful in this area. Therefore, the objective of the research was to analyse the ecological footprint of mining machines in the first phase of the LCA life cycle (obtaining and extracting materials). The analysis was based on the example of a hydraulic actuator, which is considered crucial to control machines in the mining industry. The ecological footprint burdens analysed included direct and indirect land take, sequestration of carbon dioxide (CO2) emissions, and the use of nuclear energy. Life cycle assessment was carried out using the OpenLCA software with the ecoinvent v3.10 database. It has been shown that the largest amount of emissions occurs during off-site treatment of nonsulphide waste, cogeneration of heat and energy (hard coal), production of ferrochrome, high carbon, 68% Cr, and heat production in an industrial furnace using hard coal. It is proposed to carry out improvement activities that will first contribute to reducing the main environmental burdens. Then, it will be possible to significantly reduce the negative environmental impact of the hydraulic actuator's extraction and processing of materials. The results from the analysis may be useful not only for products from the mining industry but also in other areas of activity using this type of machine.

Microscopic adsorption study from coal rank comparison on the feasibility of CO2-rich industrial waste gas injection enhanced coal bed methane recovery

A new method of injecting CO2-rich industrial waste gas (CO2-rich IWG) to displace coal bed methane (CBM) is proposed for energy conservation and green growth. In this study, theadsorption mechanisms of this method were studied by the Giant canonical Monte Carlo and molecular dynamics methods in macromolecular coal models with three ranks (brown, bituminous, and anthracite coal). It is found that the proportion of gas molecules in the adsorbed state is higher in the anthracite coal slit than in the brown and bituminous slits, indicating that anthracite coal seams are more appropriate for waste gas sequestration. The adsorption selectivity of NO and CO2 is consistent among the three coal ranks, with the order of brown > bituminous > anthracite > 1.0, and that of N2 orders as 1.0 > bituminous > anthracite > brown.This is due to the different dominant factors affecting the competitive adsorption between different waste gas components and CBM, namely competition for adsorption sites in the NO and CO2 systems and thefilling effect in the N2 system. There is a positive correlation between the number of major competitive adsorption sites and the adsorption selectivity of theCO2(NO) system. CO2 and CH4 compete for COC structures in brown and bituminous coal and OH structures in anthracite coal, and OH structures in the three coals are the major adsorption sites for NO systems. Our work advances the understanding of the microscopic adsorption mechanisms of CO2-rich IWG in the CBM reservoirs, which provides a theoretical basis for CO2-rich injection-enhanced CBM recovery technology.

Model for Fracturing Fluids Entering Soft–Hard Coal Interbedded Strata and Its Application

Model for Fracturing Fluids Entering Soft–Hard Coal Interbedded Strata and Its Application

Mineralogy and geochemical controls on the distribution of REY-Ga-Se-Nb enrichment in the No. 6 Coal Seam, Soutpansberg Coalfield, South Africa

Coal is being explored as a potential alternative source for rare earth elements (REY + Sc), which are critical for advancing modern technology. Previous research has mainly focused on assessing the concentration and distribution of REY + Sc in coals from South Africa. However, the modes occurrence of these elements in coal is yet to be investigated. This study offers new insights on the mineralogy and inorganic geochemistry of the No. 6 Seam coal from the Soutpansberg Coalfield (South Africa). The objective is to investigate the distribution, enrichment, and modes of occurrence of critical elements such as Ga, Se, Nb, and REY + Sc within this coal. The No. 6 Seam is a medium rank-B, moderate vitrinite (avg. 41.5 vol%) coal, and contains major minerals such as kaolinite, quartz, and minor minerals including muscovite, siderite, dolomite, pyrite, and calcite. The total REY + Sc concentrations in the coal samples range from 79.9 to 332.1 mg/kg (avg. 213.2 mg/kg; whole-coal/rock basis), higher than global averages for hard coal. The upper continental crust (UCC) normalized concentration coefficients (CC) of the coal shows enrichment of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, and Y. Distinct REY + Sc enrichment patterns are observed across different coal horizons, divided into two categories: light-REY (LREY) and medium-REY (MREY) in the bottom horizon coal [bottom-upper (BU) and bottom-lower (BL)], whereas the middle horizon coal [middle-upper (MU) and middle-lower (ML)] are enriched in medium-REY (MREY) and heavy-REY (HREY). The BU and BL samples show greater REY + Sc enrichment relative to the MU and ML samples. The samples also contain elevated concentrations of Ga (max. 106.1 mg/kg), Se (max. 50.9 mg/kg), and Nb (max. 14.8 mg/kg), exceeding the average values reported for Chinese coals.When considering the correlations between REY + Sc and major oxide elements, minerals, and organic petrographic assemblages, REY + Sc appears to be more closely associated with inorganic fraction, particularly aluminosilicate (such as kaolinite) and carbonate minerals (like dolomite), rather than with the organic fraction. The kaolinite and dolomite represent mostly detrital input and epigenesis, respectively. Gallium in the coal is primarily associated with aluminium oxide-hydroxide, Nb with minerals such as clay, rutile/anatase, and zircon; and Se with pyrite. Redox-sensitive elemental ratios of Al2O3/TiO2 andTiO2/Zr suggest that the detrital components of the No. 6 Seam coals were predominantly derived from a source consisting of felsic-intermediate rocks. These materials likely represent the weathering products of magmatic rocks from the passive-continental margin tectonic framework of the Limpopo Mobile Belt. Paleoclimatic conditions are inferred to be warm-humid to hot, with the peat deposited under suboxic-to-oxic environments. High values of critical REY percentage (REYdef,rel%: 29.85 to 39.75 %) and an outlook coefficient ≥ 0.7 suggest these Soutpansberg coal samples to be promising for REY + Sc recovery along with Ga.

The influence of the mole modulus of the activator SiO2/Na2O on the formation of properties of geopolymer

The objective of the study was to determine the suitability of fly ash derived from the combustion of hard coal in a heat and power plant located in Lodz to produce geopolymer. The study investigated the effect of the molar modulus of the activator (SiO2/Na2O) on the compressive strength over time in mortars modified with the addition of granulated blast furnace slag (0, 10 and 50%). An important aspect of the analyses is the possibility of managing locally occurring products from industrial processes

Evolution characteristics and molecular constraints of microbial communities during coal biogasification.

This study investigates the production of biomethane, and variation in microbial community and coal molecular structures using gas chromatography, 16S rRNA high-throughput sequencing and Fourier transform infrared spectroscopy. Additionally, the factors influencing microbial community structure at a molecular level are discussed. The results demonstrate that bituminous coal exhibits a higher biomethane yield than anthracite coal. In bituminous coal samples, Escherichia and Proteiniphilum are the predominant bacteria at day 0, while Macellibacteroides dominates from days 5 to 35. Methanofollis is the dominated archaea during days 0 to 15, followed by Methanosarcina on day 35. In anthracite coal samples, Soehngenia is the dominant bacterial genus at day 0; however, it transitions to mainly Soehngenia and Aminobacterium within days 5-15 before evolving into Acetomicrobium on day 35. Methanocorpusculum is predominantly found in archaeal communities during days 0-15 but shifts to Methanosarcina on day 35. Alpha diversity analysis reveals that bacterial communities have higher species abundance and diversity compared to archaeal communities. Redundancy analysis indicates a significant correlation between coal molecular structure and bacterial community composition (P value < 0.05), whereas no correlation exists with archaeal community composition (P value > 0.05). The research findings provide theoretical support for revealing the biological gasification mechanisms of coal.

Impact of the Location and Energy Carriers Used on Greenhouse Gas Emissions from a Building

The growth in population increases greenhouse gas (GHG) emissions into the environment. High GHG emissions are attributed to meat production, due to its high energy demand. The largest carbon footprint in the production of poultry meat is generated by combustion. This paper deals with the problem of greenhouse gas emissions (total dust, CO, CO2, NOx, SOx and benzo(a)pyrene) resulting from the generation of energy for heating broiler houses located in different locations in Europe. The study includes continuous measurements of selected microclimate parameters: temperature and relative humidity inside and outside the building, floor temperature, wind speed and direction, and solar radiation intensity. Validation and calibration of the model, emission calculations, and analysis of the obtained results were conducted. Eighteen design variants were assumed, differentiated by the heating fuel used (hard coal, fuel oil, gaseous fuels), material and construction solutions for the floor and the location of the facility. The analysis showed that CO2 emissions for a facility located in northern Europe are 123,153 kg higher compared to the same building located in southern Europe. In addition, increasing the floor’s thermal resistance by 3.69 m2·K·W−1 reduced harmful gas emissions by an average of 5.7% for each of the locations analysed.

Performance of a novel CLOU oxygen carrier (CuO/ZrO2/TiO2/MgO) in the combustion of high-rank coal: Anthracite and bituminous

Coal is the largest contributor to global CO2 emissions, and current reserves are projected to last approximately 150 years, with 71.6 % being high-rank coals (anthracite and bituminous). Chemical looping combustion is an economical CO2 capture method that uses oxygen carrier materials to supply oxygen for combustion. Copper is the most reactive due to its oxygen uncoupling capability, though it has poor stability. In our research, we developed a novel modified copper-based oxygen carrier with enhanced stability in oxygen uncoupling cycles by increasing the ZrO2 ratio at the expense of TiO2 to reduce phase interactions. The modified oxygen carrier (40 % CuO, 30 % ZrO2, 15 % TiO2, 15 % MgO) was used to combust bituminous and anthracite coal in a fixed-bed system. While bituminous coal had a high combustion rate, its efficiency was 63 %, yielding 18 mol/kg of CO2, compared to 90 % efficiency and 56 mol/kg CO2 for anthracite. The lower efficiency for bituminous was due to the rapid release of volatiles. Adding steam improved bituminous combustion efficiency to 75 % and CO2 yield to 21 mol/kg, with no significant change for anthracite. A blend of 25 % bituminous and 75 % anthracite showed better combustion efficiency, rate, and CO2 yield. This blend test was stable over 10 cycles, as confirmed by SEM, XRD, and BET analyses.

Ignition of Coal Microparticles by Laser Pulses of The Second Harmonic of a Ndodymium Laser in the Q-Switched Regime

The ignition of pelletized samples of hard coals of the long-flame gas (DG), gas (G), fat (L), coke (K) grades with particle sizes ≤63 μm by laser pulses (λ = 532 nm, τi = 10 ns) was studied. When the critical radiation energy density Hcr(1), specific for each grade of coal, is exceeded, an optical breakdown occurs and a dense plasma with a continuous emission spectrum is formed. As the plasma expands and rarefies, the spectra show the emission of carbon ions CII, excited nitrogen atoms N, excited carbon molecules C2, and carbon monoxide CO. The plasma glow intensity peaks at the end of the laser pulse, and the glow relaxation time is ~1 μs. The plasma glow amplitude increases nonlinearly with increasing laser pulse energy density. At radiation energy density H ≥ Hcr(2), specific for each grade of coal, thermochemical reactions are initiated in the volume of microparticles and coal particles are ignited in a submillisecond time interval.

Impact of Crushed Natural Aggregate on Environmental Footprint of the Construction Industry: Enhancing Sustainability in Aggregate Production

This research addresses a critical gap in understanding the environmental impact of natural rock aggregate production in Sri Lanka. The study employs life cycle assessment (LCA) and SimaPro Software to simulate natural coarse aggregates’ extraction and manufacture process. Key findings reveal significant environmental impacts, with human carcinogenic toxicity (2.45938 × 10−6 Pt), eutrophication of freshwater (1.59326 × 10−6 Pt), and fossil resource scarcity (1.4823 × 10−6 Pt) being significant concerns. The crushing process in particular shows the highest levels, contributing 2.21 × 106 to human carcinogenic toxicity and 8.92 × 107 to freshwater eutrophication. High electricity consumption, particularly from hard coal in electricity generation, is identified as a primary contributor. Although the sole source of coarse aggregate production in Sri Lanka is natural rock crushing, there is a lack of country-specific environmental impact assessment data for this process. This study provides a valuable dataset for the Sri Lankan construction industry, covering various environmental impact categories and encompassing the sub-processes inherent to natural rock aggregate production. The research highlights the necessity of implementing sustainable practices in quarry operations, proposing a transition towards more environmentally friendly energy sources. By quantifying environmental effects, this study provides valuable insights for stakeholders in the construction sector, enabling informed decision-making and targeted interventions to enhance overall sustainability while offering aggregate manufacturers opportunities to adopt more sustainable practices.

Selective Extraction of Vanadium from Vanadium-Bearing Stone Coal by a Two-Stage Leaching Process

Selective Extraction of Vanadium from Vanadium-Bearing Stone Coal by a Two-Stage Leaching Process

Oxidative weathering on the continent and seawater upwelling along the passive continental margin promoted widespread phosphorite formation at the Neoproterozoic-Cambrian boundary in South China

The latest Proterozoic to early Cambrian is characterized by major global phosphogenic events and the diversification of complex multicellular life. However, the feedback mechanism of atmospheric oxidation and upwelling processes to form voluminous phosphorite deposits is unclear. South China is a key example of the sedimentary spectrum related to the Neoproterozoic to Early Cambrian bloom of oxygenic photosynthesis, with alginite deposits (sapropelite; “stone coal”), barite, polymetallic black shales and phosphorites along the passive continental paleo-margin of the Yangtze craton. Here, we present a comprehensive geochemical analysis of drill core samples from the Zhijin phosphorite deposit, including Cr isotope, Fe speciation, and bulk elemental composition of dolostone, phosphorite and black shale from the Ediacaran to Early Cambrian sequence. The positively fractionated δ53Cr values of 0.11 to 1.81 ‰ of leachates from Ediacaran dolostone and Terreneuvian phosphorite indicate intensive oxidative terrestrial weathering. The phosphorite samples exhibit REE distribution patterns similar to modern seawater and strongly negative Ce anomalies (0.47–0.61), suggesting an oxic, open ocean environment. In contrast, the absence of Ce anomaly, high FeHR/FeT, and Fepy/FeHR ratios, enhanced redox-sensitive element concentrations, high Mo/TOC and TS/TOC, and high molar Corg:P ratios suggest euxinic to anoxic conditions for the overlying black shale sedimentation in a restricted sedimentary marine environment. Bulk-rock shale samples retain the positively fractionated Cr isotope pattern. The dramatic change from oxic to anoxic conditions aligns with the fossil record, which shows a proliferation of small shelly fossils in the phosphorite and their extinction in the overlying black shales, likely by hydrogen sulfide poisoning. We infer that nutrient-rich, oxidized upwelling seawater transported phosphorus and other nutrients to the photic zone, from where organic matter settled down to the seafloor and formed thick phosphorite beds at the oxic-anoxic boundary at and below the seafloor. Our study highlights that atmospheric and seawater oxygenation accelerated the Early Cambrian bio-diversification, and the subsequent restricted basin situation is responsible for the extinction at the Neoproterozoic-Cambrian boundary.

Multifractal Characteristics of Low-Field Nuclear Magnetic Resonance of Different Rank Coals and Its Permeability Predicting Method.

The permeability of methane in coal is a crucial factor in the production of coal-bed methane (CBM), which is dependent on the pore size distribution (PSD) of coal. The transverse relaxation time cutoff value (T2C) is a crucial parameter in nuclear magnetic resonance (NMR) techniques for converting NMR data into an absolute PSD. To investigate an appropriate approach for predicting the T2C and permeability of different rank coals, this study first revealed, through centrifuge experiments with a centrifugal force of 1.38 MPa, the T2C values of five coal samples: anthracite coal (3 ms), lean coal (8 ms), coking coal (12 ms), fat coal (11 ms), and lignite coal (13 ms). These T2C values were then employed to obtain the absolute PSD values of the coal samples. The results demonstrated that the pore structure characteristics of these coal samples are essentially identical, with micropores constituting the majority, varying between 63.47% and 93.74%. Subsequently, the multifractal analysis method was introduced to establish a new T2C value calculation model. A comparison of the model-calculated T2C values with those obtained from centrifugal experiments revealed an average deviation of only 5.26%. Finally, a new permeability model was developed by conducting multiple regressions on permeability and multifractal parameters. In comparison to classical models, such as the Timur-Coates (TC) model and the Schlumberger Dauer Research Center (SDR) model, the developed permeability model offers more accurate predictions. These results are applicable to pore structure characterization and methane permeability prediction in coal reservoirs of varying rank and other unconventional gas reservoirs.