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Organo-petrographic and geochemical characteristics of Gurha lignite deposits, Rajasthan, India: Insights into the palaeovegetation, palaeoenvironment and hydrocarbon source rock potential
No full textThe sedimentary sequence containing lignite deposits in Gurha quarry of the Bikaner-Nagaur Basin (Rajasthan) has been investigated. The samples from lignite and allied shale horizons were evaluated for petrographical, palynological, palynofacies and organic geochemical inferences, to depict the source flora and to reconstruct the palaeodepositional conditions prevailed during the sedimentation. An assessment for the hydrocarbon generation potential of these deposits has also been made. The results revealed the dominance of huminite macerals and phytoclasts organic matter (OM) indicating the existence of forested vegetation in the vicinity of the depositional site. A relatively high terrigenous/aquatic ratio (TAR) and the carbon preference index (CPI) are also suggesting the contribution of higher plants in the peat formation. However, the n-alkane distributions, maximizing at n-C17 and n-C29, showed inputs from the algal communities along with the higher plant derived organic matters. Recovered palynomorphs of the families Onagraceae, Meliaceae, Arecaceae, Rhizophoraceae, Rubiaceae, Ctenolophonaceae, etc. together with oleanene and ursane types of triterpenoids suggest the contribution from angiosperms source vegetation. Interestingly, the presence of Araucareaceae and Podocarpaceae pollen grains shows the existence of gymnosperms vegetation. Further, the presence of tetracyclic diterpanes; phyllocladane, demethylated ent-beyerane, sandaracopimarane, pimarane, and α-phyllocladane confirms the contribution of conifers. The variation in the values of the coefficient of non-equality (H: 0.68%–7.56%), the standard deviation (δ: 0.04%–0.16%) and the coefficient of variability (V: 16.10%–46.47%), also shows the heterogeneity in the source organic matter. The various petrographical indices, palynological entities, and geochemical parameters indicate that the peat-forming vegetation was accumulated under a mixed environment and fluctuating hydrological settings. The interpretation of palynofacies data on APP (Amorphous organic matter-Phytoclast-Palynomorphs) diagram suggests that the accumulation of organic matter occurred in a dysoxic-suboxic condition in a proximal (to land) setting with the shift to an anoxic condition in distal setting towards the termination of sedimentation. The huminite (ulminite) reflectance (Rr) values (av. 0.28%) showed a good relationship with average Tmax value (414 °C), suggesting the immaturity. The TOC content ranges of 13–59 wt.%, and HI values vary between 101 and 546 mg HC/g TOC in the studied samples. Collectively, the studied lignite and shale samples have the admixed kerogens (Type III–II) and exhibit the ability to generate the gaseous to oil hydrocarbons upon maturatio
Laboratory investigation on underground coal gasification technique with real-time analysis
No full textEnergy demand will continue rising in India due to increasing pressure of population; continuing urbanization; significant expansion of better living standards of the middle class peoples; electrification in more and more villages; and modernization of agriculture, infrastructure and manufacturing sectors. In India, coal is the most abundant and major fossil fuel which is going to play big role in meeting its energy demand. A major part of this requirement can be met by proper utilization of deep-seated coal. Underground coal gasification (UCG) process is a clean coal technology for utilization of unminable coal. In this article, a novel simple laboratory model of UCG is developed with advanced real-time control and monitoring. The experimental study is carried out on a high-ash single coal block for 48 h period. In this experiment, synthesis gases are produced by the gasification of coal block by using oxygen and steam as the main oxidising agents. Observation and analysis are made on the characteristic of produced gases, coal-tar, cavity-growth under variable process conditions. This laboratory-based experimental study will play a vital role for prediction on practically-difficult UCG process for successful operation in actual field by reducing its complexity
Blasting technique for stabilizing accidentprone slope for sustainable railway route
Get PDFKonkan Railway has many unstable slopes along the
741 km long route from Roha to Thokur in the states
of Maharashtra, Goa and Karnataka in India. Frequent cases of boulder fall, slope failure and landslide
used to occur on the track during the rainy season.
Such cases have resulted in several severe train accidents, traffic interruptions, loss of lives and assets.
Hence the Konkan Railway Corporation deployed
several geotechnical measures such as wire-netting, retaining wall, rock bolting and shotcreting for stability
enhancement. However, none of these measures
proved effective and accidents continued. Finally, the
Konkan Railway Corporation decided to redesign the
cut-slopes using blasting. Excavation of hard rock for
its removal without damaging the existing track (2–
3 m away from the slope) and disrupting the traffic,
was a daunting task. An unplanned blast would have
resulted in the closure of the route for hours. The
present study explains the method in which entire cutting was redesigned by formation of 5 to 2 m wide
berms at an interval of 6 m bench height from rail
track level using novel direction controlled blasting
technique. Further, stability of the cut-slope, before
and after exacavation, has been determined using
kinematic analysis and 3D numerical modelling. Similar technique can be adopted to widen or stabilize an
active transportation route in hills
Application of CMRI-ISM RMR for Stability Analysis of Development Workings for Ballarpur Underground Coal Mine — An Empirical and Numerical Approach
No full textRoof bolt failures in the mine generally occur due to the poor identification of the weak rock layers and considered as a major concern for underground coal mines in terms of its productivity and safety. The triggering factor responsible for underground roof failure is the presence of weak bedding planes and various geological discontinuities. Geological disruptions present in the mine roof seriously affect the continuity of the rock layers resulting in block failure. However, numerous improved methods have been suggested by a number of researchers but still, the upholding of the accidents due to roof fall is considered as a major challenge for underground mine workings. Thus, it is necessary to give proper emphasis on characterization of the roof fall so that stability of the mine workings could be increased and movement of the weak and layered strata can be arrested by applying an adequate roof bolting system. This mechanism of roof support gives the composite binding between the rock layers by restricting the roof fall. The stability of mine workings can be also increased by proper application of rock mass classifications system and adequate design of support system and finally, by extensive simulation methods and statistical methods like FLAC 3D numerical and statistical modelling to ascertain the stability of the workings. CMRI-ISM RMR (Central Mining Research Institute — Indian School of Mines Rock Mass Rating System) classification system is the most popular and practiced method for roof support design in Indian coal mines which is being successfully used from last several years for roof support design in Indian geo-mining conditions. This forms the basis to estimate the rock load and support design. In this paper attempt has been made to assess the stability of workings and pillars below the railway track by using empirical and numerical approach. After both the studies it can be said that, the galleries and pillars underlying the railways track are stable, as factor of safety in each case is more than 2. Later on, the study was also extended to see the effects of subsidence on the surface which reveals that, there shall be no such effect on the surface due to underground workings as the value of NEW (non-effective width) is less than 0.4 for both the cases
Mercury in Indian Thermal Coals
No full textIn India, coal utilization in power generation, constitutes as the single largest source of mercury emissions. This study presents mercury content in Indian sub-bituminous and bituminous coals that are primarily used as fuel in large-scale electricity generation facilities. A total of 165 number of coal samples have been collected from the major coal producing regions of the country. Along with the mercury content, other chemical parameters like moisture, ash, volatile matter, total Sulphur and gross calorific value were also analyzed. Mercury concentrations of these coals were found to be between 3 and 554 µg/kg, with an average of 175 µg/kg. Variation of the mercury content with the rank parameters like volatile matter, carbon content, ash and total Sulphur were also assessed. No significant correlations were observed with the rank parameters but a general trend of increasing mercury with ash content is discernible
Experimental investigations on thermal behavior during pick-rock interaction and optimization of operating parameters of surface miner
No full textOperation of surface miner has significantly expanded in mines because of its mass production ability and eco-friendly way of rock excavation. Optimal utilization of operating parameters ensures better cutting efficiency and longer machine life. Elevated temperature of a pick developed during the rock cutting process affects its life. It especially influences the wear rate of the cutting pick. During the present study, operating parameters of a surface miner were examined using the Taguchi method. In the process, an appropriate parametric combination was developed facilitating the use of optimal cutting power, higher production and minimum pick consumption. The role of operating parameters, i.e., depth of cut (DOC), cutting speed (CS) and drum speed (DS) with temperature (T) was analyzed statistically. Empirical models were also developed for studying temperature variations in cutting picks using Taguchi method, multiple linear regression (MLR) and artificial neural network (ANN). Confirmation test revealed that optimized temperature was achieved at a significance level of 0.05 and the Taguchi method enabled better outcomes with minimum deviation and a high degree of optimization of operating parameters of surface miner
Stress analysis due to internal explosion pressure of designed flameproof enclosure for hazardous area
No full textFlameproof (Ex d) enclosures are constructed in such a way that an internal ignition of a flammable atmosphere will not be transmitted outside the enclosure and thereby preventing the ignition of surrounding flammables. The large Ex d enclosure was designed for gas group IIB explosive atmosphere with the help of MATLAB and ANSYS software and further a study of stress analysis due to internal pressure had been carried out on the plates and cover by keeping the thickness of body plate and cover constant. The study showed that stress was observed more in the center of the plate and reducing toward the edges of plates. The value of the length and breadth ratio (a/b) was found out with the help of the curve fitting method to calculate maximum stress (σmax) in the designed Ex d enclosure. The calculated maximum stress of all the plates was less than the simulated results, so the simulated results indicated that the designed enclosure is within the safety limit and suitable for hazardous area
Exploitation of mica deposits at Nellore mica belt, Andhra Pradesh, India
Get PDFIndia is the leading producer of sheet mica and a
major part of this is exported. Nellore mica belt is the
largest mica-producing area covering part of Nellore
district in Andhra Pradesh, India. As most of the
mines are old and privately operated, they are developed
and operated purely based on local experiences.
In this article, we highlight the problems associated
with the present mica-mining practices in the Nellore
mica belt, and scientific approaches that have been
adopted for fixing different parameters associated
with mica extraction. Based on detailed field study,
geo-mechanical data and tested rock properties,
extensive numerical modelling is done to suggest the
best possible method of mining for safe and sustainable
mica extraction from the area
Evidence of recurrent wildfire from the Permian coal deposits of India: Petrographic, scanning electron microscopic and palynological analyses of fossil charcoal
No full textIn India hitherto fossil charcoal has been reported from Kashmir, Damodar Basin, and Mahanadi Basin. This work documents recurrent Cisuralian wildfire based on the occurrence of fossil charcoal from India. The authors used petrographical, palynological and SEM studies to analyze the anatomy of charred wood fragments and temperature of their formation. The fossil charcoal has been retrieved from the Cisuralian coal bearing subsurface sediments of Lower Barakar Formation (Artinskian) from Auranga Coalfield of Damodar Basin. Evidences of recurrent wildfire have been observed by the occurrence of charcoal at four levels of clastic sediments in Borehole 2N. The charcoal was subjected to petrographical, palynological and SEM studies to understand the burning temperature, fuel source and plant anatomy respectively. Petrographic studies indicate high frequency of semifusinite vis-à-vis fusinite having reflectance values ranging from 2.87% to 4.1%. The majority of the fusinite reflectance values fall in the range of 2.9%–3.5% indicating the temperature of formation of these charcoals to be at approximately 500°C. High temperature is also indicated by homogenization of cell walls under SEM. They also reveal fungal infestation and degradation in all charcoal samples. Moderate to high degree of preservation of charcoal indicates lesser transportation/post-depositional degradation suggesting a hypo-autochthonous nature. The botanical affinity of recovered spores and pollen suggest that the hinterland was dominated by gymnosperms and sub-dominated by filicopsids, sphenopsids, and lycopsids which contributed to the fuel source