IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Evaluating the efficacy of air-decking technique for surface mine blasts
No full textThe study underlines the effect of air-decking on rock fragmentation, blast induced ground vibration, and air overpressure. Five trial blasts have been conducted in a nearby limestone mine using wooden spacers as air-decks of 1.2 m length to replace about 20% of the explosive by weight. Also, the continuous velocity of detonation in a blast hole is measured. It is observed that the detonation wave, which comes across such large non-explosive zones, gets attenuated as no explosive is available, and the detonation becomes completely dead. The fragmentation achieved in the experimental trial blasts presented in the paper produced a significant number of boulders. The introduction of air decks in the column replaces the explosive, which leads to a reduction in the maximum charge per delay. The air-deck technique is found feasible in regions that have restrictions on the charge per delay due to excessive ground vibration and air overpressure
Decoding paleomire conditions of paleogene superhigh-organic-sulfur coals
No full textSuperhigh-organic‑sulfur (SHOS) coals (coals with organic sulfur content >4 wt%) are unique coal deposits found at a few notable locations in the world. Specific peat accumulation and preservation conditions must be met to form SHOS coals. Organic sulfur is a major constituent of such coals, and it may have various sources depending on the prevailing paleomire conditions. Understanding such paleomire conditions sheds light on the formation mechanisms of SHOS coals. This investigation decodes the paleomire conditions of the Paleogene SHOS coals from Meghalaya, India, using sulfur isotopic compositions (δ34S) of organic sulfur (δ34SOS) and pyritic sulfur (δ34SPy) along with organic petrography, pyrite morphology and trace element ratios. Thirty coal samples were collected from the Jaintia Hills in the east, Khasi Hills in the middle, and Garo Hills in the west of Meghalaya. The organic sulfur content in the Garo, Khasi, and Jaintia coals varies from 1.0 to 3.3 wt%, 1.4 to 13.8 wt%, and 1.0 to 7.2 wt%, respectively. Further, after separation from pyritic sulfur and sulfate sulfur phases, the organic sulfur content ranges from 54.4 to 69.2%, 63.8 to 79.9%, and 59.3 to 73.8%, in the Garo, Khasi, and Jaintia Hills, respectively, suggesting the SHOS nature of these coal samples. The δ34SPy varies from −29.3 ‰ to +5.7 ‰, −21.3 ‰ to +27.3 ‰, and −12.1 ‰ to −4.3 ‰, in the Jaintia, Khasi, and Garo Hills, respectively, while the δ34SOS fluctuates from −4.6 ‰ to +3.7 ‰, −9.3 ‰ to +7.8 ‰, and − 9.0 ‰ to −5.0 ‰, respectively. The δ34S values of pyrite and organic sulfur (OS) in Jaintia coals are 34S depleted compared to seawater sulfate (+22 ‰), leading to fractionations in the range of −51.3 ‰ to −16.3 ‰ (mean − 31.6 ‰) and − 26.6 ‰ to −18.3 ‰ (mean − 23.1 ‰) for pyritic and organic sulfur (OS), respectively. Pyrite in Khasi coals show a relatively heavier δ34S composition averaging at −20.5 ‰, whereas organic sulfur (OS) isotope compositions range from −31.3 ‰ to −14.2 ‰ with a mean of −22.6 ‰. Pyrite and OS in the Garo coals are depleted compared to seawater sulfate. Isotope variations in the Jaintia, Khasi, and Garo coals indicate microbial sulfate reduction (MSR) of seawater sulfate. Large isotopic fractionations between Eocene seawater sulfate and pyritic sulfur (Δ34SSO4Eocene – pyrite = up to −51.3 ‰; mean − 31.6 ‰) in Jaintia coals indicate their possible formation in the water column/near the sediment-seawater interface (open system) and also hint toward dissimilatory sulfate reduction pathways that prevailed under anoxic redox conditions. However, mean values of Δ34SSO4Eocene – pyrite (−20.5 ‰) in the Khasi coals imply pyrite formation deeper in the sediments (more closed system) under dysoxic conditions. The dominance of OS over pyritic sulfur, framboidal pyrite, and its microcrystal size distributions in Jaintia coals may suggest syngenetic pyrite formation in open water reducing/anoxic conditions under paralic environments. Elevated Sr/Ba and U/Th values in these coals further confirm the anoxic conditions. Nevertheless, the presence of euhedral pyrite with the alleviated pyrite framboids in the Khasi coals and their complete absence in the Garo coals may suggest dysoxic-suboxic and suboxic-oxic depositional conditions, respectively. The isotopic signatures of the Garo coals suggest sulfur contribution from the parent paleobiota and MSR under a freshwater-oxic environment. Insignificant fractionations between δ34SPy and δ34SOS indicate limited iron and sulfate availability for additional sulfur cycling and disproportionation reactions, typical of oxic conditions. The absence of framboidal pyrite, elevated sulfate concentration, and mean Sr/Ba and U/Th values of 0.5 and 0.3, respectively, further suggest the freshwater peat deposition in the Garo Hills under limnotelmatic to telmatic freshwater conditions. Moreover, high inertinite content (Immf = 9.77–33.16 vol%), possibly induced by atmospheric peat exposure, supports the interpretation of suboxic-oxic paleomire conditions in Garo Hills. Gradually decreasing mineral matter content from Jaintia (mean 13.6 vol%) to Garo coals (mean 7.4 vol%) additionally projects a transition from mesotrophic brackish to freshwater limnotelmatic environment, complementing the shift in the paleomire condition from eastern (Jaintia) to western (Garo) Meghalayan Hills
Evaluation of Singrauli Coals for Sustainable Energy Utilisation: Insight From Geochemical and Petrographic Perspectives
No full textThe study investigated 50 Permian coals from the Singrauli Coalfields in the Son Valley Basin, India, using advanced petro-geochemical techniques to assess their source rock properties, energy and utilisation potential and to reconstruct the paleodepositional environment. Petrological analysis indicated vitrinite reflectance values between 0.39% and 0.49%, classifying the Singrauli coals as sub-bituminous to high volatile bituminous rank and indicating a thermally immature state. The results of geochemical analysis (volatile matter: 36.8%–46.5% and Tmax: 420°C–425°C) further support the above contention. High carbon content (average 77.89%), low sulphur content (average 0.46%) and varying nitrogen and oxygen levels in studied coal enhance its environmental suitability. The hydrogen index (HI: 163–279 mg HC/g TOC) values suggest a predominance of type-III kerogen with mixed type-II–III kerogen, further supported by petrographic data. Moreover, geochemical and petrographic data suggested the suitability of Singrauli coals for gasification. The high total organic carbon (TOC ≥ 38 wt%) indicated admirable potential as a source rock for hydrocarbon generation, particularly within the gas-source rock zone, highlighting their suitability for energy production. Petrographic indices indicated a wet forest swamp origin with a telmatic source and bog region under ombrotrophic to mesotrophic hydrological circumstances. The association of macerals and total sulphur content further supported the conclusion of a freshwater environment during peat deposition
Unveiling the Interactive Dynamics: Urban Ecosystem Services in the Face of Climate Change
No full textFabrication of defective mesoporous cerium oxide nanostructure for promoting an efficient and stable electrocatalytic oxygen evolution reaction
No full textThe development of renewable energy technologies, such as fuel cells, electrolysersand metal-air batteries, relies heavily on the availability of highly efficient electrocatalysts for the anodic oxygen evolution reaction (OER). Defected ceria (D-CeO2) has a high potential to compete with the activity of RuO2 based OER catalysts. We have synthesiseda mesoporous nanostructure ceria (CeO2) with induced defects using a simple and economical approach at a relatively low temperature. The observed catalytic activity of the prepared D-CeO2 porous nanostructure was found to be remarkable. Additionally, the nanostructure exhibited a high tolerance to methanol and demonstrated durability towards OER in alkaline media. During the experiment, it was observed that the catalyst exhibited noteworthy activity in the OER compared to the commercially available RuO2 catalyst, as this is evident by a higher current density and more negative onset potential. The catalyst's remarkable OER activity is attributed to the synergistic effect resulting from the combination of defect sites and the porous structure of CeO2. CeO2 mesoporous nanostructures serve as excellent electrocatalysts for OER due to their elevated surface area, robust catalytic activity, and stability. Furthermore, their mesoporous configuration enhances mass transport, expedites oxygen transfer, mitigates electrode polarisation, and enhances the overall electrochemical performance
Emission of Polycyclic Aromatic Hydrocarbons from Co-combustion of Coal and Corncob
No full textThe emission of polycyclic aromatic hydrocarbons (PAHs) due to coal co-combustion with corncob (0, 10, 20, and 30%) was studied through a pilot scale drop tube furnace. Total PAHs (∑PAH) emission (gas + particulate) increased linearly from 19.4 µg/m3 for coal combustion to 31.6, 39.8, and 42.0 µg/m3 for 10, 20, and 30% corncob blends, respectively. Low-molecular-weight PAHs dominated the gas phase; medium- and high-molecular-weight PAHs in the particle phase. Naphthalene is the most prominent PAH in the gas phase. Emission of benzo[a]pyrene, increased by 45.9% at 10% corncob blend. However, its emission decreased by − 19.1% and − 87.3% for 20 and 30% corncob blends. Toxicity equivalence was also relatively higher for the 10% corncob blend but decreased greatly at 20 and 30% blends. For coal combustion, PAHs are generated due to the pyrolysis process, whereas for coal-corncob co-combustion, pyro-synthesis is the major route of PAH formation, as the PAH content was maximum at the later stage of combustion, i.e., at the bottom zone of the furnace. This study indicated that a minimum of 20% blending of corncob is required to achieve the beneficial effect of coal co-combustion in decreasing the emission of toxic PAHs
Integrating experimental study and intelligent modeling of pore evolution in the Bakken during simulated thermal progression for CO2 storage goals
No full textPore characteristics of the formation exert significant control over both the development and enrichment of shale plays, as well as CO2 storage capacity of shale reservoirs. This research delved into the alteration of the Bakken shale's pore structure - a major target of underground CO2 storage under the PCOR partnership - when exposed to anhydrous and hydrous pyrolysis (AHP and HP) across a broad temperature spectrum (300–450 °C), aiming to uncover the influence of water in this process. First, N2 adsorption analysis was carried out, followed by the delineation and characterization of distinct pore families within the pore size distribution (PSD) curves of the samples. Subsequently, fractal dimension analysis was employed to gauge the intricacy of the pore structure. Next, generalized regression neural network (GRNN) and radial basis function (RBF) neural network were employed to model the N2 adsorbed/desorbed volume of pyrolyzates obtained from pyrolysis tests. Throughout the process of thermal maturity, AHP and HP pyrolyzates exhibited an overall rise in N2 adsorption capacity, BET surface area, meso-, macro-, and total pore volume. Conversely, the average pore diameter decreased. Also, HP pyrolyzates displayed notably higher N2 adsorption capacity compared to AHP pyrolyzates. Differences in total pore volume and surface area, attributed to mesopores and macropores, were evident between HP and AHP pyrolyzates across all temperatures, with HP pyrolyzates consistently displaying higher values for these pore characteristics. Five pore families akin to those in the original Bakken shale were found in AHP and HP pyrolyzates, displaying similar mean pore sizes. Although there were significant differences in elevation and magnitude, the pyrolyzates showed heightened peaks and increased volumetric representation compared to unheated shale. Overall, AHP and HP pyrolyzates exhibited a general decrease in pore surface complexity and roughness, while concurrently displaying heightened complexity within the pore network during thermal maturation. In the modeling section, the GRNN model demonstrated supremacy in estimating N2 volume adsorbed or desorbed, with an average absolute percent relative error (AAPRE) of 3.61% across the entire dataset. The subsequent sensitivity analysis underscored the significant impact of relative pressure and pyrolysis method on the output, emphasizing the significant contribution of water in shaping pore development throughout shale thermal evolution. This study can serve as a guideline for identifying areas in the Bakken Formation that are better suited for CO2 storage, considering factors such as thermal maturity and water saturation, given extensive availability of such data
Empirical relation to evaluate blast induced crack development zone while using explosives of different detonation pressure in opencast bench blasting
No full textThe optimum utilisation of explosive energy in the rock blasting operation is a prime challenge for the blast designers. The explosive energy in this operation is used for movement of burden. The optimum fracturing of the rock mass to meet the production demand takes place along tension. In the process of blasting, the detonation pressure of the explosives in the blasthole induces shock wave to the rock mass. The propagating shock wave is initially compressive in nature and becomes tensile after being reflected from the free face. The extent of tensile damage zone would give the optimum burden for blasting. The explosive properties along with the rock mass properties and charge configuration influences the extent of tensile damage zone. In this study, an empirical relation has been developed for estimation of blast induced tensile damage zone. The experimental trials were conducted at a coal mine using two different types of explosives for the validation of the developed empirical relation. The ground vibration predictors were developed using the data of experimental trials. The induced damage zone was computed using empirical relation proposed by Forsyth (1993) and developed ground vibration predictors. The estimated damage zone using developed empirical predictor and Forsyth relation were compared. The difference in the induced damage zone using two approaches is within 10%. The predicted values using developed empirical relation are accurate with RMSE value of 0.227 m. Hence, the developed empirical relation would be beneficial for estimation of blast induced crack zone
Landslide monitoring and prediction system using geosensors and wireless sensor network
No full textLandslides in hilly regions are a frequently occurring natural phenomenon which takes a heavy toll of human lives and causes damage to different properties. Hence, prediction of landslide is essential for averting its deleterious effects by providing early warning to neighboring residents about the impending hazard of landslide. A landslide monitoring system has been designed using geosensors and high-range wireless network for on-line monitoring and prediction of landslides with the application of multivariate statistical analysis of prevailing site parameters. The system consists of various geosensors, wireless sensor network, server, and landslide monitoring and forecasting software. Crackmeter, in-place inclinometer, raingauge, tiltmeter, piezometer and other sensors are set up in the selected hill slope prone to landslide for continuous monitoring of influencing parameters. The system measures real-time landslide parameters using the said geosensors connected with wireless nodes and establishing a dynamic wireless network to overcome redundancy issue using wireless nodes of around 1200 m communication range using a high performance low power microcontroller, integrated solar panel and additional external omni-directional antenna for monitoring landslide in a large and hazardous hilly region from a distant safer location. The application software consists of different modules, namely data monitoring, analysis, storing, viewing, prediction, and generation of audio-visual, SMS and email alerts for 3 levels of landslides situations. The paper enumerates the system architecture and the application software details
Environmental Emission from Coal-Fired Power Plant and Control Technology
No full textCoal combustion in power plants is one of the major sources of emission of pollutants like carbon dioxide (CO2), sulphur oxides (SOx), nitrogen oxides (NOx) and potentially toxic trace elements (Hg, As, Cd etc.) in atmosphere which have several impact on environment and human health. Coal being the major energy source of India, it is important to understand the air pollution and its impact on environmental and human health. Herein, various air pollutants emitted from power plants, its sources and their impact on environment and human health are briefly described. Best available technologies (BAT) and best environmental practices (BEP) to manage different pollutants were also discussed