Browsing by Author "Pramod Kumar Rajak"

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Distribution and geochemistry of selected trace elements in the lignites of Cambay basin, Gujarat, western India
(Geological Society of India, 2016) P.K. Singh; Vijay Kumar Singh; Pramod Kumar Rajak; M.P. Singh; A.S. Naik
In the present investigation all the working lignite seams of Cambay basin of Gujarat have been studied to see the distribution and geochemistry of selected major/minor elements like Fe, Ca, Na, K, Mg, and Mn and trace elements like Cu, Co, Cr, Cd, Ni, Pb and Zn. The vertical variation of these elements along the seam profiles has been studied to see the pattern of distribution of these elements and also to know the horizons of their enrichment and the probable cause. Further, these elements have been correlated among themselves and also with organic and inorganic matter of lignite. The correlation study indicates that in Tadkeshwar upper seam Fe has its affinity with huminite while Mg and Na have their affinity with liptinite and in Tadkeshwar lower seam Na has an affinity with liptinite. In Vastan upper seam Mn and Cu are associated with inertinite and Na with huminite while in Vastan lower seam Cu relates to huminite and Cd to liptinite and huminite. In Rajpardi seam Ca and Co are associated with huminite. The study provides information on the mode of occurrence of elements of less studied lignites of western India. © 2016, Geological Society of India.
Elemental Composition and Petrographic Analysis of Coal in the Sohagpur Coalfield With Implications for Environmental Management
(John Wiley and Sons Ltd, 2025) Deepika Rathore; P. Gopinathan; Pramod Kumar Rajak; Aniruddha Kumar; Om Prakash Kumar; K. N. Singh; Amit Karmakar; T. Subramani
This paper aims to provide an overview of the geochemistry and mineralogical characterisation of coal within the Sohagpur coalfield, located in the Burhar–Amlai Sub Basin of Madhya Pradesh, India. The study involves the determination of proximate and ultimate analysis components, major elements, and trace elements by using various techniques, including x-ray diffraction (XRD), x-ray fluorescence (XRF), oranic petrography, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy–Energy Dispersive Spectroscopy (SEM-EDS). Petrological studies identify the types of macerals and minerals associated in coals, assess their concentration, and examine their association with elements found in the coal samples. Our research also delves into the environmental implications of these elements, particularly those considered environmentally sensitive, such as As, Cd, Co, Cr, Mn, Ni, Pb, Th and U. These findings are crucial for understanding the potential environmental impact associated with the utilisation of coal. This study identified several major sources of these elements within the coal, including silicate minerals (Quartz and Feldspar), oxides (Haematite, Rutile and Anatase), sulphides (Pyrite and Marcasite), sulphates (Gypsum) and carbonates (Calcite). Recognising these sensitive components is vital as they require mitigation or elimination before coal utilisation to minimise environmental risks. Our study delivers a valuable understanding of the geochemical composition and mineralogical characteristics of coal in the Sohagpur coalfield, highlighting the importance of environmental considerations in the utilisation of these resources. © 2025 John Wiley & Sons Ltd.
Geochemical and petrological characteristics coupled with stable isotope of the Permian Gondwana coals from Tatapani–Ramkola Coalfield, Son–Mahanadi Basin, India: Insights for paleodepositional and paleoclimate conditions
(Elsevier B.V., 2025) Neeraj K. Upadhayay; Amiya Shankar Naik; Shweta Rai; Prakash Kumar Singh; Alok Kumar; Afikah Binti Rahim; Mohammed Hail Hakimi; Govind Kumar; Pramod Kumar Rajak
This study aimed to investigate the quality and rank of the Tatapani-Ramkola coal and decipher the paleoclimate and depositional conditions during coal formation, explicitly focusing on vegetation sources, detrital contributions, and paleomire conditions. The studied coals exhibit a moisture between 4.0 % and 12.8 % and a volatile matter yield in the range of 28.8–49.5 wt% (dry ash–free basis), classifying them as subbituminous–A to bituminous in rank. This finding is supported by the vitrinite reflectance (VRo) values between 0.5 and 0.7 %. Maceral compositions reveal the dominance of vitrinite (average 47.8–62.4 %) followed by inertinite (average 13.0–29.9 %) and liptinite (average 8.5–13.1 %). This finding of the maceral characteristics together with the mineral composition (primarily clay, carbonate, and sulfide), show that the Tatapani–Ramkola coals were formed under mildly oxic–to–anoxic conditions in limno–telmatic to telmatic paleomires and contributions from forest and herbaceous vegetation. Geochemical isotope indicators, such as δ13C (−24.149 ± 0.825 ‰) and δ15N (+2.710 ± 0.344 ‰), suggest that the coals formed from C3 land plants under warm and humid climate conditions. Major oxide ratios indicate a moderate to high degree of chemical weathering in the source area, further confirming the prevailing warm and humid climate during the peat accumulation. The detrital/authigenic index (DAI) suggests significant detrital influence and authigenic sediment formation in the Tatapani–Ramkola coals. This study provides critical insights into the depositional history and paleoclimate of the Tatapani–Ramkola Basin, contributing to a deeper understanding of Permian coal formation processes. © 2025 Elsevier B.V.
Structural and maturity evolution of lignite using Raman spectroscopy and organic petrology of the Barmer basin, Rajasthan, India
(Springer, 2025) Om Prakash Kumar; P. Gopinathan; Amiya Shankar Naik; Pramod Kumar Rajak; Govind Kumar; Neeraj K. Upadhayay; Amit Karmakar; T. Subramani
This 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. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.