International Journal of Coal Geology最新文献

{"title":"Palaeoenvironmental reconstruction of the coal-forming conditions during Oligocene in Niger Delta, Southern Nigeria: Implications for organic matter preservation and hydrocarbons potential","authors":"J.E. Ogala , K. Perleros , E. Kyriazaki , M. Angelopoulos , O.I. Ejeh , M. Wojtaszek-Kalaitzidi , S. Kalaitzidis , K. Christanis","doi":"10.1016/j.coal.2025.104807","DOIUrl":"10.1016/j.coal.2025.104807","url":null,"abstract":"<div><div>Twenty eight (7 coal, 12 organic-rich and 9 inorganic) cutting samples obtained from six boreholes drilled over a <em>c</em>. 60-km<sup>2</sup>-large area in the alluvial plain of Niger River between Obomkpa and Issele-Azagba, southern Nigeria, were examined and evaluated by means of coal-petrography, mineralogical (XRD) and geochemical (CHNS, Rock Eval, XRF) analyses. This study aimed to provide an initial assessment of the palaeoenvironmental conditions during the Oligocene-Miocene peat accumulation.</div><div>As the samples were received a long time after sampling, moisture could not be determined. The ash and the volatile matter yields of the samples vary from 19.9 to 88.5 wt% (db) and 63.5–67.9 wt% (daf), respectively. Huminite is the dominant maceral group ranging from 60.6 to 90.6 vol% (on mineral matter-free basis), with detrohuminite being the major sub-group. The inertinite content is very low (<1.5 %), whereas liptinite macerals are frequent to quite enriched (8.8–37.9 %) with alginite and liptodetrinite being the most common. The mean random huminite reflectance of all the coal samples varies between 0.32 % and 0.39 %.</div><div>As mainly sandstones, intercalated with siltstones and claystones are the main sedimentary rocks deposited in the Niger-River alluvial plain, the inorganic part of all the studied coaly and carbonaceous samples consists primarily of quartz and kaolinite, whereas goethite, mixed clay layers (illite-montmorillonite), anatase and gypsum occur in minor amounts. Accordingly, SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> display values ranging from 9 to 58 % and up to 23 wt%, respectively, while Fe<sub>2</sub>O<sub>3</sub> up to 12 wt% and TiO<sub>2</sub> up to 2 wt%.</div><div>Palaeoenvironmental geochemical proxies indicate a mixed source area for the siliciclastic facies, with significant recycling and weathering, deposited under a pure freshwater regime. The carbonaceous layers seem to have been deposited in a relative semi-arid climate, while the palaeomires were established under a more humid regime, promoting anaerobic conditions, which is in agreement with the observed very low inertinite content. Facies diagrammes based on the maceral contents were applied to reconstruct the environmental conditions in the palaeomires. According to the TPI <em>vs.</em> GI diagramme, the peat-forming vegetation was mostly herbaceous yielding low TPI and medium GI values, and the conditions were fluvial-limnotelmatic. The GWI <em>vs.</em> VI diagramme points to herbaceous vegetation on the palaeomire surface and mesotrophic water conditions with intense mineral matter influx from palaeo-Niger River. The area received frequent rainfall along with river flooding; thus, peat remained water-logged. Within the several hundred metres thick alluvial sediments, only short periods of limnotelmatic conditions prevailed in the area, yielding coal beds less than 17 m thick. The small number of the available cores distribut","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104807"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942439","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":"Reflectance as an indicator of biochar permanence","authors":"Maria Mastalerz ,&nbsp;Agnieszka Drobniak ,&nbsp;Bei Liu ,&nbsp;Peter E. Sauer","doi":"10.1016/j.coal.2025.104809","DOIUrl":"10.1016/j.coal.2025.104809","url":null,"abstract":"<div><div>Biochar, a carbon-rich product of biomass pyrolysis, holds considerable potential for carbon sequestration, soil amendment, and environmental remediation. Its effective application, however, hinges on understanding biochar permanence and on employing robust methodologies to reliably assess its stability and reactivity.</div><div>This study investigates the relationship between reflectance and the chemical composition (elemental ratios and organic functional groups) of biochar produced from sycamore wood, wheat straw, and peanut shells across well-controlled pyrolysis temperatures ranging from 300 °C to 700 °C, aiming to assess the potential of biochar reflectance as an indicator of biochar permanence.</div><div>The results demonstrate strong correlations between biochar reflectance and H/C and O/C molar ratios and show that the reflectance increases systematically with pyrolysis temperature. A strong correlation between the elemental O/C ratio and the FTIR-derived ratio of oxygenated groups to aromatic carbon across different pyrolysis temperatures provides additional valuable insights for predicting biochar stability.</div><div>The findings point to pyrolysis temperature as the dominant factor influencing biochar longevity and reinforce the suggestion that biochars with reflectance values above 2.0 % are non-reactive and are expected to be stable in the environment for a very long time. The results highlight biochar reflectance as a rapid and effective proxy for predicting biochar permanence, supporting its utility in carbon sequestration and environmental management.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104809"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070582","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":"Characterization of the ash samples before and after thermal processing aiming phosphorus extraction and residues valorization","authors":"Georgeta Predeanu ,&nbsp;Bruno Valentim ,&nbsp;Luminita Georgeta Popescu ,&nbsp;Alexandru Traian Abagiu ,&nbsp;Lucica Anghelescu ,&nbsp;Mihaela Niculina Bălănescu ,&nbsp;Barbara Białecka ,&nbsp;Elza Bontempi ,&nbsp;Magdalena Cempa ,&nbsp;Marius Florin Drăgoescu ,&nbsp;Alexandra Guedes ,&nbsp;Özben Kutlu ,&nbsp;Mattia Massa ,&nbsp;Elsayed Mousa ,&nbsp;Adrian Ionut Nicoară ,&nbsp;Hayati Olgun ,&nbsp;Valerica Slăvescu ,&nbsp;Bogdan Stefan Vasile ,&nbsp;Guozhu Ye","doi":"10.1016/j.coal.2025.104808","DOIUrl":"10.1016/j.coal.2025.104808","url":null,"abstract":"<div><div>This paper presents the prospect of phosphorus (P) - rich poultry litter manure ash (PLA) used to recover P through microwave heating methods, aiming for residual slag recycling in constructions.</div><div>The results show the complex composition of the ashes characterized by X-ray fluorescence (XRF), reflected light optical microscopy, X-ray microanalysis (SEM/EDS) and X-ray diffraction (XRD), which explains the differences between the ash types and the operation temperature in the combustion chamber. At the same time, the results present a novel approach of using microwave heating by reducing energy consumption to extract/enrich P from PLA and forming a by-product/residual slag used as a supplementary cementing material.</div><div>Samples of fly ash (FA) and bottom ash (BA) were collected from two fluidized bed incinerators (Güres and Beypi in Türkiye) operating at 750 °C and 850 °C within the PHIGO project funded by the 3rd ERA-MIN Program of the European Union Commission.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"307 ","pages":"Article 104808"},"PeriodicalIF":5.6,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221756","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":"Near surface lithium isotopic fractionation and lithium enrichment in coal-hosted Li-rich clays from the South China Block","authors":"Rongjie Wang ,&nbsp;Shifeng Dai ,&nbsp;David French ,&nbsp;Ian T. Graham ,&nbsp;Victor P. Nechaev ,&nbsp;Robert B. Finkelman","doi":"10.1016/j.coal.2025.104803","DOIUrl":"10.1016/j.coal.2025.104803","url":null,"abstract":"<div><div>Surficial low-temperature sedimentary clay-type Li deposit is one of three major types of Li deposits in the world; however, its formation and corresponding Li isotope fractionation mechanisms are still unclear. In this study, we demonstrate an unusually high Li concentration (89.1 ppm to 520 ppm) within a Late Triassic coal-hosted clay Li deposit from the Sichuan Basin, China. In-situ mapping of the Li distribution combined with isotopic analysis of Li occurring as clay-hosted ion-exchangeable and structurally bound Li was carried out to investigate low temperature Li migration and enrichment processes near the Earth's surface. The in-situ mapping shows that the dominant host of Li is fracture-fill and vermicular chlorite, while massive illite aggregate and fracture-fill paragonite contains lesser amounts of Li. Kaolinite and chlorite also absorbed a part of Li on surface/interlayer sites. The Li enrichment processes involve a contribution from detrital clastics (aggregate illite and kaolinite), especially felsic pyroclastics (vermicular-kaolinite) from collisional- and subduction setting, as well as the water-rock interactions during peat accumulation/burial stage between the acidic groundwater and primary Li-bearing clays. The primary kaolinite and illite was replaced with chlorite and paragonite accompanied with Li isotopic fractionation (Δ⁷Li: +2.67 ‰ to +15.4 ‰).</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104803"},"PeriodicalIF":5.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942437","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":"Biomechanics and physiology of Odontopteris cantabrica and Odontopteris schlotheimii (Medullosales, Pennsylvanian, Canada)","authors":"José A. D'Angelo ,&nbsp;James C. Hower ,&nbsp;Gerardo Camí ,&nbsp;Maiten A. Lafuente Diaz","doi":"10.1016/j.coal.2025.104804","DOIUrl":"10.1016/j.coal.2025.104804","url":null,"abstract":"<div><div>As part of the ongoing research project “<em>Chemistry, Biomechanics, and Physiology of Carboniferous plants</em>”, this study investigates two of the largest Canadian specimens of <em>Odontopteris cantabrica</em> <span><span>Wagner, 1969</span></span> (22-cm long) and <em>Odontopteris schlotheimii</em> <span><span>Brongniart, 1828-1831</span></span> (7-cm long) from the Pennsylvanian Sydney Coalfield. Specimens of both species co-occur in the roof shale of the Lloyd Cove coal seam (Asturian-Cantabrian boundary; vitrinite reflectance Ro% = 0.65) at Brogan's pit locality, Cape Breton Island, Nova Scotia, Canada. Well-preserved compressions of pinnules (rachises were not preserved) are analyzed by Fourier transform infrared (FTIR) spectroscopy. These data are examined with the purpose of (i) calculating pinnular density (δ) and associated biomechanical and physiological properties, i.e., tensile strength (TS = resistance to fracture), tensile modulus of elasticity (TME = stiffness), and leaf mass per area (LMA = biomass investment and construction cost); (ii) comparing the data for δ, TS, TME, and LMA of <em>O. cantabrica</em> and <em>O. schlotheimii</em> at two levels: interspecific differences and intraspecific variations between pinnules representing different (proximal and distal) parts of each frond; (iii) comparing data for δ, TS, TME, and LMA of <em>O. cantabrica</em> and <em>O. schlotheimii</em> with those of previously studied medullosalean frond taxa, namely <em>Alethopteris ambigua</em> and <em>Neuropteris ovata</em> var. <em>simonii</em>; and (iv) obtaining new insights into the possible growth habit of both fronds. Results indicate that pinnular density, resistance to fracture, stiffness, and leaf mass per area vary continuously throughout the fronds and indicate biomechanical resistance and physiological efficiency. ANOVA tests show that the pinnules of <em>O. cantabrica</em> and <em>O. schlotheimii</em> are not significantly different in terms of density and biomechanical/physiological characteristics overall. However, within each species, proximal pinnules exhibit statistically higher density, stiffness, resistance to fracture, and metabolic construction cost compared to distal pinnules. The δ, TS, TME, and LMA data for <em>O. cantabrica</em> and <em>O. schlotheimii</em> are notably lower than those of <em>N. ovata</em> var. <em>simonii</em> and <em>A. ambigua</em>. The order of values for δ, TS, TME, and LMA follows: <em>N. ovata</em> var. <em>simonii</em> &gt; <em>A. ambigua</em> &gt; <em>O. cantabrica</em> = <em>O. schlotheimii</em>. Considering the values for δ, TS, TME, LMA, and general morphology, it is possible that <em>O. cantabrica</em> and <em>O. schlotheimii</em> had a semi-self-supporting to self-supporting (arborescent) growth form.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104804"},"PeriodicalIF":5.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947695","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":"Application of image analysis to quantify maceral composition of source rocks: Examples from the Devonian New Albany Shale and Marcellus Shale","authors":"Hao Yuan ,&nbsp;Maria Mastalerz ,&nbsp;Bei Liu ,&nbsp;Simon Brassell","doi":"10.1016/j.coal.2025.104800","DOIUrl":"10.1016/j.coal.2025.104800","url":null,"abstract":"<div><div>The composition of sedimentary organic matter (OM) is an important parameter that determines the hydrocarbon potential and reveals the depositional conditions of organic-rich shales. Several automated analysis methods have been developed to determine the maceral composition of coals, but few studies have applied these techniques to assess the composition of OM in source rocks. This research developed an image evaluation method that combines maceral identification with machine-learning algorithms to quantify OM compositions. Three Devonian shales, two samples of New Albany Shale and one of Marcellus Shale, ranging from marginally mature to overmature were selected to evaluate the thermal evolution of maceral components, including vitrinite, inertinite, liptinite, and secondary products (i.e., solid bitumen and pyrobitumen). The method provides an efficient approach for identifying pyrobitumen and alginite in samples and is superior to automated coal analysis methods. Comparison of traditional point-counting methods with the new approach validates the effectiveness of image analysis in quantifying vitrinite and inertinite contents. However, the challenge of extracting amorphous OM mixed with mineral matter from the background requires further refinement. This methodological advancement provides a new tool for assessing the composition, sources, and thermal evolution of OM, offering valuable data to complement organic geochemical interpretations of depositional environments.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104800"},"PeriodicalIF":5.6,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931675","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":"Relating systematic molecular and textural properties of graptolite pyrolyzed via gold tube hydrous pyrolysis: Implications for thermal proxies in lower Paleozoic marine shales","authors":"Xiaowei Zheng ,&nbsp;Hamed Sanei ,&nbsp;Fujie Jiang ,&nbsp;Qingyong Luo ,&nbsp;Ye Wang ,&nbsp;Jennifer L. Nedzweckas ,&nbsp;Brett J. Valentine ,&nbsp;M. Rebecca Stokes ,&nbsp;Liu Cao ,&nbsp;Paul C. Hackley","doi":"10.1016/j.coal.2025.104793","DOIUrl":"10.1016/j.coal.2025.104793","url":null,"abstract":"<div><div>A series of gold tube pyrolysis experiments (72 h, 300–550 °C, 50 MPa) conducted on a graptolite-rich lower Paleozoic marine shale generated pyrolysis residues for a comprehensive evaluation of the molecular and structural variability of three types of graptolite periderm. Organic petrology, Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM) with energy dispersive spectroscopy (EDS) were combined to evaluate the thermal evolution process. The three types of graptolite periderm, namely granular, non-granular, and nodular graptolite, were analyzed by Raman spectroscopy wherein point measurements were obtained after the maceral was identified and the location verified by organic petrology. Distinct thermal evolution pathways among non-granular, granular, and nodular graptolite periderms were recorded. The evolution patterns of the Raman parameters, particularly D1 and G bands, highlight the differences in geochemical composition of the graptolite periderm types and the alteration of molecular structure with increasing thermal maturity. Raman parameters D1 (position of the D1 peak), G-FWHM (full width at half maximum of the G peak), and ratios D1-FWHM/G-FWHM (full width at half maximum of the D1 peak ratioed to G-FWHM) and A_D1/A_G (ratio of D1 and G peak intensities) showed effectiveness in assessing thermal maturity. Bireflectance with increasing gold tube pyrolysis temperature followed a hierarchy: non-granular &gt; granular &gt; nodular, reflecting different molecular alignment intensities. Qualitative FE-SEM evaluation showed that fine-grained mineral inclusions (primarily Fe-sulfide as determined via EDS) were associated with the graptolite populations, with granular graptolite containing greater amounts of coarser-grained (e.g., ∼300–1400 nm) mineral inclusions relative to non-granular and nodular graptolite, which contain finer-grained (e.g., ∼100–200 nm) inclusions difficult to resolve with optical microscopy. These findings are investigated to highlight the mechanisms that drive organic matter evolution within graptolite during thermal maturation, as well as to explore some of the limitations of using spectroscopic parameters as thermal maturity proxies.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104793"},"PeriodicalIF":5.6,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143935656","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":"Characterizing hydrocarbon-bearing fluid inclusions using CLSM-based microspectrometry with application to the Upper Permian rock salt in the Gorleben and Morsleben sites, Germany","authors":"J. Kus,&nbsp;L. Richter,&nbsp;G. Scheeder,&nbsp;C. Ostertag-Henning,&nbsp;M. Blumenberg,&nbsp;M. Mertineit","doi":"10.1016/j.coal.2025.104792","DOIUrl":"10.1016/j.coal.2025.104792","url":null,"abstract":"<div><div>Hydrocarbon-bearing fluid inclusions (HCFI) in halite from the Gorleben and Morsleben sites (Germany), petroleum from Gorleben, and epoxy resins have been analysed in-situ using a combined approach of confocal laser-scanning microscopy (CLSM), incident light, and transmitted light fluorescence microscopy. The HCFI contain vapour and liquid hydrocarbon phases and their optical appearance varies widely and distinctively. 405 nm based excitation allowed for in-situ CLSM-associated acquisitions and distinction of HCFI emission spectra for both sites. In contrast to transmitted light microscopy equipped with barrier filter &gt;515 nm, the CLSM-related emission &gt;410 nm employed full emission spectra essential for observation of the entire emission spectrum of HCFI. While maximum emission intensity (λ_max) of HCFI at the Gorleben site peaks at 455–456 nm, the corresponding λ_max at the Morsleben site ranges from 485 to 495 nm, indicating that emission spectra of HCFI at Gorleben site are “blue-shifted” in comparison to those at Morsleben. It is implied that the blue-shift is caused by a shift to a less aromatic/polar composition of the HCFI at Gorleben site. Both, HCFI and petroleum differ noticeably in spectral properties from epoxy resins indicating no contamination of epoxy resin in the examined thick sections. Coarse approximations of °API (a standard for petroleum liquid density), based on red/green coefficient (Q_max) and empirical correlation equation as well as direct measurements of °API, suggested markedly different °API gravities for Gorleben and Morsleben sites with higher °API values, of up to 52.4 for the first. Collectively, the results of this research study demonstrated the applicability and adaptability of CLSM as a well-advanced method to acquire in-situ spectral properties of HCFI in salt rock, as a basis for understanding hydrocarbon generation and migration in sedimentary environments.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104792"},"PeriodicalIF":5.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912502","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":"Assessment of biocoke behaviour in a ferromanganese smelting pilot furnace: A petrographic approach","authors":"M. Wojtaszek-Kalaitzidi ,&nbsp;M. Rejdak ,&nbsp;M. Książek ,&nbsp;S.Y. Larsen ,&nbsp;S. Rørvik ,&nbsp;R. Muzyka ,&nbsp;S. Drewniak","doi":"10.1016/j.coal.2025.104791","DOIUrl":"10.1016/j.coal.2025.104791","url":null,"abstract":"<div><div>This study presents a pioneering investigation into the behaviour of biocoke, particularly its biogenic component (biochar), during ferromanganese production. Employing μCT scanning, micro-Raman spectrometry, and organic petrology, the research explores the transformation of organic matter throughout different zones of a pilot ferroalloy furnace. The results reveal that the degradation of biocoke and its biocomponent varies significantly depending on the relevant position within the furnace and the temperature conditions. Notably, the biocoke with a 20 % charcoal addition maintained structural integrity and functioned effectively as a reducing agent, contrary to concerns about premature gasification due to the high reactivity of biochar. Microscopic analysis confirmed the presence of partially preserved biochar even at the furnace's lowest levels, indicating active participation in the reduction process. Furthermore, the study provides compelling evidence of partial graphitisation within both the coke matrix and the biogenic component, most likely facilitated by catalytic effects from molten and/or vaporised metals such as iron and manganese at temperatures exceeding 1500 °C. The occurrence of semi-graphitic structures was confirmed by Raman spectroscopy. The work also advocates for a distinct classification of organic inerts of biomass origin, acknowledging their unique gasification and thermal behaviours. This classification should be refined through broader studies involving diverse biochar sources and interlaboratory comparisons. The findings validate the viability of biocoke as a sustainable and economically feasible reductant in ferroalloy production, as demonstrated through the Biocoke4FAI research project.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"306 ","pages":"Article 104791"},"PeriodicalIF":5.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923677","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":"Systematic differences in the microstructure of cokes made from medium/high-reflectance Northern hemisphere and Australian coals","authors":"Eugene Donskoi ,&nbsp;Andrei Poliakov ,&nbsp;Lauren Williamson ,&nbsp;Oliver Scholes","doi":"10.1016/j.coal.2025.104790","DOIUrl":"10.1016/j.coal.2025.104790","url":null,"abstract":"<div><div>Cokes prepared from Northern Hemisphere (NH) and Australian coals (AU) were characterised by structural/textural parameters obtained using automated optical image analysis. Comparison of matched cokes from NH and AU with similar parent coal rank and amount of vitrinite revealed significant differences between their structural parameters.</div><div>The study showed that, NH cokes had coarser structure, including larger porosity pockets, coagulated nodes and connecting walls. However, AU cokes had more connections/walls per unit area which in total were thicker. Inert Maceral Derived Components (IMDC) in NH cokes were smaller, more rounded and less elongated. The IMDC boundary smoothness was higher in NH cokes. There are fewer voids within Reacted Maceral Derived Components on the IMDC boundary in NH cokes, and the average size of these voids is significantly larger. Porosity in AU cokes was more tortuous and there was less fine optically recordable porosity in NH cokes.</div><div>For all 26 structural parameters where the difference between NH and AU cokes was significant and where the correlation of each parameter with RMax obtained from a large set of Australian cokes was also significant, the difference was such that the structure of Australian cokes was corresponding to higher RMax than matched NH cokes.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"305 ","pages":"Article 104790"},"PeriodicalIF":5.6,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143902060","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}