Sulfur In Coal Research Articles

Comparative experimental study on the co-firing characteristics of water electrolysis gas (HHO) and lean coal/lignite with different injection modes in a one-dimensional furnace

Zero-carbon fuels (H2/NH3) replacing coal co-firing is a promising way to address carbon emissions. Hydrogen co-firing helps improve combustion stability at low loads and control pollutant emissions. This study used a safer water electrolysis gas (HHO) for the multi-coal co-firing adaptability test. The effects of HHO injection mode and flow rate on combustion intensity, flue gas emissions, and fly ash characteristics were investigated. The results showed that HHO and lean coal/lignite co-firing could significantly increase the combustion temperature. The maximum temperature increases after co-firing were 108 °C and 95 °C. As the HHO increased, the CO2 in lignite co-firing increased, and CO and unburnt carbon decreased, while the opposite results were observed for lean coal (LC). At the 2200L/h HHO co-firing, CO2 decreases by 14.46 % and 27.22 % for LC premixed co-firing (PC) and staged co-firing (SC). Compared to SC, PC is more conducive to promoting the complete combustion of coke. The NOX emissions of HHO/LC co-firing are lower than those of pure coal, reaching the lowest value of ∼ 9 ppm under SC. As the HHO increases, the NOX of Lignite-PC first increases and then slowly decreases, while Lignite-SC has the opposite effect. Although various NOX emission trends are observed under different conditions, the results are dominated by a common mechanism − the competition between NOX reduction caused by HHO gas and the increase in co-firing temperature on NOX generation. The NOX of SC is all lower than that of PC. The SO2 emission from the LC co-firing decreases with the increase of HHO, while the SO2 from lignite increases. The SO2 of LC-SC can be reduced from ∼ 142 ppm to 0 ppm. HHO gas injection inhibits the release and oxidation of sulfur in lean coal. The differences in coal types lead to different changes in SO2 of co-firing. HHO gas reduced the SO3 content of lignite fly ash by 38.01 %. The high-temperature reduction atmosphere promotes the decomposition of sulfates and increases SO2 emissions. HHO co-firing refines the particle size of fly ash. The ultra-fine and micron particle matter (PM) increases, and the content of PM>100μm in Lignite-SC decreased by 10.32 %.

The Sulfur Conversion Functional Microbial Communities in Biogas Liquid Can Participate in Coal Degradation.

The addition of biogas liquid is a practical way to improve the yield of biological coalbed methane. The microbial composition in biogas liquid is complex, and whether it could participate in the sulfur conversion of coal remains unknown. In this study, sulfur conversion-related microbial communities were enriched from biogas liquid, which was dominated by genera Anaerosolibacter, Bacillus, Hydrogenispora, and Oxobacter. The co-culture of these groups with coal significantly changed the coal microbial community composition but did not increase the content of CH4 and H2S. The changed microbial communities mainly belonged to phyla Firmicutes, Proteobacteria, and Actinobacteriota, and increased the relative abundance of genera Bacillus, Thermicanus, Hydrogenispora, Oxobacter, Lutispora, Anaerovorax, Desulfurispora, Ruminiclostridium, and Fonticella. From the microscopic structure of coal, an increase in the number of holes and roughness on the surface of the coal was found but the change of surface functional groups was weak. In addition, the addition of S-related microbial communities increased the contents of phoxim, methylthiobenzoylglycine and glibornuride M5 in aromatic compounds, as well as the content of lauryl hydrogen sulfate in alkyl compounds. Furthermore, the dibenzothiophene degradation-related microbial communities included Bacillus, Brevibacillus, Brevundimonas, Burkholderia-Caballeronia-Paraburkholderia, and Thermicanus, which can break C-S bonds or disrupt benzene rings to degrade dibenzothiophene. In conclusion, the S-related microbial communities in biogas liquid could rebuild the coal microbial community and be involved in the conversion process of organic sulfur in coal.

Experimental Study on Combined Microwave-Magnetic Separation-Flotation Coal Desulfurization.

In order to reduce the content of sulfur and ash in coal, improve the desulfurization and deashing rates, a combined experiment method of microwave magnetic separation-flotation was proposed for raw coal. The desulfurization and deashing rates of three experiment methods, namely, single magnetic separation, microwave magnetic separation, and microwave magnetic separation-flotation, were compared. Taking the microwave magnetic separation-flotation experiment method as the main line, the effects of the microwave irradiation time, microwave power, grinding time, magnetic field intensity, plate seam width, foaming agent dosage, collector dosage, and inhibitor dosage on desulfurization and deashing were discussed, and the mechanism of microwave irradiation on magnetic separation and flotation was revealed. The results show that under the conditions of a microwave irradiation time of 60 s, a microwave power of 80% of the rated power (800 W), a grinding time of 8 min, a plate seam width (the plate seam width of a magnetic separator sorting box) of 1 mm, a magnetic field intensity of 2.32 T, a foaming agent dosage of 90 g/t, a collector dosage of 2125 g/t, and an inhibitor dosage of 1500 g/t, the desulfurization and deashing effect is the best. The desulphurization rate is 76.51%, the sulfur removal rate of pyrite is 96.50%, and the deashing rate is 61.91%. Microwaves have the characteristic of selective heating, and the thermal conductivity of organic matter in coal is greater than that of mineral. Microwave irradiation can improve the reactivity of pyrite in coal, pyrolyze pyrite into high-magnetic pyrite, improve the magnetic properties, and improve the magnetic separation effect. Therefore, microwave irradiation plays a role in promoting magnetic separation. Through microwave irradiation, the positive and negative charges in coal molecules constantly vibrate and create friction under the action of an electric field force, and the thermal action generated by this vibration and friction process affects the structural changes in oxygen-containing functional groups in coal. With the increase in the irradiation time and power, the hydrophilic functional groups of -OH and -COOH decrease and the hydrophilicity decreases. Microwave heating evaporates the water in the pores of coal samples and weakens surface hydration. At the same time, microwave irradiation destroys the structure of coal and impurity minerals, produces cracks at the junction, increases the surface area of coal to a certain extent, enhances the hydrophobicity, and then improves the effect of flotation desulfurization and deashing. Therefore, after the microwave irradiation of raw coal, the magnetic separation effect is enhanced, and the flotation desulfurization effect is also enhanced.

Impact of Organic Sulfur on Coal Graphitization

AbstractThe utilization of high‐sulfur coal, especially high‐organic coal, has always been a difficult hot spot in the energy field. To study the influence of sulfur in coal on coal‐based graphite products, a series of coal samples with different sulfur content and different degrees of coalification were collected for proximate analysis, ultimate analysis, and sulfur species analysis. The structural characteristics of coal‐based graphite products were analyzed by X‐ray diffraction (XRD). The relationships between the sulfur in coal and the yield (Y), graphitization degree (G), cell diameter (La), and stacking height (Lc) of coal‐based graphite products were explored. The yield of coal‐based graphite ranges from 8.92 % to 64.45 %, and it was found that the yield of coal‐based graphite is not only affected by the degree of coalification, fixed carbon content, and volatile matter content of coal but also significantly inhibited by organic sulfur in coal when the reflectance is less than 2.00 %. The graphitization degree (G) of coal‐based graphite is distributed between 76.02 % and 91.02 %, and positively related to the degree of coalification, and negatively related to the content of volatile matter. Organic sulfur in coal is an unfavorable factor for the graphitization degree (G) of coal‐based graphite. Both the cell diameter (La) and stacking height (Lc) of coal‐based graphite are positively correlated with the degree of coalification and negatively correlated with the volatile matter content in coal. Organic sulfur in coal plays an important inhibitory role on the cell diameter (La) of coal‐based graphite. Still, it has almost no effect on the stacking height (Lc) of coal‐based graphite, resulting in a low ratio of horizontal‐to‐vertical (La/Lc), which is not conducive to the horizontal development of coal‐based graphite cells.

Sulfur stable isotopes in Paleogene coals of Northeast India

Sulfur stable isotope signatures are instrumental in tracing the sources and tracking the movement of sulfur in different environmental compartments, besides providing vital insights into the origin and transport dynamics. Sulfur stable isotope composition in coal can give valuable information regarding sulfur sources and the process of sulfur incorporation in coal. The present study was conducted to determine the total sulfur content and sulfur isotopic composition for bulk sulfur (bulk S δ34S) in Oligocene and Eocene coal samples from coal mines and a few coal stockings in northeast India. The results revealed that the total sulfur content in coal samples varied between 1.03 and 4.80 (wt%) with an average value of 2.64 wt%. The bulk S δ34S in coal samples exhibited a wide range between −4.66 ‰ to 14.78 ‰ (VCDT). Oligocene coal samples from mines in Arunachal Pradesh, Assam, and Nagaland were enriched with heavier sulfur isotopes relative to Eocene coal samples from the Jaintia Hills region of Meghalaya. A moderate positive correlation was observed in the Oligocene coal samples, in contrast to the moderate negative correlation found in the Eocene coal samples. The bulk S δ34S values and sulfur content in coal samples from coal stockings matched closely with Assam and Meghalaya mine samples. The findings of this study can be used to track the sources and movement of coal sulfur in various environmental compartments, besides providing valuable information about sulfur sources, the process of sulfur incorporation in coal, and the depositional environment.

Optimization of coal desulfurization method by sub/supercritical fluid extraction with binary mixtures of carbon dioxide and ethyl lactate as a solvent

Coal combustion for energy results in the emission of air pollutants such as NOx and SOx, which negatively affect human health and the environment. Reducing toxic gas emissions and ash production is needed to achieve cleaner coal. This study aimed to develop an extraction method for desulfurizing coal with non-toxic solvents before combustion. Mixtures of sub/supercritical carbon dioxide and ethyl lactate (EL) were used at temperatures of 60–80 °C and extraction times of 15–45 min. Box-Behnken design (BBD) was used to assess the influence of the extraction parameters and to optimize the extraction method. The results show that higher temperatures and lower EL content significantly increased desulfurization. The optimal conditions for desulfurization were CO2/EL (95:5, v/v) at 80 °C, 300 bar and 15 min, reducing total sulfur in coal from 1.90 to 0.13% by weight. The extraction was efficient for removing organic sulfur, sulfones and sulfates, whereas there were still traces of sulfoxides and sulfides remaining in the coal after extraction. Moreover, the ash content slightly decreased while the calorific value increased by 8% and 3% by weight, respectively. The use of a temperature less than 100 °C and an extraction time of 15 min make this method "greener" in comparison to other proposed "green" methods, which use temperatures above 200 °C. Thus, the method has the potential to produce clean coal.

Experimental study on the impact of “IDS + JFCS” complex wetting agent on the characteristics of coal bodies

As China's coal mines have transitioned to deep mining, the ground stress within the coal seams has progressively increased, resulting in reduced permeability and poor wetting ability of conventional wetting agents. Consequently, these agents have become inadequate in fulfilling the requirements for preventing washouts during deep mining operations. In response to the aforementioned challenges, a solution was proposed to address the issues by formulating a composite wetting agent. This composite wetting agent combines a conventional surfactant with a chelating agent called tetrasodium iminodisuccinate (IDS). By conducting a meticulous screening of surfactant monomer solutions, the ideal formulation for the composite wetting agent was determined by combining the monomer surfactant with IDS. Extensive testing, encompassing evaluations of the composite solution's apparent strain, contact angle measurements, and alterations in the oxygenated functional groups on the coal surface, led to the identification of the optimal composition. This composition consisted of IDS serving as the chelating agent and fatty alcohol polyoxyethylene ether (JFCS).Subsequent assessment of the physical and mechanical performance of the coal briquettes treated with the composite wetting agent revealed notable enhancements. These findings signify significant advancements in the field and hold promising implications. Following the application of the composite wetting agent, notable reductions were observed in the dry basis ash and dry basis full sulfur of coal. Additionally, the water content within the coal mass increased significantly, leading to a substantial enhancement in the wetting effect of the coal body. This enhanced wetting effect effectively mitigated the coal body’s inclination towards impact, thereby offering technical support for optimizing water injection into coal seams and preventing as well as treating impact ground pressure.

High organic sulfur coal derived carbon-based sorbent for Hg0 capture from coal-fired flue gas

To develop the high value utilization of high organic sulfur coal instead of combustion as well as save the cost of mercury pollution control, we attempted to transmute the inherent sulfur of high organic sulfur coal, in the case of LF coal (which is from Linfen city, China), to active sulfur species for mercury capture by doping metal oxides, and CuO performed best among various metal oxides. The sorbent (or activated sample) prepared from LF coal with doping CuO is labelled LF+Cu-A, around which a series of experiments were conducted. Firstly, the effects of operational conditions, including GHSV (gas hourly space velocity), temperature and flue components, on the mercury capture performance of LF+Cu-A were thoroughly investigated, and results showed that LF+Cu-A had an excellent mercury capture performance. The average mercury capture efficiency is 97.8 % during a two-hour test under N2+O2+H2O+SO2+NO atmosphere with GHSV of 240000 h−1 and temperature of 120 °C. Secondly, the experimental data were fitted by four kinetic models, and it is found that the mercury adsorption process under low temperatures (60, 90, 120 °C) and high temperature (150 °C) are in the best agreement with the pseudo-first-order model and the intra-particle diffusion model respectively. Last, the mercury capture mechanisms of LF+Cu-A were revealed by Hg-TPD (Hg-temperature programed desorption) experiment, Raman analysis and XPS (X-ray photoelectron spectrometer) spectra, and it is indicated that the multiple sulfur species and Cu2+ play roles in the mercury capture process, during which elemental mercury are oxidized to HgS and fixed on the surface of LF+Cu-A.

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.

Numerical investigation of boiler waterwall corrosion by integrated tube temperature prediction and sulfur evolution model

High temperature corrosion has become one of the leading causes of boiler waterwall tube failures because of the wide application of air-staged combustion in coal-fired boilers. High temperature corrosion is strongly affected by the H2S concentration and wall tube temperature distributions in the furnace. Particularly, the corrosion rate increases exponentially with the increase of tube temperature. However, by far most of the numerical studies on high temperature corrosion only considered the effects of H2S concentration while the critical effects of tube temperature were overlooked. Thus, this paper presents a comprehensive corrosion model that incorporates the key effects of both tube temperature and H2S concentration. Specifically, the tube temperature is predicted by a coupled combustion and hydrodynamic model that integrates the critical effects of both the boiler gas flow and steam flow on waterwall tube temperature. The H2S concentration is predicted by a sulfur evolution model describing the devolatilization process of coal sulfur species and their subsequent gaseous reactions. The tube temperature prediction model and H2S evolution model provide all the key parameters for accurate prediction of boiler waterwall corrosion. The corrosion model is applied to a 350 MW supercritical wall-fired boiler. The results show that the tube temperature varies significantly over the boiler waterwall, and hence, has significant impacts on the distribution of wall tube corrosion. Particularly, local high tube temperature zones could form on the waterwall areas of relatively low H2S concentration leading to substantially higher tube corrosion rates than the adjacent wall areas. The results demonstrate the importance of incorporating both the wall tube temperature and H2S concentration in the prediction of boiler waterwall corrosion.

Super High Organic Sulphur (SHOS) in Tertiary coals of North-East India

Super High Organic Sulphur (SHOS) in Tertiary coals of North-East India

Assessment of microwave-induced combustion in disposable vessels as a low-cost approach for sulfur determination in coal

The determination and removal of sulfur from coal has become important to the industry and the environment for the pollution control. Therefore, the microwave-induced combustion in disposable vessels (MIC-DV) for sulfur determination in coal by inductively coupled plasma optical emission spectrometry (ICP-OES) was proposed. The parameters that could influence in the combustion, such as sample mass (5 to 30 mg), influence of pressurization (1.0 to 1.8 bar), and type (H2O and HNO3), concentration (1.0 to 14.4 mol L−1) and volume (2.5 to 12.5 mL) of absorbing solution were evaluated. The proposed method was compared with microwave-assisted digestion (MAD), microwave-induced combustion (MIC) and direct solid sampling elemental analysis (DSS-EA) and the agreement was better than 91, 82 and 91%, respectively. The limits of detection and quantification for sulfur in coal after optimized MIC-DV and determination by ICP-OES were 11 and 37 µg g−1. It is important to mention, that the MIC-DV employs low cost and environmental friendly materials and instrumentation. Moreover, the speed of the sample preparation process was increased comparing to MAD, MIC and DSS-EA, since sample combustion was achieved in less than 30 s in a rotor containing 5 positions. Last, but not least, the MIC-DV method is based on the single vessel principle, using the same vessel comprising the sample preparation and quantification, avoiding the use of additional vessels for dilution, reducing the risk of contamination by excessive handling.

SO3 removal rate and emission test of the limestone-gypsum wet desulfurization system for coal-fired power plants

This paper studies the SO3 removal ability of dual tower wet desulfurization (in series) and adopts a combination of on-site flue gas sampling and laboratory condensation control. A dual tower (series) supported boiler is used. The SO3 content in the original and clean flue gas of the dual cycle wet desulfurization device was measured, and the removal rate of SO3 of the device was measured. Desulfurization is calculated on the basis of the influence of unit electrical load, coal sulfur content, and desulfurization (raw material flue gas) inlet particle concentration on removal rate. This paper discusses and analyzes the SO3 and SO3 emission concentrations for SO3 removal rules in desulfurization systems. The results indicate that the total sulfur content of coal is relatively high, and the concentration of SO3 is relatively high. The traditional flue gas and net flue gas content in the dual tower wet desulfurization system (series) is relatively high. When burning sulfur-containing coal, there may be “blue smoke” in the flue gas. When the unit load changes between 182 MW and 350 MW, the SO3 removal rate of dual tower wet desulfurization (in series) is between 46.7% and 65.3%, with a net flue gas SO3 concentration of 16.0 mg/m3∼20.5 mg/m3. Due to equipment layout and other reasons, the SO3 removal rate of the primary tower is lower than that of the secondary tower. The removal rate of SO3 is also affected by the concentration of original smoke particles. Due to the condensation of SO3 on the particles and the dust removal of the adsorption tower, the higher the concentration of raw flue gas particles is, the higher the removal rate is. SO3 will be higher. The study also suggests the SO3 removal ability of double tower (series) and double ring wet desulfurization, which is better adapted to changes in load and coal. The next step is to explore the SO3 removal capacity of the dual tower system by optimizing its operating parameters. In addition, due to the arrangement of a desulfurization system after dust removal, it is impossible to control the SO3 source. Subsequent research can control the production of existing SO3 through coal distribution and combustion control.

Effect of extracts of petroleum ether, dichloromethane and methanol on thiophenic sulfur release during coal pyrolysis

The existing forms and thermal transformation of sulfur in high sulfur coal directly influence the efficiency of coal clean utilization by the staged pyrolysis conversion. Low molecular compounds distributed in coal are very different from the macromolecular structure of coal and play an important role during coal pyrolysis. In order to investigate the effects of low molecular compounds on the release of typical thiophenic sulfur species during coal pyrolysis by Py-GC/MS, petroleum ether, dichloromethane, and methanol were used for sequential ultrasonic extraction of Linfen coal (LFC). The compositions of extracts were detected by GC×GC/MS. Results show that three primary kinds of thiophenic sulfur species (2-methyl thiophene, benzothiophene, and dibenzothiophene) were released during coal pyrolysis and they are mainly derived from the cracking of macromolecular skeleton containing thiophenic sulfur in coal. The amounts of thiophenic sulfur released during raw coal and residues pyrolysis both increase with temperature. Besides, extracts with different compositions have different effects on the release of thiophenic sulfur during pyrolysis. In detail, the cyclization of aliphatic compounds could provide active hydrogen. On the one hand, the active hydrogen promotes the break of bridge bonds around thiophenic sulfur. On the other hand, active hydrogen may attack sulfur atoms of thiophenic sulfur, reducing the energy barriers of thiophenic sulfur decomposition. Aromatic compounds polymerize with sulfur-containing groups converting to benzothiophene and dibenzothiophene with larger molecular weight. In addition, thiophenic sulfur may be oxidized by esters to sulfones or sulfoxides, which further decompose, resulting in the inhibition effect on thiophenic sulfur formation during coal pyrolysis.

Evaluating net life-cycle greenhouse gas emissions intensities from gas and coal at varying methane leakage rates

The net climate impact of gas and coal life-cycle emissions are highly dependent on methane leakage. Every molecule of methane leaked alters the climate advantage because methane warms the planet significantly more than CO2 over its decade-long lifetime. We find that global gas systems that leak over 4.7% of their methane (when considering a 20-year timeframe) or 7.6% (when considering a 100 year timeframe) are on par with life-cycle coal emissions from methane leaking coal mines. The net climate impact from coal is also influenced by SO2 emissions, which react to form sulfate aerosols that mask warming. We run scenarios that combine varying methane leakage rates from coal and gas with low to high SO2 emissions based on coal sulfur content, flue gas scrubber efficiency, and sulfate aerosol global warming potentials. The methane and SO2 co-emitted with CO2 alter the emissions parity between gas and coal. We estimate that a gas system leakage rate as low as 0.2% is on par with coal, assuming 1.5% sulfur coal that is scrubbed at a 90% efficiency with no coal mine methane when considering climate effects over a 20 year timeframe. Recent aerial measurement surveys of US oil and gas production basins find wide-ranging natural gas leak rates 0.65% to 66.2%, with similar leakage rates detected worldwide. These numerous super-emitting gas systems being detected globally underscore the need to accelerate methane emissions detection, accounting, and management practices to certify that gas assets are less emissions intensive than coal.

Study on the experiment and reaction kinetics of sulfur removal from coal by microorganisms.

To solve the safety problem of spontaneous combustion of high-sulfur coal, applied microbiology, physical chemistry, reaction kinetics theory, combined with the SEM, FTIR and TG-DTG-DSC experiments and analysis of testing methods, the microbial desulfurization experiments were carried out, and the change law of the desulfurization reaction of coal before and after the element composition, main physical and chemical properties, the coal spontaneous combustion point was studied. The results show that when the temperature is 30°C, the coal particle size is 120 mesh, the initial pH value is 2.0 and the bacteria liquid amount is 15 mL, the desulfurization effect of the coal sample is the best, and the maximum desulfurization rate can reach 75.12%. There is obvious erosion on the surface of the coal sample after microbial desulfurization, the pyrite in the coal is obviously reduced, and the molecular structure in the coal is basically unchanged. Under the action of microorganism, part of inorganic sulfur in coal is removed, the spontaneous combustion point of coal is increased by 50°C, the activation energy of coal has increased more than three times, and the possibility of spontaneous combustion of coal is reduced. By analyzing the reaction kinetics of the microbial desulfurization process, it can be seen that the microbial desulfurization reaction is controlled by external diffusion, internal diffusion and chemical reaction, among which internal diffusion is the main influencing factor.

Rapid Estimation of Sulfur Content in High-Ash Indian Coal Using Mid-Infrared FTIR Data

High-ash Indian coals are primarily used as thermal coal in power plants and industries. Due to the presence of sulfur in thermal coal, flue gas is a major environmental concern. Conventional methods (Ultimate Analysis of Coal) for sulfur content estimation are time-consuming, relatively costly, and destructive. In this study, Fourier-transform infrared (FTIR) spectroscopy has emerged as a promising alternative method for the rapid and nondestructive analysis of the sulfur content in coal. In the present study, the actual sulfur content in the coal samples was determined using Ultimate Analysis (CHNS analyzer). In contrast, mid-infrared FTIR spectroscopic data (4000–400 cm−1) were used to analyze the functional groups related to sulfur or its compounds in the coal samples to predict the sulfur content. A comparison of sulfur estimated using a CHNS analyzer and predicted using mid-infrared spectroscopy (FTIR) data shows that it can accurately predict sulfur content in high-ash Indian coals using the piecewise linear regression method (Quasi-Newton, QN). The proposed FTIR-based sulfur prediction model showed a coefficient of determination (R2) of up to 0.93, where the total no. of samples (Coal + KBr pellets, n) was 126 (using 17:1 split, K-fold cross validation). The root-mean-square error (RMSE, wt.%) is 0.0035, mean bias error (MBE, wt.%) is −0.0003, MBE (%) is 3.31% and mean absolute error (MAE, wt.%) is 0.0020. The two-tailed t-test and F-test for mean and variance indicated no significant difference between the pair of values of observed sulfur (SCHNS, wt.%) using CHNS data and the model predicted sulfur (SFTIR, wt.%) using FTIR data. The prediction model using mid-infrared FTIR spectroscopy data and the Quasi-Newton method with a breakpoint and loss function performs well for coal samples from the Johilla Coalfield, Umaria. Thus, it can be a valuable tool for analyzing sulfur in other ash-rich coals from various basins worldwide.

Coal-based sulfur hybrid sorbent for removal of Hg0 from flue gas. Part 2. High organic sulfur coal

It is a win–win strategy to prepare mercury sorbents from low-cost high-sulfur raw materials. In part 1, mercury sorbents with excellent performance were prepared from high inorganic sulfur coal through KOH activation. However, this method does not work for high organic sulfur coal. In this work, a two-step preparation method is developed to prepare mercury sorbents from high organic sulfur coal. The first step is the co-pyrolysis/carbonization of Fe2O3 and coal, during which organic sulfur in coal is converted into FeSx. XPS shows that the percentage of Sx2–/S on the surface of the carbonized samples gradually increases from 5.4% to 22.2% with the m(Fe):m(So) ratio from 0:4 to 5:4. The second step is KOH activation, and it converts FeSx into various S species, including C-S, S0, S22− and S2−. Among the prepared mercury sorbents, LF+3Fe/4S-A (m(Fe):m(So) = 3:4) shows the best mercury removal performance, and its mercury removal efficiency remains above 84% for 120 min under N2+O2 at 120 °C. The Hg-TPDD and XPS results indicate that S*, including C-S, S0 and S22−, are the major active sites for mercury removal rather than Fe element, and HgS is the main existing form of mercury on the used sorbents. Besides LF coal, this two-step process is also applicable to other high organic sulfur coals (such as LL coal, WJZ coal, and SY coal) and high-sulfur petroleum coke.

Bioprocess development and optimization of parameters for enhancing bio-assisted method for sulfur removal from lakhra coal using rhodococcus sp SL-9

ABSTRACT The burning of coal releases toxic gases that disturb the environmental conditions. It is imperative to use this energy as much as possible. Due to its characteristics, it is possible to manipulate unused loss reserves. In this case, it is necessary to continue research emphasizing clean coal technology from an energy perspective, safety, and environmental sustainability problem. It wants to be implemented that 50% of the world’s coal reserves are low grades. In this regard, the current work is related to removing sulfur obtained from coal using newly isolated bacteria sl-9. It was determined that different process parameters might be used to remove Sulfur. There is a reduction of 45% of the total Sulfur in unprocessed coal when several parameters are controlled, such as 20% (w/v) pulp density, 180 rpm, 20 mesh (850 microns), and pH 7. So, Sl-9 has the potential to lower coal’s sulfate content.

Microbial desulphurisation of coal: a review

ABSTRACT During the production and processing of coal, burning it for energy production may cause a series of environmental pollution due to the amount of sulphur in it. When the consumed sulphur in coal is in the form of sulphur dioxide at the end of combustion, it reacts with water at high altitudes. Moreover, it goes down to the earth in the form of sulphuric acid, as well as damaging plants. The corrosive harmful impact on industrial plants is the removal of the sulphur in the coal when it is environmental. Microorganisms that use sulphur as food to eliminate the anxiety of clean production brought about by the chemical method. This review determined the study contains information about which microorganism is effective in removing sulphur in coal and also the types of organisms that should be according to the organic sulphur type in coal.