IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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The significant role of cerium, gallium, and zirconium in cu-based catalyst for syngas to methanol: a bench scale experimental approach
No full textThe Cu-based catalysts mainly accounted for the synthesis of methanol from synthesis gas. The promotion of Cu-based catalysts resulted in a significant increase in methanol selectivity, even with small quantities of an effective promoter. The Cusingle bondZn system without promoter and with promoters such as Cerium (Ce), Gallium (Ga), and Zirconium (Zr) are induced in the Cusingle bondZn system individually and studied their ease of Cu reduction. All four catalysts have been prepared via the coprecipitation method, and an experimental study has been carried out for syngas hydrogenation to methanol on a bench-scale fixed bed tubular reactor at 60 bar and 200 °C. The synthesized catalysts were characterized by multiple techniques, including Field Emission Scanning Electron Microscopy (FE-SAM), and Energy Dispersive X-ray Spectroscopy (EDS), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Temperature programmed reduction (TPR), Brunauer–Emmett–Teller (BET) surface area analyzer, X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), True Density-Porosity, Thermogravimetric Analysis (TGA), and the liquid product has been studied by Gas chromatography-FID and Karl fisher titrator. The determinantal effect of Ce, Ga, and Zr doping in the Cusingle bondZn catalyst and their respective activity has been studied based on electronic, geometric, reaction kinetics, and acid/base surface properties. This paper has briefly deliberated on the syngas, mainly CO hydrogenation to methanol over each of the catalysts for 72 h as well as the space-time yield (STY) and methanol selectivity. The cause of significant improvements in activity and stability regarding STY of Ce-promoted Cusingle bondZn catalyst over Ga and Zr promoted on the Cusingle bondZn system has been elaborated. The Influence of Ce, Ga & Zr for higher active Cu dispersion on the catalyst surface to promote its activity towards methanol synthesis has been briefly annotated
Structural and maturity evolution of lignite using Raman spectroscopy and organic petrology of the Barmer basin, Rajasthan, India
No full textThis study investigates the structural and thermal evolution of lignite from the Barmer Basin, Rajasthan, India, using Raman spectroscopy and organic petrology. Lignite samples were collected from active mines in Kapurdi, Giral, and Sonari and analyzed through proximate and ultimate analyses, petrography and Raman spectroscopic techniques to assess their rank and structural characteristics. Vitrinite reflectance measurements, ranging from 0.24% to 0.38%, to assess maturation of organic matter. The volatile matter, a conventional maturity parameter, ranges from 38.5% to 46.5%, indicating low rank and limited thermal evolution. Ash yield values vary from 2.32% to 28.24%. Petrographically, the lignite’s are rich in huminite, ranging from 58.0% to 77.4%, with inertinite content between 3.6% and 13.6% and liptinite concentration from 5.4% to 13.0%. The maceral composition suggests carbonaceous materials in an early diagenetic phase. Raman spectroscopy reveal the presence of D and G bands, typical spectral signatures of carbon-rich natural materials. The Raman shift for the D band ranges from 1343 to 1391 cm−1 and for the G band, from 1565 to 1588 cm−1. The intensity ratio of the ID/IG band ranged from 0.71 to 0.97, while the (G-D1) parameter varied from 187 to 238 cm−1, indicating sample heterogeneity. However, the AD1/AG ratio shows an irregular pattern, with values between 1.19 and 2.74. The study demonstrates that integrating Raman spectroscopy with Vitrinite reflectance (VRo) provides insights into the structural attributes of immature kerogen which denotes organic matter that has not yet undergone sufficient thermal evolution to generate oil or gas, which is typical of low-rank coals like lignite. The petrological, proximate and ultimate analyses collectively confirm the carbonaceous, coaly material in its early coalification stages. This study emphasizes the use of Raman spectroscopy and Organic petrology as a proxy to evaluate lignite thermal evolution, enhance the interpretation of carbon structural disorder (e.g., D/G band ratios) and offer deeper insights into the aromaticity, maturity and heterogeneity of lignite, comparing its results with traditional maturity indicators
Geochemical Characteristics of Talcher Coal, India: Insights on Mode of Occurrence of Trace Elements and Palaeoenvironmental Condition
No full textUnderstanding the elemental concentration and distribution in coal has significant importance in assessing its mobility and behaviour during utilisation processes. The depositional environment of coal controls the concentrations of elements that can adversely affect human health and the environment. Thus, this study investigates the detailed mineralogy and elemental composition of Talcher coal, the largest coalfield in India, in order to gain insight into the mode of occurrence of elements and palaeodepositional conditions. The coal is enriched in detrital mineral matter and exhibits a high detrital/authigenic index. Quartz and kaolinite are abundant, while siderite, calcite, plagioclase, goethite, illite, dolomite, apatite, and Ti-oxide have also been identified. This coal is enriched with Hg, Mo, Cr, and Th concerning the world hard coal. The Ti, Na, Cu, Cr, Rb, U, and Th have a strong association with silicate minerals. The Sr, K, Mg, Ca, and P exhibit both carbonate and phosphate affinities, whereas Fe, S, and Co are mostly associated with organic matter. Similarly, Mn, Ba, Ni, Zn, Pb, Cd, Mo, As, and Nb display both organic and inorganic affinities. The inorganic matters in coal are predominantly derived from intermediate rocks and have undergone strong weathering. Various elemental proxies suggest that the coal is formed predominantly in a freshwater depositional environment under a fluctuating oxygenating conditions. The Sr/Cu and Rb/Sr ratios have implied the prevalence of a warm humid climate with intermittent transitional warm to dry climatic conditions during coal formation. This research will be helpful in future palaeowetland research as well as understanding the behaviour of trace elements during coal utilisation
A DFT study of the ternary metal chalcogenides (XAlS2) materials for photovoltaic and high-temperature applications
No full textThis work employs density functional theory (DFT) to investigate the structural, electronic, and optical properties of XAlS2 (X = Li, Na, K, Rb, and Cs) nanomaterials for potential use in photovoltaic applications. A comprehensive first-principles analysis has been conducted using GGA-PBE, GGA-PBEsol, and LDA functionals to examine LiAlS2, NaAlS2, KAlS2, RbAlS2, and CsAlS2. The findings reveal distinctive band gaps within this set of materials, with LiAlS2 and NaAlS2 exhibiting indirect band gaps and KAlS2, RbAlS2, and CsAlS2 possessing direct band gaps. Analyzing the partial density of states indicates that the valence band predominantly arises from S-3p and Al-3p orbitals, showcasing covalent bonding through hybridization. Furthermore, the examination of the optical properties of XAlS2 materials suggests their notable light absorption in the ultraviolet range, positioning them as promising candidates for photovoltaic applications. Additionally, the lattice thermal conductivity of two dynamically stable systems has been investigated and their thermoelectric properties have been calculated. Notably, a dimensionless figure of merit of 2.78 for LiAlS2 has been identified, marking it as a strong contender for high-temperature thermoelectric applications
Severity of Hand-Arm Vibration Exposure and Prevalence of Hand-Arm Vibration Syndrome Among Jackhammer Operators in Indian Stone Quarries
No full textHand-arm vibration (HAV) poses a significant occupational hazard for workers using vibrating tools and can lead to hand-arm vibration syndrome (HAVS), which includes vascular, neurological, and musculoskeletal disorders (MSD). This research examines the severity of HAV exposure and the prevalence of HAVS among jackhammer operators in Indian stone quarries. By integrating field measurements and health surveys, the study evaluates the daily HAV exposure of 27 jackhammer operators and assesses health outcomes in 47 workers (27 exposed and 20 unexposed). The findings reveal that the operators’ average 8 h of daily vibration exposure surpasses the threshold limit of 5 m/s2 stipulated by the EU Directive and American Conference of Governmental Industrial Hygienists. Among the exposed workers, high rates of non-vascular symptoms were observed, including tingling (33.3%), numbness (33.3%), and hand pain (29.6%). In contrast, vascular symptoms such as Raynaud’s phenomenon were less prevalent, affecting only 3.7% of the exposed workers. There was a significant correlation between lifetime vibration dose and the severity of sensorineural symptoms (r = 0.74, p < 0.001). The exposed workers were 7.2 times more likely to develop sensorineural disorders and 8 times more likely to develop MSDs compared to their unexposed counterparts, as determined through the odds ratio. These findings emphasize the importance of including HAVS in India’s recognized occupational diseases under the Mines Act of 1952. Such inclusion would prompt greater awareness among mine operators and support the implementation of protective measures to mitigate HAVS in Indian mining operations
Integration of fluid-invasive, scattering, and imaging methods in resolving pore structures in coal and shale
No full textIn this study, coal and shale samples were collected from the gas-rich Barakar Formations and investigated using various analytical and imaging methods, to quantify their pore attributes. The results indicate that coal contains an abundance of nanopores that occur in clusters, along with evidence of microfractures in its structure, as observed through scanning electron microscopy (SEM). The accessible micropore surface area (SA) of coal samples is around 2.5 times higher than that of shale samples, while the total mesopore SA in coal is around half that of shales. However, the average pore width of coal samples is approximately 0.82 times that of shale samples. These findings suggest that a higher percentage of organic carbon in coal contributes to an abundance of organic pores, which results in greater porosity in coal samples when compared to shale. The total SA determined by gas adsorption for the entire spectrum of pore sizes in coal is around two times that of shale. Interestingly, despite the difference in the pore SA and the pore volume, the pore surface roughness in the studied coals is almost equal to or slightly higher than that of shales. The study observations show that the total organic carbon and mineral composition in coal and shale play little influence on the degree of pore connectivity. The degree of pore connectivity for the coal samples varies from 0.4–0.93, whereas for shale samples it ranges from 0.50–0.82. This study provides analytical insights into the pore structure of coal and shale collected from the same reservoir by considering factors such as depth, mineralogical content, and surface roughness. During CO2 injection, coal and shale reservoirs may experience swelling induced stress changes, potentially impacting their mechanical stability. Thus, this study provides insight into estimating the gas-storage capacities of both coal and shale reservoirs and aims to optimise the gas adsorption and maintain structural integrity. This approach ensures the long-term feasibility of implementing Enhanced Coalbed Methane (ECBM) recovery and shale gas recovery in other gas basins
Thermal and spectral Studies to Assess the spontaneous Combustion Propensity of coal seams of Raniganj Coalfield, India
No full textThe extraction of coal from Raniganj Coalfield (RCF) plays a vital role in the country’s industrial growth. The mechanisation of underground coal mines of RCF for excavation raises several issues in India, namely: multi-seam workings, upper seam worked-out areas, strata management, subsidence, ventilation, heat, humidity, spontaneous heating, and mine fires. This research is focused on studying the spontaneous combustion characteristics of ten RCF coals by investigating the CPT, TGign and FTIR, along with intrinsic properties of coal, viz. proximate analysis. The proximate analysis and spontaneous combustion study reveal that seven samples have optimum moisture (4-8 %), high volatile matter content (>30.0%), low CPT (180°C) and TGign (>320°C) values. FTIR study of these coals reveals that the same samples have quality organic functional groups (mainly including alcoholic group, carboxylic group, aldehyde group, ketonic group, alkene and alkyne group, etc.) which enhance the propensity of coal to spontaneous combustion. Based on all the results, it was observed that RCF coal has a critical issue of spontaneous combustion in many coal seams, which ultimately leads to coal mine fire in such cases.
Major Findings: Coal samples of RCF with VMd > 30%, Mad range 4 to 8 %, CPT < 160 °C, TGign < 290 °C are more susceptible to spontaneous combustion. This finding is also confirmed by FTIR analysis of coal samples
Investigations on Influence of Physico-Mechanical Properties on Blast-Induced Ground Vibration Using Numerical Simulation and Physical Modeling
No full textThe propagation characteristics of blast-induced ground vibration have a paramount influence on the physico-mechanical properties. The study of the trend of variation of PPV with these properties enables the designers in proper designing of a blast. However, it is very difficult to assess these properties while conducting experiments at the blasting sites as the actual blasting sites have heterogeneity. So, physical and numerical modeling approaches have been used in this study. The physical models consisted of the concrete blocks of 1m3. These blocks were blasted using slurry cartridge explosives. The geophones were placed at a horizontal distance of 0.4 m and vertical distances of 0.35–0.5 m The replica of physical model was made in the numerical model. The variations were made in the charging position, charging quantity, density, moisture content, elastic modulus, compressive strength and tensile strength. The outcomes have been recorded as nearfield PPV. The outputs of the physical models were analyzed using multivariate statistical analysis. The analysis reveals that the numerical simulation-based results followed the similar trend as of the physical models. The major findings of the study suggest that the PPV in near field decreases exponentially with increasing distance. It follows Ghosh and Daemen (1983) predictor characteristics. The outcomes also suggest a strong correlation of PPV with the ratio of tensile strength to the elastic modulus. The developed numerical model of this study may be useful in determining the design parameters of a blast
Tree species influence on heavy metals content in degraded mining soils: Environmental impact and remediation strategies
No full textRestoring environmental and ecological health in post-mining landscapes requires effective mitigation of heavy
metals (HMs) and potentially toxic elements (PTEs). Examining the impact of topography and vegetation,
particularly trees, on the spatial distribution of PTEs, can help develop site-specific reclamation strategies aimed
at minimizing their toxicity. This research study investigated the impact of topographical locations and the
nature of tree species (Leucaena leucocephala, Senna siamea and Azadirachta indica) on the total and bioavailable
concentrations of PTEs in soils from a reclaimed overburden dump in the Jharia coalfield region, India. Findings
revealed elevated levels of Cr (315 ± 27.90 mg/kg), Cd (1.62 ± 0.13 mg/kg), and Zn (140 ± 32.20 mg/kg)
across the mine soil, suggesting potential environmental risks. This was confirmed by a higher geo-accumulation
index value (Igeo) and contamination factor value (Cf). Despite these elevated total concentrations, the
bioavailable fractions remained relatively low, with Cd ranging from 2.92 to 11.46 %, Cr from 0.10 to 0.22 %,
and Zn from 5.15 to 22.4 %. The overall pollution load index (PLI) was significantly affected by the tree species
but not by the topography. Specifically, L. Leucocephala (0.955) exhibited a low PLI, followed by S. siamea
(1.014) and A. indica (1.074). These findings reveal the influential role of tree species in shaping the total
concentration and bioavailability of PTEs in soils impacted by mining activities. To control the off-site movement
of PTEs from overburden heaps, peripheral trenches may be established. These trenches can be selectively
vegetated with L. leucocephala for phytoremediation due to its tolerance to harsh conditions
Distribution and mode of occurrence of mercury in Talcher and IB valley in India: insights on Hg environmental release and coal cleaning
No full textMercury is a global pollutant due to its toxicity, long range transfer and bioaccumulation. Coal combustion is one of the major sources of mercury in environment. Though the pre-combustion coal cleaning technologies for Hg removal have been advocated, the knowledge on the association of Hg with various components of coal is essential. Though in India, coal is the largest source of Hg emission, the mode of association of Hg is not well studied. In this article, various chemical association of mercury in coal sample from Talcher and Ib valley coalfield, India was studied in detail. The Hg concentration in the studied coal was 0.140 to 0.754 µg/g. Correlation studies show positive and significant correlation with total sulphur content, especially with pyritic and sulphate sulphur of coal. The sequential leaching study showed that majority of Hg was associated with pyritic fraction (57–84%) followed by clay (8–10%) and organic fraction (8–9%). Weathering of pyrites transformed a significant portion of Hg as HgSO4 and similar Hg containing iron-sulphate minerals. Pyritic association of Hg indicates that mild pyrolysis, density fraction, wet cleaning or a hybrid technology can be potential technique for Hg removal. However, a detailed techno commercial evaluation is needed between the alternative processes and the expected benefits of Hg cleaning