Major and trace-element enrichments in the Karapınar coals (Konya,Turkey)

Ten major oxides and 27 trace elements were determined in 21 samples collected from four holes that were drilled into the fault-controlled coals of the Karap?nar (Turkey) basin. On the basis of X-ray diffraction analyses, the coals contain, in order of abundance, calcite, quartz, dolomite, feldspar, mica, clay minerals, and gypsum. In samples from the study area, a high level of correlation was determined between Mo, Sb, As, U, and V, and S and TOC (Mo, r = 0.697; Sb, r = 0.902; As, r = 0.927; U, r = 0.653; V, r = 0.721). Relative to coals of the world, USA, Turkey, and China, coals of the study area are seen to be enriched up to 1,000 times with respect to Mg, Ca, Na, and K. The Karap?nar coals were determined to be enriched in Pb, U, Ba, Cs, Nb, Y, Sr, Rb, Ni, Co, V, and Sc relative to average Turkish coals; in Mn, Na, Ca, Mg, Cs, Sr, Ni, and Cr relative to average Chinese coals; in Ti, K, Na, Ca, Mg, U, Ta, Ba, Cs, Sr, Rb, As, Ni, Co, V, and Cr relative to average worldwide coals; in Mn, P, Ti, K, Na, Ca, Mg, Si, U, Ta, Ba, Cs, Nb, Zr, Sr, Ni, Co, V, and Cr relative to average USA coals; and in Mn, P, Ti, K, Ca, Mg, Fe, Sb, Nb, Zr, Sr, Rb, Zn, Cu, Ni, Co, and Sc relative to crustal averages (Clarke values). The aim of the present study was to determine the enrichment factors of the major- and trace-element contents of the Karap?nar coals relative to coals of the world, USA, China, and Turkey, and to crustal averages.     

Concentrations of elements in Lias coals from the eastern Black Sea Region,NE-Turkey

The element contents and organic matter-element relation between Lias-aged coals exposed in four fields in Gümü?hane and Bayburt were investigated. In general, fixed carbon and gross calorific values of the Edire and Balkaynak coals are higher than Güvercinlik and Çerçi coals. The highest ash yields were observed in the Çerçi coals. The concentrations of Mg, P, Ca, Mo, Y, Ni, U, Zn, Ga, Ba, W, Sr, Ta, and Be of the analysed coals are positively correlated with ash yield, indicating an organic affinity. The Lias-aged coals located in Gümü?hane and Bayburt are low-rank coals.     

Elemental characterization of Nigerian coals and their ashes using particle induced X-ray emission (PIXE) spectrometry for environmental pollution assessment

Nigerian coals and their ashes were investigated using PIXE spectrometry to ascertain their elemental composition, characterize and correlate them, and to determine their environmental risk assessment when combusted. Eleven and 18 elements detected in the raw coals and the ashes, respectively, were subjected to appropriate statistical analyses. Mean elemental summation (%) of the coals and ashes were 8.4 and 39.0, respectively, while average % ash content was 29.6, indicating that they were rich in potential toxic elements which could be emitted into the environment during coal combustion. This was corroborated by t-test results. It is found that pollution index (PI) values for V, Co, Mn, Ni, Cu, and Zn in the coal ash are greater than 1.0. This implies that combustion coal/coal ash may serve as a source of toxic element pollution in environmental media which could produce ill-health. Cross-plot analysis results showed moderate positive correlations, suggesting inter-element correlations among the samples, establishing relationships among the coals. This was validated by the clustering analysis results which indicated three major groups which were also fairly correlated with one another, signifying similar genetic origin. Elemental clustering indicated closest inter-element association among transition metals. This was also confirmed by their Pearson correlation matrices results, indicating chemical affinity and/or similar genetic origin.     

Platinum group elements in terrestrial oil shale from the Lunpola Basin,northern Tibet,China

The Lunpola oil shale is the largest oil shale resource in Tibet. Twenty-four samples were collected from this deposition to determine the platinum group element (PGE) characteristics. The total PGE contents in terrestrial oil shale are low (average 2.386 ng/g). The PGEs are enriched in the oil shale samples near the boundary between the oil shale and its underlying strata. The PGE enrichment may be the result of a change of oxic–anoxic conditions. The individual PGEs of oil shale samples from the Lunpola oil shale exhibit similar modes of occurrence, and their distributions are controlled mainly by Fe-bearing minerals (pyrite). The source of PGEs in the Lunpola oil shale is probably related to water chemistry and terrigenous supply.     

煤中易挥发痕量元素赋存形态的分析方法及实验研究

讨论并比较了煤中痕量元素赋存形态的分析方法及其应用范围，应用逐级化学提取法对3种典型煤进行浸提，根据易挥发痕量元素不同形态的溶解度，将煤中砷、汞、硒分为可交换态、硫化物结合态、有机物结合态和残渣态。结果表明，砷在煤中主要以硫化物结合态存在，汞在煤中主要以硫化物结合态和残渣态存在，硒赋存在硫化物、有机物和残渣态中，不同煤种中易挥发痕量元素各种形态的分布不同，应用浮沉法将煤按不同密度分级后，分别测定了各级煤粉中砷、汞含量，表明砷、汞主要存在于煤的矿物质中。     

A preliminary method for determining acceptable trace element levels in coal

A preliminary method for determining acceptable trace element levels in coal was established. In addition to the conventional coal quality parameters ash and sulfur, potentially hazardous trace elements As, Be, Cd, Cl, Cr, F, Hg, Mn, Ni, Pb and Se were selected for the evaluation, and their environmentally acceptable concentrations in coal were quantified at 5 and 0.5 weight %, and 6.5, 1, 0.8, 400, 15, 120, 0.15, 80, 30, 15 and 2.5 mg/kg, respectively. A pollution index (I) is proposed, by which coal is ranked into four classes: acceptable (I ≤ 0.252), marginal (0.252 < I ≤ 0.514), unacceptable (0.514 < I ≤ 0.751), and ultra-unacceptable coal (I > 0.751). 36 coal samples collected from the north of Ordos basin and Shanxi Province, China were classified with the method. Most of the cleaned coals were rated as acceptable or marginal, while the run-in-mine coals, feed coals, middlings and coal slimes were generally ranked as unacceptable or ultra-unacceptable coal. The evaluation results reflect the degree of cleanliness of these coal samples.     

Distributions of environmentally hazardous elements in the Tertiary oil shale deposits from NW Anatolia,Turkey: A statistical analysis

The environmentally hazardous element concentrations (As, Cd, Cr, Cu, Hg, Mn, Pb, S, and Zn) and element–organic matter relations of the oil shale deposits in six different fields in NW Anatolia, Turkey, were investigated and the characteristics of fields were compared. The enrichment factor (EF) for most of the trace elements in the studied oil shales generally show enrichment patterns for all the fields. Only Cr, Hg, and Pb for oil shale samples from the Bahçecik field samples and Hg for oil shale samples from the Gölpazar? field samples are depleted. Arsenic in the Bahçecik field samples and Hg in the Himmeto?lu field samples are neither depleted nor enriched. The lowest and highest element enrichments in these fields are determined to be Hg and S, respectively. In general, all elements have high concentrations in the Beypazar? and Seyitömer fields and low concentrations in the Himmeto?lu, Bahçecik, and Gölpazar? (except for As) fields. A positive correlation at significance level of p ≤ 0.05 was observed for total organic carbon content with Cd in four of the fields, with Cu and S in two fields and with Cr, Mn, and Zn in only one field.     

The geochemistry of trace elements in marine oil shales and their combustion residues: Occurrence and environmental aspects

With the aim of better understanding geochemistry of trace elements in marine oil shale and its combustion residues, 23 raw samples, 17 oil shale combustion residues, and 18 selected minerals from Bilong Co oil shale are studied. Potentially hazardous trace elements in raw samples include As, B, Cd, Mo, and Se, while Se, Mo, Cd, As, Bi, and U are potentially hazardous trace elements in combustion residues. As is controlled mainly by Fe-bearing minerals. B occurs mainly in clay minerals. Cd is enriched mainly in calcite. Mo is controlled mainly by organic matter. Se is mainly controlled by P-bearing minerals.     

Source rock characteristics of Eocene bituminous shales and the effect of redox conditions on source rock potential,Nallıhan (Ankara) Central Anatolian Basin

Eocene bituminous shales within the Çamalan Formation of Paleocene-Eocene aged K?z?lçay Group exposing around Tekirler (Nall?han, Ankara), central Anatolia, were deposited under oxic and suboxic redox conditions and have Corg values in the range of 2.37 to 12.42 wt% (average 6.32 wt%). Samples are represented by Type-I kerogen and their maturity level is immature-early mature. Eocene bituminous shales are enriched in some major and trace elements, such as Ca, Mg, Si, Na, K, V, Ni, U, Th, P, S, Mo, Cu, Zn, Cr, Co, Pb, Au, Ag, As, Re, La, Ce, Pr, Nd, Li, Sm, and Y. Paleoredox indicators (e.g., V/(V+Ni), Ni/Co, U/Th, V/Sc, Mo/Mn) yield that Eocene bituminous shales were mostly deposited oxic–suboxic conditions.     

Element mobility during the hydrothermal alteration of rhyolitic rocks of the Los Azufres geothermal field, Mexico

The effects of hydrothermal alteration on major, rare-earth, and other trace-element concentrations in rhyolitic rocks of the Los Azufres geothermal field, Mexico, were investigated by statistically comparing the chemical compositions of altered drill cuttings (taken above 450 m depth) with those of fresh rock outcrop samples. Altered rhyolitic rocks show predominantly vitreous and fluidal textures, with alteration products (mainly clay minerals, chlorites and, less commonly, sericite) comprising up to 40% of the rock mass; cryptocrystalline quartz, chlorite, and zeolites fill fractures and vesicles. In altered rocks the greater statistical variances of several elements (Y, Ce, Pr, Nd, Sm, Lu, and Pb) are probably due to alteration effects, whereas smaller variances for CaO, Sr, Rb/Sr, and Rb/Ba suggest that alteration processes have resulted in more uniform chemical compositions. Only MnO, P₂O₅, Ta, Zr, and Nb have significantly different concentrations in hydrothermal altered rocks as compared to fresh rocks. MnO, P₂O₅, Ta, Rb/Zr, and Rb/Nb decrease, whereas Zr, Nb, and Nb/Y increase in the altered rocks. The present study stresses that caution should be taken when using these chemical parameters for petrogenetic studies of old hydrothermally altered areas, particularly with rhyolitic rocks. Rare-earth element (REE) concentrations were not significantly different between fresh and altered rhyolitic rocks. This may indicate that these elements were relatively immobile during the hydrothermal alteration processes affecting the rhyolites at Los Azufres, or more likely that they were reincorporated into hydrothermal minerals after being mobilized from the primary phases.     

Pre-combustion removal possibility of hazardous trace elements from Indian high-ash coal by coal preparation technologies

Many of the potentially hazardous air pollutants listed in the 1990 Clean Air Act are elements commonly found in trace amounts in coal. When coal is burned, these elements release into the environment. An option for controlling the release of these elements into the atmosphere is to remove them before combustion. Conventional physical coal cleaning processes are effective in reducing the concentration of many of these trace elements in coal. In addition, advanced cleaning processes directed toward reduction of various elements may perform better than conventional processes. Therefore, current research focuses on the advanced coal cleaning technology which is directed toward reduction of mineral matter and various toxics elements as well. Results of recent studies indicate that the degree to which a specific trace element can be reduced by coal cleaning depends on its distribution in the coal. To quantify the capabilities of a gravity-based coal cleaning process for removing these hazardous air pollutants, a detail study was conducted on a coal sample collected from one mine of Talcher area. Careful analysis of the experimental data indicates that most of the trace elements of greatest environmental concern are strongly associated with the organic matter of the investigated coal, thus during beneficiation these elements are concentrated in the clean coal fraction. Therefore, it makes the situation more complex and the expected pre-combustion removal of these trace elements seems to be not possible for the high-ash non-coking coals of Talcher coal field.     

The influence of ibuprofen ((RS)-2-[4-(2-methylpropyl)phenyl]propanoic acid) additive on the structure ordering of coals of different rank during the process of co-pyrolysis

The mechanism of influence of the addition of 2 wt% of the expired pharmaceuticals (EPs) containing 80% of ibuprofen ((RS)-2-[4-(2-methylpropyl)phenyl]propanoic acid) on the transformation of the ordered structure of the three coals of different ranks was studied. The co-pyrolysates of coals with EP additive were studied with the method of X-ray diffraction (ХRD) and scanning electron microscopy (SEM). It was stated that the addition of 2 wt% of EP to all coals under study increases the intra-crystalline ordering. Under the influence of the addition of 2 wt% of EP at the stage of swollen grains of the co-pyrolysates of all coals, the amount of carbon ordered in crystallites decreases. In the co-pyrolysates of lower-rank coals (LRC) and higher-rank coals (HRC) under the influence of this additive at the stage of coke, the amount of the ordered phase decreases compared to the pyrolysates. In the co-pyrolysate of a medium-rank coal (MRC), the degree of ordering of coke does not change compared to the coke from single coal.     

Concentration of Major and Trace Elements in the Miocene Lignite from the Çanakkale-Çan Coalfield

Abstract

This study focuses on major and trace element concentrations of three lignite samples, of which two are from the working lignite seam and one from a feed coal to Çan thermal power plant. The Çanakkale-Çan lignite deposit is currently being mined by open-cast mining methods despite its high sulfur content. The production lignites are mainly consumed by Çan fluidized-bed thermal power plant with 2 × 160 MW capacity and less domestic heating and industrial factories around Çan. Major oxide compositions of the coal ash samples imply that the more abundant oxides are SiO₂ and Al₂O₃ and less CaO and Fe₂O₃. Trace element concentrations in the samples on whole-coal basis show that three samples analyzed were enriched in V, and also concentrations of B, Sc, Sn, Th, Tl, and U in one sample that exceed the range values of most world coals.     

Thermodynamic characterization of H2-brine-shale wettability: Implications for hydrogen storage at subsurface

Large-scale underground hydrogen storage (UHS) appears to play an important role in the hydrogen economy supply chain, hereby supporting the energy transition to net-zero carbon emission. To understand the movement of hydrogen plume at subsurface, hydrogen wettability of storage rocks has been recently investigated from the contact angles rock-H₂-brine systems. However, hydrogen wettability of shale formations, which determines the sealing capacity of the caprock, has not been examined in detail. In this study, semi-empirical correlations were used to compute the equilibrium contact angles of H₂/brine on five shale samples with various total organic content (TOC) at various pressures (5–20 MPa) and at 343 K. The H₂ column height that can be securely trapped by the shale and capillary pressures were calculated. The shale's H₂ sealing capacity decreased with increasing pressure, increasing depth and TOC values. The CO₂/brine equilibrium contact angles were generally higher than H₂/brine equilibrium, suggesting that CO₂ could be used as favorable cushion gas to maintain formation pressure during UHS. The utmost height of H₂ that can be safely trapped by shale 3 (with TOC of 23.4 wt%) reduced from 8950 to 8750 M while that of shale 5 (with TOC of 0.081 wt%) reduced slightly from 9100 M to 9050 M as the pressure was increased from 5 to 20 MPa. The capillary entry pressure decreased with increasing depth and shale TOC, implying that the capillary trapping effect, as well as the over-pressure required to move brines from the pores by hydrogen displacement, reduces with increasing depth, and shale TOC. However, the shales remained at strongly water-wet conditions, having an equilibrium contact angles of not more than 17° at highest pressure and TOC. The study suggests that the increasing contact angles with increasing pressure and shale TOC, as well as decreasing column height and capillary pressure with increasing depth for H₂-brine-shale systems might not be sufficient to exert significant influence on structural trapping capacities of shale caprocks due to low densities of hydrogen.     

Petrography of Feed Coals in the Soma Power Plant,Manisa, Turkey

The coal-bearing Soma basin is one of the most productive lacustrine coal basins of western Anatolia-Turkey. This study mainly focuses on petrography of the feed coals (FCs) in the Soma power plant. A total of 16 feed coal samples were systematically collected once a week over an eight-week period from both group boiler units, B1–4 with 660 MW and B5–6 with 330 MW capacity. The most abundant maceral group of FCs is huminite, in which texto-ulminite, eu-ulminite, attrinite, densinite are rich. Liptinite group macerals in FCs include mainly sporinite, resinite, and liptodetrinite, which are considerably higher than the other identified liptinite macerals. In the inertinite group, fusinite and inertodetrinite are more abundant. Identifiable minerals with petrographical studies are pyrite, siderite, other minerals (e.g., carbonates, clay minerals, quartz, feldspar, etc.), and fossil shells. This study shows that FCs used are subbituminous in rank with mean random ulminite reflectance of 0.43%Rr oil from B1–4 units and 0.39%Rr oil from B5–6 units. This indicates that coal rank is slightly higher in the central mines (southern Soma) than in the Denis mines (northern Soma).     

Investigation of gasification characteristics of some coals in Turkey by the thermogravimetric analysis method

When the coal is heated, conversion process starting with moisture loss passes through pyrolysis, burning and gasification processes depending on the atmosphere, temperature rise rates, final temperature and other parameters. Since coal has a heterogeneous structure, interpretation of these phases is difficult. Thermogravimetric analysis, on the other hand, has a wide range of applications and allows valid approaches to the physical and chemical properties of coal. Therefore, the thermogravimetric analysis makes it possible to analyze the characteristics of the coal gasification phase in a practical and rapid manner.

In this study, the gasification characteristics of coal samples taken from Ilg?n, Ermenek and Zonguldak regions in Turkey were determined. Conversion time and gasification rates of Ilg?n and Ermenek coals were investigated using thermogravimetric analyzer at 700°C, 750°C, 800°C and 850°C in CO₂ atmosphere and comparisons were made between samples. In addition, conversion and gasification rates of coal samples taken from Zonguldak region at 1150°C were investigated. It was observed that the conversion time of the Ilg?n coal at 800°C and the Ermenek coal at 850°C was shorter than the other temperatures. When the 80% conversion rates of Ilg?n coal at 800°C, Ermenek coal at 850°C, and Zonguldak at 1150°C, are compared; it is observed that there exist a 1,2 min difference between Ilg?n-Zonguldak, 1,05 min between Ilg?n-Ermenek and 1,96 min between Ermenek and Zonguldak coals.     

Immobilization of Heavy Metals and Phenol on Altered Bituminous Coals

Abstract

This article evaluates adsorption ability of the altered bituminous coals to remove heavy metals and/or phenol from aqueous solutions. As for heavy metals, copper (II), cadmium (II) and lead (II) cations were used. In addition to phenol, cyclohexanol and 2-cyclohexen-1-ol were also examined. Adsorption experiments were conducted in the batch mode at room temperature and at pH 3 and 5. To characterize the texture of coal samples, adsorption isotherms of nitrogen at ?196°C, enthalpies of the immersion in water, and pH values in aqueous dispersions were measured. Coal hydrogen aromaticities were evaluated from the infrared spectrometric examinations (DRIFTS). Based on the investigations performed, cation exchange was confirmed as the principal mechanism to immobilize heavy metallic ions on coals. However, apart from carboxylic groups, other functionalities (hydroxyl groups) were found to be involved in the adsorption process. During adsorption of phenol, π-π interactions between π-electrons of phenol and aromatic rings of coal proved to play the important role; however, no distinct correlation between adsorption capacities for phenol and hydrogen aromaticities of the coal was found. Probable involvement of oxygenated surface groups in the immobilization of phenol on coal was deduced. As a result, for waste water treatment, oxidative altered bituminous coal can be recommended as a suitable precursor, with the largest immobilization capacities both for metallic ions and phenol, as found in the studied samples.     

Ash effects during combustion of lignite/biomass blends in fluidized bed

Aiming at investigating the role of minerals in evaluating co-firing applications of low rank coals and biomass materials, agricultural residues characteristic of the Mediterranean countries, one lignite and their blends with biomass proportions up to 20% wt, were burned in a lab-scale fluidized bed facility. Fly ashes and bed material were characterized in terms of mineralogical, chemical and morphological analyses and the slagging/fouling and agglomeration propensities were determined.The results showed that combustion of each fuel alone could provoke medium or high deposition problems. Combustion of raw fuels produced fly ashes rich in Ca, Si and Fe minerals, as well as K and Na minerals in the case of biomass samples. However, blending of the fuels resulted in a reduction of Ca, Fe, K and Na, while an increase of Si and Al elements in the fly ashes as compared to lignite combustion, suggesting lower deposition and corrosion problems in boilers firing these mixtures. The use of bauxite as an additive enriched bottom ash in calcium compounds. Under the conditions of the combustion tests, no signs of ash deposition or bed agglomeration were noticed.     

Determining the effect of trace elements on biohydrogen production from fruit and vegetable wastes

Trace elements are one of the important parameters for dark fermentative H₂ production because they work as co-factors in H₂ formation biochemistry. Lack or excess of trace element and its concentrations could be an important reason for the low yield of H₂ production. In this study, the effects of 11 different trace elements (Fe, Ni, Zn, Co, Cu, Mn, Al, B, Se, Mo and W) were tested at two levels in terms of biohydrogen production from Fruit and Vegetable Wastes (FVW) with Biochemical Hydrogen Potential (BHP) Tests using Plackett-Burman statistical design. 1.1–2.8 times enhancement of biohydrogen production was determined with its addition. The most effective trace elements were found as Zn and Ni. In order to reveal the resident microbial flora, Denaturing Gradient Gel Electrophoresis (DGGE) analysis was carried out on all BHP effluent samples. Results of DGGE analysis, four microbial sequences evaluated as Clostridium sp., Clostridium baratii, Uncultured bacterium, Uncultured Streptococcus sp., and their similarity rates were 99%, 100%, 89%, 98%, respectively.     

Inorganic elements in tree compartments of Picea abies—Concentrations versus stem diameter in wood and bark and concentrations in needles and branches

Concentrations of elements in stem wood, bark, branches and needles, and empirical functions for the variation in concentrations with stem diameter in bark and stem wood for Norway spruce (Picea abies) are presented. The samples were collected from 36 trees from nine different localities from the central and southern parts of Sweden. Disc samples were taken from the trunk of each tree at five heights and the diameters of each disc were measured. Living branches and their needles from each tree were collected and separated and each fraction was treated as one bulk sample. Concentrations of 23 elements were analysed by ICP-MS. The needles contained the highest concentrations of most of the elements, followed by branches, bark and wood in that order. The element concentrations for Ba, Cd and Pb in wood and Ba, Ca, Cd, Co, Mn, Sr and Zn in bark were significantly positively correlated with diameter, while negative correlations were found for Cu, Fe, K, Mg and P in wood and Cr, Cu, Fe, K, Na, Ni and P in bark. Due to high variation in element concentrations between single trees, the functions should be used at the stand level rather than for single trees. Calculations of export of elements through removal of logging residues using the diameter-based functions were compared with calculations using average concentrations of elements in the stem and bark. The average concentration method resulted in an underestimation of 26%, 17%, 30%, 22% and 51% for Cu, Fe, K, Mg and P, respectively, and an overestimation of 29%, 24% and 29% for Ba, Cd and Pb, respectively.