Pyritic Sulfur Content Research Articles

Study on controlling factors and developing a quantitative assessment model for spontaneous combustion hazard of coal gangue

Developing a quantitative hazard assessment model for spontaneous coal gangue combustion is imperative to ensuring the safety of coal mining operations. In this study, eight types of coal gangue from different coalfields were used to determine the controlling factors for spontaneous combustion. A variety of physical and chemical characterization methods were employed to investigate the physical and chemical characteristics of the samples. Based on the experimental results, six key parameters were identified, namely the aliphatic C–H components, pyrite sulfur content, physical oxygen absorption capacity, ash content, ignition point temperature, and activation energy for thermal decomposition. The results show that the spontaneous combustion hazard of coal gangue is positively correlated with the first three of these and is negatively correlated with the rest. Using the entropy-weight method combined with the analytic hierarchy process, appropriate weighting factors for each parameter were obtained and used to establish a quantitative assessment model for the spontaneous combustion hazard of coal gangue. This model is expected to enhance the current industrial best practices for the prevention and control of spontaneous coal gangue combustion.

Assessment of SO2 Emissions from Cement Industries Utilizing Limestone with High Pyritic Sulfur Content: Case Study of Cement Plants in the Jaintia Hills District, Meghalaya, India

In properly operated Cement Plants, SO2 emissions are mostly caused by pyritic sulfur (sulfides) in the used limestones, accounting for approximately 85% of the raw mill in the plant. However, the pyritic sulfur content in limestones of the Jaintia Hills district of Meghalaya and their influence on the SO2 Emission from cement industries of Meghalaya have not been studied so far. The current study is conducted to perform an in-depth investigation of pyritic sulfur content in limestone reserves used by Meghalaya Cement Industries to assess the SO2 emission in the cement industries using high pyritic sulfur limestones and review the existing technology for the recommendation of the most suitable technology to minimize the SO2 Emissions. Random testing of collected limestone samples from various locations of Captive Mining sites in Cement Industries is performed to assess average pyritic sulfur concentration along different mining benches. Pyritic Sulfur Content (wt.%) in collected limestones varies from 0.15% to 3.5%. Polynomial Regression Analysis shows that Avg.SO2 Emission(Y) from Klin Stack can be represented as a function of pyritic sulfur content (X) (wt.%) of used limestones in the process: Y = 273.7X2 + 21.46X + 422.76. Based on the pyritic sulfur content in limestones, it is observed that “the more the Pyritic Sulfur content is, Darker the Limestone Samples are.” Hence, A Colour Scale has been prepared to visualize higher pyritic sulfur content in limestones. For longer-term sustainability, installing a Flue-Gas Desulfurization (FGD) unit at the kiln stack outlet may be included in the manufacturing process of cement plants to reduce the SO2 Emissions from Stack.

Geochemistry of the Leatherwood coal in eastern Kentucky with an emphasis on enrichment and modes of occurrence of rare earth elements

The Middle Pennsylvanian (Bolsovian) Leatherwood coal in the central part of eastern Kentucky is a moderately thick, moderate-S seam that has been one of the major energy resources in the region. Much of the seam profile consists of clarain, dull clarain, and durain with some brighter lithologies at the base of the seam and in the upper portion of the coal at one site. A previous study emphasized petrographic trends. In this investigation, the geochemistry of the coal is examined. Some elements, such as Ge and Ga, are enriched at 2× and 5× the World hard coal averages in the coal lithotypes adjacent to rock (roof, floor, partings). Arsenic and other chalcophile elements (Zn, Co, Ni) tend to be concentrated at the top and bottom of the seam profiles and below partings, generally in the coals with the highest pyritic sulfur content. Manganese enrichments occur in bright clarain lithologies at one site. No coal lithology reaches a 5× the World hard coal average, but samples between the 2× and 5× World hard coal averages tend to be at the top and bottom of the coal seam. Most coal samples tend to have a light rare earth element (LREE) enrichment. The basal lithotype at all sites, though, has a heavy REE enrichment and, via inference from the Zr and TiO2 concentrations, a smaller influx of detrital minerals than the basal lithotypes in many Appalachian coals. While the nature of REE associations is complicated by the high volatile A bituminous coal rank, the relatively high concentrations of the heavy REE suggest an original, albeit possibly not exclusive, organic association for those elements.

Late Quaternary marine transgressions inferred from the pyrite sulfur content and isotopes within core sediments from the southeast coast of China

Paleoenvironmental reconstructions of coastal areas during geological history are critical for understanding past responses to marine transgression. Identifying transgressive layers in sedimentary strata is therefore of great importance. To this end, we examined the content and isotopic composition of pyrite sulfur, in combination with classical organic geochemical indicators (e.g., C/N ratio and the δ13C of organic carbon), to trace the marine transgressions along the southeast coast of China since Marine Isotope Stage (MIS) 5. Our results suggest that the mass ratio of total organic carbon and pyrite sulfur (C/S ratio) is sensitive to seawater intrusion. Three transgressive layers were identified by low C/S ratios in core NDGK2, which correspond to sea level rise during MIS5, MIS3, and MIS1. Sediments deposited during MIS1 are represented by low C/S ratios with an average of 2.31, while those deposited during MIS5 and MIS3 have slightly higher C/S ratios, indicating a less extensive influence of seawater. Pyrite production in sediments deposited during MIS5 and MIS3 may have been limited by sulfate supply, as reflected by more positive values of δ34Spyr, whereas pyrites deposited during MIS1 were likely formed without sulfate limitation, as reflected by more negative values of δ34Spyr. The isotopic signals of pyrite sulfur thus further confirm the inference based on the C/S ratio. The magnitude of the transgression increased from MIS5 to MIS1, which is in agreement with the findings from classical organic geochemical indicators examined in this study, as well as geochemical and micropaleontological salinity indicators from previous studies. Our findings provide a promising method for identifying marine transgressions and their magnitude from the depositional record, especially when sedimentary strata lack diagnostic micropaleontological and sedimentological characteristics.

Occurrence Characteristics of Fine-Grained Pyrite in Coal and Its Scaling Effect on Flotation Desulfurization.

To explore the occurrence and distribution characteristics of fine-grained pyrites in coal and the effect of pyrite particle size on flotation efficiency, coal samples from Guizhou province and Shanxi province, China, were selected for pyrite morphology observation and sulfur content test before and after flotation desulfurization experiments with different coal particle sizes. Experimental results showed that the fine-grained fine pyrites in coal have various occurrence forms and complex connections with the coal matrix. The fragmentation process can change the distribution of pyrite content in coal. Flotation desulfurization experiments showed that the sum of pyrite content in the cleaned coal and middlings gradually became significantly higher in coal particles with size 15-37 μm compared with particle sizes 37-44 and 44-75 μm. The complex occurrence morphology and crystal structure of fine-grained pyrite make it difficult to be removed from the coal matrix by ore grinding during flotation. Fine-grained pyrite mainly occurs in the form of framboïdal pyrite, disseminated pyrite, and monomer pyrite with a size of 0.69-33.94 μm in the middlings and cleaned coal. Therefore, 37 μm is considered as the critical dimension for ore grinding to improve the effective flotation desulphurization efficiency in this study, and some more effective methods should be used to increase the desulfurization efficiency of fine-grained pyrite.

Investigation of origin, sedimentary environment and preservation of organic matter: A case study in Garau Formation

Knowing the characteristics of suitable environments for precipitation of oil prone source rocks facilitates oil explorations and leads to development of oil fields. The current study investigates the organic matter properties and sedimentary environment conditions of the Garau Formation in various outcrop sections in Lurestan province from south-west of Iran (High Zagros) with using elemental analysis, visual kerogen analysis and Rock-Eval pyrolysis data. The geochemistry parameters indicate that the Garau Formation is an excellent oil prone source rock and composed of kerogen type I and II. The oxygen index (OI) is very low which reveals that organic matter deposited in an anoxic sedimentary environment and suitable for the preservation of organic matter and hydrocarbon generation. The visual analysis of isolated kerogens from source rock samples indicates the abundance of dark amorphous organic matter (AOM) with small amounts of phytoclasts and pyrite with no palynomorphs. Sedimentation seems to have occurred in deep and reduced parts of a carbonate basin during a rapid transgression. In addition, due to the effect of thermal maturation, the color of amorphous organic matter has darkened. The elemental analysis and Van-Krevelen diagram was shown that the type of organic matter and reveals the thermal maturity of the oil window. Moreover, amount of pyritic sulfur (Sp) and organic sulfur (So) contents have been calculated, and it was reveals that the high content of organic sulfur is a key element in the structure of organic matter.

Integrated chemostratigraphy (δ13C-δ34S-δ15N) constrains Cretaceous lacustrine anoxic events triggered by marine sulfate input

During the Late Cretaceous period (~100.5–65 million years ago), two episodes of expansive lake anoxia occurred in the Songliao Basin (~3× the size of Lake Superior), NE China, either lasting less than one million years. These events, known as lacustrine anoxic events (LAEs), were the factors driving the development of the main source rocks for the most productive oilfields in China. The details underpinning the initiation of the LAEs, however, remain problematic. As a test of this scientific issue, we present time series of bulk organic carbon isotopes, pyrite sulfur isotopes, nitrogen isotopes and trace element concentrations from the Turonian–Coniacian Qingshankou Formation in the Songliao Basin. A notable δ34S excursion (~−10‰) and a spike in pyrite sulfur content are recorded in the basal Qingshankou Formation when the basin reached the maximum expansion. We attributed these changes to marine transgression, which would have brought high sulfate concentrations to the lake, thereby promoting microbial sulfate reduction (MSR). Subsequent sulfate limited by MSR and pyrite burial associated with isolation of the lake from the seawater drove a 20‰ positive δ34S shift. Note that the modes of the δ34S that fluctuations we describe from the LAEs have also been recognized in marine black shale during Oceanic Anoxic Event (OAE) 2, implying a common signature of anoxia. The carbon isotope data suggest that the maximal fractionation found in Qingshankou Member I was likely a consequence of the increased [CO2]aq in lake water and inputs from chemoautotrophs. Increased sedimentary δ15N during the interval of Qingshankou Member I implies intensified denitrification in the oxygen minimum zone, which lowered the water-column N/P ratios, thereby stimulating bacterial nitrogen fixation in Qingshankou Members II-III. By comparing and summarizing the sulfur, carbon and nitrogen cycles of the LAEs during deposition of the Qingshankou and Nenjiang formations, we argue that the forcing function underlying LAEs was enhanced sulfate levels from marine transgression, which might have intensified nutrient recycling and further regulated the lacustrine carbon and nitrogen cycles.

Spatial distribution of fine high-sulfur lean coal in enhanced gravity field

ABSTRACTThe spatial distribution of fine high-sulfur lean coal under different backwash water pressures and rotational frequencies in enhanced gravity field using the Falcon concentrator was investigated. It deals with the distribution characteristics of products, including yield, ash content, sulfur content, and pyritic sulfur content, in overflow, upper groove, and lower groove from the top to the bottom in space. Backwash water pressure had coarse adjustment while rotational frequency had fine adjustment on the Falcon concentration process; meanwhile, the desulfurization and de-ashing results were discussed by combining them. The extensive migration characteristic of pyritic sulfur in space was also studied.

On Improving the Separation Efficiency of a Wet High Gradient Magnetic Separator for the Removal of Pyrite from Egyptian Coal

ABSTRACTWet high gradient magnetic separation (WHGMS) of an Egyptian coal sample was carried out to minimize its pyritic-sulfur content reaching 1.60% (2.9% total sulfur). Optimization of the process using the Boxmag Rapid separator included feeding rate, pulp density, applied magnetic field, and the canister loading %. This was conducted through the CCRD and RSM, using Design Expert 6.0 software. Results showed that, at the optimum separation conditions, i.e., 10 l/h feeding rate, 5% pulp density, 2200 Gauss, and 0.6% canister loading, a coal concentrate assaying 0.57% pyritic sulfur was obtained with a recovery 58% and separation efficiency 79.34%.

Petrological, geochemical, and mineralogical compositions of the low-Ge coals from the Shengli Coalfield, China: A comparative study with Ge-rich coals and a formation model for coal-hosted Ge ore deposit

To better understand the formation mechanism of coal-hosted Ge ore deposits, this paper reports on the petrological, mineralogical, and geochemical compositions of the low-Ge coals in the Shengli Coalfield (Inner Mongolia, China), using optical microscopy, field emission-scanning electron microscopy, X-ray fluorescence, X-ray diffraction, and inductively coupled plasma mass spectrometry. The samples in the present study closely neighbor the previously-reported Wulantuga coal-hosted Ge ore deposit (both No. 6 Coal). In comparison with the Wulantuga Ge-rich coals, the low-Ge coals of the Shengli field display higher moisture (27.59% on average) and lower pyritic sulfur contents (0.53%). Both the low-Ge and Ge-rich coals are generally high in inertinite, and have varying but relatively low huminite contents. Preservation of fecal pellets as macrinite is notable in both the low-Ge and Ge-rich coals, and the position of the fecal pellets appears to be within tunnels or chambers within the wood. Quartz, kaolinite, pyrite, and gypsum are the major crystalline phases identified in most of the Ge-rich and low-Ge coals, but the low-Ge coals contain significantly less pyrite and are more abundant in non-mineral Ca and Mg. Ca-oxalate of authigenic origin is observed, generally occurring as cell-fillings in the low-Ge coals. Otherwise mineral-free organic matter in the low-Ge coals would be expected to have an inherent ash yield of around 6%, derived from the inorganic elements (mainly non-mineral Ca and Mg) that occur either in the organic matter or as dissolved ions in the pore water and form the sulfate species in low-temperature (oxygen-plasma) ash residues. The highly-elevated trace elements, including Be, Ge, As, Sb, W, Hg, and Tl, that occur in the Ge-rich coals of the Wulantuga deposit, are significantly depleted in the low-Ge coals. Lateral migration of Ge–W- and As–Hg–Sb–Tl-rich solutions through the original peat swamp for the Wulantuga Ge ore deposit has led to significant enrichment of Ge on the margin of the coal basin but decreasing Ge concentrations toward to the inner part of the basin. Such a migration direction is different to those in the previously-reported for the hydrothermal solutions in the Lincang (Yunnan of China) and Spetzugli (Russian Far East) Ge ore deposits, where the solutions migrated vertically from granite to peat along faults and led to a dome-shaped Ge distribution in the relevant coal seam.

Changes in sulfur form during coal desulfurization with microwave: Effect on coal properties

The changes in sulfur form in coal were analyzed by sulfur K-XANES (K-edge X-ray absorption near edge structures) spectra before and after the coal microwave desulfurization in a NaOH solution. After the desulfurization, the pyritic sulfur content of coal decreased significantly from 53.6% to 39.2%, while the sulfate sulfur content increased from 17.3% to 34.6%. Only a small amount of thiophene sulfur (20.1–16.1%) was removed. Some sulfur-containing components were oxidized to sulfate sulfur. Under the optimum conditions, the ash content decreased, while the volatile content increased. The calorific value of coal slightly decreased with a slight variation in the amplitudes. The overall structure of coal did not change significantly based on Fourier transform infrared (FTIR) spectral analyses. Thus, the desulfurization of coal with microwave irradiation in a NaOH solution did not significantly change the properties of coal.

Carbon isotopic shift and its cause at the Wuchiapingian–Changhsingian boundary in the Upper Permian at the Zhaojiaba section, South China: Evidences from multiple geochemical proxies

The Late Permian environmental change, connecting the Guadalupian–Lopingian (G–L) (Middle–Upper Permian) boundary mass extinction and the Permain–Triassic (P–Tr) boundary mass extinction, has attracted more and more attentions. A significant negative shift for carbon isotope had been found at the Wuchiapingian–Changhsingian (W–C) boundary in the Upper Permian recently. However, the cause(s) of this negative excursion is still unknown. To resolve this problem, we analyzed the bulk organic carbon isotope, total organic carbon (TOC) content, pyritic sulfur (Spy) content, major element concentrations, and molecular organic biomarkers in the Wujiaping and Dalong formations in the Upper Permian from the Zhaojiaba section in western Hubei province, South China. Our results show that (1) there was a significant negative excursion in organic carbon isotopes at the W–C boundary and again a negative excursion at the top of Changhsingian stage; (2) the significant negative excursion at the W–C boundary was probably a global signal and mainly caused by the low primary productivity; and (3) the negative carbon isotope excursion at the top of Changhsingian was probably caused by the Siberian Traps eruptions. A decline in oceanic primary productivity at the W–C boundary probably represents a disturbance of the marine food web, leading to a vulnerable ecosystem prior to the P–Tr boundary mass extinction.

Two-stage coal flotation to remove pyritic sulfur, arsenic, selenium and mercury

This study focuses on partial leaching of coal pyrite with sodium sulfite in order to increase its degree of liberation from the coal matrix, which might help to increase the removal of coal pyrite, together with trace elements of arsenic (As), selenium (Se) and mercury (Hg) by froth flotation. The U.S. Bureau of Mines’ two-stage reverse flotation process was applied to further reject coal pyrite in the second stage, where pyrite was floated while coal was depressed. The residts show that the leached coal flotation with sodium sulfite produced lower pyritic sulfur content in the clean coal by approximately 25% compared to the flotation of unleached coal. The synergism mechanism between the leaching and the two-stage flotation is delineated. The rejection of trace elements (As, Hg and Se) after the two-stage flotation process with unleached coal followed approximately that of pyritic sidfur (64.6%). However, after the two-stage flotation with leached coal, the rejection ofSe was as high as that of pyritic sulfur (77.9%), while the rejections of As and Hg were 20% lower than that of pyritic sulfur, or followed approximately the same rejections obtained through the two-stage flotation with unleached coal.

Inflammatory stress response in A549 cells as a result of exposure to coal: Evidence for the role of pyrite in coal workers’ pneumoconiosis pathogenesis

On the basis of a recent epidemiological study it is hypothesized that pyrite content in coal is an important factor in coal workers’ pneumoconiosis (CWP) pathogenesis. While the role of pyrite in pathogenesis remains to be resolved, the ability of the mineral to generate reactive oxygen species (ROS) through various mechanisms is likely a contributing factor. The aim of this study was to elucidate the importance of the pyrite content of coal in generating an inflammatory stress response (ISR), which is defined as the upregulation of ROS normalized by cell viability. The ISR of A549 human lung epithelial cells in the presence of natural coal samples with variable pyrite contents was measured. Normalized to surface area, five particle loadings for each coal reference standard were analyzed systematically for a total of 24h. The ISR generated by coals containing 0.00, 0.01, and 0.49wt.% pyritic sulfur is comparable to,though less than, the ISR generated by inert glass beads (299% of the control). The coals containing 0.52 and 1.15wt.% pyritic sulfur generated the greatest ISR (798% and 1426% of the control, respectively). ConclusionsWhile ISR does not increase proportionally to pyrite content in coal, the two coals with the highest pyritic sulfur and available iron contents generate the greatest ISR. Therefore, the present study indicates that coals with elevated pyrite contents are likely to induce a significant health burden by stimulating inflammation within the lungs, and may contribute to the development of CWP.

Use of ultrasonic emulsification in oil agglomeration for coal cleaning

Emulsification is one of the most important stages in coal cleaning by using oil agglomeration. Reduction in size of oil droplets and increase in total surface area provided by emulsification result in coverage of entire coal surface with oil, thereby reducing the oil dosage and affecting rapid agglomeration. Ultrasonic emulsification which has been used recently in many sectors such as pharmaceutical, cosmetic, food, chemical industries may be a beneficial and promising operation in oil agglomeration of coal. In the present study, an oxidized fine coal with high ash and pyritic sulfur content was cleaned by oil agglomeration process after ultrasonic emulsification and the effects of power level and time of ultrasonic treatment on the performance of the agglomeration process were determined. Ash and pyritic sulfur rejections that was found to be 50.38% and 85.28%, respectively, at agglomeration test without ultrasonic emulsification was increased to maximally 56.89% and 88.69% by using ultrasonic emulsification before agglomeration. While increase in power of ultrasonic treatment did not affect ash and pyritic sulfur removals considerably, ultrasonic treatment time had positive affect at higher power levels. Contrary to expectations, ultrasonic emulsification affected the combustible recovery and separation efficiencies adversely.

The Removal of Sulfur from Dursunbey and İskilip Lignites in Turkey, Using Natural Trona: 2. The Effect of the Microwave Radiation Method

This article describes the removal of pyritic and total sulfur contents of Dursunbey and İskilip lignites in microwave radiation atmosphere using trona, which is a natural mineral. Preliminary experiments were carried out aimed at determining optimum conditions using trona solutions with concentrations in the 2.50–15.00% range at microwave radiation powers of 90, 180, and 360 W for microwave radiation durations ranging from 30 to 480 sec. The effect of variables, such as distilled water (0%), trona solution concentration (1.25–15.00%), and microwave radiation power (90, 180, and 360 W), on sulfur removal was determined under optimal conditions. As a result of experiments conducted in microwave radiation atmosphere, the pyritic sulfur contents of Dursunbey and İskilip lignites were reduced by 48 and 38% and the total sulfur contents by 38 and 32%, respectively.

The Removal of Sulfur from Dursunbey and İskilip Lignites in Turkey, Using Natural Trona: 1. The Effect of the Thermal Method

This article is concerned with removing the pyritic and total sulfur contents from Dursunbey and İskilip lignites by means of trona, which is a natural mineral. The experiments were performed at 20, 50, and 90°C for periods ranging from 15 to 180 minutes using trona solutions with concentrations in the 2.50–15.00% range, and the optimal conditions for sulfur removal were determined. The effect of variable temperature (20, 50, and 90°C), concentrations of distilled water (0%) and trona solution concentration (1.25–15.00%), and experimental duration (15–180 minutes) on sulfur removal was investigated under the optimal conditions determined. It has been established that trona affects sulfur removal in thermal atmosphere and it reduces the pyritic sulfur contents of Dursunbey and İskilip lignites by 41 and 31% and the total sulfur contents by 41 and 38%, respectively.

Biodesulphurized low rank coals appraisal: Initial, treated, their bitumens and solid residues

Low rank high sulphur containing Bulgarian coals are biodesulphurized on laboratory scale. Treatment of Maritza East lignites by bacteria Pseudomonas putida B2 ( PP) attained 44% total desulphurization, while biodesulphurization of Bobov dol subbituminous coal by Acidothiobacillus ferrooxidans F3 ( AFe) demonstrated 14%. The caloric values were slightly altered, 0.8% for lignites and 4.7% for subbituminous coal. Bitumens from the initial and biotreated coals and fractions of their neutral oils are studied. For subbituminous coal treated by AFe F3 bacteria increase in polar diterpenoids is registered by GC/MS. Concerning the set of polar diterpenoids produced during lignites treatment by PP B2 their relative contents are comparable with the ones for initial lignites. GC/MS analyses of soluble products from both coals did not give any information for sulphur containing compounds. Temperature programmed reduction coupled “on-line” with mass spectrometry (AP-TPR/MS) and its “off-line” TD-GC/MS version are used for sulphur tracking in solid residues after bitumen extraction. Quantitative interpretation of TD-GC/MS profiles revealed changes in organic sulphur compounds, elemental sulphur and SO 2. Results gave us ground to conclude that AFe F3 bacteria decrease pyritic sulphur content and slightly oxidize coal organic matter while PP B2 bacteria influence lignite organic matter and also affect pyritic sulphur.

Mode of Occurrence and Thermal Stability of Mercury in Coal†

Mode of occurrence of mercury in three coals was studied using sequential selective extraction, physical separation, and thermal treatment methods. Mercury speciation in the selected coals was determined using a five step sequential selective extraction method showing associations of mercury fractions with the organic and mineral structure in the analyzed coals. One of the coals was further subjected to thermal treatment with results revealing release of the organo-complexed mercury from coal at temperatures below 400 °C, while the mercury fraction associated with the coal mineral lattice was found to be the more stable form, released at temperatures of 600 °C. The mercury content was also determined for a selected range of coal density fractions showing strong correlation between mercury concentration in coal and the coal density fractions. The heaviest density fraction of the coal exhibited the largest ash as well as the highest pyritic sulfur content. Previous studies have established a strong relationship between mercury and the pyritic sulfur in coal, which was also confirmed in this work.

Chemistry of coal and coal combustion products from Kentucky power plants: Results from the 2007 sampling, with emphasis on selenium

Kentucky produced over 8 Mt of coal combustion products (CCPs) in 2006, with 30% of the CCPs being utilized, a significant increase from our 1996 and 2001 surveys. As much of the increase is related to increased utilization of flue-gas desulfurization (FGD) gypsum, the increased production of FGD gypsum coincident with the commissioning of new FGD units and the saturation of the (currently) weak market for new construction, the percentage of utilization may decrease by the time of the next planned survey (2011). The concentration of volatile trace elements in the feed coal and in the pulverizer reject, while associated with pyritic sulfur, are somewhat independent of the pyritic sulfur content owing to provincial variations in the trace element content of coal minerals. Consequently, high-pyrite/high-S coals do not necessarily produce the highest-As, -Se, and –Hg (among other elements) fly ashes. Among the power plants in Kentucky, plants with intermediate sulfur contents have some of the highest concentrations of volatile trace elements in their fly ashes. In general, volatile trace elements in fly ash increase in concentration from the first through to the last row of the pollution control system owing to the decrease in flue gas temperature and decrease in particle size (and increase in surface area) in that direction. Mercury is dependent upon the carbon content in addition to the flue gas temperature. Selenium is more problematical, showing no consistent trend within the ash