High Inertinite Coal Research Articles

Occurrence of Differences between Alkali and Alkaline Earth Metals (AAEMs), Including Sodium, Potassium, Calcium, and Magnesium, in the Maceral Groups of the Xiheishan Coal, Zhundong Coalfield, Xinjiang, China

This study investigated the differences and correlation between the occurrence characteristics of alkali and alkaline earth metals (AAEMs) among different maceral groups in high-alkali, high-inertinite coal, and provides scientific guidance for the co-separation of AAEMs and inertinite groups in Xinjiang coal. The total AAEMs of inertinite-enriched samples were significantly higher than those in raw coals and vitrinite-enriched samples. Five-step sequential extraction showed that Na mainly occurs as water-soluble sodium (Na-Water) in raw coal and inertinite-enriched samples, accounting for about 53% of the total content, while it exists as organic sodium (Na-NH4Cl and Na-EDTA) in vitrinite-enriched samples, accounting for about 52% of the total content. Ca and Mg are both mainly present in organic form (Ca/Mg-NH4Cl and Ca/Mg-EDTA) in all the samples, with slightly higher proportions present in vitrinite-enriched samples. The contents of K are low in all the samples, which exist in an insoluble state (K-I). Combined microscopy and SEM-EDS analyses have revealed that the localized enrichment of Na in raw coal and inertinite-enriched samples occurs in the inertinite cell cavity, which primarily exists as NaHCO3 combined with quartz crystals, with a maximum content of up to 5.85 wt%. In this study, although EDS spectra could not directly characterize organic Ca and Mg, dolomite and calcite minerals were repeatedly found in the inertinite cell cavity. Moreover, the contents of Ca and Mg in the vitrinite-enriched samples were significantly lower than those in the other samples, which suggests that Ca and Mg are enriched with the inertinite groups. The localized enrichment of AAEMs could not be detected in any of the vitrinite-enriched samples. In summary, though there are significant differences between the occurrence modes of AAEMs in different maceral groups of high-alkali coal, AAEMs have a strong affinity with inertinite, which may be due to the inertinite’s abundant pore structures.

Ignition Studies on High-Vitrinite and High-Inertinite Coals Using TGA/DSC, DTIF, EFR, and 20 L Dust Explosive Chamber

The aim of this work was to study the ignition behaviour of eight coals of different coal ranks, petrographic compositions, and places of origin. The research allows us to gain deeper insight into the ignition mechanism and the relationship between certain properties of coals and their behaviour during ignition. The methodology utilised standard fuel ASTM data, petrographic analysis, pyrolysis and oxidation reactivity, and ignition characteristics generated through lab-scale tests using various ignition measurement methods. The results show that, in the dust explosion, a homogeneous ignition of coal dust took place. The ignition potential was the highest for coals with a high content of liptinites and a low content of inertinites. The ranking of coals in terms of ignition potential under these conditions can be determined on the basis of the measurements of the devolatilization rate. During the combustion of coal dust in TGA/DSC, a dust cloud, and a pulverised fuel stream, the ignition of particles was performed according to a heterogeneous mechanism. The study showed that the reflectance index may be the most reliable method of predicting and comparing ignition temperatures of both vitrinite-rich and inertinite-rich coals. Due to the lack of regularity in the ignition temperatures of some coals, depending on the proportion of inertinites, the petrographic composition of coal cannot be used to predict ignition temperatures during the combustion of coal dust. The ranking of the coals according to their ignition potential can be determined using TGA/DSC.

Chemical structural characteristics of high inertinite coal

Inertinite content is a main factor affecting oil yield. In this study, raw coal with high inertinite content was selected to investigate the chemical structural characteristics of inertinite of different densities. Inertinite-rich (>1.30 kg/L) in raw coal was further separated into low (LDI, 1.30–1.38 kg/L)- and high (HDI, >1.38 kg/L)-density samples via density flotation. Structural models of raw coal, LDI, and HDI were built on the basis of the analytical results obtained from solid-state 13C nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The characterization data and molecular structural models showed no significant difference in the aromaticity of raw coal, LDI, and HDI, and the types and quantities of structural units in all samples were nearly identical. Bond length and bond order data obtained by using quantum chemical calculation were simultaneously combined with the molecular structural models, and raw coal, LDI, and HDI demonstrated progressive differences in number of active breaks of chemical bonds and fragment structures after bond breakage.

Recurrent palaeo-wildfires in a Cisuralian coal seam: A palaeobotanical view on high-inertinite coals from the Lower Permian of the Paraná Basin, Brazil.

Distribution and abundance of charcoal in coal seams (in form of pyrogenic macerals of the inertinites group) have been considered as a reliable tool to interpret the local and regional palaeo-wildfire regimes in peat-forming depositional environments. Although the occurrence of inertinites is globally well documented for the Late Palaeozoic, the description of palaeobotanical evidence concerning the source plants of such charcoal is so far largely missing. In the present study, we provide the first detailed analysis of macro-charcoal preserved in the Barro Branco coal seam, Rio Bonito Formation, Cisuralian of the Paraná Basin, Santa Catarina State, Brazil. Charcoal, in form of macro-charcoal and inertinites, was documented in all the six coal-bearing strata that compose the succession, confirming the occurrence of recurrent palaeo-wildfires during its deposition. Reflectance values indicated a mean charring temperature reaching ~515°C (and up to 1,045°C in excess) and the macro-charcoal exhibits anatomical features of secondary xylem of Agathoxylon. Combination of results derived from palaeobotanical and petrological data demonstrates that gymnosperm-dominated vegetation was repeatedly submitted to fire events and reinforced the hypothesis that Gondwanan mires were high-fire systems during the Cisuralian.

Structure and combustion characteristics of high inertinite coal demineralized by stepwise chemical methods

ABSTRACT A high inertinite coal was chosen and its stepwise demineralization samples were prepared. Their structures and combustion characteristics were researched by proximate and ultimate analyses, N2-adsorption isotherms, and thermogravimetric analysis methods. The results show that the specific areas and pore volumes reduce and the average pore diameters enlarge when the minerals in coal samples are gradually removed by deionized water, HCl, and HF. The structure of a coal sample is nearly unchanged while they are treated with deionized water and HCl, and their chemical composition changes in a way when they are treated with HF. A small amount of water soluble minerals in coal obstruct and the majority acid soluble minerals promote coal sample combustion. The bigger the specific areas, the higher the coal sample combustion activity. The moderate moisture in coal can promote sample combustion.

Reactivity Study of Two Coal Chars Produced in a Drop-Tube Furnace and a Pulverized Coal Injection Rig

The combustion behavior of coal depends upon not only the coal characteristics but also the combustion conditions. The current understanding about the combustion of coal char during the extreme conditions of pulverized coal injection into blast furnaces is incomplete. To increase the understanding, this research aims to compare the combustion performance of chars obtained from a drop-tube furnace (DTF) and a pulverized coal injection (PCI) rig, thereby giving an indication of the development of reactivity with the heating rate and combustion temperature. Two coals with similar volatile contents were selected, namely, VH, a vitrinite-rich coal, and VL, an inertinite-rich coal. Chars were prepared from these coals in either a DTF or a PCI rig. Different combustion performances of the two coals were observed in the two combustion test rigs. The high-vitrinite coal exhibited similar burnout in the two rigs, but the high-inertinite coal had significantly lower burnout in the DTF than in the PCI rig. Both the chars produced in the DTF had higher reactivity at temperatures over 750 °C than the corresponding chars produced in the PCI rig. Coal maceral composition, char microstructure, and combustion conditions appear to contribute to this phenomenon, with the testing of additional coals being necessary to clarify influence.

Parameters influencing the variation in mercury emissions from an Alberta power plant burning high inertinite coal over thirty-eight weeks period

Feed coals and fly ashes from a coal-fired power station burning Alberta subbituminous coal were examined for a period of thirty-eight weeks to determine the variation in emitted mercury. Feed coal samples were analyzed for proximate, calorific value and Hg content, while fly ash samples were examined for C and Hg contents. The maceral content of the feed coal was also determined. The emitted mercury was calculated and compared to mercury emitted from the stack according to a mass-balance calculation from a previous study for the same station. Mercury contents ranged from 0.029 to 0.066 mg/kg for feed coal, and from 0.069 to 0.112 mg/kg for fly ash. The carbon/char in fly ash was separated into reactive (vitrinitic/bimacerate) and less reactive (inertinitic) chars using ZnBr 2 at specific gravities of 1.7, 2.0, and 2.25 to 2.4. The result shows that there is a positive correlation between the carbon and mercury content of the fly ash. The reactive char particles in the fly ash may be responsible for the capture mercury in fly ash. The percentage of estimated captured mercury by fly ash increases with increasing carbon content (%) in fly ash. The percentage of emitted mercury for the period of 38 weeks is estimated to be within the range of 49% to 76% of the total input of mercury.

Study on coal liquefaction characteristics of Chinese coals

The New Energy and Industrial Technology Development Organization (NEDO) has implemented the collaborative research work with China Coal Research Institute (CCRI) on the liquefaction of Chinese coals for about 20 years. A total of 53 runs in a 0.1 t/d bench scale coal liquefaction plant installed at the CCRI were made on 27 kinds of coal selected among coals existing throughout China. The bench plant was operated in a direct hydrogenation (DH) mode and NEDOL mode. In the DH mode, 25 MPa of reaction pressure was employed with decrystallized anthracene oil used as the solvent, while 17 MPa of reaction pressure was employed and hydrogenated solvent was used in the NEDOL mode. This study confirmed that the NEDOL mode, which uses comparatively mild in liquefaction conditions, can liquefy each coal with the high oil yield more efficiently, and is capable of liquefying about 60% of inertinite in high inertinite coals.

Open Tubular Supercritical Fluid Chromatography (ot-SFC) Applied to the Separation of Coal-Derived Products Obtained by Supercritical Fluid Extraction (SFE)

This work describes the construction and evaluation of a simple and versatile capillary supercritical fluid chromatographic (SFC) system and its application to the analysis of liquid fuels obtained by SFE. The modular supercritical fluid chromatography (SFC) system uses a syringe pump, a fused silica capillary column (100 μm i.d., coated with a 0.2-μm thick film of 5% phenylpolymethylsiloxane), a FID detector, and a high pressure injection valve with a 60-nL internal loop. Coal-derived samples were obtained by supercritical fluid extraction (SFE) of a Brazilian high-inertinite coal from Amando Simoes mine, located in Parana state (Brazil) using toluene as solvent and operating in the static mode. SFE was followed by preparative liquid chromatography fractionation into eight discrete fractions (PLC-8 method). Two of those fractions (F-2 and F-8) were used to evaluate the proposed set-up. The system described proved to be simple, easy-to-use, and versatile when used in the analysis of a range of samples from low molecular weight-low volatility (F-2) to higher molecular weight-high polarity asphaltols (F-8).

High-resolution gas chromatography and high-resolution gas chromatography/mass spectrometry study of the volatile fraction obtained from high-inertinite Brazilian coal by supercritical fluid extraction

This work presents the results of a study involving a high-inertinite coal from Amando Simões Mine, located in Paraná state (Brazil). The organic matter was extracted in a supercritical fluid (static mode) apparatus using toluene as the extraction fluid in the presence of hydrogen. The variables were studied using a 23 factorial design (two levels for three variables: temperature, reaction time, and pressure) with three center points. The liquid coal extracts obtained were fractionated by preparative liquid chromatography into eight fractions (PLC-8) by using an adequate series of eluents. Each eluted fraction was collected and quantified by gravimetry. The relative fraction yields were used to calculate the influence of the variables and their interaction in the factorial design. All hydrocarbon-rich fractions were analyzed by high-resolution gas chromatography (HRGC)-fluid ionization detection and HRGC-mass selective detection (MSD). The characterization of chemical classes of interest in the collected fractions was carried out using HRGC-MSD in the extracted ion mode. This approach allowed fine monitoring of compounds of interest by their characteristic m/z values and was a fast and very selective setup for detection of specific compounds in a very complex matrix. ©1999 John Wiley & Sons, Inc. J Micro Sep 11: 501–512, 1999

98/00903 The chemical structure and properties of bitumens of different origin: Baginska, K. and Gawel, I. Pet. Coal, 1996, 38, (2), 35–37

Petrographic analyses were carried out on thin coals and coaly sediments from the Lower Carboniferous Mattson Formation at Clausen Creek and Jackfish Gap-Yohin Ridge in the northern part of the Liard Basin, northern Canada. The composition and optical characteristics indicate that the coals are high-volatile bituminous B, predominantly sapropelic (canneloid) and accumulated subaquatically.The coals are dominantly composed of inertinite-rich and exinite-rich durities with subsidiary inertites and clarodurites; vitrite is minor and liptite is rare. The inertinite-rich microlithotypes are dominated by semifusinite, but micrinite, semimacrinite and ?resino-inertinites are abundant. Sporinite, comprising megaspores, crassispores, tenuispores and miospores, is the dominant liptinite maceral with subsidiary cutinite and minor alginite. Except for pyrite, mineral matter is minimal.Three populations of telocollinite are observed: a low-reflectance variety (I), commonly associated with micrinite (as vitrinertite), displays weak brown fluorescence and a reflectance some 0.4-0.5% lower than type II; type II is non-fluorescing telocollinite, with intermediate reflectance (0.67-0.74% Rom), it occurs as vitrite and is also associated with micrinite; and a higher-reflectance telocollinite (III), having no fluorescence or association with micrinite, has variable reflectance (0.74-0.8% Rom) implying higher oxidation or gelification levels.The abundance of semimacrinite, macrinite and ?resino-inertinites in inertites and durites (I) suggests that much of the peat accumulated subaquatically. Furthermore, fluorescing vitrinite and an abundance of micrinite (derived by oxidation or coalification of bituminite), suggest that the coal accumulated under anaerobic conditions. The predominance of semifusinite in humic laminae and micrinite in sapropelic layers suggests extensive surface or near-surface oxidation of the peat. Oxidised sporinites suggest that they were wind-borne.Depositional environment is interpreted as marginal marine, perhaps in shallow lakes in the middle to upper delta plain. Peat accumulations probably began subaquatically at the oxygen-hydrogen sulphide interface, but periodic subaerial exposure and natural oxidation gave rise to the high inertinite coals. Upper Mattson coals are interbedded with algal laminites and probably accumulated in a lagoonal setting.

96/00298 Processing of coal coking byproducts in Poland

The New Energy and Industrial Technology Development Organization (NEDO) has implemented the collaborative research work with China Coal Research Institute (CCRI) on the liquefaction of Chinese coals for about 20 years. A total of 53 runs in a 0.1 t/d bench scale coal liquefaction plant installed at the CCRI were made on 27 kinds of coal selected among coals existing throughout China. The bench plant was operated in a direct hydrogenation (DH) mode and NEDOL mode. In the DH mode, 25 MPa of reaction pressure was employed with decrystallized anthracene oil used as the solvent, while 17 MPa of reaction pressure was employed and hydrogenated solvent was used in the NEDOL mode. This study confirmed that the NEDOL mode, which uses comparatively mild in liquefaction conditions, can liquefy each coal with the high oil yield more efficiently, and is capable of liquefying about 60% of inertinite in high inertinite coals.

Decreases in the swelling and porosity of bituminous coals during devolatilization at high heating rates

Petrographic analyses were carried out on thin coals and coaly sediments from the Lower Carboniferous Mattson Formation at Clausen Creek and Jackfish Gap-Yohin Ridge in the northern part of the Liard Basin, northern Canada. The composition and optical characteristics indicate that the coals are high-volatile bituminous B, predominantly sapropelic (canneloid) and accumulated subaquatically.The coals are dominantly composed of inertinite-rich and exinite-rich durities with subsidiary inertites and clarodurites; vitrite is minor and liptite is rare. The inertinite-rich microlithotypes are dominated by semifusinite, but micrinite, semimacrinite and ?resino-inertinites are abundant. Sporinite, comprising megaspores, crassispores, tenuispores and miospores, is the dominant liptinite maceral with subsidiary cutinite and minor alginite. Except for pyrite, mineral matter is minimal.Three populations of telocollinite are observed: a low-reflectance variety (I), commonly associated with micrinite (as vitrinertite), displays weak brown fluorescence and a reflectance some 0.4-0.5% lower than type II; type II is non-fluorescing telocollinite, with intermediate reflectance (0.67-0.74% Rom), it occurs as vitrite and is also associated with micrinite; and a higher-reflectance telocollinite (III), having no fluorescence or association with micrinite, has variable reflectance (0.74-0.8% Rom) implying higher oxidation or gelification levels.The abundance of semimacrinite, macrinite and ?resino-inertinites in inertites and durites (I) suggests that much of the peat accumulated subaquatically. Furthermore, fluorescing vitrinite and an abundance of micrinite (derived by oxidation or coalification of bituminite), suggest that the coal accumulated under anaerobic conditions. The predominance of semifusinite in humic laminae and micrinite in sapropelic layers suggests extensive surface or near-surface oxidation of the peat. Oxidised sporinites suggest that they were wind-borne.Depositional environment is interpreted as marginal marine, perhaps in shallow lakes in the middle to upper delta plain. Peat accumulations probably began subaquatically at the oxygen-hydrogen sulphide interface, but periodic subaerial exposure and natural oxidation gave rise to the high inertinite coals. Upper Mattson coals are interbedded with algal laminites and probably accumulated in a lagoonal setting.

The petrology and origin of coals from the lower Carboniferous Mattson formation, southwestern district of Mackenzie, Canada

Petrographic analyses were carried out on thin coals and coaly sediments from the Lower Carboniferous Mattson Formation at Clausen Creek and Jackfish Gap-Yohin Ridge in the northern part of the Liard Basin, northern Canada. The composition and optical characteristics indicate that the coals are high-volatile bituminous B, predominantly sapropelic (canneloid) and accumulated subaquatically. The coals are dominantly composed of inertinite-rich and exinite-rich durities with subsidiary inertites and clarodurites; vitrite is minor and liptite is rare. The inertinite-rich microlithotypes are dominated by semifusinite, but micrinite, semimacrinite and ?resino-inertinites are abundant. Sporinite, comprising megaspores, crassispores, tenuispores and miospores, is the dominant liptinite maceral with subsidiary cutinite and minor alginite. Except for pyrite, mineral matter is minimal. Three populations of telocollinite are observed: a low-reflectance variety (I), commonly associated with micrinite (as vitrinertite), displays weak brown fluorescence and a reflectance some 0.4-0.5% lower than type II; type II is non-fluorescing telocollinite, with intermediate reflectance (0.67-0.74% R om), it occurs as vitrite and is also associated with micrinite; and a higher-reflectance telocollinite (III), having no fluorescence or association with micrinite, has variable reflectance (0.74-0.8% R om) implying higher oxidation or gelification levels. The abundance of semimacrinite, macrinite and ?resino-inertinites in inertites and durites (I) suggests that much of the peat accumulated subaquatically. Furthermore, fluorescing vitrinite and an abundance of micrinite (derived by oxidation or coalification of bituminite), suggest that the coal accumulated under anaerobic conditions. The predominance of semifusinite in humic laminae and micrinite in sapropelic layers suggests extensive surface or near-surface oxidation of the peat. Oxidised sporinites suggest that they were wind-borne. Depositional environment is interpreted as marginal marine, perhaps in shallow lakes in the middle to upper delta plain. Peat accumulations probably began subaquatically at the oxygen-hydrogen sulphide interface, but periodic subaerial exposure and natural oxidation gave rise to the high inertinite coals. Upper Mattson coals are interbedded with algal laminites and probably accumulated in a lagoonal setting.

Combustion in the burnout stage: the fate of inertinite

The paper reports on the fate of inertinite-type chars during high temperature combustion. The aim is assessing the extent to which inertinite macerals affect combustion efficiency as measured from percentage burn-out. Char samples from three medium to high-inertinite coals varying in burn-off between 20% and 99.7% were taken from the KEMA 1 MW combustion test facility. The samples were analyzed by classical microscopy. Char particles were identified as inertinite-type by visual observation. The concentration of inertinite-type particles in char does not change significantly at intermediate stages of combustion, between 30% and 98% burnoff. When less than 2% of the original coal is left unburnt, there is a shift in char composition. Higher concentrations of large (>8 μm) fusinoid and inertoid particles are found in the last stage of burn-out for two of three coals. During most of the time solid chars from inertinite burn at the same rate as porous chars. In the fly char, the percentage unburnt from inertinite is only slightly higher than the average unburnt from the whole coal.

Applications of microscopy to coke making

A Canadian perspective of the petrographic, thermal rheological and grade of metallurgical coals required to make coke with high strength and strength after reaction (CSR) properties is presented. The development of automated microscopic techniques to obtain reproducible and reliable petrographic data to predict coke quality is discussed. The amount of “altered vitrinite” in the microscopic coke textures has been used as a reference to quantifiy in situ coal oxidation. Relationships between coke microscopy, coal petrography and thermal rheological data show that FSI can be used to estimate the amount of oxidized vitrinite plus petrographic inert contents of coal. Plastic temperature ranges determined from microscopic examination of the coal/coke transformations for Appalachian and Canadian coals show that standard thermal rheological tests underestimate the plastic range for high inertinite coals.

Behaviour of different char components in fluidized bed combustion: a char petrography study

Residues of fluidized combustion were shown to contain slightly more anisotropic char than is consistent with the vitrinite content of the parent coals. The composition of the cyclone residues gradually shifted to higher contents of anisotropic char as the recycle ratio increased, but remained constant over a wide range of air-to-fuel ratios. Cyclone chars were richer in anisotropic matter than filter chars, in which the inertinite residues tended to concentrate. The surface structure, as determined by the size of mosaic units, was not influenced by either residence time or air-to-fuel ratio. The combined data suggest that greater abrasion resistance, rather than reduced chemical reactivity of vitrinite char, may explain its slower combustion. A practical implication is that fly ash recycling may be more effective with high inertinite coals than with coking coals.