Letteratura scientifica selezionata sul tema "Coal"

A detailed coal-petrographic and mineralogical-geochemical study of humic coals and coaly rocks in the Sargaev deposits of the Upper Devonian of the Northern Timan (Sula River), which is an example of the burial of the most ancient coal-forming plants, has been carried out. The following types of organic rocks are identified in the section: “jet-like” coal, liptobiolitic silty-clayey coal, and silty-clayey-coaly mixtolites. The studied coals and coaly rocks are composed of humic organic components, represented by vitrinite and liptinite macerals, the inertinite group is of subordinate importance. Vitrinite macerals include gelinite, collotelinite, and telinite (xylenite), liptinite macerals include sporinite, cutinite, liptodetrinite, bituminite, alginite, and a resinous substance, and inertinite macerals include inertodetrinite, semifusinite, fusinite, and funginite. The level of organic matter maturity according to the vitrinite reflectance RV = 0.45–0.55%, corresponds to the transition from proto- to meso-catagenesis (gradations PC3–MС1). The mineral component of mixtolites and high-ash coals consists of kaolinite, chlorite/smectite (with a predominance of the chlorite component) and quartz.

Upper Triassic coaly and lacustrine source rocks complicate efforts to determine the source of hydrocarbons in Sichuan Basin. Total organic carbon analyses, pyrolysis experiments, petrological examinations, and gas chromatography and gas chromatography–mass spectrometry determinations were conducted on coals, carbonaceous mudstones and mudstones collected from two outcrop sections and cores of nine wells. Results revealed that the abundant organic carbon content will prolong the hydrocarbon generation cycle for coals and then the hydrocarbon generating capacity of coals will be enhanced by salinization, thereby contributing bacteria and algae microorganisms into humic coal of the Xujiahe Formation. Compared with mudstone, coal with the same maturity has a stronger adsorption effect on free hydrocarbons. When Ro is greater than 1.35, coal still has a strong hydrocarbon generation ability. The stable water column stratification and euxinic bottom water conditions are evidenced from the lower Pr/Ph and the higher gammacerane indices. The mixing of sea water has been proven by the existence of 4α,23,24,-trimethylcholestanes.

The composition characteristics of altered coals in the Huaibei Coalfield, China, was investigated through a comparative analysis between altered and unaffected coals from the Wolonghu, Taoyuan and Renlou coal mines. Results indicated that the altered coals in Wolonghu coal mine are mostly anthracite coals, with a maximum vitrinite reflectance of 1.6–3.9% (average of 2.9%). Coals from Wolonghu coal mine were mainly consisted of vitrinite (66.2–97.0%), followed by inertinite (2.0–4.0%) and exinite (0.4–6.9%). Differences in volatile matter content were observed between the altered coals in Wolonghu coal mine and unaffected coals from neighboring coal mines, implying that the chemical composition and maturity of coals were changed after magmatic alteration. In addition, differences in hydrogen element were noted among the coals from Wolonghu, Renlou and Taoyuan coal mines, and the phenomenon of “deficient in hydrogen element” was observed in Wolonghu coals. The aliphatic hydrocarbon structure parameters suggested that the aliphatic chain lengths of Wolonghu coals are shorter than those of coal samples from the Renlou and Taoyuan coal mines. In addition, maturity is positively correlated with hydrogen enrichment degree, but negatively related with aliphatic hydrocarbon structure. Coals from Renlou and Taoyuan coal mines showed great weight loss with various heating rates at temperatures of 0–1000 °C, whereas those from Wolonghu coal mine had less weight loss.

Substitution of coal in coking coal blend with bio-coal is a potential way to reduce fossil CO2 emissions from iron and steelmaking. The current study aims to explore possible means to counteract negative influence from bio-coal in cokemaking. Washing and kaolin coating of bio-coals were conducted to remove or bind part of the compounds in the bio-coal ash that catalyzes the gasification of coke with CO2. To further explore how the increase in coke reactivity is related to more reactive carbon in bio-coal or catalytic oxides in bio-coal ash, ash was produced from a corresponding amount of bio-coal and added to the coking coal blend for carbonization. The reaction behavior of coals and bio-coals under carbonization conditions was studied in a thermogravimetric analyzer equipped with a mass spectrometer during carbonization. The impact of the bio-coal addition on the fluidity of the coking coal blend was studied in optical dilatometer tests for coking coal blends with and without the addition of bio-coal or bio-coal ash. The result shows that the washing of bio-coal will result in lower or even negative dilatation. The washing of bio-coals containing a higher amount of catalytic components will reduce the negative effect on bio-coke reactivity, especially with acetic acid washing when the start of gasification temperature is less lowered. The addition of bio-coal coated with 5% kaolin do not significantly lower the dilatation-relative reference coking coal blend. The reactivity of bio-cokes containing bio-coal coated with kaolin-containing potassium oxide was higher in comparison to bio-coke containing the original bio-coal. The addition of ash from 5% of torrefied bio-coals has a moderate effect on lowering the start of gasification temperature, which indicates that the reactive carbon originating from bio-coal has a larger impact.

The Queensland coal seam gas industry has grown over the last 12 years. During this time the vast majority of exploration wells have targeted the Late Permian coal measures in the Bowen and Galilee Basins. These formations have been the major target because they contain coals with a vitrinite reflectance ranging above 0.7%. This range has always been seen as the main period for methane generation.As well as containing vast quantities of Permian coal, Queensland also has vast quantities of Middle Jurassic coals within its Mesozoic Basins. These coals have received little-to-no exploration for their coal seam gas potential as they have always been interpreted as being immature for gas generation.Over 550 petroleum exploration wells drilled in the Mesozoic Surat Basin of eastern Queensland were reviewed to determine the coal volume of the intersected Walloon Coal Measures. A significant number have intersected large volumes of sub-bituminous to high volatile bituminous coals, in seams ranging up to 11.7 m in thickness. While the individual seams are not laterally persistent, the coal packages can be traced over hundreds of kilometres of the eastern Surat Basin.While only one well has tested the gas content, gas quality and saturation of the Walloon Coal Measures, numerous water bores have reported gas flows from the zone, and petroleum wells intersecting the formation have recorded high mud gas readings during drilling.The relatively shallow depth of the unit over much of the basin, the thickness of the coal packages, the proximity to major gas trunk pipelines and markets make the Walloon Coal Measures an ideal target for the next generation of coal seam gas explorers.

There are over 300 coal basins and deposits known in Kazakhstan, the largest of them is the Karaganda Coal Basin. There is approximately a half of all industrial reserved of coal of Kazakhstan is located in its subsoils. The Karaganda Coal Basin is the forth in the CIS according to its size and coal reserves. Unique coal resources require a comprehensive and scientifi cally justifi ed approach to their research. This paper studies the impurity elements distribution pattern to assess the geochemical speciation of coals in the Karaganda Coal Basin. As a result of the research performed, it has been found that the basin is characterized by mainly lithophylous and weal chalcophilous (Te, Cu, Ga, Ge) speciation. Siderofylous association is represented by Co, Ag. In the basin coal, increased concentrations of Ba, Sr, U, Sm, As, Sb, Fe, Br, La, Ce, Th, Cr, Hf, Cs, Co, Sc are detected if compared to the coal clarke, which is conditioned by the provenance area of the coal accumulation basin Қазақстанда 300-ден астам көмір бассейндері мен кен орындары белгілі. Қарағанды көмір бассейнінің жер қойнауында Қазақстандағы барлық өнеркәсіптік көмір қорларының жартысына жуығы шоғырланған. Қарағанды көмір бассейні көлемі мен көмір қоры бойынша ТМД-да төртінші орында. Көмірдің бірегей ресурстары оларды зерттеуге кешенді және ғылыми негізделген тәсілді қажет етеді. Жұмыста Қарағанды көмір бассейні көмірінің геохимиялық мамандануын бағалау үшін қоспа элементтерінің таралу заңдылықтары зерттелді. Жүргізілген зерттеулер нәтижесінде бассейн негізінен литофильді және әлсіз халькофильді (Te, Cu, Ga, Ge) мамандандырумен сипатталатыны анықталды. Сидерофильді ассоциацияны Co, Ag ұсынады. Бассейн көмірінде көмір кларкімен салыстырғанда Ba, Sr, U, Sm, As, Sb, Fe, Br, La, Ce, Th, Cr, Hf, Cs, Co, Sc концентрациялары жоғарылаған, бұл көмірді сақтау бассейнінің қоректену аймағына байланысты В Казахстане известно свыше 300 угольных бассейнов и месторождений, из них наиболее крупнейшим считается Карагандинский угольный бассейн, в недрах которого сосредоточена примерно половина всех промышленных запасов угля в Казахстане. Карагандинский угольный бассейн занимает четвертое место в СНГ по величине и запасам угля. Уникальные ресурсы угля требуют комплексного и научно-обоснованного подхода к их изучению. В настоящей работе изучены закономерности распределения элементов-примесей для оценки геохимической специализации углей Карагандинского угольного бассейна. В результате проведенных исследований установлено, что для бассейна характерна преимущественно литофильная и слабая халькофильная (Te, Cu, Ga, Ge) специализация. Сидерофильная ассоциация представлена Co, Ag. В углях бассейна установлены повышенные по сравнению с угольным кларком концентрации Ba, Sr, U, Sm, As, Sb, Fe, Br, La, Ce, Th, Cr, Hf, Cs, Co, Sc, что обусловлено областью питания бассейна угленакопления

This work investigated the effect of coal blending on ash fusibility and slurryability of Xinjiang low-rank coal. The results showed that Xinjiang low-rank coals were characterized by high internal water content, high volatile content, high ash fusing point, and poor slurryability, which can not be directly used in coal water slurry gasification. The blending method not only reduced the ash fusibility but also improved the slurryability of these low-rank coals. When the coals with low calcium and high silicon contents (KG and YK) were blended with coal with high calcium content (SH), the ash fusion temperatures of the blended coal were significantly reduced. Moreover, the SH coal showed the worst slurryability performance with a concentration of 48.56%. The slurryability of HS coal can be dramatically improved by blending with KG. When the mass fraction of KG coal reached 70%, the concentration of coal water slurry increased by 11%. For the blended coal of KG and YK, the concentration and stability of coal water slurry gradually increase with the increasing mass ratio of KG. The coal blending method can effectively improve the concentration of coal water slurry for the low-rank coals, which were difficult-to-prepare slurry.

The preservation of coking coal and the reduction of coke cost are gaining much importance in iron and steel industry. An effort is being made worldwide to maximize the use of inferior quality of coking coal in cokemaking without sacrificing the coke quality to minimize the coke cost. In general, Indian coking coals contain lower content of vitrinite (≤ 50%) and higher content of ash (≥ 15%) as compared to imported coking coal. Indian coking coals have poor washability characteristics also. Therefore, for making coal blend for coke making, selection of an appropriate proportion of Indian coking coals with imported coking coals is a major challenge for Indian steel industries. Proper selection of Indian coal not only reduces the coking coal import but also minimizes the coal blend cost with added benefits of the increase in the captive mine life. This paper touches the opportunities and challenges for efficient utilization of Indian coking coal as a component in the coal blend to produce the desired quality of coke.

Coal SJC, coal WJG, coal ZJM, and coal HCG were selected to investigate the pyrolysis kinetics of northern Shaanxi coals. TG and DSC experiments of four coals were carried out with a synchronous thermal analyzer at heating rates 5, 10, 15, and 20 C/min, respectively. The pyrolysis characteristics were described by thermogravimetric data, and the kinetic parameters were calculated by Flynn–Wall–Ozawa (FWO), Kissinger, general integration, and MacCallum–Tanner methods. The results show that coal SJC, coal ZJM, and coal HCG all conform to the reaction series equation, the thermal decomposition reaction rate is controlled by chemical reaction, and coal WJG conforms to Avrami–Erofeev equation. The activation energies of the four coals are 177.53 kJ/mol, 200.34 kJ/mol, 158.59 kJ/mol, and 240.47 kJ/mol, respectively.

Mercury in coals is one of the important sources of atmospheric mercury, which is potentially harmful to the ecological environment. Based on the data of 970 coal samples, the concentration, spatial distribution and occurrence of mercury in Chinese coals were analyzed. The main conclusions are as follows: The distribution of mercury concentration in Chinese coalfields is uneven; medium and high mercury coals are mainly distributed in southwest China and eastern Inner Mongolia. The mercury concentrations in various coal-forming periods are as follows: K (0.320 mg/kg) > P2 (0.220 mg/kg) > C3 (0.179 mg/kg) > J (0.177 mg/kg) > D (0.165 mg/kg) > P1 (0.136 mg/kg) > C1 (0.090 mg/kg) > E (0.086 mg/kg) > T3 (0.066 mg/kg). The mercury concentrations in different coal ranks are as follows: Lignite (0.164 mg/kg), long flame coal (0.078 mg/kg), non-caking coal (0.256 mg/kg), weakly caking coal (0.086 mg/kg), gas coal (0.151 mg/kg), fat coal (0.122 mg/kg), coking coal (0.171 mg/kg), lean coal (0.393 mg/kg), meagre coal (0.161 mg/kg), anthracite (0.160 mg/kg). Sulfide bound state is the main form of mercury in coals, and pyrite is the main occurrence medium.

In order to reduce expensive coke usage, blast furnace operators inject coal to replace a portion of the coke. However, the use of some injection coals can result in blast furnace instability and lowered permeability. This thesis is concerned with the injection of coal under entrained flow, high heating rate (104-106 °C/s) blast furnace conditions, namely the possibility of coal particle agglomeration via the use of caking coals. Methods of mitigating agglomeration via blending and pre-oxidation are tested, whilst the resultant performance implications of agglomerated coal chars are considered and analysed. A drop tube furnace (DTF) was used to experimentally test coal injection under conditions that are applicable to the blast furnace 'hot blast' region. Relatable DTF parameters include an operating temperature of 1100°C, and heating rate of 104 °C/s. Four industrial injection coals with varying volatile matter and caking properties were tested at both granulated and pulverised particle size specifications. It was found that coals defined as 'caking coals' showed consistent agglomeration during DTF injection, a potentially problematic effect regarding blast furnace injection. Agglomeration percentages (as defined by sieve classification) for the industrially problematic MV4 coal were 11% and 23% for the granulated and pulverised samples respectively. Blending of whole coals was effective in reducing the amount of agglomerated material in the char, as was sample pre-oxidation prior to injection. Regarding performance, agglomerated chars had greater combustion performance and gasification reactivity than the non-agglomerated samples. With agglomeration shown to be present under high heating rate conditions at temperatures akin to the blast furnace hot blast, it is concluded that agglomeration is a possibility during blast furnace injection. However, due to differing feed systems between the DTF and blast furnace, the precise form and extent of agglomeration in the blast furnace remains uncertain. Based on char combustion and gasification analysis, chars characterised by fine agglomerated material are not likely to be problematic for blast furnace operators relative to 'standard' injection coals.

Coal-bed methane (CBM), also referred to as Coal seam gas (CSG), relates to the production of methane from coal beds by drilling wells, hence lowering formation pressure, and triggering methane release. While the potential of this resource is significant, the assessment of the quantity and the producibility of methane from coal seams is highly variable. For this reason the objective of this work is to investigate the assessment of gas content, gas-in-place and coal permeability through petrophysical of analysis and by gaining a better understanding of coal bulk properties,. In this study 17 cored production wells were analysed from the Walloon Sub-group coal seams fairway in the Surat Basin in Queensland Australia, which is today the most ambitious investment in CSG worldwide. A total of 2374 coal beds were investigated to understand how the nature of the different coal lithotypes are reflected in core analysis, wireline logs measurements and DST test results, and how they affect coal quality, and control gas content, fracture development and reservoir permeability. High-resolution studies involving fine scale are required to estimate volumes and CSG formation evaluation turns to the interpretation of standard wireline tools readings in hundreds of coal seam wells. Nevertheless, the heterogeneous thin-bedded nature of coal seams, together with the fact that methane within coal is mainly stored by adsorption, create several difficulties in wireline log petrophysical analysis. Consequently core description is used to validate the combination of the density log with the shallow focused electric and induction resistivity measurements, benefitting the recognition and thickness estimation of thin coal beds and coal laminae rich mudstones. This observation, and a refined coal quality and gas content estimation methodology, are presented and tested against previously published workflows and provide an improved and tested strategy for petrophysical analysis of CSG.

This thesis describes various applications of high field n.m.r. for the elucidation of coal structure, and concentrates on discovering the chemical environments of the heteroatoms in coal i.e. those elements other than carbon and hydrogen. Chapter 2 describes how hydroxyl groups may be converted to trimethyl siloxyl groups, observation of which by 29si n.m.r. allows one to determine the types of hydroxyl functionalities present in the original material. Such derivatization methods are well known. However trimethyl siloxyl groups give 29si resonances that have predictable chemical shifts and so the derivative spectra of complex coal tars and extracts are easy to interpret. Using this technique we have investigated the nature of hydroxyl groups in a rank series of coal tars. This has given us some insight into the way the hydroxyls are affected by coalification. Chapter 3 is a demonstration of the use of n.m.r. as a detector for H.P.L.C. This has two principle novelties over previous work. Firstly it does not involve building a special probe and secondly, the data is presented as a contour plot of intensity vs. retention time and chemical shift. This method has been used to investigate the nature of several tar fractions and complements the derivatization technique of chapter 2. The final chapter shows how the nature of sodium in coal was determined by 23Na MAS-NMR. By using the information contained in the chemical shift and linewidths of raw and dried coal it was concluded that sodium exists bound to the surface of coal pores by oxygen functions such as carboxylates and phenoxides. It does not exist as sodium chloride microcrystals as once thought.

The main objective of this PhD thesis is the study of coal mine dust patterns produced by different types of mining operations and different types of coal. In addition, the potential links between oxidative potential (OP) of coal dust and its geochemistry have been investigated in order to identify indicators of potential concern for human health. To these ends, extensive particle size, chemical, mineralogical and OP analyses were carried out on: i) deposited coal mine dust collected in from different areas in underground and open-pit coal mines; ii) a selection of powdered coal samples from in-seam channel profiles covering a wide and contrasting variety of coal geochemistry patterns. In both cases, the respirable fractions (<4 µm) were extracted and analysed to simulate actual suspended respirable coal dust (PM4). The novelty of these sampling and analytical programmes made it necessary to calibrate and validate new methodologies, and design and implement new protocols, in order to separate the respirable fractions of dust and obtain comprehensive particle size, geochemical and mineralogical characterisations. The results of this thesis are summarised in five scientific articles in high-impact journals. Article #1 introduces the subject and includes a review of major health-relevant coal dust geochemical patterns. Articles #2 to #4 show results from the sampling of deposited coal dust in a number of underground coal mines (China and Europe) and an open-pit coal mine (China), and describe the separation and characterisation of respirable fractions. The samples were collected from different zones of the coal mines in order to encompass the most relevant mining operations being undertaken. In addition, in Article #5, powdered coal seam samples, covering a wide range of geochemical patterns from China, were used to separate and characterise their respective respirable fractions. In Articles #3 to #5 the respirable coal dust samples were selected (according to size and geochemistry) in order to evaluate the relationships among OP markers (ascorbic acid, AA; glutathione, GSH; and dithiothreitol, DTT). This toxicological methodology was applied using cross-correlation and multilinear regression analyses on underground mine dust samples (Article #3), open-pit mine samples (Article #4) and powdered coal samples (Article #5). The approach was repeated including both respirable fractions from deposited coal mine dust and from powdered coal samples (Article #5). Suspended coal dust measurements were reported in Articles #2 to #4 (Europe and China), including online ambient measurement of PM2.5, PM10, BC and UFP (PM <2.5 µm, <10 µm, black carbon, and ultrafine particles, respectively) around several mining open-pit mine (Article #4). The results of this thesis demonstrate that coal dust particle size is a key parameter controlling coal dust resuspension. Coal dust levels, also provide evidence that respirable coal dust levels are markedly higher in the working front areas. Moreover, concentrations and geochemical patterns of coal dust are noticeably influenced by the mining operations carried out in a given mine area. Results for the evaluation of the impact geochemical patterns on the OP demonstrated that OPAA is mostly linked with inorganic species, whereas OPGSH and OPDTT are linked with organic species of coal. The main drivers were found to be Fe, pyrite, sulphate minerals and anatase for OPAA, as well as moisture content, Ca, Mg, Na and Ba, for OPGSH and OPDTT. Furthermore, the correlations of the contents of most of these components in dust or coal with the OPAA, OPGSH and OPDTT increase only in high-rank coal or high coal-rank mine dust (mostly bituminous in this study). Moreover, PM10 measurements reported in this study demonstrate the importance of the effectiveness of dust control measures implemented in underground and open-pit coal mines in order to reduce airborne dust concentrations.
L’objectiu principal d’aquesta tesi doctoral és l’estudi dels patrons de la pols de carbó produïts pels diferents tipus d’operacions mineres i l’estudi dels principals patrons composicionals de diferents tipus de carbó, cobrint un ampli rang geoquímic. A més, la relació entre el potencial oxidatiu (OP) i la geoquímica de la pols de carbó va ser investigada amb la finalitat d’identificar possibles indicadors o traçadors potencials que puguin perjudicar la salut humana. Amb aquesta finalitat, es van dur a terme anàlisis de mida de partícula, químics, mineralògics i d’OP per a: i) la pols de carbó recol·lectat en diferents zones i processos miners per a mines de carbó subterrànies i de cel obert, ii) una selecció de mostres de perfils de capes de carbó moltes, cobrint una àmplia i contrastada varietat de paràmetres geoquímics dels carbons explotats actualment a la Xina. En tots dos casos, les fraccions respirables (<4 µm) van ser separades i analitzades per simular la pols de carbó respirable en suspensió (PM4). La novetat d’aquests protocols de mostreig i anàlisi van requerir tasques de calibratge i validació d’aquestes noves metodologies, i dissenyar i implementar nous mètodes per separar les fraccions respirables de pols i obtenir caracteritzacions completes de mida de partícula, geoquímiques i mineralògiques. L’article #1 és introductori i conté una revisió dels patrons geoquímics de la pols de mineria del carbó més rellevants per la salut humana. De l’article #2 al #4 es mostren resultats per al mostreig de pols de carbó dipositat a nombroses mines de carbó subterrànies (Xina i Europa) i una mina de cel obert (Xina), i descriu la separació i caracterització de fraccions respirables. Les mostres es van recollir a diferents zones de les mines per tal de cobrir les operacions mineres més significatives. També, les mostres de carbó molt de l’article #5, comprenent un ampli rang de patrons geoquímics a la Xina, es van utilitzar per separar i caracteritzar detalladament les fraccions de pols respirable. Als Articles #3 a #5 van ser seleccionades mostres de pols respirable (d’acord amb la seva mida i els patrons geoquímics) per tal d’avaluar les relacions entre els marcadors OP (àcid ascòrbic, AA; glutatió, GSH; i dithiothreitol, DTT) amb els patrons fisicoquímics més rellevants, duent a terme una anàlisi de relació creuada i regressió multilineal per a les mostres de pols de mines subterrànies (Article #3), mostres de pols de la mina de cel obert (Article #4) i mostres de carbó molt (Article #5). Finalment, les anàlisis van ser repetides incloent totes les fraccions respirables de les mostres dipositades de pols de carbó i de les mostres de carbó molt (Article #5). A més de les mesures de pols de mina respirable extretes de pols sedimentada o de carbó molt, es van reportar mesures directes de pols de mina en suspensió dels Articles #2 a #4 (Europa i la Xina), incloent-hi mesures ambientals de PM2.5, PM10, BC i UFP (PM <2.5 µm, <10 µm, carboni negre, i partícules ultrafines, respectivament) al voltant de diverses operacions mineres a la mina de cel obert (Article #4). Els resultats d’aquesta tesi doctoral subratllen la importància de continuar investigant sobre les propietats i nivells de pols a la mineria del carbó en el context de la millora de les condicions laborals dels miners, especialment atès que, probablement, es mantindrà una producció de carbó molt elevada a països com la Xina durant les dècades vinents.
El carbón ha sido un recurso muy valioso en nuestra sociedad durante siglos; sin embargo, sus beneficios como fuente de energía siempre han sido parcialmente contrarrestados por el daño ambiental causado por sus emisiones contaminantes. Aunque se han propuesto muchos acuerdos y políticas para reducir el uso de las energías fósiles, como el Acuerdo de París sobre el cambio climático que trata de reducir las emisiones de gases invernadero, el carbón se sigue consumiendo y produciendo actualmente a gran escala. Además, se pronostica que este escenario permanezca intacto durante las siguientes tres décadas. La exposición a elevados niveles de polvo de minería es considerada un factor de riesgo ocupacional muy importante para los mineros del carbón. Durante el paso del tiempo, las regulaciones mineras, los avances en la ingeniería minera y la mayor consciencia de la seguridad de los trabajadores del carbón ha fomentado mejoras en la protección ocupacional. A pesar de ello, la exposición ocupacional al polvo de carbón durante su minería y manipulación sigue siendo la principal causa de enfermedades pulmonares del polvo del carbón (CMDLD), como la neumoconiosis (CWP), la silicosis y la fibrosis masiva progresiva (PMF). Esto, en parte, probablemente se deba a la mejora en la eficiencia tecnológica de la maquinaria minera usada para trabajar el carbón, resultando en la emisión de partículas más finas y concentraciones más altas de polvo de carbón (al explotarse mayores cantidades de carbón), un efecto que ha estado relacionado con el incremento de CMDLD, afectando incluso a trabajadores más jóvenes. Sin embargo, a pesar de los cambios en los métodos mineros y sus emisiones de polvo, sigue existiendo una notable escasez de estudios paralelos sobre temas relevantes para la salud, relacionándolos con la inhalación de partículas en las minas de carbón modernas. El principal objetivo de esta tesis doctoral es el estudio de los patrones de polvo de carbón producidos por los diferentes tipos de operaciones mineras y el estudio de los principales patrones de distintos tipos de carbón cubriendo un amplio rango geoquímico. Además, se ha investigado la relación entre el potencial oxidativo (OP) y la geoquímica del polvo de carbón con el propósito de identificar posibles indicadores potenciales que puedan perjudicar la salud humana. Con estos fines, se llevaron a cabo análisis de tamaño de partícula, químicos, mineralógicos y de OP para: i) el polvo de carbón recolectado en diferentes zonas y procesos mineros para minas de carbón subterráneas y de cielo abierto, ii) una selección de muestras de perfiles de capas de carbón molidas cubriendo una amplia y contrastada variedad de parámetros geoquímicos de carbones explotados en China. En ambos casos, las fracciones respirables (<4 μm) fueron extraídas y analizadas para simular el polvo de carbón respirable en suspensión (PM4). La novedad de estos protocolos de muestreo y análisis hizo necesario calibrar y validar las nuevas metodologías, y diseñar e implementar nuevos métodos, con el fin de separar las fracciones respirables de polvo y obtener caracterizaciones completas de tamaño de partícula, geoquímicas y mineralógicas. Los resultados de esta tesis doctoral se incluyen en cinco artículos científicos publicados en revistas de alto impacto. El Artículo #1 es introductorio y contiene una revisión de los patrones geoquímicos más relevantes en la salud humana. En los Artículos #2 a #4 se muestran resultados para el muestreo de polvo de carbón depositado en numerosas minas de carbón subterráneas (China y Europa) y una mina de cielo abierto (China), asimismo se describe la separación y caracterización de fracciones respirables. Las muestras fueron recogidas en diferentes zonas de las minas de carbón con el fin de cubrir las operaciones mineras más significativas realizadas en ellas. Además, las muestras de carbón pulverizado del Artículo #5, que comprenden un amplio rango de patrones geoquímicos en China, fueron utilizadas para separar y caracterizar detalladamente sus fracciones respirables. En los Artículos #3 a #5, se seleccionaron muestras de polvo de mina y carbón molido (de acuerdo con su tamaño y los patrones geoquímicos) para evaluar las relaciones entre los marcadores OP (ácido ascórbico, AA; glutatión, GSH; y ditiotreitol, DTT) con los patrones fisicoquímicos más relevantes, llevando a cabo un análisis de relación cruzada y regresión multilineal para las muestras de polvo de minas subterráneas (Artículo #3), muestras de polvo de la mina de cielo abierto (Artículo #4) y muestras de carbón pulverizado (Artículo #5). Por último, se repitieron los análisis incluyendo todas las muestras de las fracciones respirables de las muestras depositadas de polvo de carbón y de las muestras de carbón pulverizado (Artículo #5). Además de las medidas de polvo de carbón respirable extraídas de polvo sedimentado o carbón pulverizado, se llevaron a cabo medidas directas de medidas in-situ y en continuo de polvo de mina en suspensión en los Artículos #2 a #4 (Europa y China), incluyendo medidas en aire ambiente de niveles de PM2.5, PM10, BC y UFP (PM <2.5 μm, <10 μm, carbono negro, y partículas ultrafinas, respectivamente) en torno a varias operaciones mineras en la mina de cielo abierto (Artículo #4). Los resultados de esta tesis doctoral demuestran que el tamaño de partícula del polvo de mina es un parámetro clave para el control de su suspensión. Los resultados también muestran que el tamaño de partícula del polvo depende de los contenidos de humedad y ceniza del mismo, que están negativa y positivamente correlacionados, respectivamente, con el porcentaje de las partículas finas en el polvo sedimentado/depositado. Basándose en la observación de los niveles de polvo de mina de carbón, los resultados evidencian que los niveles de fracción respirable son marcadamente superiores a las áreas del frente de trabajo de la capa de carbón. Desde allí, el polvo decrece considerablemente, aunque las fracciones finas sean fácilmente transportadas a otras partes de la mina, donde también reciben contribuciones de otras fuentes de emisión, como por ejemplo de la minería y manipulación de los estériles, transporte del carbón, sales del drenaje ácido de minas, desgaste de la maquinaria y erosión de galerías gunitadas. Estas contribuciones modifican notablemente el tamaño del polvo de mina y su composición, en comparación con el polvo proveniente del frente de trabajo donde se explota directamente la capa de carbón. Los resultados muestran, pues, que los niveles y patrones geoquímicos del polvo de mina de carbón están notablemente influenciados por las operaciones mineras llevadas a cabo en cada zona específica de la mina. La manipulación y el trabajo del carbón generan un polvo relativamente grueso, con proporciones variables de contenido mineral y matriz orgánica; mientras que la manipulación y el trabajo de los materiales de los estériles producen polvo fino y con alto contenido en ceniza, enriquecido en minerales como arcilla, cuarzo y calcita; los accesos a las galerías están caracterizados por bajos contenidos en polvo, pero con mayor proporción en material respirable, que contienen especies minerales enriquecidas en Ca, y también componentes potencialmente peligrosos (especies sulfatadas ácidas, Fe, As, Sb, entre otros) derivados de las sales de las aguas freáticas infiltradas, que se ven afectadas por el drenaje ácido de minas. El análisis de las fracciones respirables de las muestras de polvo mostró que la mayor parte de las ratios de concentración de las especies y elementos estudiados en ese polvo respirable versus el polvo depositado original fue menor o similar a 1.0. En cambio, ratios para minerales de la arcilla y algunos metales (Se, Mo, Pb, Zn, Sn, As, Cu, Sb, Ni, Co y Cr) alcanzó valores >1.0, indicando su enriquecimiento en su fracción respirable debido a su modo de ocurrencia más fino. Estos enriquecimientos pueden indicar la presencia de polvo proveniente de otras fuentes distintas a las emisiones de polvo de carbón del frente de trabajo, como el drenaje ácido de la mina y emisiones del desgaste de la maquinaria. Ello se ve corroborado por el hecho de que varios de estos elementos también tienen concentraciones más elevadas en PM10, comparados con el polvo respirable depositado. Así pues, aunque los niveles de PM son marcadamente inferiores lejos del frente de trabajo de la capa de carbón, su enriquecimiento en determinados metales y sales evidencian la importancia de monitorizar el polvo de minería en diferentes áreas de la mina, y no tan solo en el frente de trabajo de la capa. Los resultados de OP total (OPTOT) presentados aquí, junto con los de un artículo publicado en 2021 de polvo de mina de carbón en minas turcas, son pioneros en investigar las conexiones de los patrones geoquímicos del polvo de mina y OP. En esta tesis doctoral, los valores de OPTOT obtenidos para el polvo de carbón son marcadamente inferiores a los de otros estudios de PM publicados provenientes de los sistemas de metro urbano, PM en aire ambiente de áreas con altas emisiones de quema de biomasa doméstica y de calles urbanas transitadas. Se dedujo que las especies inorgánicas del polvo de carbón están más relacionadas con OPAA, mientras que las especies orgánicas lo están con OPGSH y OPDTT. Las especies y/o elementos que controlaron el OPAA fueron Fe, pirita, minerales sulfatados y anatasa, mientras que para los indicadores OPGSH y OPDTT fueron los contenidos en humedad (reflejando el contenido en materia orgánica carbonosa), Ca, Mg, Na y Ba. Además, las correlaciones de las concentraciones de la mayor parte de estos componentes en polvo de mina o carbón pulverizado con OPAA, OPGSH y OPDTT incrementaron cuando fueron evaluados sólo los carbones o polvo de carbón de alto rango (bituminosos en este estudio). Los resultados de la evaluación de las características geoquímicas de los carbones explotados en China que controlan el OP del polvo potencialmente generado durante su extracción y manipulación (Artículo #5) demuestran que los contenidos en pirita, ceniza, anatasa, cuarzo, S, Ti y varios metales traza, como Mn, Mo y U, gobiernan la OPAA. Por otra parte, al igual que lo deducido para el polvo de mina, es el contenido en la materia orgánica carbonosa el que gobierna los niveles de OPGSH y OPDTT de las muestras de carbón molido. Estos resultados son similares a los obtenidos en el polvo de mina de carbón respirable, indicando que la extracción de la fracción respirable de las muestras de capas de carbón pulverizado para su posterior análisis geoquímico y de OP se pueden utilizar como indicador del OP del polvo de mina de carbón, atendiendo a las limitaciones indicadas anteriormente, de las posibles fuentes de polvo adicionales a la del frente de trabajo en la capa. Los resultados de los indicadores de OP concuerdan con los de estudios y modelos previos que proporcionan evidencias de asociaciones de determinados elementos y especies en polvo de minería con la generación de especies reactivas del oxígeno (ROS). Especialmente en lo referente a las marcadas correlaciones entre Fe y pirita con OPAA, que demuestran la relevancia de los contenidos de Fe y pirita en polvo de mina y de carbón inhalables con el estrés oxidativo, incluyendo la posibilidad de provocar enfermedades pulmonares y el desarrollo de CWP. Las mediciones de PM10 realizadas en este estudio demuestran la importancia de aplicar medidas efectivas para el control del polvo de minería en las minas de carbón subterráneas y de cielo abierto para reducir su concentración. Especialmente relevantes son los altos niveles de polvo fino medidos en áreas donde los estériles son manipulados sin medidas de control, en la mina de cielo abierto. También, las mediciones in-situ y online de BC y UFP mostraron niveles de exposición moderados, obteniéndose niveles de exposición en cielo abierto comparables a los típicamente registrados en entornos de tráfico urbano intenso. Obviamente este no era el caso para los niveles de PM, siendo estos muy superiores en la mina. La baja dispersión atmosférica en el fondo de la mina de cielo abierto, en comparación con las áreas más elevadas, combinado con la alta maquinaria usada, y el denso tráfico de la zona, proporciona elevados niveles de contaminantes, en especial UFP y PM. Los resultados de esta tesis doctoral subrayan la importancia de seguir investigando sobre las propiedades y niveles de polvo en la minería del carbón en el contexto de la mejora de las condiciones laborales de los mineros; en especial debido a que probablemente se mantenga una producción de carbón muy elevada, en países como China, durante las próximas décadas.
Recursos naturals i medi ambient

Traditional float and sink analyses are undertaken to determine the washability of coal. Float and sink analyses are costly, require toxic heavy organic liquids and the procedure to wash and dry the float and discard fractions is lengthy. QEMSCAN has the ability to characterise particle density based on the mineralogical composition of the particle. The objective of this research is to determine if QEMSCAN is a viable alternative to float and sink analysis. Float and sink analysis typically requires coarse size fractions while QEMSCAN analysis requires samples to be crushed down to 1mm. Any crushing will liberate minerals, which will alter the particle density distribution. Crushing a large particle generates 'puzzle pieces' of the original particle. The smaller 'puzzle pieces' have densities frequently different to the original particle. A mineralogical based particle density prediction model confirms that the float and sink analysis data used in this study is valid. The measured ash contents for the different float and discard fractions were within the expected limits. It is observed that there are a set of controls over the liberation of particles when crushed. Particles in the low float fractions (<1.6g/cm3) predominantly comprise vitrinite rich coal with fine lamellae of kaolinite. The higher float fractions (>1.6-2.0g/cm3) comprise bright and dull coal incorporated into an 'inertodetrinite' texture. Cleats and kaolinite laminae serve as preferential cleavage planes in the lower density fractions, while bright and dull coal serve as preferential breakage planes in the higher float fractions. As a result, these phases are liberated and there is evidence to support that liberation of minerals have controls that can be identified and corrected for. Thus, washability can be determined using QEMSCAN since the significant effect of liberation can be calculated and corrected, for a specific coal type.
Dissertation (MSc)--University of Pretoria, 2015.
Geology
MSc
Unrestricted

The influence of the electrokinetic properties of coal on the adsorption and gasification activities of calcium acetate and potassium carbonate has been studied. It has been found from zeta potential measurements on lignite, subbituminous and bituminous coals that the coal particles are negatively charged in both acidic and basic solutions, although the negative charge density is more pronounced in strongly alkaline media. In general, the extent of calcium or potassium adsorption correlated with the negative zeta potentials. Calcium or potassium adsorption followed the order lignite > subbituminous > bituminous coal. Increased char reactivities were observed with catalysts loaded from basic or neutral solutions compared to catalysts impregnated from acidic solutions. The enhanced activities are attributed to increased contact between the anionic coal surface and the metal ions during catalyst loading. It is suggested that the extent of coal-catalyst interaction during catalyst loading from solution plays an important role in coal char reactivity.

Coals contain considerable amounts of oxygen in their structures ranging from 30% in brown coal to about 1.5% in anthracites. The distribution of coal oxygen in various functionalities changes drastically with increasing rank. The hetero-atom functionalities in coal and coal products are of importance in the processing of coal. The process of coal conversion relevant to the steam and gas turbine applications are pyrolysis, oxidation and combustion processes. Initial stages of pyrolysis and oxidation (combustion) are the thermal decomposition of the solid coal matrix to free radicals. Oxygen, sulfur, nitrogen and mineral containing free radicals play an important role during combustion thermodynamically. The differences between the coal functionalities in the solid coal matrix contribute to oxidation reactions of first and second order. The first and second order reactions affect the corrosion and deposition rates of the machine components differently. In this paper functionality differences of various coals with respect to their oxidation characteristics will be discussed.

This paper represents an analytical model for predicting mineral particle redistribution of coal blending during pulverized coal (PC) combustion in a pulverized coal-fired boiler. The objective of this research is to develop a computer program to perform the mass balance of total minerals after transformation during combustion. A MATLAB code was developed for coal blending mineral redistribution from single coal mineral redistribution in modular approach based on relative Hardgrove Grindability Index (HGI) of coals. The calculations of the single coal number of ash particles before and after combustion both for excluded and included minerals from the single coal proximate analysis, Malvern analysis, Computer Controlled Scanning Electron Microscopy (CCSEM) analysis, density and composition analysis were designed in a submodule. Utilizing single coal sub-module, the calculations of coal blending number of ash particles before and after combustion both for excluded and included minerals were designed in a module of MATLAB code. The blending modeling was designed to blend up to five sub-bituminous coals. Calculations were made for typical boiler combustion conditions ranging from 1,500K to 2,500K as flame temperature. The organically-associated ash content or mineral grains of each coal smaller than 1 micrometer was not included in the calculation of redistribution modeling. Coal particle fragmentation of blended coal was considered as same as single coal and size dependent phenomena. Partial coalescence model was assumed as more likely to occur. Blended coal was assumed to follow additive rule applied to mineral mass percentage based on sizes and mineral phase regardless grinding of coals separately or after blending if the HGI difference between highest and lowest HGI of coals arranged in ascending order stands within five. The modeling was demonstrated for KPU: AVRA and AVRA: Solntsevsky with specific blending ratio 80:20 and 20:80 respectively. The model for blended coal was validated by the mass balance of minerals before and after combustion. The resulting simplified particle size distribution of mass fraction of KPU: AVRA shows good agreement with experimental results of Kentucky #9 coal because of having a larger amount of included minerals of KPU coal. The model for blended coal mineral redistribution before and after combustion will be developed for the HGI difference between highest and lowest HGI of coals arranged in ascending order becomes greater than five and validated by minerals mass balance before and after combustion. This modeling will be used to predict number of mineral particles and its sizes that is a key parameter as to predict the problems like fouling and slagging and the related reduction of boiler efficiency. The results from this study will be further carried out to investigate ash deposition rates in post-boiler heat exchangers.

The Integrated coal Gasification Combined Cycle (IGCC) is considered to be a very clean and efficient system for coal-fired power generation. And given the development of 100 MW-scale solid oxide fuels cells (SOFCs), the integrated coal Gasification Fuel Cell combined cycle (IGFC) would be the most efficient coal-fired power generation system. However, more energy efficient power generation systems must be developed in order to reduce CO2 emissions over the middle and long term. Thus, the authors have proposed the Advanced Integrated coal Gasification Combined Cycle (A-IGCC) and Advanced IGFC (A-IGFC) systems, which utilize exhaust heat from solid oxide fuel cells (SOFCs) and/or gas turbines as a heat source for gasification (exergy recuperation). The A-IGCC and A-IGFC systems utilize a twin circulating fluidized bed coal gasifier consisting of three primary components: a pyrolyzer, steam reformer and partial combustor. The temperature of the steam reformer is 800 °C, and that of the partial oxidizer is 950 °C. Since the syngas, produced by pyrolysis and the reforming process involving volatile hydrocarbons, tar and char, contains carbon monoxide and hydrogen, the A-IGCC technology has considerable potential for higher thermal efficiency while utilizing low-grade coals. The coal types utilized in the study were bituminous Taiheiyo, sub-bituminous Adaro and Loy Yang coal. Milewski’s formula was used to model the circuit voltage of the SOFC. Cool gas efficiency increases, in order, from Taiheiyo coal to Adaro coal to Loy Yang coal. The A-IGFC system has the potential to achieve high thermal efficiency using various coals, with Loy Yang coal achieving the highest thermal efficiency. However, the drying process for Loy Yang and Adaro coal is an important issue.

Coal bound moisture is a key issue in pulverized coal fired power generation. Coal being hygroscopic, accumulates considerable surface moisture with seasonal variations. A few varieties of coals are having unusually high inherent as well as surface moisture that affects the pulverizer performance and results lower thermal efficiency of the plant. A proper coal drying is essential for effective pulverization and pneumatic conveyance of coal to furnace. But, the drying capacity is limited by available hot airflow and temperature of hot primary air. Even, use of high-grade coal for blending would not provide the entire useful heat value due to moisture, when used for matching power plant design coal parameters. Besides, the inefficient mining, transportation, stacking and associated coal fleet management deteriorates the “as fired” coal quality affecting cost while purchased on “total moisture and gross heat value” basis. Partial devolatilisation of coal in a controlled heating process, prior combustion in fuel-rich environment ensures better in-furnace flame stability and less residual carbon in product of combustion. It improves the opportunity of a lower flame zone temperature, delivering better control over thermal NOx formation from fuel bound nitrogen. The pulverized coal fired power plants use coal feeders in either gravimetric or volumetric mode of feeding that needs correction for moisture in coal which changes the coal throughput requirement. In this paper an integrated coal drying and partial coal gasification system model is discussed to improve the useful heat value for pulverized coal combustion of high moisture typical power coals so that related improvement in coal throughput can be carried out by application of suitable coal drying mechanism like Partial Flue Gas Recirculation through Pulverizer (PFGR©) for mitigating the coal throughput demand with optimizing available pulverizing capacity along NOx control opportunity without derating steam generation capacity of the boiler.

Combustion tests for 2 types of coal (SC and BT coals), which have similar combustion performance and main fraction in the ash compositions, were conducted, using an electrically heated drop tube furnace. The burning particles were sampled by the Low Pressure Impactor (LPI) and analyzed concentration of alkali metal in the collected particles. Furthermore, they were observed by a scanning electron microscope (SEM) to discuss formation behaviors of the fine particles during combustion. In order to elucidate the relationship between formation characteristics of fine particulates during combustion and coal types, analysis of included and excluded mineral particles in the raw coals was conducted by a Computer Controlled SEM (CCSEM). Additionally, the composition analysis of the mineral particles in the raw coal was also carried out, using an energy dispersive X-ray spectrometer (EDS). As a result, the particle size distribution of ash particulates formed was different each other for two types of coal. Especially for the fine particulates with the size of less than 1 μm, the result for SC coal showed much more fine particulates formation than those for BT coal. Sodium compounds were enriched in the fine particulates for both the coals. Shapes of the fine particles with the size less than 1 μm for both the coals were spherical. For the coarse particles, however, spherical particles were observed for only SC coal. This difference was due to difference of the characteristics of mineral particles in the raw coals. The CCSEM analysis indicated that the excluded mineral matters, which tended to fragment during combustion, were contained more in SC coal than those in BT coal. This is the reason why SC coal forms more fine particulates during combustion than BT coal. From the EDS analysis, moreover, content of sodium in the excluded minerals of SC coal was higher than that of BT coal. This result suggests that SC coal tends to form the spherical fine particulates, in which the sodium compounds are enriched, during combustion.

Low rank or grade coals (LGC) are widely distributed over the world. Coal plays a vital role in the global energy demand especially through power generation and it mitigates the energy poverty. The major challenges by the utility of coal as regarding to energy security, a risk of climate change, and increasing of the energy demands are the main portfolio to develop the advanced technology for coal beneficiation. The gradual depletion of high quality coal and cost effective which become a significant issue for power generation while the low grade coals were served as low cost fuel and as an alternative energy security issue. In current research the low grade coal (>35% ash) has been upgraded to higher grade (<10%) by chemical cleaning method. The low grade coal was selected from Mahanadi Coalfields Limited, Odisha, India. Each test was conducted of 50 g coal (250 μm particle size) with 40% NaOH at 100 °C for 3 h and followed with 20% of H2O2, H2SO4, HCl, and HF acids at similar conditions. The research study revealed that ash content (mineral matter) of coal is reduced to >70% by NaOH followed HF treatment as compared to other solvents. The greater liberation of mineral results increases the ash reduction from low grade coal because mineral associated in the coal matrix may formed elution by the leaching effect. The greater extent of demineralization was caused due to the high affinity of OH− and F− with minerals in the coal matrix. The characterization of pre and post treatment coal and coal ash was investigated by the FESEM, XRF and XRD analysis. Overall the current research study challenges the chemical cleaning of low grade coal has been efficient techniques for reducing the minerals to a certain limit.

In spite of the high ash content, Indian coals have been widely used for the generation of power and industrial steam in India. Being considered as the technology for future in terms of efficiency and cleaner environment, coal gasification carries much importance since India has a large amount of coal reserves. In this paper, the numerical simulations have been performed on gasification performance of three types of Indian coals in atmospheric as well as pressurized conditions in an entrained flow, air-blown tubular gasifier. In the model, continuous phase conservation equations are solved in an Eularian frame and those of particle phase are solved in a Lagrangian frame, with coupling between the two phases incorporated through interactive source terms. Phenomena such as devolatilisation, combustion of volatiles, char combustion & gasification and the dispersion of coal particles due to turbulence are taken into account. The P-1 model has been adopted for radiative heat transfer in which scattering is taken into account for the particles. It is observed that as the ash percentage increases, the heat and mass transfer are strongly affected and the gasification performance decreases. This is attributed to the lower char reactivity due to thick ash layers and lower oxygen and other gas diffusion rates. Various regions such as devolatilisation, combustion and gasification zones inside the gasifier have been identified using the temperature plots, devolatilisation plots and mass depletion histories of coal particles. The overall gasification performance indices such as carbon conversion, heating value of the exit gas and cold gas efficiency have been predicted.

A modified version of a commercially available General Electric MS7001E gas turbine has been successfully operated on synfuel derived from coal at the Cool Water Coal Gasification Program. This paper addresses Cool Water’s experience with the MS7001E gas turbine in base load applications; starting and operating reliability; maintenance experience; modifications to the gas turbine including fuel delivery, combustion and control systems; and, future applications of advanced gas turbines in Integrated Coal Gasification Combined Cycle (IGCC) service.

In china, many thermal power plants have to burn blended coals forced by the complexity of coal type and market tension and transportation pressure of coal purchasing. As a engineering implementation method of coal blending, “different coals grinding in different mills and then mixed burning in the furnace” has many advantages such as low investment, easy to control milling system parameters and can be optimized online, etc, compared with traditional coal blending methods. But it is limited by the number of mills and cannot achieve high-precision ratio of blending. To remedy this shortcoming, a model of two-level optimization of coal blending for the thermal power plant with direct blowing pulverizing system was established in this paper. The tradional coal blending was regarded as first step of optimization. The secondary optimization was implemented by adjusting the outputs of different mills, then the blend was changed to accurate ratio. Furthermore, since the existence of coal bunker, it made a time lag from coal discharge to combustion, meanwhile, the real-time load was unpredictable and the coal utilization rate was inconsistent of each bunker. The three reasons make it uncertain of the current coal of bunker. To identify each coal in the mill(equivalent to bunker) correctly was the basis of achieving the second blending optimization. Therefore, a soft-sensing model of coal moisture based on the heat balance equation was used to take this work. At last, a intelligent coal blending system by the two-level optimization model was developed for a power plant and achieved good results.

Explosibility measurements on coal dusts from the Cape Breton Development Corporation's Lingan Mine, TransAlta's Highvale Mine and the Quintette Mine in B.C. have been carried out along with some tests on Pittsburgh Standard coal dust. The Quintette coal dust would not explode in the classical Hartmann apparatus, but did explode in the new 20-L vessel using a more powerful ignition source. The minimum explosible concentrations of the Lingan, Highvale and Pittsburgh coal dusts were all about the same (40 - 45 mg/L), that of the Quintette was higher (140 mg/L). The difference may be attributed to the much greater mean particle size of the Quintette dust. The explosion pressures (in kPa) were: Highvale, 600, Pittsburgh, 520, Lingan, 510, and Quintette, 440. The minimum oxygen concentrations required for explosions were (in % oxygen): Highvale 10.4, Lingan 10.5, and Quintette 14. The minimum ignition temperatures of dust clouds were (in °C): Highvale 510, Lingan 600, Quintette 620 and Pittsburgh 620. Further work is required to reconcile limit values.

Indonesia, the world’s third largest coal producer after China and India, committed to becoming a “net-zero” economy by 2060 at the UN Climate Change Conference (COP26) in Glasgow in 2021. However, reaching this objective will be difficult, given the importance of coal for both the country’s economy and power generation, but also necessary. Included in the many challenges are diverging visions of stakeholders as to how and sometimes whether to phase out coal usage, and how to follow a “just energy transition” pathway. This paper, based both on a desk review of scientific and other literature and on in-country stakeholder consultations, explores how those diverging visions and priorities might hinder a coal phase-down and, in the end, a phase-out of coal in Indonesia. In addition to exploring those visions, the report also sheds light on the socio-economic barriers to a truly just energy transition in the country.

The findings reported in this paper provide insights into the power dynamics and distributional politics that shape resistance to phasing out coal and to opportunities for change, as part of a broader project comparing these lessons and experiences in Colombia, South Africa and Indonesia, aiming to understand challenges to a just energy transition in coal-producing countries in the Global South. The current Colombian government has helped centre the concept of a just energy transition in public debate, encompassing a broad range of questions and concerns. National, regional and local discussions have different frameworks and visions for a future beyond fossil fuels, particularly regarding coal, which is a major export commodity but not a major fuel for domestic use in Colombia. For thermal coal–producing regions in Colombia, this debate touches on the challenges of both the legacy of extractive activities and the repercussions of losing a significant industrial sector, affecting local and regional economies and communities. Drawing on a series of workshops, a literature review, and interviews around transitions from coal in the Colombian departments of Cesar and La Guajira, researchers identified different visions of a just energy transition put forward at the national and regional levels, as well as some of the interests and strategies leveraged by different actors and groups in pushing certain visions of such a transition. In addition to presenting these results, the authors of this report provide insights into the power dynamics that shape resistance to phasing out coal and opportunities for transitions to more sustainable futures, with a strong emphasis on the efforts of civil society to create and achieve their visions of transition.

This file provides whole-rock assay and supporting metadata for samples of coal and associated sediments from mine and outcrop sites in central and eastern Montana. These assays are to investigate the critical mineral potential of coal in Montana.

Although coal has powered the nation for generations and today offers well-paying jobs—often the best opportunities in more rural areas—coal negatively affects human health and the environment at every point in its life cycle: when it is mined, processed, transported, burned, and discarded (Freese, Clemmer, and Nogee 2008). Local communities— often low-income communities and/or communities of color—have for decades borne the brunt of these negative impacts, including air pollution, water pollution, and work- place injuries, illnesses, and fatalities.

Although coal has powered the nation for generations and today offers well-paying jobs—often the best opportunities in more rural areas—coal negatively affects human health and the environment at every point in its life cycle: when it is mined, processed, transported, burned, and discarded (Freese, Clemmer, and Nogee 2008). Local communities— often low-income communities and/or communities of color—have for decades borne the brunt of these negative impacts, including air pollution, water pollution, and work- place injuries, illnesses, and fatalities.