Texture Of Cokes Research Articles

Insights on the regional thermal evolution from semianthracite petrology of the Fengfeng coalfield, China

Igneous intrusions induce alterations in coal and minerals. Alteration degree depends upon the in-situ coal rank and maceral composition, the intrusion temperature, heat source proximity, and intrusion size. In the Permo-Carboniferous Fengfeng coalfield, coal rank increases over some 50 km distance south to north from high volatile bituminous coal to anthracite. The coal seams were commonly intruded, and the regional elevation of rank was augmented by Jurassic-Cretaceous igneous intrusions, not just burial coalification. The petrographic examination of a semianthracite from the Dashucun mine in the north of the Fengfeng coalfield shows development of coke microstructure and increased reflectance approaching the dike in the No. 2 Seam. Based on 11 samples at 50-cm horizontal intervals, random vitrinite reflectance value (Rr) declines from 5.41% at the contact to the background value of 2.05% at 5-m distance from the contact. Towards the dike, vitrinite anisotropy increases and the microtexture shows development of circular, coarse mosaic, and ribbon anisotropic coke textures and devolatilization vacuoles. Natural coke textures respond to an estimated temperature > 570 °C at the intrusion/coal contact. However, the occurrence of coke structures within a semianthracite reveals a local and regional thermal evolution. Coke textures suggest that coal rank was high volatile A bituminous coal at the time of intrusion. This has implications for burial history, heating, and subsidence rates. Assuming a paleogeothermal gradient of 40 °C/km, high volatile A bituminous coal (1% Rr) would have been buried to 3 km at the time of the Jurassic intrusion. The intrusion metamorphosed high volatile bituminous coal to natural coke and subsequent larger-scale regional metamorphism then metamorphosed the coal to semianthracite.

INVESTIGATING RELATIONSHIPS BETWEEN INTRINSIC PROPERTIES, PREPARATION PARAMETERS OF COAL AND COKE QUALITY: A SYSTEMATIC LITERATURE REVIEW

The purpose of this study is to review some of the key research concepts related to metallurgical coke. As the research landscape for coke metallurgy is evolving, researchers are increasingly interested in the effects of the intrinsic properties of coal, coal preparation parameters, and the technological conditions of coke production on the quality of metallurgical coke. As part of this review, a specific protocol, content analysis and thematic coding of cases of the “Preferred Reporting Items for Systematic Review and Meta-Analyses” method were used to investigate the simultaneous effect of these two parameters on the quality of coke in selected journal articles. A review of 118 articles was conducted, including their abstract, introduction, methodology, and results. According to the results of this study, coal blends and coal particle sizes have a direct effect on the three sections of coke mechanical properties, coke texture, and coke reactive properties. Reviewing various articles has shown that the presence of fatty coals in smaller size distribution, combined with largersized weak coals, leads to the formation of a stronger structure in the produced coke. However, this does not guarantee an improvement in the coke reactivity parameters. On the other hand, increasing the blending ratio of coking coals in the final mixture for producing normal-sized coke (dimensions smaller than 3 millimetres) improves the coke reactivity parameters. Studies investigating coke structure have demonstrated that a cohesive mosaic structure in high-quality cokes results from well-distributed maceral blends of coking coals with optimal size distribution among other coals.

Novel method for coke optical texture measurement and application on coke derived from different ranks of coking coal

AbstractThe optical texture of coke is undoubtedly one of the important factors that determined many properties of coke, but it still mostly depends on the skills and experience of manual analysis. In this paper, a novel automatic measurement method is proposed for coke optical texture. this method through two analyzer angle images(10° and 170°) under polarizing microscope to recognize isochromatic regions which occurs color changed between blue and red by image processing, then characterize the dimensional sizes of isochromatic regions and classify them into different anisotropic texture type. Two fitted ellipse methods are used to characterize the regions' dimensional sizes by the range of shape factorS, followed by classifying different types of anisotropic texture according to the long and short axes of fitted ellipse. An automatic image acquisition and analysis system is established based on the above method. Finally, eight coke samples derived from different ranks of coking coal were selected to test the proposed method. The result shows that it can effectively recognize different types of anisotropic texture and provide composition of different anisotropic texture type for each coke. Moreover, the anisotropic degree of coke shows a significant positive correlation with parent coal rank and a negative correlation with coke reactivity index (CRI).

Flow structures and mineralisation in thermally altered coal from the Moatize Basin, Mozambique

This paper examines changes in structural and petrographic characteristics of organic and inorganic matter developed in a cored 35 m thick Permian coal seam from the Moatize Basin (Mozambique) in proximity to an Early Jurassic intrusive igneous body. Megascopic and microscopic examinations of hand samples and polished blocks, respectively, were carried out to characterise the deformation and petrographic changes of the coal. SEM/EDS analysis was used for mineral identification and modes of occurrence. The upper part of the core is thermally altered, exhibiting intense megascopic folding of the bedding. At microscopic level, vitrinite presents an incipient mosaic coke texture (semi-coke); whereas fusinite and semifusinite layers are deformed, exhibiting folded structures. Coal petrographic characteristics suggests the temperature in the coal at this location reached no higher than 400 °C but was enough for softening and ductile deformation of bands to occur.Apart from epigenetic chamosite occurring exclusively in the upper section, and monazite that appears only in the lower section of the core, microscopic studies showed similar distribution of the mineral species in both sections of the seam, except with a change in their mode of occurrence. Detrital or syngenetic minerals in the lower section of the seam occur also as epigenetic in the thermally affected upper section. Siderite occurs as syngenetic nodules in the lower section but appears as epigenetic fracture filling developed with the cooling of the organic material in the upper section. Quartz occurs as detrital grains in the lower section, whereas in the upper section this mineral occurs also as an epigenetic euhedral mineral filling the fracture system. Fluorapatite occurs as detrital, syngenetic and euhedral epigenetic. The mineralisation in the fractures also gives indications about the fluid circulation associated with the magmatic intrusion. At least three stages of hydrothermal fluids were distinguished (from the first to the last stage): a P/F- and Si-rich fluid, an Fe-, Ca-, Mg-rich fluid and an Al-, Si-rich fluid. These fluids gave origin to the minerals in the fractures and to some of the minerals inside the cell lumina of the inertinite macerals. Given the euhedral shape of some of the epigenetic minerals, there was sufficient time for them to grow into euhedral forms.

Revisiting the thermally metamorphosed coals of the Transantarctic Mountains, Antarctica

Petrographic and geochemical data for Late Permian coals and carbonaceous shales from the Transantarctic Mountains, Antarctica (source: Polar Rock Repository, PRR), were used to evaluate maturation levels and assess the effects of contact metamorphism. Coals were evaluated for locations in the Southern Transantarctic Mountains, the Central Transantarctic Mountains, and South Victoria Land, including samples from the Buckley, Mt. Glossopteris, and Queen Maud formations and the Weller Coal Measures. These formations have been intruded by sills and dikes of the Jurassic Ferrar Group (177–183 Ma) associated with the breakup of Gondwanaland. Proximate (129 samples), total sulfur (69) analyses, vitrinite reflectance analysis (92), and petrographic composition (34) were determined. One third of the samples have >50% ash yields (dry basis). A subset of samples (87) with <50% ash (dry basis) was treated with 6 N HCl to remove any carbonates formed during the intrusive events. Acid treatment did not significantly reduce ash, suggesting silicates are a major component; sulfur contents of 1–2% (dry basis) decreased to <0.8% reflecting gypsum dissolution (as confirmed by XRD). Volatile matter (VM) contents (dry, ash-free or daf basis) for samples with <50% ash range from 3 to 43%. Based on VM, samples range from high volatile bituminous to anthracite; however, reflectance analysis indicates anthracite to meta-anthracite, with some reflectances >7%. Thus, VM does not reveal true rank of the Antarctic coals. Vitrinite reflectance (Rr) typically surpasses that of inertinite. The VM–Rr relationship for these coals does not follow that of coals matured by normal burial maturation, but more closely follows that of intruded coals. Coke textures, including isotropic coke and anisotropic mosaics, vacuoles, pyrolytic carbon, and coked bitumen are observed, indicating alteration by contact metamorphism and providing insights to the rank of the coal at the time of intrusion. Coarse-grained circular and fine-grained lenticular mosaic textures suggest coal rank at the time of intrusion was medium volatile bituminous coal (maximum vitrinite reflectance ~1.2%). This would imply a burial depth by time of intrusion of ~5–5.5 km (assuming 25 °C/km) or ~ 4 km (assuming 34 °C/km). Modern-day background reflectance levels of ~2.5% Rr indicate continued post-intrusion maturation, possibly due to exposure to higher regional heat flow. Coals and carbonaceous shales from the Polar Rock Repository (PRR) can provide reliable petrographic and maturation data (using reflectance) to help decipher the burial history for various parts of the Transantarctic Mountains. However, geochemical data must be used with caution due to the high original inorganic content, and possible formation of gypsum and changes in VM during long-term storage. HCl-treatment removes some of the neoformed minerals, but samples should be treated extensively with HCl-HF to remove all silicate minerals prior to proximate and ultimate analysis to ensure more reliable data.

Microstructural evolution of metallurgical coke: Evidence from Raman spectroscopy

Raman spectroscopy traces the microstructural evolution of carbonaceous matter (CM) during artificial heating. Thermo-chemical reactivity and strength of blast furnace coke at 1100 °C is dependent on the graphitization state of the feed coke. A standard coke reactivity index (CRI) sample is composed of lumps, showing a high microstructural variability. The frequency distribution of the D-STA parameter estimated by the “Interactive Fitting of Raman Spectra” (IFORS) software suggests a positive correlation between degree of CM organization and CRI. Samples from the tuyere region of an operating blast furnace evidence graphitization of CM at temperatures higher than 1900 °C. IFORS parameters, calibrated by x-ray diffraction-based lattice dimensions and transmission electron microscopy data constrain a temperature gradient decreasing from the raceway to the deadman zone. The gradient controls a continuous variation of the petrographic coke texture. As an application, the IFORS method is able to map the graphitization zones in the hearth of a working blast furnace.

Coke texture, reactivity and tumbler strength after reaction under simulated blast furnace conditions

The reactivity and tumbler strength after reaction of cokes made from coals of different ranks and different regions of the world were tested under standard and simulated blast furnace (BF) conditions. The composition of coke optical textures and reactivity of different textures were investigated. It was found that reactivity and tumbler strength (I10600) after reaction of cokes are strongly related to the optical texture. For most cokes containing large amounts of isotropic textures, the reactivity index (RI) tested under simulated BF conditions is lower than CRI tested under standard conditions, and the I10600 under simulated BF conditions is higher than CSR under standard conditions. The reactivity of isotropic textures in most cokes is appreciably higher than that of anisotropic textures under standard conditions. Under simulated BF conditions, however, the reactivity of isotropic textures decreases significantly and the reactivity of anisotropic textures increases for the most part. This leads to narrowing the reactivity gap between isotropic and anisotropic textures.

Occurrences and origin of reservoir solid bitumen in Sinian Dengying Formation dolomites of the Sichuan Basin, SW China

Reservoir solid bitumen is pervasive throughout the Sinian Dengying Formation dolomites of the Sichuan Basin and neighboring areas, yet its origin remains controversial. Optical and scanning electron microscope (SEM) studies of the Dengying Formation were carried out to elucidate the nature and origin of the solid bitumen. Solid bitumen in dissolution pores, intercrystal pores, and stylolites appears to have formed in association with regional hydrocarbon charging processes. Reservoir solid bitumen displays a variety of morphologies, each of which appears to reflect different precursor hydrocarbons. Massive/crust-like solid bitumen was probably derived from solid precursors whereas finger-like solid bitumen likely evolved from liquid precursors. Sheet-like and thin skinned globular solid bitumen appeared to have precipitated from wet gas precursors. Analyzed solid bitumen is characterized by high random reflectance (average = 3.4%) and bireflectance values (4.2–6.9%), exhibits strong optical anisotropy, and displays different coke structures, including granular mosaic, domain, and fibrous. The coke textures, which appear to reflect the nature of bitumen precursors, formed by physical coalescence of mesophase spheres and parallel arrangement of laminated aromatic sheets in association with a rapid heating event. The inferred thermal episode, which is evidenced by the presence of hydrothermal minerals, including saddle dolomite, quartz, authigenic illite, and barite, may have been associated with the Late Permian eruption of the Emeishan Traps. Thus, widespread solid bitumen in the Dengying Formation reflects the effects of hydrothermal alteration rather than the impact of normal burial-related thermal maturation. Further, the close association of sold bitumen and authigenic kaolinite indicates that natural deasphalting plays a role in the formation of reservoir solid bitumen.

Coke Structure Evaluation for BF Coke Making

ABSTRACTThe microscopic structure and texture of coke are intrinsically important to the cold strength indices (M10 and M40) and hot strength indices (CRI and CSR) properties of the coke. Traditionally, Blast Furnace (BF) coke is characterized by its composition, porosity, and strength indices. There are different conventional methods for the determination of porosity as well as the structure of coke mass. In the present work, a comparative study was carried out for measurement and interpretation of the coke microstructure using volumetric analysis, image analysis, mercury porosimetry, and X-ray Computed Tomography (CT) scan measurements. The measurement of coke structural parameters based on image analysis provided information on porosity, pore size distribution, pore wall thickness, radius, perimeter, shape, and other structural parameters. Image analysis provided much more structural information on coke as compared to the volumetric method which is desirable for scientific investigation.

How coke optical texture became a relevant tool for understanding coal blending and coke quality

The scope of this work was to examine the cause-effect relationships between the characteristics of coking coals and blends, and the optical texture and the quality parameters of the resultant cokes. Although a detailed quantitative analysis of the several anisotropic carbon forms, according to size and shape, was carried out, the data used for the calculation of optical texture index (OTI) were compiled into only five microtextural categories: isotropic, incipient anisotropy, circular or mosaics, lenticular and ribbon. Considering the optical texture components of the carbon matrix of the cokes obtained from individual coals, a simple mathematical model is presented on the basis of the additivity law in order to estimate each optical texture component within the matrix of the cokes produced from coal blends. When looking at the good linear relationship between experimental and calculated data, it can be concluded that the proposed model is a useful way of describing the optical texture of cokes from coking blends. As an additional top objective of this study, the coal blends were made for the purpose of lowering the amount of high-cost coking coals. The individual coals and their blends were carbonized in a pilot scale coke oven and, then, the resultant cokes were evaluated in terms of mechanical strength before and after partial gasification with CO2. The degree of coke anisotropy clearly increased with the coal rank and it is correlated to coke reactivity and strength after reaction. From coke characteristics, the optimum quantity of each low-cost coal in the blends to avoid a deterioration of coke properties and structure was established.

Influence mechanism of zinc on the solution loss reaction of coke used in blast furnace

The influence mechanism of zinc on the solution loss reaction of coke at high temperature was studied using the method of liquid phase adsorption. The microcrystalline structure, pore structure, micro morphology and optical texture of coke were analyzed by X-Ray diffraction (XRD), BET, scanning electron microscopy (SEM) and optical microscopy in present research. The results show that zinc can increase the coke reactivity index (CRI) and decrease the coke strength after reaction (CSR). Furthermore, the CRI is the highest, as well as the CSR is lowest and the coke structure is severely damaged when the enriched zinc content in coke reaches to 1.17%. The results of XRD and polarizing microscopy show that the zinc catalysis on the solution loss reaction of anisotropic texture with higher degree of graphitization is larger than that of the isotropic texture. Combined with BET and optical panorama, it can be reveals that zinc can promote the generation and combination of coke pores during its catalysis process on gasification reaction, resulting in the increase of specific surface area and volume of micropores, which in turn provides favorable conditions for the permeation of zinc vapor and the kinetics condition of gasification reaction, thereby the reaction is further intensified. Meanwhile, large connected pores and honeycomb cavern caused by catalysis reduce the coke strength greatly. A compound phase containing zinc was not found in the reacted Zn-enrich coke after careful inspection through SEM/EDS and XRD, which reveals that the catalysis is derived from zinc. The zinc catalysis on the solution loss reaction of coke is mainly attributed to accelerating the decomposition of the ketone group, promoting the formation of CO gas.

Effects of Two-stage Heat Treatment on Delayed Coke and Study of Their Surface Texture Characteristics

In the present study, surface texture features and chemical properties of two types of cokes, made from coal tar by either 1-stage heat treatment or 2-stage heat treatment, were researched. The relationship between surface texture characteristics and the chemical properties was identified through molecular weight distribution, insolubility of coal tar, weight loss with temperature increase, coking yield, and polarized light microscope analysis. Rapidly cleared anisotropy texture in cokes was observed in accordance with the coking temperature rise. Quinoline insolubility and toluene insolubility of coal tar increased with a corresponding increases in coking temperature. In particular, the cokes produced by the 2-stage heat treatment (2S-C) showed surface structure of needle cokes at a temperature approximately 50°C lower than the 1-stage heat treatment (1S-C). Additionally, the coking yield of 2S-C increased by approximately 14% in comparison with 1S-C.

Effects of organic liquids on coking properties of a higher-inert Western Canadian coal

The effect of organic liquids (white spirit, perchloroethylene and methylene bromide) typically used in float/sink gravity separations (specific gravity 1.4–1.8) on the fundamental properties of a higher-inert Western Canadian metallurgical coal of mvb rank (Romax 1.22) and its resultant coking ability were examined. Over a 6-month period, untreated (control) and treated coal were characterized using a wide range of analyses including elemental chemistry, FTIR spectroscopy, alkali extraction via light transmittance test and thermal rheology, specifically fluidity, Dilatation, FSI and Caking Index G. Exposure to organic liquids was found to have a minor effect on coal chemistry (Ultimate) and oxidation level (Alkali Extraction via Light Transmission Test and FTIR-Spectroscopy). Trends of H/C, O/C, Light Transmittance and FTIR absorbance spectra versus storage time, following initial 1h exposure to the organic liquids of varying specific gravities, revealed only minor changes, within the scatter/accuracy of the measurements. However, several coal plastic properties were decreased significantly including Gieseler Maximum Fluidity, Dilatation and G Caking Index. Of these, most affected was Maximum Fluidity which underwent an immediate and dramatic decrease of over 80% following organic liquids treatment. Other rheology indicators including FSI and Sapozhnikov were significantly less sensitive in detecting initial stages of degradation in plastic properties. The coking ability of both the untreated and treated coal in perchloroethylene (PCE) organic liquid, s.g. 1.6, after storage for 1 and 6months was assessed through carbonization trials in both a small-scale sole-heated oven (12.5kg capacity) and in a pilot-scale movable wall oven (350kg capacity) at CanmetENERGY Carbonization facility, Ottawa, Canada. The treated samples had appreciably poorer quality ambient (ASTM, IRSID, JIS tumbler tests) and hot (CSR, CRI) coke strength and modified coke structure. Coke ASTM strength for untreated and treated coal at time 1month was respectively decreased from 62 down to 57 for Stability and from 72 to 67 for Hardness. Similarly, Coke CSR and CRI for untreated and treated coal at time 1month was respectively decreased from 74 down to 58 and increased from 21 to 29. The treated sample resulted in a lower coke yield, 71%, in comparison with 78% for the untreated sample, produced coke of smaller mean size, 46mm, than the untreated sample, 53mm, and generated an appreciably higher fraction of fines (−12.5mm), 21%, than untreated sample, 4%. The coke textures from the untreated coal consist of higher carbon forms, mosaic and flow in medium size, compared to those from s.g. 1.6 treated coal of lower carbon forms, very fine and fine mosaic, which renders the coke more reactive to CO2 gasification during CSR test. The higher effective coking rank, 1.2, and Coke Mosaic Size Index, 2.4, of untreated sample relative to that of treated one, 1.1 and 2.2, respectively, supports the better coke quality of the untreated sample. Extension of storage time to 6months resulted in negligible changes in coke quality showing that the greatest changes occurred within the first month following exposure to organic liquids. Comparison of 1month untreated and PCE treated mid coking rank Western Canadian (Romax 1.22) and Australian (Romax 1.17) coals show both to undergo comparable decrease in fluidity (50–60%) post treatment with PCE although only the Western Canadian coal leads to lower dilatation. Coke yield is also decreased for the Western Canadian coal and essentially maintained for the Australian coal. Both CSR and CRI are affected negatively and more so for the Western Canadian coal, 16 point drop in CSR and 8 point increase in CRI, relative to the Australian coal, 3 point drop in CSR and 4 point increase in CRI.

Influence of presence/addition of asphaltenes on semi-coke textures and mesophase development in petroleum feed stocks

In this paper, effect of asphaltenes on optical textures of semi-coke and pitches prepared from vacuum residues (VRs) and their deasphalted oils (DAOs) during heat treatment at a temperature 390°C was investigated. Optical microscopic image analysis shows that VR-1 which contains 10.44wt% asphaltenes produces semi-coke VR-390-1 having 29vol% mesophase content and flow type coalescence. On the other hand, VR-2 which contains 24.57wt% asphaltenes produces semi-coke VR-390-2 having 27vol% mesophase content and mosaic type texture. Further, it was observed that deasphalting of these vacuum residues improve the optical textures as well as enhance the mesophase content in DAO-390-1 (48vol%) and DAO-390-2 (36vol%) semi-cokes. Furthermore, we have also concluded that asphaltenes molecules affect the growth of mesophase development in an adverse manner. In this study, we have prepared pitches from clarified oil (CLO) and aromatic extract (AE) having very low asphaltenes content at temperatures 380 and 390°C respectively without and with the addition of 3% asphaltenes. Optical microscopic images of these pitches show that mesophase contents were decreases with the addition of asphaltenes externally. In addition, semi-cokes and pitches were also characterized by using elemental analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analyses (TGA). The study revealed that asphaltenes either present in the feed stock or externally added in the feed stock play a negative role on mesophase development as well as on coke texture.

Effects of coal moisture control and coal briquette technology on structure and reactivity of cokes

In this work, the influences of coal moisture control (CMC) and coal briquette technology on structure and reactivity of cokes were investigated by adding a certain proportion of briquette into raw coal with different moisture. The coking experiments were carried out in a tested coke-oven of 70 kg, and the properties of as-obtained coke were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and so on. The coke reactivity index (CRI), coke strength after reaction (CSR) and the optical texture of different cokes were also measured. The results indicated that the two technologies both can improve the structure of coke and reduce the reactivity of coke. The improved coke properties can be attributed to forming a more compact microcrystalline structure of coke to enhance its pore wall structure, its optical texture index (OTI) and its graphitization degree. Noticeably, the introduction of CMC technology in coal briquette process can produce the superposition effect to the great improvement of the coke properties. In addition, the results also indicated that the introduction of CMC technology in coal briquette process can reduce the sulfur content of coke due to the overflowed sulfur in the form of gas during the coking, and can almost be equivalent to substitute 10% briquette in coal briquette process in the improvement of the CRI and CSR from coke, implying the reduced amount of briquette to save coal resources.

Influence of alkaline (Na, K) vapors on carbon and mineral behavior in blast furnace cokes

A series of adsorption–alkalization experiments were conducted in a muffle furnace on two types of blast furnace cokes at 1300°C in the presence of alkali vapors. Coke textures were found to peel off layer by layer after the alkalization process by potassium vapor, and macro fissures were observed for K/Coke ratios higher than 3/100. This phenomenon was not observed in the coke samples alkalized by sodium vapor. A number of additional potassium-bearing and sodium-bearing phases were detected with scanning electron microscope and energy dispersive spectrometer after the alkalization process. The formation of kalsilite or potassium aluminum silicate (KAlSiO4) and sodium alumina silicates (Na6Al4Si4O17) was confirmed through X-ray diffraction, however the formation of intercalation compounds that were expected to form in the alkalized coke samples could not be confirmed. The catalytic effect of sodium and potassium-bearing minerals appeared to be quite similar; the degradation of coke strength by sodium was however found to be stronger than that caused by potassium. The severe degradation of coke quality caused by alkali vapors was attributed to their strong influence on the coke carbon matrix, coke minerals, as well as their catalytic effect on the carbon gasification reaction.

Reprint of “The original concept of description of the coke optical texture”

The aim of the present study was to prove that the image analysis is a useful tool in coke texture characterization. The authors proposed the method of measurement of the gray color gradient vector in the prepared microscopic images with visible anisotropic effects. The research was performed for totally different samples of chars and cokes. The total texture fibrosity index for each sample was determined. The results show a strong positive correlation between proposed fibrosity index and technological parameters according to NSC test (CRI, CSR). The new parameter characterizes with universal character resistant to changes in conditions of coking process and coked coal properties.

The original concept of description of the coke optical texture

The aim of the present study was to prove that the image analysis is a useful tool in coke texture characterization. The authors proposed the method of measurement of the gray color gradient vector in the prepared microscopic images with visible anisotropic effects. The research was performed for totally different samples of chars and cokes. The total texture fibrosity index for each sample was determined. The results show a strong positive correlation between proposed fibrosity index and technological parameters according to NSC test (CRI, CSR). The new parameter characterizes with universal character resistant to changes in conditions of coking process and coked coal properties.

Effects of rapid thermal alteration on coal: Geochemical and petrographic signatures in the Springfield (No. 5) Coal, Illinois Basin

Igneous intrusion into a coal bed can change the geochemical and petrographic properties of the coal including vitrinite reflectance, maceral petrographic composition, optical texture, mineralogy, stable isotope composition, trace element composition, and bulk geochemistry. The intent of this study was to evaluate petrographic and geochemical changes in an intruded coal and compare them to trends seen in coals altered by normal burial maturation, thereby evaluating whether or not the intruded coals followed a different maturation pathway. The current study reports petrographic, bulk geochemical (proximate, ultimate), Leco total organic carbon (TOC), and Rock-Eval pyrolysis data for a suite of samples from the Springfield (No. 5) Coal (Pennsylvanian, Desmoinesian) in the southern part of the Illinois Basin where the coal had been intruded by a Permian-age peridotite dike.Petrographic analysis shows an increase in vitrinite reflectance (Rm) from background levels of 0.55–0.63% up to ~4.80%, a loss in ability to differentiate liptinite macerals, formation of isotropic coke and, at the dike/coal contact, development of fine-grained mosaic anisotropic coke texture. Volatile matter (VM) content decreases and fixed carbon (FC) content, ash, and mineral matter (Parr formula) increase approaching the intrusion contact. Carbon increases whereas nitrogen, hydrogen, and oxygen decrease approaching the intrusion. The presence of carbonate minerals (confirmed by X-ray diffraction and petrographic analysis) has a significant impact on proximate and ultimate data. However, even after removal of carbonates, trends for VM vs. Rm, %C vs. Rm, and H vs. C do not follow typical trends associated with normal burial coalification. Approaching the contact, Leco TOC, Rock-Eval free oil content (S1), remaining hydrocarbon potential (S2), CO2 from pyrolysis of the organic matter (S3), and hydrogen (HI) and oxygen (OI) indices decrease whereas thermal maturity (Tmax, °C) increases. S2 vs. Rm and Tmax vs. Rm diverge from the pathways seen in previous studies of coals that have undergone normal burial maturation.Geochemical data from this study suggest that the intruded Springfield (No. 5) Coal may have followed a maturation track that differed from that seen under normal burial maturation, perhaps due to the geologically rapid, high heating event associated with the emplacement of the intrusion. It is also suggested here that the natural coke textures produced by this rapid geological heating may differ from those observed for metallurgical cokes produced under standard industrial coking conditions. Typically, in an industrial coke oven, a coal of this initial rank (Ro=~0.6%) would produce an isotropic coke, rather than the fine-grained circular anisotropic coke seen here. However, as variations in heating rate, duration of heating, maximum temperatures attained, hydrothermal conditions, and pressure are mostly unknown for the intrusive event, it is not unreasonable to suggest that differences in these variables contributed to the higher anisotropy of the coke. Alternatively, the development of this texture may reflect “pre-heating” of the coal during the intrusion event.

The Influence of Plastic Properties of Coal Blends on Evolution of Reflectance Indicating Surface (RIS) Parameters of Cokes

Abstract The aim of this work was to characterize cokes optical texture influence of plastic properties of coal blends on degree of cokes optical texture ordering. Three samples of coal blend characterized by different composition and properties were pyrolysed in Karbotest furnace (laboratory scale). To characterize plastic properties of the blends studied, temperatures at the beginning, maximum and at the end of plasticity (t1, tmax and t3, respectively) were determined as well as maximum fluidity Fmax. Texture of resultant cokes was determined by means of optical microscopy. As the result of these studies a set of optical parameters that describe reflectance indicating surface such as maximum, intermediate and minimum reflectance (RMAX, RINT, RMIN respectively) as well as values of Killby’ transformates (Rst, Ram, Rev) were determined for each sample. The optical texture parameters of the cokes were discussed in relationship to plastic properties of coals blends. Correlation between cokes anisotropy and fluidity of initial blends was detected.