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Opencast coal mining produces trash of soil and rock containing various minerals, that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage (AMD) through oxidation pyrite minerals. The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India. In order to have a comprehensive overview of the AMD problem in Makum coalfield, the physico-chemical, geochemical, and petrological characteristics of the coal and overburden (OB) samples collected from the Makum coalfield (Northeast India) were thoroughly investigated. The maceral compositions reveal that coal features all three groups of macerals (liptinite, vitrinite, and inertinite), with a high concentration of liptinite indicating the coal of perhydrous, thereby rendering it more reactive. Pyrite (FeS2) oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and (OB) samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods, and to replicate the actual mine site leaching. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment. The Rare earth element (REE) enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB. These experiments reveal the change in conductivity, acid producing tendency, total dissolved solid(TDS), total Iron(Fe) and dissolved Sulfate(SO42−) ions on progress of the leaching experiments. Moreover, the discharge of FeS2 via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics. A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station. Apart from neutralisation of AMD water, this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water. [ABSTRACT FROM AUTHOR]

Coal mining and its unfavourable consequences have generated global attention. It has further stimulated the paradoxical debate of development and desolation in the contemporary scenario. Since the coal resources are profusely available in India and it is comparatively less expensive, the country has been largely relying on it for its essential and non-essential consumption needs. Coal resources indirectly fulfil many of the modern requirements and comforts. Consequently, mining of minerals in general and coal in particular has become the prime focus. It helps to generate revenue, augment industrialisation and promote employment opportunities in India. Despite these progressive features, the opencast coal mining activities impose serious threats to the livelihood of the local communities. Based on critical review of the relevant literature, the article seeks to exhibit the mineral reserves and coal mining activities at global, national and regional context. The paper has incorporated a special focus on Odisha—a resource-rich state located in eastern part of India. Particularly, the two existing major coalfields—Talcher and Ib valley, situated in western part of the state—have been emphasised. The manifold adverse externalities of the coal mining practices on the livelihood pattern among the affected people have been assessed. Furthermore, the paper aims to examine the mining-induced threats on different livelihood capitals which has given rise to multiple risks and challenges. [ABSTRACT FROM AUTHOR]

Sub-surface coal mine fires burn valuable resources and give rise to great threat in the local environs and people's health. Jharia coal field is one of utmost fire affected coal fields in India. This paper deals with the study of sub-surface coal fire using self-potential (SP) method, a cost-effective and non-invasive passive geophysical technique. SP method in coal fire mapping works based on redox potential generated by oxidation of coal and also on Thomson potential due to temperature gradient. Initially, SP anomaly map generated using electrode drift corrected field data. The SP anomalies in the present study area vary from ∼95 to ∼ −40mV. SP anomaly map has been continued to a height of 10m from the ground to remove the possible shallow surface noises. The upward continued anomaly map has been enhanced using first vertical derivative. Further, Euler's depth solutions have been estimated to understand possible geometry and source depth of sub-surface coal fires. The local geological map and field photograph corroborate well with the results for the characterization of coal seam fires. [ABSTRACT FROM AUTHOR]

Longwall Top Coal Caving (LTCC), a relatively newer technology in India, is an underground mining method developed for thick seam extraction. Various factors and systematic approaches are to be considered and properly evaluated in order to qualify and gain confidence in the assessment of introducing LTCC mining method. The proposed paper presents the various processes involved in designing a LTCC technology in one of the mine sites at Singareni Coal Company Limited (SCCL), India. The project undertook a comprehensive analysis of geological and geophysical data of the mine site and developed detailed geotechnical frameworks for the assessment of LTCC technology. [ABSTRACT FROM AUTHOR]

A response by P. Behera to a commentary about his article "Volatile Displacement of Meghalaya Coals: A Pointer to Explore Low Sulphur Coals," which was published in the April 2007 issue is presented. He explains that the volatile displacement means the difference between calculated and experimental volatile matter, the formula in practice is written as (-). He notes that some of the errors in his paper were mostly typographical mistakes.

Underground coal mine environment is hazardous and accident prone. The present work proposes an internet of things (IoT) based smart under- ground mine monitoring system at the excavation site. The developed system establishes a communication link to enable data transmission between underground smart devices and above the ground monitoring station. The smart device of the system includes sensors and sx1276 long range (LoRa) transceiver module. LoRa technology ensures through-the-Earth (TTE) wireless communication using 868 MHz frequency. The developed system monitors the concentration of methane (CH4) gas, carbon mono oxide (CO) gas, and the ambient condition of the mine environment. The sensor data collected is analyzed by the decision-making algorithm which has also been proposed in the work. The algorithm runs at the application server. The algorithm has been developed based on the mine environment safety index (MESI) designed by the authors. The data is available at the application server and can be monitored by the mine authorities. The developed system gives early warning of hazardous levels of gas concentration or uncomfortable values of temperature and humidity and can thus ensure a safe working environment. The system has been tested in an operational coal mine at Pandaveswar, Eastern Coalfield Limited, India. The testing has demonstrated the efficacy of the developed system and has proven that the developed system will be useful to initiate faster rescue operations in case of fatal accidents, if any. [ABSTRACT FROM AUTHOR]

The utilization of innovative technology by the coal mine industry requires proper guidance of sub-surface information so that it can provide uninterrupted exploration with less time and minimum cost. Sufficient knowledge about the coal beds that is variation of thickness, depth, and associated structures will facilitate the mine engineer to run machinery systematically. Conventional geological reports based on borehole data may not sufficient to adopt state-of-the-art drilling technology. To address these issues, high-resolution seismic survey (HRSS) was conducted to delineate the thickness of coal seams and mapping of structural features which are associated with coal seams. An effort was made to demonstrate the high-resolution seismic reflection study for picking of minor faults locations and thickness of coal seams in the central part of the Sohagpur, Gondwana basin that occurs at the junction of the Mahanadi and Son-Narmada rift systems in central India. The study reveals thick Barakar Formation and coal seams at a depth range of 300 to 550 meters. The thickness of coal seams and the location of minor faults were interpreted with the help of attribute analysis from the seismic sections. The obtained results from the seismic survey were useful for the selection of potential target zones which are favourable for drilling. [ABSTRACT FROM AUTHOR]

Purpose: Coal mine overburden is a term typically used to refer to the waste rocks and the soil materials generated from the open cast method of coal extraction. Previous investigations have found that recycled aggregates from coal overburden are suitable as subballast material in railway trackbed. But no study has been reported yet that analyzes the environmental consequences of this option using the life cycle assessment (LCA) technique. To ensure sustainability, it is vital to examine the environmental consequences of alternatives which is performed in this study. Method: The present study compares the environmental impacts of processed aggregates from coal mine overburden with that of natural subballast material. The study also investigates the environmental sustainability of using geocell-reinforced overburden aggregates (GOBA) in the subballast layer. The database used for this LCA study is Ecoinvent 3 database and the impact assessment method adopted is IMPACT 2002 + method. The effects on 15 midpoint indicators and four endpoint indicators along with the contribution of each of the processes involved in the production toward the categories are presented in this study. Results: According to the findings, when compared to natural aggregates, processed aggregates from overburden lower the potential for climate change by 35% and the demand for non-renewable energy by 33%. Furthermore, the production of geocell-reinforced OB aggregates reduces the potential for climate change by 16%. Conclusions: Based on the IMPACT 2002 + method used in this study, the use of OB aggregates in the track bed's subballast layer significantly lowers the negative effects on human health, climate change, ecosystem quality, and resources and reduces the impacts on all midpoint category indicators. Lastly, the obtained results can be a major support in advancing the resourceful management of coal overburden and the conservation of natural aggregate sources. [ABSTRACT FROM AUTHOR]

Methane content in a coal seam is a necessary parameter for evaluating coal bed gas, and it poses an environmental risk to underground coal mining activities. Keeping in pace with comprehensive studies of coal bed gas, 12 coal samples were selected from the Sitarampur block of Raniganj Coalfield for analysis. The Petrographic examination illustrated that significant values of reactive macerals present in samples demonstrate that organic matter is dominated by the prominent source of aromatic hydrocarbons with a minor proportion of aliphatic hydrocarbon, which falls in the region of (Type III) kerogen, confirms the suitability for the potential of hydrocarbon generation. "A" factor (aliphatic/aromatic bands) and "C" factor (carbonyl/carboxyl bands) value concluded that the sample has the lowest aromaticity and the highest hydrocarbon-generating potential, which was also validated by the Van Krevelen diagram. The Van Krevelen diagram plots between the H/C and O/C ratio indicate that coal samples lie in the type III kerogen, and bituminous coal (gas prone zone) is present in the block, which is confirmed by the cross-plot between desorbed and total gas (cc/g). The in situ gas content values are high enough to produce methane from coal beds. The overall study concludes that the Sitarampur block from Raniganj Coalfield is suitable for hydrocarbon generation and extraction. [ABSTRACT FROM AUTHOR]

The inclined coal pillars, formed during the underground extraction of the inclined coal seam, are different from the flat coal pillars due to the high strength anisotropy of the inclined bedded rock, and the asymmetrical stress distribution. To ease the manoeuvring of the men and machinery in the inclined coal mine, the pillars are developed along the apparent dip. Thus, the pillars become rhombus-shaped with acute-angled corners which crush rapidly due to the high stress concentration. No suitable formula is found to estimate the strength of the inclined coal pillar that incorporates all these factors. Thus, the use of the available coal pillar strength formulae may endanger the extraction of the inclined coal seams. This study elucidates the procedures to estimate the strength of the inclined coal pillars by the numerical modelling technique. The ubiquitous joint model is used to simulate the shearing characteristics of the inclined strata. The parametric study shows that the strength of the inclined coal pillars decreases with the increase of the dip of the coal seams. It is also obtained that the strength of the pillars decreases with the decrease of the value of the acute angle of the corners. The peak stress distribution and the strain accumulation over the inclined pillars at the time of failure are plotted in three-dimensional graphs which show the asymmetrical characteristics of the inclined coal pillars. The analysis of variance shows that the dip of the coal seams and the acute angles of the corners have a statistically significant effect on the strength of the inclined coal pillars. Based on the results of the simulation, the best fit relation is established by the multivariate non-linear regression technique to estimate the strength of the inclined coal pillars. The coefficient of determination (R2) and the root mean square error of the model are obtained as 0.92 and 0.065, respectively. The validation of the developed model has been carried out by the stable and failed inclined pillar cases of different underground inclined coal mines in India. Comparisons of the safety factors, obtained from the developed model and the flat pillar strength formula, indicate that the flat pillar strength formula overestimates the strength of the inclined coal pillars. The developed model can be used to design the inclined coal pillars for safe extraction of inclined coal seams. [ABSTRACT FROM AUTHOR]

The recent global scenario in the mineral sector may be characterized by rising competitiveness, increasing production costs and a slump in market price. This has pushed the mineral sector in general and that in the developing countries in particular to a situation where the industry has a limited capacity to sustain unproductive costs. This, more often than not, results in a situation where the industry fails to ensure environmental safeguards during and after mineral extraction. The situation is conspicuous in the Indian coal mining industry where more than 73% production comes from surface operations. India has an ambitious power augmentation projection for the coming 10 years. A phenomenal increase in coal production is proposed from the power grade coalfields in India. One of the most likely fall-outs of land degradation due to mining in these areas would be significant reduction of agricultural and other important land-uses. Currently, backfilling costs are perceived as prohibitive and abandonment of land is the easy way out. This study attempts to provide mine planners with a mathematical model that distributes generated overburden at defined disposal options while ensuring maximization of backfilled land area at minimum direct and economic costs. Optimization has been accomplished by linear programming (LP) for optimum distribution of each year's generated overburden. Previous year's disposal quantity outputs are processed as one set of the inputs to the LP model for generation of current year's disposal output. From various geo-mining inputs, site constants of the LP constraints are calculated. Arrived value of economic vectors, which guide the programming statement, decides the optimal overburden distribution in defined options. The case example (with model test run) indicates that overburden distribution is significantly sensitive to coal seam gradient. The model has universal applicability to cyclic system (shovel-dumper combination) of opencast mining of stratified deposits. [ABSTRACT FROM AUTHOR]