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Protective water barrier pillars (PWBPs) are inter-mine barrier pillars. An adequate PWBP can protect active mine workings from the danger of inundation from adjoining inundated workings. This paper discusses a hydro-mechanical coupled numerical modeling approach for the design of PWBPs, considering different flow regimes. The coupled model considers the effect of seepage through the roof, pillar, and floor on the mechanical strength of the rock mass and vice-versa. A statistical model based on the extent of positive volumetric strain zones (ZoPVS, %) was formulated to assess the mechanical stability of the pillar. The model considers the pillar width, cover depth, strength, modulus of elasticity of coal and roof/floor, and the extraction ratio as the input parameters. Based on the results of numerical modeling-based parametric studies, statistical models were developed to estimate the seepage rate for assessing the hydraulic performance of the pillar. The seepage rate of water through a PWBP was estimated in terms of the cover depth of the seam, compressive and tensile strengths and modulus of elasticity of the pillar system, mean in-situ horizontal stress, pillar width, extraction ratio, and permeability of the rock mass. A ZoPVS of 95% represented unstable behavior and piping failure of the pillar. The maximum seepage rate of 315 L/s/km (5000 GPM/km) was reckoned as the acceptable hydraulic performance of the PWBP based on the field experience in Indian geo-mining conditions. The validation of the model for two case studies with minimum pillar widths of 30–60 m at a cover depth of 84.5–134.5 m was in agreement with the field experiences. [ABSTRACT FROM AUTHOR]

Air is the basis for the existence of life on Earth; but in the present age of modernization the degrading quality of air year by year, due to the growth of Industrialization, urbanization, automobiles, coal-fired thermal power plants, and various other factories is the matter of real concern. To predict the future growth of air pollutants numerous prediction models have been developed by researchers. Time-series ARIMA model although quite useful for forecasting but fails to handle non-stationary problems. Among all the existing forecasting models, wavelets along with the Machine learning models have proved to be very successful and have been widely used in various fields like mathematical modeling, signal recognition, image recognition, classification, function approximation, data processing, filtering, clustering, compression, robotics, and decision making. It is also used in the field of mathematical forecasting for developing efficient prediction models. This paper aims to develop a wavelet-ANFIS conjugation model and a wavelet-ARIMA coupled model along with the time-series ARIMA model for the prediction of black carbon concentration over the Raniganj, Jharia, and Bokaro coal mines of India, by considering a long term data obtained by NASA (http://nasa.gov/) and compare the results obtained by these models for determining the best prediction model. The validity of the results is tested with the help of error measures like RMSE, MSE, MAPE, MAE, and relative error. Results over the three sample sites conclude that the Wavelet-ANFIS conjugation approach outperforms the wavelet-ARIMA coupled approach and the simple time-series ARIMA model. [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]

Anthropogenic activities such as gold and coal mining, oil and gas production, filling of artificial water reservoirs, harnessing of geothermal energy, etc., have induced/triggered earthquakes. Koyna dam, located in the Deccan volcanic province of India, was impounded in 1962, and soon after tremors were reported from the vicinity of Koyna dam. The largest triggered earthquake of magnitude (M) 6.3 occurred on 10 December 1967. The triggered earthquakes have continued until now and the region has experienced 22 events of an M~5, over 200 events of an M~4 and several thousand smaller events. The reservoir-triggered seismicity has continued until 2021, which is unique. Some of the early investigations, leading to drilling of a 3 km deep pilot borehole at Koyna for near-field studies of earthquakes, and a few recent results are summarised in this paper. Research highlights: Koyna, located near the west coast of India, in the Deccan volcanic province is one of the most prominent sites of artificial water reservoir-triggered seismicity (RTS). Triggered earthquakes started soon after the impoundment of Shivaji Sagar lake created by Koyna dam in 1962 and have continued until now. Unlike other RTS sites where triggered earthquakes did not continue for long, Koyna is still active, and it is estimated that RTS may continue for another one to two decades. Detailed field work and analyses of earthquake data demonstrated that Koyna is a very suitable site for near-field studies of earthquakes: an observation that is much needed to validate earthquake genesis models. International Continental Drilling Programme sponsored workshops and participation of experts from all over the world helped in deciding to dig a 3 km deep pilot borehole. The borehole was completed in June 2017. Recent research studies further demonstrated that the Koyna region is under critical stress. Studies under progress would help in designing the proposed ~7 km deep borehole laboratory. [ABSTRACT FROM AUTHOR]

A fully mechanised mining method using continuous miner (CM) for pillar extraction in single-pass is introduced in the year 2010 at Pinoura Mine of South Eastern Coalfields Limited, Bilaspur in India. Overall mining cycle time is reduced by single-pass pillar extraction as it does not require drivage of split galleries in pillars and support installation for such galleries. Further, inherent technical abilities of the deployed CM for faster cutting and quad-bolter for supporting, helped in faster recovery of pillars without creating any strata control issues. Rate of face advance varied between 5–15m/day with an average of 8m/day. Field observations found that CM based single-pass extraction is capable in dealing with the strata control issues during depillaring under weak and laminated (incompetent in nature) roof layers having rock mass rating value around 42. A total of eleven panels, have been depillared under the weak and laminated geology, ranging depth of cover from 59 to 149m in different panels of the mine. During field investigations in these panels, a maximum of 2.89MPa induced vertical stress is recorded and influence of caved roof over underground mining structures is observed up to 15m in the out-bye from the goaf edge. This paper deals with estimation of snook size and limiting roof movement value based on numerical simulation and field studies during the single-pass extraction below the incompetent geological formations. [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]

Indian coal mining industry is in transition phase with the growing demand of coal and is likely to escalate further with the need of ultra-mega power projects as well as announcement of smart cities projects. Although, there exist sufficient coal reserves in India, continuous acquisition and possession of coal bearing land is required to minimize the existing gap prevailing between coal demand and supply.The solution of the problem lies not only in modification of laws and policies of industry, but also in modification of mining engineering practices towards sustainable development. This paper critically examines the cause of the problem in the light of Indian laws and practices of the industry. In this paper a method of exact reclamation of post-mining land has been designed as a solution to make easier land acquisition by way of proposing a system of returning back the exact reclaimed land to its owners under corporate social responsibility activity of the industry. The proposed conceptual model of interlinking corporate social responsibility with land exchange will encourage sustainable development practice by mining engineers, and may turn around the public image of the industry. [ABSTRACT FROM AUTHOR]

With growing demand for mineral resources and favourable policy towards the mining sector, developing countries have become investment hubs for mineral extraction, which has changed the socioeconomic and ecological scenarios particularly in rural areas. Extractive industries such as coal mining generate negative externalities that bring irreversible changes in the local ecological conditions, which adversely affect the local economy and threatens the sustainability of local livelihood systems. The objective of this paper is to analyse the effects of coal mining on local traditional livelihood systems in the eastern Indian state of Odisha. The study is carried out using household level data collected from four mining villages located in the Ib valley coal field of Odisha. The problem of sustainability of local traditional livelihoods is examined in the light of economic theories of sustainability (e.g. weak and strong sustainability) and sustainable livelihood approach (SLA). The results show that rural households in the mining area experience both positive and negative outcomes from the coal mining activities. The expansion of mines has provided employment to locals directly as well as indirectly, which has helped to increase financial as well as physical capitals. On the other hand, the reduction in the provision of ecosystem services due to adverse effects of coal mining resulted in lower yields in traditional livelihood activities such as forest, agriculture, and animal husbandry. The paper suggests that in order to effectively internalize the externalities arising from coal mining and maintain the sustainability of local livelihood system in Odisha, there is a need to reinvest some part of resource rents in regeneration of natural capital of the region. [ABSTRACT FROM AUTHOR]

The mineralogy and geochemical studies of the coal-mine shale collected from the Tirap opencast coal-mine (Makum coalfield, Northeast India) are reported in this paper. Thermo-chemical conversion (pyrolysis) of coal-mine shale has been studied to see its hydrocarbon potential. A combined approach using X-Ray diffraction (LTA-XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrophotometer (EDS), X-ray fluorescence spectrometry (XRF), thermogravimetry-derivative and differential thermogravimetric (TG-DTG and DTA) analysis is made to obtain new information on the mineralogical and geochemical studies of a coal-mine shale (CMS) sample. Gas chromatography-mass spectrometry (GC-MS) analysis is performed to evaluate the quality of the liquid fraction (tar) obtained after pyrolysis at 600°C. The shale sample is dominated by quartz, clay minerals (kaolinite and illite), sulphate bearing phase like gypsum with minor proportion of anatase, probably as artifacts of the plasma-ashing process. GC-MS analysis illustrates the presence of highly oxygenated organic components (M.W. around 94-108) and high molecular weight (M.W. 256) cyclic sulphur (e.g. octathiocane with molecular formula S) compounds along with the complex N-containing organic sulphur compounds (M.W. around 255-486) in the tar produced. [ABSTRACT FROM AUTHOR]

During the pre-nationalisation period due to unscientific mining, large number of old workings exist below important structures at various coal fields in India. Mostly these old workings exist below National Highways and Railway track. These workings are generally at shallow depth. It has been observed that subsidence and pot holing are common in those areas. As a result the safety of vehicles and passenger trains plying over these areas endangered. Since the old workings are more than 60 years old in most of the cases the proper plan and survey documents are not available. So it is extremely difficult to exactly locate the underground mine workings/galleries/voids from the surface such that precautionary measures can be initiated for the safety of roads and railway tracks. Eastern Coalfields Limited (ECL) has indicated that there may be some old workings below the national highway (NH-2) near Dalmia colliery of SalanpurArea of ECL. The most sophisticated system, MineVue Radar was used for delineation of abandoned mine workings or mine galleries below NH-2. Two voids of size 1.8 m height at depth of 40 m and another of size 1.35 m height at a depth of 33.5 m were delineated and confirmed using direct core drilling method. After that, Mine management was informed about these voids to take precautionary measures for the safety of NH-2. Thus, this system has played an important role for the safety of important surface structures. This paper deals the application of MineVue radar system for delineation of mine galleries below NH-2. [ABSTRACT FROM AUTHOR]

Mine fire is a major problem for the Indian coal mining industry and exists since beginning of the mining. A huge amount of the prime coking coal reserves of different coalfields are blocked due to existence of fire and thus cannot be extracted without extinguishing it. Many approaches have been attempted in this direction to minimize this socio-technological problem. Use of chemical retardants to inhibit smouldering combustion phenomenon is an important method, which can be adopted to prevent or delay its occurrences. In this situation, it may sometimes be necessary to use fire retardants for reducing the intensity of fire so that the coal production will not be hampered. This paper presents the impact of chemical additives on coal oxidation process, studied from the mechanistic perspective aiming to search effective retardant materials to prevent and control coal self-heating phenomenon. A numbers of chemicals and combinations along with coal, which are moderately prone to smouldering combustion, were studied to determine its efficacy to prevent and combat it. In the process CPT, IPT and DSC study of coal samples and chemicals were observed. Based on the results, suitable retardants were selected and mixed with coal samples. The mixtures were further analysed for above properties. Finally, the best suitable combination of inhibitors were determined and applied in the field, which gave desired results. [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]

The author presents a number of comments on the article "Volatile Displacement of Meghalaya Coals: A Pointer to Explore Low Sulphur Coals," which was published in the April 2007 issue. He argues that the paper is full of common mistakes, wrong computations, and long-drawn conclusions. In methodology, he notes that the author of the said paper indicates about drawing of regression curves which is wrong.

Continuous mining is a most popular mining method in USA and Europe. Nearly 60% of coal mining in the West is through continuous mining process in underground mines. Continuous miner technology, which has of late been introduced in India, is able to extract 65-74% of the coal in a panel depending upon the seam parameters as against 50-60% by semi-mechanized Bord and Pillar system of mining with SDL/LHDs, which is popular in India. The rate of extraction by the continuous miner being high is able to create larger panels, and thus, reduces the coal loss in barrier pillars. Presently, efforts are being made to introduce this technology on a larger scale in underground coal mines of Coal India Limited in India. When the first depillaring panel started its operation in November 2009 at Jhanjra, the panel was stopped after extraction of nine pillars by the Indian regulatory body (Directorate General of Mines Safety, DGMS, GOI) as the geological conditions of the overlying strata gave trouble of non-caving. The anticipated roof fall did not take place. The exposed roof area reached 10,400 m, which was equivalent to 46,800 m of the void volume posing a threat of air blast. Since all the attempts to induce caving by underground blasting failed, an attempt was made from surface to induce the caving by destress blasting. This paper deals with the design of blasting parameters and execution of destress blasting keeping in view the safety and sentiments of nearby villages. [ABSTRACT FROM AUTHOR]

Maslow's hierarchy-of-needs theory has been used to predict development of Quality of Life (QOL) in countries over time. In this paper an attempt has been taken to derive a methodological validation of quality of life questionnaire which have been prepared for the study area. The objective of the study is to standardize a questionnaire tool to assess the QoL of residents in a problem area in India. From a pre tested 16 parameter questionnaire tool factorial validity were established to extract three domains and were mapped in accordance to Abraham Maslow's Hierarchy of Needs theory. Out of these 16 parameters 13 were found relevant. Then a new tool was conceptualized with 13 pre selected parameters and other parameters were pooled from existing tool and reviews to form a 36 parameter tool. Factor analysis was done to extract the domains. Reliability of the tool was also tested to find the relation between the domains of QoL. Then the quality of life of the study area was interpreted to find the distribution of respondents among the categories of QoL. 70% of respondents reported to have average quality of life. The tool was found to be highly reliable and valid. [ABSTRACT FROM AUTHOR]

Abstract  Shallow land cover over old underground workings at Kamptee Colliery has led to the development of ground collapse, with three crown hole subsidences recorded in a 10 year period. As the land above the workings has been developed, it was considered that for safety purposes areas with less than 15 m of competent rock should be established. The paper discusses the Multi-electrode Resistivity Imaging (RI) and Ground Penetrating Radar (GPR) undertaken over an area of 800 m � 200 m, which indicated that where a competent cover was present it was very thin. [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.