IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Photothermal conversion and geochemical characterization of sulfur-rich lignite for non-conventional energy applications
No full textLignite has emerged as a critical material in contemporary energy portfolios, particularly in electricity generation. However, this work explores lignite’s potential beyond conventional uses, exploring on its energy conversion applications. In a pioneering move, lignite samples have been directly utilized as materials for photothermal conversion applications, along with a description of their geochemical features, such as sulfur compositions, forms, and microscopic characteristics. Among the twenty lignite samples that were geologically studied, two sulfur-rich samples (CS-1 and CS-2) were chosen to explore their photothermal conversion performance. The powder-XRD diffraction patterns of CS-1 and CS-2 reveal the presence of the hexagonal phase of carbon C1 with kaolinite (Al2Si2O5(OH)4). Their XPS spectra indicate that both organic and metal-bonded sulfide moieties are present in the lignite samples. CS-1 and CS-2 were implemented under 1 Sun irradiation, and it was found that CS-2 exhibits superior light-absorbing properties, resulting in enhanced water evaporation rates. In addition, the photothermal imaging also shows a temperature increase to 58.2 °C within 10 min for lignite-coated membranes, compared to 31 °C for the blank under similar conditions. These findings can be leveraged to explore lignite’s untapped potential in various technological domains, propelling the global transition towards cleaner energy solutions
Elastic anisotropy and deformation characteristics of Pennsylvania anthracite
No full texthe mechanical behavior and elastic anisotropy of coal under stress are critical to understanding its structural integrity and performance in subsurface environments. Despite its significance, limited research has systematically analysed the elastic anisotropic responses of coals under such conditions. This study investigates the elastic anisotropy of three anthracite-rank coals, Primrose, Lattimer, and Mt. Carmel, subjected to conventional triaxial loading. P-wave (VP) and S-wave (VS) velocities, along with Thomsen parameters (ε and γ), were evaluated to elucidate the effects of increasing vertical stress on the structural integrity and anisotropy of each coal type. The results reveal that the Primrose coal exhibits the highest structural integrity, maintaining elevated VP and VS values and stable Thomsen parameters under stress due to its dense microstructure, higher inertinite content, and low porosity, which resist stress-induced microcracking. In contrast, the Lattimer coal demonstrates a significant reduction in VP and ε beyond 45 MPa, indicating greater susceptibility to microstructural damage and a trend towards isotropy as stress increases. The Mt. Carmel coal shows intermediate behavior, with moderate decreases in VP and ε but relatively stable γ values, reflecting a balanced resistance to structural degradation. S-wave anisotropy, as evidenced by shear wave splitting, remains most prominent in the Primrose coal, suggesting its superior ability to retain directional properties and resist stress-induced deformation. Principal component analysis highlights the role of rank, inertinite-to-vitrinite ratio, and aromaticity in influencing the mechanical responses of the coals, with Primrose coal consistently segregating as the most robust and anisotropically stable sample. These findings underscore the critical influence of compositional and microstructural differences on coal's anisotropic behavior under conventional-triaxial loading. They provide valuable insights for applications in subsurface energy extraction and storage, where understanding the mechanical and anisotropic properties of coal is essential for optimizing performance and mitigating risks
Insights from Optical-Electron Correlative Microscopy on Shales Subjected to Underground Thermal Treatment
No full textExtracting hydrocarbons from low-permeability shale is challenging. While hydraulic fracturing is typical, it poses environmental risks. This study explores underground thermal treatment (pyrolysis) using optical-electron correlative microscopy on an organic-rich shale from the Permian Barakar Formation, Rajmahal Basin, India. Thermal treatment (350–650°C) expanded liptinite pores (10 – 294 μm), while inertinite retained primary pores, and vitrinite showed no SEM-detectable pores. At 650°C, extensive pore enlargement and rupture indicate hydrocarbon expulsion. These findings provide key insights into maceral-specific porosity evolution, improving understanding of in-situ thermal treatment for unconventional hydrocarbon recovery
Application of multivariate adaptive regression splines technique for blast-induced air overpressure control in mines using large dataset
No full textRock mass in open cast mines is generally fragmented by blasting. The sudden release of explosive energy not only fragments rock but also generates undesirable nuisances such as ground vibrations, fly rock, dust, toxic fumes, back break, air overpressure (AOp) etc. AOp can vibrate civil engineering structures, shatter glass windows and doors, and adversely affect living quality. The present study strives to develop a reliable artificial intelligence model (AI) for predicting AOp in some Indian mines. For the objective, a large data set consisting of 699 data-points were collected from 33 open-cast mines to develop two white box AI techniques (multivariate adaptive regression splines and classification and regression tree), one black-box AI technique (support vector regression), multiple linear regressions, and USBM empirical predictor. The models were trained and tested using 70% (489) and 30% (210) datasets. Ten inputs, namely, hole diameter, hole depth, number of holes, burden, spacing, stemming length, charge per hole, total charge, maximum charge per delay, and distance, were used to develop these models. The performance of models was assessed using coefficient of determination (R2) and, root means squared error (RMSE). The results showed that the multivariate adaptive regression splines (MARS) model outperformed other models in predicting AOp with an R2 of 0.926, RMSE of 1.822. The proposed MARS model with a large dataset should better result in efficient prediction of AOp and can be easily implemented in different geo-environments for impacts minimization
Development of Coal Quality Exploration Technique based on Convolutional Neural Network and Hyperspectral Imaging
No full textCoal is India's prime energy source, contributing about 60% of total electricity production. Coal India, a major coal-producing public sector unit, has produced record 703.2 million tons of coal during the year 2022–2023. Therefore, this paper proposes an idea of instant prediction of coal quality parameters using hyperspectral imaging and deep neural network. We have collected coal samples from 35 different coal mines of all areas of Western Coalfields Ltd (WCL), and 257 different types of samples have been generated. All 257 coal samples were imaged using camera PIKA NIR 320. The RegNet model was applied to predict coal quality based on moisture, ash, volatile matter, gross calorific value, fixed carbon, and sulphur. The results were validated through chemical analysis results received from the lab. The proposed approach achieved good prediction accuracy, nearly 96% for coal quality parameters. Moisture showed the highest accuracy, 96.09% in quality prediction. [Received: October 25, 2023; Accepted: April 14, 2024
Source Rock Properties, Depositional Environment and Kerogen Degradation Kinetics of Lower Permian Shales from the Ib River Sub-Basin, Mahanadi Basin, Eastern India
No full textLower Permian organic-rich shales and coals from the Ib River sub-Basin, part of the Mahanadi Basin in Eastern India, were studied using Rock-Eval pyrolysis, kerogen kinetics, biomarker, and organic carbon isotopic analyses to investigate the source rock characteristics, depositional environment, and thermal degradation kinetics of the sedimentary organic matter (OM). The samples are organically rich (>5 wt% total organic carbon [TOC]) and possess higher hydrocarbon generation potential (>54 mgHC/g rock). The primary contributors to the OM supply were identified as terrestrial plants, supplemented by emergent aquatic plants, resulting in a Type II–III kerogen. The broader activation energy indicates OM input from heterogeneous sources, whereas the earlier and faster kerogen transformation ratio (TR), along with a high hydrocarbon generation rate (HGR), suggests excellent kerogen quality. Despite the samples’ favorable source rock characteristics, their relatively low Tmax values (<435°C) indicate immaturity, limiting their potential for natural hydrocarbon production. Marine incursions have been identified in the Barakar Formation of the Ib River sub-Basin, accompanied by climatic fluctuations (inferred from Paq, average chain length [ACL], and δ13C) that correspond to alternating dry and wet periods during the deposition of various lithotypes. The samples exhibit an abundance of even lower n-alkanes, indicating that the OM inputs are derived from aquatic vegetation rather than microbial activity. The gammacerane index (GI) averages ∼0.29 for the Barakar Formation and ∼0.24 for the Karharbari Formation, indicating greater water stratification and higher salinity in the Barakar Formation compared to the Karharbari Formation. Likewise, other key parameters such as tricyclic terpanes (TTs) and polyaromatic hydrocarbons (fluorenes [FLs], dibenzothiophenes [DBTs], and DBFs) differentiate certain Barakar samples as being deposited in a saline lacustrine environment, whereas the other Barakar samples and all Karharbari samples indicate a swampy, oxic environment. The pristane (Pr)/phytane (Ph) ratio supports this conclusion, indicating a reducing to oxidizing depositional setting for the Barakar Formation, while suggesting an oxic environment for the Karharbari Formation. Integrating all parameters, we conclude that the Barakar Formation was influenced by marine activities during Permian Period. Drawing on our research and prior studies, we propose two scenarios for marine interaction in the Ib River sub-Basin during the Permian Period: Either the region was covered by an extended marine embayment or marine influence extended to the NW-SE slope of the basin, notably affecting the Rewa region in the northwest
Genesis of coexisting authigenic ferric illite and glauconite in the Deodongar Sandstones, Chattisgarh Basin, India: Unraveling redox dynamics of a Mesoproterozoic Sea
No full textThis study investigates the co-occurrence of ferric illite and glauconite in the Deodongar sandstone of the Mesoproterozoic Chattisgarh Supergroup in India. Forming a Member within the stromatolitic Chandi Formation, these glauconitic arenites were deposited in a shallow marine setting, as revealed by field relationships. Electron Probe Micro Analyzer (EPMA) data shows that these ferric illites and glauconites are rich in magnesium and aluminum, although they exhibit considerable variation in iron and potassium content. Oxide cross-plots indicate that ferric illite and glauconite followed different geochemical pathways of formation. Textural observations indicate that these minerals formed over K-feldspar, quartz and chert fragments as authigenic phases. Mass balance calculations suggest that potassium released during the conversion of K-feldspar to glauconitic minerals may aid in transforming quartz/chert fragments to these minerals, though additional sources for iron, magnesium and aluminum ions are necessary. Thermodynamic calculations show that ferric illite formation is favorable than glauconite at 1 atmospheric pressure and 298 Kelvin temperature. Yet, occurrence of ferric illite and glauconite forming over adjacent substrates suggests that each substrate acted as a closed independent chemical system for mineral authigenesis
Fluoride and nitrate contamination in groundwater of Naini Industrial Area, Uttar Pradesh: Assessing non-carcinogenic human health risk
No full textGroundwater is the main source of drinking water globally; however, its quality has been deteriorated due to various geogenic and anthropogenic activities. The groundwater quality of Naini Industrial Area, Prayagraj was studied seasonally to evaluate the fluoride and nitrate contamination pertaining to human health risk assessment. The samples were collected from 60 locations in the pre-monsoon, monsoon, and post-monsoon season. The fluoride and nitrate were assessed with the help of Ion chromatography. The NO3− concentration exceeded the Indian drinking water quality standards in 27% of the groundwater samples. The NO₃⁻ contamination is predominantly associated with agricultural practices, while F⁻ can be linked to natural geological sources. The non-carcinogenic human health risk assessment was quantified by calculating the Hazard Quotient (HQ) and Hazard Index (HI) were calculated as per USEPA methodology for male, female and child population. The findings indicate that the child population is particularly susceptible to health risks associated with the ingestion of F− and NO₃⁻ through the drinking water pathway. Across all the sampled sites, the Hazard Index (HI) values varied from 0.10 to 12.3 for males, 0.09 to 10.6 for females, and 0.16 to 19.7 for children suggesting substantial risk to the local populace at more than half of the locations which is largely related to nitrate contamination. Thus, the study suggests that groundwater at many locations is unsuitable for drinking without treatment pertaining to the probable health risk they pose to consumers advocating upgraded water management plan for the residents
IMPACT OF SOLAR RADIATION AND HEAT TRANSFER ALONG THE RIVER DAMODAR
No full textThis study investigates the impact of solar radiation and heat transfer processes along the Damodar River, emphasizing their influence on riverine thermal dynamics and ecological processes. Solar radiation is a critical driver of surface water heating, leading to thermal stratification, which affects the physical, chemical, and biological properties of the aquatic ecosystem. Data on heat fluxes, including net radiation, latent heat, and sensible heat fluxes, were collected and analyzed for both pre-monsoon and post-monsoon seasons. The results reveal significant spatial and temporal variability in heat fluxes along the river, with higher net radiation
Reopening and Recovery of Fire Affected Sealed Panels: A Scientific Approach
No full textA mine or a part of a mine is sealed to control fire in a particular mine or a panel. Fire area should be sealed with stoppings and explosion proof stoppings, if necessary. There should be provision of sampling pipe such that air samples obtained from these represent the whole sealed off area. A considerable amount of time must elapse before the conditions become favourable for reopening and recovery of a mine or a panel. Status of sealed panel must be observed with respect to pressure behaviour, temperature measurement, gas content, and explosibility study. The reopening and recovery of a sealed off area should be undertaken with utmost effort keeping in mind the safety of mine and miners involved in that operation. There should be discussion with regulatory body, Directorate General of Mines Safety (DGMS), mine authority and scientific body to ensure that the sealed area may be opened at a suitable date and all arrangements to meet up any untoward incidents. Reopening should be undertaken with the help of rescue trained persons with adequate precautions. During recovery operation air sample from strategic locations should be monitored at regular interval, initially with greater frequency. Generally, controlled ventilation technique is implemented in recovery operation. The papers deals with a case study on reopening and recovery of sealed panel in Churi underground mine of Central Coalfields Ltd, a subsidiary of Coal India Ltd, India. Gas analysis data of more than one year, pressure behaviour study for more than 14 days have been interpreted to ensure that sealed area is safe to reopen. Reopening was done under rescue cover with due care to mine and miner. Controlled ventilation, provision of water pipe, quick recovery of fallen coal was adopted to deal with the situation