International Journal of Coal Geology最新文献

{"title":"Fossil cutin of Karinopteris (Middle Pennsylvanian pteridosperm) from the “paper” coal of Indiana, U.S.A.","authors":"José A. D'Angelo ,&nbsp;James C. Hower ,&nbsp;Gerardo Camí","doi":"10.1016/j.coal.2024.104460","DOIUrl":"10.1016/j.coal.2024.104460","url":null,"abstract":"<div><p>For the first time, a cutin-like, highly chemically resistant macropolymer has been isolated from rachises of <em>Karinopteris</em> sp. (lyginopteridalean pteridosperm, Middle Pennsylvanian). Samples are obtained from a cuticular or “paper” coal-shale, i.e., an organic-rich and highly clastic rock associated with the Upper Block Coal Member of the Brazil Formation, Parke County, west-central Indiana, U.S.A. <em>Karinopteris</em> specimens are preserved as naturally oxidized compressions, termed “fossilized cuticles”, and possibly represent vegetation of mineral substrate environments. Employing laboratory oxidation reactions, the fossilized cuticle of <em>Karinopteris</em> rachises is used to obtain the cuticle. After additional and long-term oxidation treatment, the cuticle yields the cutin-like macropolymer, here referred to as “cutin” for simplicity. The fossilized cuticle, cuticle, and cutin samples of <em>Karinopteris</em> sp. are chemically analyzed using semi-quantitative Fourier transform infrared (FTIR) spectroscopy. Cutin IR spectra of <em>Karinopteris</em> rachises are characterized by (a) a predominantly aliphatic composition as indicated by intense aliphatic (CH_al) C<img>H stretching peaks at 3000–2700 cm⁻¹, which are assigned to methylene (CH₂) and methyl (CH₃) groups; (b) carbonyl (C=O) groups at 1730–1640 cm⁻¹, and aromatic carbon (C=C) absorption bands at 1600–1500 cm⁻¹. A comparison with the cuticle, the cutin stands out due to relatively higher values of CH₂/CH₃ and C=O/C=C, while displaying notably low values of CH_al/C=O and C<img>C contribution. Specifically, the relatively low value of CH_al/C=O ratio obtained for the cutin of <em>Karinopteris</em> rachises is consistent with those found in the cutin of extant and fossil leaves. This lower CH_al/C=O ratio indicates the important role likely played by C<img>O groups in creating a deformable and flexible structure in both the cutin and the cuticle. Such a reduced rigidity suggests a high level of rachis flexibility of the once-living <em>Karinopteris</em> plant, supporting the interpretation of a climbing or liana habit. Cutin isolation and its chemical characterization shed light on the probable biomechanical (flexibility) properties of <em>Karinopteris</em> rachises, thereby enhancing our understanding of the plant growth habit.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139655955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancements in machine learning techniques for coal and gas outburst prediction in underground mines","authors":"A. Anani, S. Adewuyi, Nathalie Risso, W. Nyaaba","doi":"10.1016/j.coal.2024.104471","DOIUrl":"https://doi.org/10.1016/j.coal.2024.104471","url":null,"abstract":"","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139818698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of goaf gas drainage from surface vertical boreholes on goaf explosive gas zones","authors":"Yuehan Wang ,&nbsp;Guangyao Si ,&nbsp;Bharath Belle ,&nbsp;David Webb ,&nbsp;Liang Zhao ,&nbsp;Joung Oh","doi":"10.1016/j.coal.2024.104461","DOIUrl":"10.1016/j.coal.2024.104461","url":null,"abstract":"<div><p>Goaf gas drainage is extensively employed in Australian gassy underground coal mines to manage safety and productivity and to mitigate gas emissions. As mining operations reach greater depths and produce higher levels of gas emissions, narrower spacing between adjacent vertical goaf boreholes and higher suction pressure are increasingly being adopted. While this proactive goaf gas drainage design enhances gas extraction efficiency, there is a concern that an increased amount of ventilation air might be drawn back into the deep goaf, potentially resulting in the formation of an explosive gas zone (EGZ) composed of methane-air mixtures. Extensive goaf gas drainage data from various Australian coal mines have undergone detailed analysis in preceding back analysis studies (Wang et al., 2022a, 2023). These findings serve as crucial validation input for a CFD model of the goaf, providing ventilation engineers with visualization of an otherwise inaccessible environment. In this paper, the simulation outcomes of the CFD model were integrated with Coward's triangle to demarcate potential EGZ within the active goaf areas. It indicated that the EGZ was pushed far away from the longwall face under the impact of intensive goaf gas drainage compared to the EGZ without the active goaf boreholes, exhibiting a ‘U-shaped’ distribution. Furthermore, this study delves into the gas drainage factors influencing EGZs in the goaf, emphasising the impact of various gas drainage designs on gas explosion risks within the goaf. Factors such as the number of active boreholes and completion depth are assessed, with the size of EGZ serving as a quantitative evaluation criterion. Therefore, this paper plays a pivotal role in optimising goaf gas drainage efficiency, striving to minimise gas emissions into the atmosphere while upholding the priority of mining and worker safety.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139660201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hyperspectral imaging of coal core: A focus on the visible-near-shortwave infrared (VN-SWIR) region","authors":"W.M. Langa ,&nbsp;C. Ndou ,&nbsp;L. Zieger ,&nbsp;P. Harris ,&nbsp;N. Wagner","doi":"10.1016/j.coal.2024.104456","DOIUrl":"10.1016/j.coal.2024.104456","url":null,"abstract":"<div><p>Analytical technology is constantly being developed, refined, and applied to different materials. A key objective is to develop technologies that are non-destructive, rapid, and improve data accuracy. Hyperspectral imaging (HSI) is a non-destructive analytical technique that measures the spectral response of molecular bonds within mineral crystals or organic matter, caused by their excitation by light. The technique has a potential to save time and money for the coal exploration and mining companies. Typically, minerals within borehole cores are characterised based on their unique spectral properties within specific infrared ranges and presented as a function of reflectance versus wavelength. to examine spectra generated on coal core samples using HSI. The HSI spectral data were compared to traditional approaches X-ray fluorescence, X-ray diffraction, proximate data, and Fourier-transform infrared spectroscopy (FTIR). A coal core from Witbank Coalfield, South Africa (Medium Rank C bituminous, inertinite-rich, generally high ash), was examined within the visible-near infrared (VNIR) (350–1000 nm) and shortwave infrared (SWIR) (1000–2500 nm) regions. The HSI coal spectra exhibit positive slopes with low reflectance values within the VNIR region and gradual increase of reflectance values in the SWIR region. The spectra are influenced by very-fine grained clay and Fe-rich minerals (pyrite and siderite) included in the coal; the latter was verified by XRD as pyrite and siderite. The spectra with higher amounts of organic matter are flat and the absorption features are weaker due to the absorbing nature of the carbon. The identified absorption features for coal functional groups within VN-SWIR are 1700 nm (C<img>H), 2200–2206 nm (CH₂, C<img>C, C<img>O) and ∼ 2310 nm (CH₃), which were confirmed by FTIR data. However, the absorption features between 2200 and 2450 nm are affected by overlapping bands of inorganic phases, resulting in uncertainty. The bright banded coal (vitrinite-rich) can be adequately separated from the dull coal (inertinite-rich) through the extraction (D) of D2200 and the deepest feature between D2100 - D2450. The technique can also distinguish the carbonaceous shale from coal, demonstrating the ability to differentiate rock types based on the mineral composition and proportions.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0166516224000132/pdfft?md5=0fd5edba47afeee15727cf92195383bf&pid=1-s2.0-S0166516224000132-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139655957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin of organic matter pore heterogeneity in oil mature Triassic Chang-7 mudstones, Ordos Basin, China","authors":"Yingzhu Wang ,&nbsp;Jijin Yang","doi":"10.1016/j.coal.2024.104458","DOIUrl":"10.1016/j.coal.2024.104458","url":null,"abstract":"<div><p><span>Organic matter (OM)-hosted pores play a crucial role in hydrocarbon storage and migration in unconventional shale oil<span> and gas systems. An accurate identification of different OM compositions is critical to understanding the origin of heterogeneity in OM-hosted pore development, which remains challenging due to the lack of apparent intrinsic connection between them. This study correlates light-electron-Raman spectroscopy to investigate various OM maceral<span> types and their molecular structures with respect to the pore characteristics in an oil mature Triassic Chang-7 lacustrine mudstone from the Ordos Basin, China. Moreover, the occurrence and distribution of soluble bitumen and its effect on OM-hosted pore development were directly characterized by comparison of a stitched large SEM image mosaic (∼1 mm</span></span></span>²<span><span>) before and after organic solvent extraction. Results show that terrestrial OM including </span>inertinite<span> and vitrinite<span> fragments display well-preserved biological structure and high reflectance intensity in light microscopy. They often are nonporous under SEM, and have no change before and after solvent extraction. Solid bitumen is the predominant maceral of the examined mudstone, and shows two general populations: 1) nonporous or weakly porous solid bitumen (SB1) that often occurs in large-sized and structured accumulation; 2) porous solid bitumen (SB2) that is filled or dispersed in mineral matrix. After extraction, SB2 was completely removed and have a noticeable recovery of pores, while SB1 changed slightly. The heterogenous pore characteristics can be related to the varying OM molecular structure which shows a decreasing trend of aromaticity in the order of terrestrial macerals, SB1, and SB2 as indicated by Raman parameters. A relatively higher pore abundance in SB2 may be attributed to chromatographic fractionation which led to more mobile and compliant components of SB2.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139523118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracing the geochemical imprints of Maastrichtian black shales in southern Tethys, Egypt: Assessing hydrocarbon source potential and environmental signatures","authors":"Douaa Fathy ,&nbsp;Alireza Baniasad ,&nbsp;Ralf Littke ,&nbsp;Mabrouk Sami","doi":"10.1016/j.coal.2024.104457","DOIUrl":"10.1016/j.coal.2024.104457","url":null,"abstract":"<div><p><span><span>This study conducted comprehensive bulk and molecular geochemical analyses, as well as elemental investigations, on seventeen black shale<span> samples collected from the Upper Cretaceous sediments on the western margin of the Red Sea. The primary objective is to assess the </span></span>hydrocarbon generation<span><span> potential, maturity, source input, biodegradation levels, and depositional environment characteristics within the Lower </span>Maastrichtian<span> interval near the Safaga area. Lower Maastrichtian black shales demonstrate very good to excellent source rock generative potential based on pyrolysis data. The prevalent kerogen type in the older black shale at the Heweitat mine is Type II, whereas within the younger units at the Queih mine, it predominantly exhibits Type II/III kerogen. These Maastrichtian black shales remain thermally immature, as evidenced by </span></span></span>vitrinite reflectance (VRr &lt; 0.5%), pyrolysis data, and biomarker proxies.</p><p><span>The studied black shales show that the organic matter input comprises bacterial and algal biomass<span> with minor terrigenous contributions. Additionally, there is no evidence of significant biodegradation in the studied samples based on molecular fossils data. Microscopic analysis and various bulk and molecular characteristics, in conjunction with major and trace element profiles, collectively indicate a marine depositional environment with oxygen-deficient bottom water conditions during </span></span>source rock deposition<span><span>. The presence of isorenieratene and aryl isoprenoids suggests persistent and episodic </span>photic zone<span> anoxia during the Maastrichtian period. Elevated nutrient inputs and paleobioproductivity were recorded in the older black shale at the Heweitat mine compared to the younger one at the Queih mine. Paleoproductivity and oxygen depletion emerge as pivotal factors influencing the accumulation and preservation of organic matter within the black shales. These findings provide valuable insights into the environmental conditions prevailing during the deposition of Maastrichtian sediments in the Eastern Desert.</span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139523115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic petrology in the service of public awareness: How safe are barbeque briquettes?","authors":"Maria Georgaki ,&nbsp;Małgorzata Wojtaszek-Kalaitzidi ,&nbsp;Kimon Christanis ,&nbsp;Stavros Kalaitzidis","doi":"10.1016/j.coal.2024.104448","DOIUrl":"10.1016/j.coal.2024.104448","url":null,"abstract":"<div><p><span>Charcoal has been an important source of energy for centuries and remains till today. Currently charcoal is used, mostly for cooking purposes, in the form of lumps, as well as processed in the form of briquettes. Charcoal briquettes are formed by compressing pyrolyzed biomass (charcoal) particles together with a suitable binder, such as </span>starch<span> mixed with water. Based on the European standard<span> EN 1860-2 (2005) the moisture and the ash yield for the dry charcoal briquettes shall not be above 8 wt% and 18 wt%, respectively, and the total of all detected inadmissible additions should not exceed 1 vol%. The main purpose of this study is to examine the quality of charcoal briquettes from the Greek market. Nine samples were purchased from various vendors in Patras and examined according to the EN 1860-2 (2005) standard. To assess their quality, incident light microscopy is applied to identify the pyrolyzed material and the range of impurities, including raw biomass<span>, mineral matter, plastic, metallic artifact, oxidized metallic artifact, particles of coal origin, etc. The petrographic analysis reveals that the content of impurities exceeds 1 vol% and that four (out of the nine) samples consist almost exclusively of coal particles. Considering the above and the public health hazards that are posed by grill fuel of subpar quality, the need for effective and reliable quality control methods is urgent. The petrographic analysis of charcoal briquettes seems to be the most appropriate technique.</span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139435493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early Cretaceous wildfires and their palaeoenvironmental significance in the Jiuxi Basin, Gansu Province, Northwestern China","authors":"Jianguo Hui ,&nbsp;Baoxia Du ,&nbsp;Mingzhen Zhang ,&nbsp;Shaohua Lin ,&nbsp;Dunzhu Jiaoba ,&nbsp;Jing Zhang ,&nbsp;Shuang Dai ,&nbsp;Aijing Li ,&nbsp;Jing Peng ,&nbsp;Guolong Liu","doi":"10.1016/j.coal.2024.104446","DOIUrl":"10.1016/j.coal.2024.104446","url":null,"abstract":"<div><p>The occurrence of palaeowildfires in terrestrial ecosystems<span> coincides with the colonization of plants, rendering it one of the most significant geological events and holding paramount importance for comprehending paleoclimate<span> and paleoenvironmental changes. This study provides strong evidence of persistent palaeowildfire occurrences in the Jiuxi Basin, Northwestern China, during the Aptian<span><span> to Albian period, considering the abundant, continuous, sedimentary charcoal </span>fossils<span> from the uppermost Chijinbao, Xiagou, and Zhonggou Formations of the Hanxia Section. Micromorphological studies based on the scanning electron microscopy indicate that substantial portion of the charcoal fossils originated from conifers. The fusinite reflectance values of the charcoal fossils range from 1.32% to 4.32%, indicating that the palaeowildfire temperatures may have been 330 °C to 700 °C, and can be divided into three stages, evolving from ground fires to surface fires and crown fires, and finally developing to ground fires. Furthermore, high atmospheric oxygen and seasonally dry climate promoted the frequent palaeowildfire environment in the Jiuxi Basin during the late Early Cretaceous<span>. However, the persistent and repeated wildfires may have effected the palaeoecosystem of the Jiuxi Basin during the late Early Cretaceous, which is evidenced by the decline of coniferous trees and the increase of the early herbaceous angiosperms.</span></span></span></span></span></p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139431437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic and microstructural properties of the lacustrine Chang-7 shale kerogen: Implications for in-situ conversion of shale","authors":"Changrong Li ,&nbsp;Zhijun Jin ,&nbsp;Liuping Zhang ,&nbsp;Xinping Liang","doi":"10.1016/j.coal.2024.104447","DOIUrl":"10.1016/j.coal.2024.104447","url":null,"abstract":"<div><p><span>In-situ conversion processes (ICP) represents an effective approach for the commercial exploitation of low- to medium-maturity shale oil. The thermodynamic and microstructural properties of kerogen, as the primary organic matter in shale, have important implications for the design and optimization of ICP. However, the thermodynamic and microstructural properties of the lacustrine Chang-7 shale remain unclear, and conducting ICP pilot tests continues to pose challenges. By employing elemental analysis, pyrolysis-gas chromatography/mass spectrometry (Py-GCMS), solid-state carbon nuclear magnetic resonance (</span>¹³<span>C NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy<span> (FTIR), the representative models for lacustrine Chang-7 shale kerogens with different organic matter types and maturity levels were established. Semiempirical quantum mechanics and molecular dynamics were leveraged to study thermodynamic and microstructural properties of kerogen. Subsequently, by integrating cluster analysis and partial least squares methods, quantitative correlations among kerogen structural parameters and thermodynamic, kinetic, and volumetric properties were identified. The findings suggest that low-maturity type I kerogen is predominantly consisted of long-chain aliphatic hydrocarbons, whereas the degree of aliphatic chain branching increases in type II</span></span>₁ kerogen. Medium-maturity type II₁ kerogen exhibits the highest degree of condensation, but the length and degree of branching of its aliphatic chains are closely analogous to low-maturity type I kerogen. Between 273 K and 473 K, the ideal heat capacity of Chang-7 shale kerogen increases linearly by approximately 51%. The enthalpy of formation and ideal heat capacity of medium-maturity type II₁ kerogen are the highest. With increasing maturity and declining H/C ratio, the density of Chang-7 kerogen increases. Its matrix pore sizes are primarily concentrated at 0.1–0.2 nm, constituting &gt;80% of all pores. Kerogen with long and abundant aliphatic chains, a moderate degree of condensation, high porosity, low activation energy, and moderate heat capacity is considered the preferred target. The findings offer substantial guidance for the ICP of lacustrine shale.</p></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139435525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An original set of nanometer-scale mineralogical analyses of cookeite and the implications for Li enrichment: No. 21 coal, Mengjin Mine, western Henan","authors":"Duoen Yuan ,&nbsp;Xiaomei Wang ,&nbsp;Detian Yan ,&nbsp;Jing Li ,&nbsp;Baoqing Li ,&nbsp;Bei Liu ,&nbsp;Zixuan Liu ,&nbsp;Liwei Zhang","doi":"10.1016/j.coal.2024.104445","DOIUrl":"10.1016/j.coal.2024.104445","url":null,"abstract":"<div><p><span>Critical elements in coal deposits, such as lithium (Li), have attracted attention recently due to their economic value. Many studies have suggested that the high enrichment of Li in coals is predominantly associated with cookeite, a Li–bearing chlorite mineral of hydrothermal origin. However, the identification of cookeite in coal has primarily relied on indirect methods, owing to the low atomic number of Li, which presents significant challenges for precise observation. The Shanxi Formation No. 2</span>₁<span><span> coal in North China is enriched in Li. This study established a nanometer–scale mineralogical analytical technique (including high–resolution transmission electron microscopy (HR–TEM), fast Fourier transformation (FFT), and standard mineral simulation single-crystal diffraction (SSCD)) for the identification of the cookeite and evaluated the Li enrichment mechanism and recovery in this coal (low–volatile bituminous to semi–anthracite) based on a model for the Li </span>mineralization. The Li content of the No. 2</span>₁ coal ranges from 25.2 to 203 ppm. The Li content shows a strong correlation with the ash yield, Al₂O₃, SiO₂<span><span>, and detrital elements, indicating a dominant aluminosilicate affinity and detrital origin. The major aluminosilicate minerals in coal are </span>kaolinite<span>, chlorite, and illite. The geochemical indicators (the Al</span></span>₂O₃/TiO₂ ratio and its relationships with the Zr/TiO₂<span>, Nb/Y, and Nb/Yb ratios) indicate that the sediment sources are determined to be intermediate–felsic igneous rocks, probably the Mesoproterozoic moyite (a type of K– feldspar granite) in the Yinshan Oldland. Additionally, the coal can be divided vertically into three sections (Sections I, II, and III), corresponding to three stages of peat formation. Overall, from Section I to Section III, the degree of detrital input increased, and the groundwater and marine influences strengthened and weakened, respectively. Section II exhibits anomalous Li enrichment mainly associated with reducing environments and the geochemical barrier caused by the interaction between infiltrating seawater and groundwater. The detrital kaolinite assemblage with authigenic minerals such as secondary REE–rich minerals (bastnasite), chamosite, and quartz, as well as the REY enrichment patterns, suggests that the No. 2</span>₁<span> coals, mainly Section II, may have existed the hydrothermal alteration<span>. Cookeite is identified primarily in Section II and coexists with kaolinite based on TEM observations, suggesting that the cookeite is of hydrothermal origin and formed from pre–existing Li–rich kaolinite. Most samples from Section II meet the mining grade of Be–Li–Nb–Ta ore deposits (Li</span></span>₂<span>O &gt; 0.2%). Thus, this study offers valuable insights into the extraction and recovery of Li from ","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139407650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}