Forms Of Sulfur In Coal Research Articles

Analysis of the Formation Mechanism of Hydrogen Sulfide in the 13# Coal Seam of Shaping Coal Mine.

In order to accurately predict the law of occurrence and migration of hydrogen sulfide (H2S) in the underground and effectively solve the problem of excessive concentration of H2S gas, laboratory experiments on the content of various forms of sulfur in coal, sulfur isotopes, thermal evolution history, and coal seam water samples were carried out by applying the theories of coal mine geology, microbiology, and analytical chemistry, and based on the experimental results, the cause of H2S gas was explored. Through the analysis of the geological conditions of the coal seam mined, it can be seen that the coal mine experienced the alternation of marine and continental phases in the process of coal formation and that there was no magma intrusion. The experimental results showed that iron sulfide in coal accounts for 73.25% of the total sulfur, indicating that the coal seam was rich in pyrite. The results of the isotope test showed that the sulfur isotopes in coal samples were all negative, indicating that the sulfur isotope fractionation in coal was large, the loss was serious, and the coal seam was greatly affected by seawater. According to the experimental results of vitrinite reflectance, it can be concluded that the highest temperature during the thermal evolution of the coal seam is 108.12 °C, which has not reached the temperature condition of sulfate thermochemical reduction. Comparing the concentration of acid ions in coal seam water and tap water, it was found that the concentration of SO42- in coal seam water is low, while the concentration of HCO3- is high. According to the experimental results and theoretical analysis, the H2S gas in the high-sulfur coal mine was caused by microbial sulfate reduction. Finally, the transformation path of sulfur in the coal seam was deduced and analyzed. The results showed that sulfur in coal is positively correlated with H2S gas concentration.

Changes in sulfur functionality during solvent extraction of coal in HyperCoal production

In this paper, the structural changes of the chemical forms of sulfur in coal, as induced by thermal extraction with industrial solvents (HyperCoal [HPC] production), were examined using X-ray photoelectron spectroscopy (XPS). In raw coal, thiophenic sulfur is more common than alkyl sulfides, and the observed structural changes during solvent extraction depend on the initial chemical form of sulfur. The majority of sulfur remains in the residue after extraction, and inorganic sulfur is found only in the residue. Only thiophenic sulfur (~84%) and sulfoxides (~16%) were found in the resulting HPC; no other types of sulfur (e.g., alkyl sulfides) were detected. These results demonstrate that, during HPC extraction, sulfates are not extracted and that some or most of the extracted alkyl sulfides, sulfoxides, and sulfones are likely decomposed and eliminated as gases. It was found that thiophenic and sulfate sulfur are unaffected by the extraction process and are found in the HPC and/or the extraction residue.

Study on the change of organic sulfur forms in coal during low-temperature oxidation process

Organic sulfur functional groups in coal not only have certain oxidation characteristics at low temperature and but also can break to produce free radicals, which is bound to have a considerable effect on coal spontaneous combustion. However, this area has not been reported yet. There are relatively few studies on variation laws of organic sulfur functional groups in coal in the coal spontaneous combustion process (especially low-temperature oxidation stage), and the release of SO2, the gaseous product of organic sulfur during the low-temperature oxidation, is also rarely reported. Therefore, it is necessary to systematically obtain the change laws of organic sulfur forms in coal during low-temperature oxidation. In this paper, the morphological changes of organic sulfur in coal during low-temperature oxidation were studied first, and then the changes of organic sulfur forms in coal before and after low-temperature oxidation and the release of the low-temperature oxidation product SO2 were studied by using the X-ray photon spectroscopy (XPS) technique and the XLZ-1090 infrared gas analyzer. The XPS analysis results show that the relative contents of mercaptan and sulfide are reduced; the content of thiophene sulfur decreases slightly or remains unchanged; and the contents of sulfone, sulfonate and sulfate all increase. This verifies that the low-temperature oxidation process of active organic sulfur functional groups in coal is: sulfide → sulfoxide → sulfone, mercaptan → disulphide → sulfoxide → sulfone → sulfonic acid. The study reveals that the release of gaseous SO2 is not detected during the low-temperature oxidation of the raw coal samples, whereas it is detected during the low-temperature oxidation of the acid-treated coal samples. This is because the acid treatment can remove alkaline minerals in coal, weakens the inhibitory effect of alkaline minerals on SO2 and enable SO2 to escape almost completely. In addition, the study also discovers that the time and amount of SO2 gas release during the low-temperature oxidation process are directly related to the metamorphic degree and organic sulfur content of coal.

Changes of sulfur forms in coal after tetrachloroethylene extraction and theirs transformations during pyrolysis

Two different rank coals with high organic sulfur content were selected and pretreated with tetrachloroethylene (PCE) under ultrasonic field. The effects of pretreating process on sulfur forms in two coals have been investigated by chemical analysis and sulfur K-edge X-ray absorption spectroscopy (S-XAS). The transformation behaviors of sulfur forms during pyrolysis of raw and PCE-treated coals in the fixed bed reactor with temperature-programmed apparatus were studied by gas chromatography (GC) and S-XAS. Results show that sulfur removal degree of Coal A and Coal D are 29.7% and 24.1%, respectively; and the removal of organic sulfur are dominant, accounting for 87.1% and 66.1% of total removal of sulfur from Coal A and Coal D. The sulfur compositions in coals obviously change before and after PCE extraction, and these changes appear to be unevenly distributed on the surface and in the bulk of coal. The effects of PCE extraction on the release of sulfur-containing gases are different for two coals, which are dependent on the sulfur forms in the coals, as well as the chemical structure in coals. The sulfur forms retained in the chars are significantly different for low rank Coal A before and after PCE extraction, but there is little change for high rank Coal D.

Calcium-promoted catalytic activity of potassium carbonate for steam gasification of coal char: Transformations of sulfur

K2CO3-catalyzed char gasification with steam was carried out on a laboratory fix-bed reactor and it featured in the preparation of char from a high-sulfur coal by the prior addition of Ca(OH)2 to the coal. This work was focused on the clarification of sulfur transformations during the coal pyrolysis and the char gasification. Sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy was employed to determine quantitatively the forms of sulfur in coal and their changes in process. Results showed that the addition of Ca(OH)2 to coal promoted the decomposition of both pyrite and organic sulfur during the charring. In the K2CO3-catalyzed char gasification, the calcium additive enabled more sulfur to be retained eventually as K2SO4 rather than CaSO4. The formation of K2SO4 would be conducive to the recycled use of potassium catalyst.

Correlation for the Total Sulfur Content in Char after Devolatilization

The overall process of coal combustion takes place in two successive steps: devolatilization and char combustion. The fate of sulfur during the devolatilization of coal of different rank was investigated. The significance of the investigation is in fact that a major part of sulfur release occurs during devolatilization of coal, (i.e., emission of sulfur oxides during combustion of coal largely depends on sulfur release during devolatilization). The experimental investigations were conducted to obtain the data about the quantitative relation between sulfur content in the coal and sulfur content in the char. Standard procedures were used for obtaining the chars in a laboratory oven and determining the sulfur forms in the coal and char samples. The experiments were done with grounded coal samples (<0.2 mm), at the temperatures in the range of 500−1000 °C. We showed that the amount of sulfur remaining in the char decreases, but not significantly in the temperature range 600−900 °C. On the basis of the theoretical consideration of behavior of sulfur forms during devolatilization, certain simplifying assumptions, and obtained experimental data, we propose two correlations to associate the content of sulfur in the coal and in the char. The correlations are based on the results of the proximate analysis and sulfur forms in coal. Good agreement was found when the proposed correlations were compared with the experimental results obtained for investigated coals. Moreover, the correlations were verified by results found in the literature for numerous Polish, Albanian, and Turkish coals. Significant correlations (P < 0.05) between observed and calculated data with correlation coefficient, R > 0.9, were noticed in the case of all coals.

Petrographic and geochemical contrasts and environmentally significant trace elements in marine-influenced coal seams, Yanzhou mining area, China

The Yanzhou mining area in west Shandong Province, China contains coals of Permian and Carboniferous age. The 3 1 and 3 2 seams of the Permian Shanxi Formation and seams 6, 15–17 of the Carboniferous Taiyuan Formation were analyzed for coal petrology, mineralogy and geochemical parameters. The parameters indicate that the coal is high volatile bituminous in rank. The coal is characterized by high vitrinite and low to medium inertinite and liptinite contents. These properties may be related to evolution of the coal forming environment from more reducing conditions in a marine influenced lower delta plain environment for the early Taiyuan coals to more oxidizing paleoenvironments in an upper delta plain for the upper Shanxi coal seams. The major mineral phases present in the coal are quartz, kaolinite, pyrite and calcite. Sulfur is one of the hazardous elements in coal. The major forms of sulfur in coal are pyritic, organic and sulfate sulfur. Pyritic and organic sulfur generally account for the bulk of the sulfur in coal. Elemental sulfur also occurs in coal, but only in trace to minor amounts. In this paper, the distribution and concentration of sulfur in the Yanzhou mining district are analyzed, and the forms of sulfur are studied. The sulfur content of the Taiyuan coal seams is considerably higher than that of the Shanxi coals. Organic sulfur content is positively correlated to total and pyritic sulfur. The vertical variation of Cu, Zn, Pb, As, Th, U and sulfur contents in coal seam 3 of the Shanxi Formation in the Xinglongzhuang mine show that all these trace elements, with the exception of Th, are enriched in the top and bottom plies of the seam, and that their concentrations are also relatively high in the dirt bands within the seam. The pyritic sulfur is positively correlated with total sulfur, and both are enriched in the top, bottom and parting plies of the seam. The concentrations of the trace elements are closely related to sulfur and ash contents. Most of the trace elements are correlated with the ash content, and may be associated with the mineral matter in the coal.

Sulfur in coal and its environmental impact from Yanzhou Mining District, China

Sulfur is one of the hazardous elements in coal. The concentrations of sulfur are relatively high in coal. The major forms of sulfur in coal are pyritic, organic and sulfate. Pyritic and organic sulfur generally account for the bulk of sulfur in coal. Elemental sulfur also occurs in coal, but only in trace to minor amounts. When coals are burned, leached and washed, sulfur will be released in the form of sulfide and H2S, which then react with O2, water and other substances to change into vitriol, and in some places it may form acid rain. And they will impact water environment, acidify the soil and do great harm to plants and human health. In this paper, on the basis of the data from the Yanzhou mining district, the distribution and concentrations of sulfur are analyzed and the existing forms of sulfur are studied. The variation of sulfur and its impact on the environments also are described when coal is used.

XAFS study of sulfur forms in coals during rapid pyrolysis

XAFS study of sulfur forms in coals during rapid pyrolysis

Sulfur in coal and its environmental impact from Yanzhou mining district, China

Sulfur is one of the hazardous elements in coal. The concentrations of sulfur are relatively high in coal. The major forms of sulfur in coal are pyritic, organic and sulfate. Pyritic and organic sulfur generally account for the bulk of sulfur in coal. Elemental sulfur also occurs in coal, but only in trace to minor amounts. When coals are burned, leached and washed, sulfur will be released in the form of sulfide and H2S, which then react with O2, water and other substances to change into vitriol, and in some places it may form acid rain. And they will impact water environment, acidify the soil and do great harm to plants and human health. In this paper, on the basis of the data from the Yanzhou mining district, the distribution and concentrations of sulfur are analyzed and the existing forms of sulfur are studied. The variation of sulfur and its impact on the environments also are described when coal is used.

00/02296 Sulfur forms in coal and desulfurization characteristics

00/02296 Sulfur forms in coal and desulfurization characteristics

00/01187 The direct determination of the forms of sulphur in coal using microwave digestion aid i.c.p.-a.e.s. analysis

00/01187 The direct determination of the forms of sulphur in coal using microwave digestion aid i.c.p.-a.e.s. analysis

00/00624 Structure determination of sulfur forms in coals by XANES

00/00624 Structure determination of sulfur forms in coals by XANES

The direct determination of the forms of sulphur in coal using microwave digestion and i.c.p-a.e.s analysis

A sequential digestion method is reported for the direct determination of sulphate, pyrite and organic sulphur concentrations in coals of either bituminous or sub-bituminous rank. A three stage extraction was developed, using acid digestion in a microwave oven. In the first stage, 5 M HCl is used to dissolve sulphate phases in the coal. Pyrite is then extracted from the stage 1 residue using 2 M HNO 3. The final stage, for the determination of organic sulphur, involves the use of concentrated HNO 3, HCl, HF and boric acid for the complete decomposition of residue that remains following stage 2. The extract solutions from each stage are rapidly analysed for sulphur using i.c.p.-a.e.s. The sums of the three forms of sulphur have shown consistent agreement with certified total sulphur data for most of the coals studied. This correlation, in addition to the good precision achieved by this technique, suggests that the sequential digestion method is reliable. Furthermore, significant timesavings are achievable over some of the standard techniques demonstrating the suitability of the method for routine analyses.

99/03015 The selective oxidation of phenol-formaldehyde resins as a model in the speciation of organic sulfur forms in coals and petroleum heavy oils v

99/03015 The selective oxidation of phenol-formaldehyde resins as a model in the speciation of organic sulfur forms in coals and petroleum heavy oils v

99/01775 Relationship between the contents of trace elements and three forms of sulfur in coal: Lu, X. et al. Huazhong Ligong Dazue Xuebao, 1997, 25, (5), 19–21. (In Chinese)

99/01775 Relationship between the contents of trace elements and three forms of sulfur in coal: Lu, X. et al. Huazhong Ligong Dazue Xuebao, 1997, 25, (5), 19–21. (In Chinese)

石炭中の硫黄形態と脱硫特性

Removal of sulfur, nitrogen and ash-forming minerals from coal by pretreatment is one of the promising technologies not only to lower the damage of environment but also to accelerate the development of efficient coal utilization processes. This review concerns sulfur in coal which causes air pollution and acid rain in the world. The origin and forms of sulfur in coal, analytical method of sulfur forms, distribution of sulfur in macerals, sulfur behavior during heat treatment, and advanced desulfurization technologies are discussed.Sulfur in coal was derived from (1) sulfate in sea water that overlaid peat swamps and (2) parent plant material. Lower density group of organic matrix which is composed of exinite and vitrinite contains high sulfur. XANES analysis indicates that the low-density group contains sulfide and sulfoxide, which could contribute to the high extent of organic sulfur removal during rapid pyrolysis. Ferrous-sulfide sulfur and thiophene remains in char.A combined process of alkali treatment with rapid pyrolysis is introduced which has aimed to transform the thermally stable form of organic sulfur to reactive species before pyrolysis. More than 90 % of organic sulfur has been removed from a subbituminous coal.

Speciation of the Organic Sulfur Forms in a Recent Sediment and Type I and II-S Kerogens by High-Pressure Temperature-Programmed Reduction

Temperature-programmed reduction (TPR) with a well-swept fixed-bed reactor operating at 15 MPa of hydrogen pressure has facilitated the speciation of the organic sulfur forms in coals and petroleum source rocks through complete hydrodesulfurization with typically 75-80% of the sulfur being released as hydrogen sulfide with the remaining 20-25% occurring as primarily thiophenic compounds in the oils obtained in high yield. In this study, the technique has been applied to kerogens isolated from a series of unconsolidated Peru margin sediments, and for comparison, to type I and II-S kerogens (Goynuk oil shale and Monterey Fm, respectively) from immature organic-rich rocks. Visual resolution in the hydrogen sulfide TPR evolution profiles has been achieved between mono- and di/polysulfidic forms with the latter being reduced below 250 °C. Indeed, di/polysulfides account for high proportions of the reduced sulfur in surficial sediment samples collected from close to the top of the sediment. In contrast, monosulfides are the dominant sulfur form in the sample analyzed from deeper in the Peru margin sediment where thiophenes account for up to ca. 35% of the organic sulfur. This distribution is remarkably similar to those found for both the type I and II-S kerogens investigated, indicating that the major changes in organic sulfur forms occur during the early stages of diagenesis.

97/00003 Analysis and desulfurization reactivity of sulfur forms in coals

97/00003 Analysis and desulfurization reactivity of sulfur forms in coals

96/05678 Phenolic resites as calibrants for temperature programmed reduction and probes for the thermal behavior of organic sulfur forms in coals

96/05678 Phenolic resites as calibrants for temperature programmed reduction and probes for the thermal behavior of organic sulfur forms in coals