A. S. Naik

Petrological and Geochemical Investigations of Rajpardi Lignite Deposit, Gujarat, India

The present paper entails the petrographic and chemical characteristics of the lignite samples drawn from the Rajpardi lignite deposit of Bharuch district, Gujarat. This lignite contains a high concentration of huminite which is dominated by telohuminite, followed by detrohuminite. Liptinite and inertinite macerals are very low in concentration. The dominant microlithotype is humite. Its elevated volatile matter and high hydrogen content depicts its perhydrous nature. The study reveals that this lignite originated in a limno-telmatic to telmatic condition. The paleomire is further characterized as a wet moor having moderate to high flooding with good tissue preservation and increasing bacterial activity.

Petrographic and geochemical characterization of coals from Tiru valley, Nagaland, NE India

In Tiru valley region of Mon district coals occur in Barail Formation and are of Oligocene age. This study is the first investigation on the petrographic and geochemical characterization of these coals. These thinly bedded seams (<2 m) need systematic exploration for proper evaluation of the resource. The coals are bright to moderately bright in appearance and at places look moderately dull. The study reveals that Tiru valley coals are sub-bituminous to bituminous-D in rank. The chemical study reveals that these coals are perhydrous in nature with moderately high volatile matter content. The sulphur content was probably increased with pyrite inclusion as the most abundant mineral. Vitrinite is the most dominant maceral group constituting nearly 98% of all the macerals while liptinite and inertinite occur in very low concentration. Facies-critical models used to decipher the paleodepositional environment suggest that these coals evolved under wet moor with moderately high flooding in the paleomire which allowed the sulphate reducing bacteria to thrive.

Studies on thermal maturity and hydrocarbon potential of lignites of Bikaner–Nagaur basin, Rajasthan

In the present investigation, an attempt has been made to study lignite samples from the working mines of Bikaner–Nagaur basin of Rajasthan with reference to their maturity and their hydrocarbon potential. The study has been made on the basis of petrological and geochemical characteristics. The assessments made through the empirically derived equations have been cross-checked and correlated with the rock-eval data. The study reveals that the low rank coals of Bikaner–Nagaur basin contain mainly kerogen type-III organic matter and are dominantly composed of huminite (77–87%) with small concentrations of liptinite (4–11%) and inertinite (2–14%), which are worth liquefying to obtain liquid oil and gas. Further, the high conversion factor (93–95%) and high oil yield (63–65%) make them industrially significant, considering the vast lignite resource of the region.

Environmental geochemistry of selected elements in lignite from Barsingsar and Gurha mines of Rajasthan, Western India

The present paper contains the result of investigation carried out on selected trace elements in the less studied lignite deposits of Rajasthan, Western India. The study has been made on two new lignite deposits–Barsingsar and Gurha. The former has elevated ash content (mean 20.8%) than the latter one (mean 5.1%) and both of them have high volatile matter (mean 43.7% and 49.9% respectively). The lignite samples have been studied for selected elements like Fe, Ca, Mg, Mn, K, Na, Cu, Co, Ni, Cr, Zn, Pb, Cd and As. The elements like Cd, Co, Ni, Pb and Cu occur in high concentration when compared to the Clarke values for brown coal. Ca and Mg relate positively with organic matter in Barsingsar lignite indicating their organic source while K, Cu, Co, Pb and Cd indicate their inorganic origin. Ca might have come in contact with the organic matter during humification and would have become a part of humate. The elements like Cu, Co, Ni, Cr, Cd and Pb showing strong affinity with inertinite could have got associated with the mineral matter present in the fusinite and funginite macerals. In Gurha lignites Pb and Co have shown their affinity with inorganic matter which could have been drawn from sulphides and clay minerals.

The Petrology of Coals from the Rampur Seam-IV and the Lajkura Seam, Ib River Coalfield, Mahanadi Valley, Orissa, India

This article entails results of the study designed to characterize the coals of Ib River coalfield of Mahanadi Valley, Orissa. The study reveals that durain is the dominant lithotype of these coals, which has imparted a dull appearance. This is reflected in its microscopic constituents by the dominance of the macerals of inertinite group and high mineral matter content. This is followed by vitrinite, while liptinites occur in small quantity. Further, it is evolved that these coals are sub-bituminous in rank and have originated from forest and open moors under oxic conditions with intermittent flooding.

The Prediction of the Liquefaction Behavior of the East Kalimantan Coals of Indonesia: An Appraisal through Petrography of Selected Coal Samples

The present study is undertaken to investigate the coals of East Kalimantan for their oil proneness and their suitability for hydrogenation. These coals are Sub-bituminous/Low rank A and per-hydrous in nature. They also have elevated sulphur content. Petrographically, they have high huminite (90.7–98.1%) and poor concentration of liptinite and inertinite. The study reveals that the coalification is characterized by loss of hydrogen and oxygen in this region. The richness of hydrogen, in relation to carbon, is probably responsible for vitrinite suppression and makes these coals per-hydrous and oil prone. The role of petrofactor has also been evaluated to predict reactivity of these coals during hydrogenation. There is a good correlation between petrofactor and conversion. These coals do possess favorable characteristics for hydrogenation and have a high conversion (~95%) and oil yield (>65%).

Distribution and geochemistry of selected trace elements in the lignites of Cambay basin, Gujarat, western India

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.

Petrological characteristics of lower Gondwana coal from Singrauli coalfield, Madhya Pradesh, India

This paper entails the results of petrological studies carried out on coal samples drawn from two lower Gondwana coal bearing horizons (Raniganj formation and Barakar formation) of the Singrauli coalfield, Son basin. It emerges from this study that the coals of this basin are banded in nature and are dominated by ‘banded dull’ and ‘dull’ components. Further, vitrinite and inertinite are the dominant maceral groups while the macerals of liptinite group occur in relatively low concentration. Chemically, the coals are high in volatile matter and ash contents. The study further reveals that the Jhingurdah top seam of Raniganj formation characteristically has elevated concentration of detrital macerals when compared with the coals of Purewa top, Purewa bottom and Turra seams of Barakar formation. Furthermore, it is evolved that these coals have been generated under a fluvio-lacustrine setting, largely from forest swamp, where an alternate oxic to mildly anoxic moor conditions prevailed.

Coal Mining and Organic Pollutants: A Case of Mahanadi Basin Coalfields, India

Coal has been the leading fuel in the energy industry. Its usage has shown far reaching consequences to health and environment. Occurrence of PAH in coal is well known fact but its effect to the human health is least addressed. It is one of the dangerous carcinogens with its ubiquitous presence in the environment. The present investigation on few coal samples reveals presence of substantial amount of PAH in the Mahanadi basin coalfields. Proper mitigation of this substance is required to ensure proper health of the miners and personnel in coal industry. Among the PAH reported are Anthracene, Benzo(a)pyrene, Phenanthrene and Pyrene etc. According to International Agency for Research on Cancer (IARC) a study in 1936 by investigators in Japan and England showed lung cancer mortality among workers in coal carbonization and gasification processes. Later on studies in US was carried on coke oven workers which confirmed the lung cancer mortality, with the suggestion of excessive genitourinary system cancer mortality. Given these implications this investigation attempts to address PAH in the coals of Mahanadi basin.