IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Evaluation of a Preliminary Support Design of Railway Tunnel Adit in Inner Lesser Himalaya India: An Empirical Analysis
No full textThis article addresses the excavation method and support design for the adit tunnel in the Rudraprayag District, Lesser Himalayas of India, using Rock Mass Rating (RMR), Tunneling Quality Index (Q), and New Austrian Tunneling Method (NATM). Based on ONORM B 2203 correlations with RMR and Q systems, the New Austrian Tunneling Method rock structure classes were developed. Because the geology was constantly changing, NATM concepts were applied. The RMR-based rock mass estimates were overestimated, but the qualitative investigation was correct. The NATM method is more appropriate for a Garhwal Himalayan rock with varying rock mass uncertainty. The present adit research reveals several outstanding questions about rock mass quality, tunnel behavior during construction, and use. The analysis results might be used to build new tunnels in comparable terrain in other parts of the world
Impact of Supercritical CO2 on Shale Reservoirs and Its Implicationfor CO2 Sequestration
No full textHydraulic fracturing has transformed the interna�tional energy landscape by becoming the go-to method for the
exploitation of natural gas from unconventional shale reservoirs.However, in the recent years, the search for an alternative method of shale-gas exploration has intensified, because of various problems (e.g., contamination of ground and surface water,overexploitation of precious water resources, air pollution, etc.) associated with the usage of water-based fracturing techniques. The use of CO2 for shale gas exploitation has emerged as a better
alternative to aqueous-based gas exploration techniques. CO2
when injected into deep shale reservoirs, transitions into
supercritical CO2 (SC-CO2) when temperature and pressure
condition exceeds the critical point, i.e., 31.1 °C and 7.38 MPa. In this paper, we comprehensively review the impact of SC-CO2 on shale gas reservoirs during the different stages of shale-gas exploration, i.e., (i) drilling, which involves the superiority of SC-CO2 over water-based drilling fluids, in terms of achieving under�balanced well condition, higher rates of penetration, and resistance to formation damage; (ii) fracturing, which involves factors affecting the tortuosity of fractures created by SC-CO2 fracturing, breakdown pressure, and proppant-carrying capacity; and (iii) injection, which involves the twin-headed benefit of enhanced recovery due to CO2/CH4 competitive adsorption and geological sequestration, CO2 vs CH4 excess sorption as a function of pressure, etc. Several research works have indicated discrepancies on how
SC-CO2 impacts different shale properties. Some studies show low-pressure N2-gas-adsorption-derived surface area and total pore volume to be increasing with SC-CO2 imbibition, while others show a decreasing trend for the same. Similarly, for some shales, the quartz content, along with the clay mineral contents, decreased as the exposure to SC-CO2 increased, while in some other studies, with similar long-term exposure to SC-CO2, the quartz content was observed to increase along with the decrease in clay content and vice versa. Essentially, the increased exposure to SC-CO2 results in the dissolution of primary porous structures and fractures, and reformation of newer porous structure and conduits in shales. Nonetheless, these changes in the mineralogy weaken the microstructure of the rock bringing significant changes in the mechanical properties of the shales with implications on the wellbore
stability and fracturing efficiency. The mechanical properties such as uniaxial compressive strength (UCS), Young’s modulus, and tensile strength decrease as the SC-CO2 saturation period increases. However, some studies have shown factors like bedding angleand phase-state of CO2 having varying effect on the strength behavior of the shales. Moreover, changes in the structure of shalescaused by the creation of fractures and the reduction of their strength can also pose major risks, because of potential leakage of CO2through these created pathways. How these processes would interact at field scale would control the sealing capacity, especially at field-scale for addressing long-term seepage of CO2
Structural and thermal properties of vitrain lithotype in coal-inferences from TG-DTG-DSC, Rock-Eval and X-ray diAraction
No full textVitrain is one of the most important lithotype for the end utilization of humic coals in relevant industries.
In this work, we examine the thermal, structural and pyrolysis properties of vitrains, manually isolated
from coals of three distinct thermal maturity levels (rank). The high volatile bituminous (HvbA) vitrain
showed highest moisture content and reactivity during combustion, while showing least Rock-Eval S2
Tmax and S4 Tpeak. On the other hand, the low volatile (Lvb) sample showed properties exact opposite to
that of the HvbA sample. Thus, the rank of the vitrains was observed to directly control their behaviour.
Owing to their inherently lower ash content, all the vitrains during thermogravimetric analysis developed
smooth thermograms, indicating easy burning. Interlayer spacing (d002), obtained from XRD displayed a
strong decrease with increasing coal rank, indicating formation of condensed stacking structures with
increasing rank. On the other hand, other XRD parameters, viz., the crystallite height (Lc) and the
crystallite diameter (La) were not correlated with the rank of the samples. Rock-Eval S2 pyrograms
depicted distinctive responses for the vitrains. While smooth curves were observed for the HvbA vitrain,
the pyrograms showed unevenness and spikes for the Mvb and Lvb vitrains. We interpret these spikes or
ruggedness to be caused due to melt formation during pyrolysis of Lvb and Mvb vitrains, and concomitant
gas/bubble-bursting. We back our results with distinctive observations from the Beld emission scanning
electron microscope (FE-SEM) of the pyrolysis-residues of the vitrains. We interpret that the distinctive
S2 signatures shown by coals can be useful in predicting their end usag
Source rock properties of Permian shales from Rajmahal Basin, India
No full textIn the present study, shale samples from Rajmahal Basin, India, were analysed in terms of their source rock properties using
an open-system programmed pyrolysis instrument (Rock–Eval 6). Comprehensive analysis of the diferent Rock–Eval graph�ics was conducted for the samples under consideration. Construction of S2 (mg HC/g rock) vs. total organic carbon (wt%)
cross-plot using iso-HI (iso-hydrogen index) lines classifed the studied suit of samples into three zones with increasing
hydrogen index (Zone A<Zone B<Zone C). Analysis of S2 curves of samples from diferent zones revealed distinctive
features attributed to the variable nature of kerogen present within the sample as well as the levels of S2 and HI. S2 curves
of sample with higher Tmax were observed to be asymmetric, broad, and marked by lower fame ionization detector signals.
However, for those samples, the S4 Tpeak was observed to be similar to that of the other samples. On the other hand, the higher
S2 Tmax of some samples coincided with higher S4 Tpeak indicating the samples to be more mature. Additionally, samples with higher levels of oxygen index (OI), and siderite content, were observed to have S3′ curve marked by pronounced release of
CO2 above 400 °C, whereas the samples with higher OI but without any presence of siderite were marked by noisy curves
due to low IR CO2 signal. The results reiterated the importance of careful monitoring of the diferent curves obtained during
the pyrolysis and oxidation stage so that erroneous characterization of the samples could be avoided
TGA/DSC study to characterise and classify coal seams conforming to susceptibility towards spontaneous combustion
No full textThermogravimetric analysis/differential scanning calorimeter (TGA/DSC) technique along with basic coal characteristics study is carried out for eighty coal samples of Indian coalfields, to determine spontaneous combustion propensity behaviour of coal. TGA study of coal samples indicates that there is an increase in the mass of coal samples in the temperature range 150–350 ℃, which may be due to oxygen adsorption and absorption. The correlation and principal component analysis states that the component of proximate analysis (Mad, VMd, FR, and VR) have an acceptable correlation with the TGA experiments results i.e., Tgsh and Tgign. Multiple fixed nonlinear regression analysis shows that thermogravimetry (TG) experiment results Tgign may be the best index to categorise/classify the coal as per their susceptibility towards spontaneous combustion. The authors proposed four groups of classification as per their propensity towards spontaneous combustion depending upon the moisture (Mad), volatile matter (VMd), and TG ignition temperature from differential thermogravimetric (DTG) curve (Tgign) using hierarchal clustering analysis. The coal samples of different seams from Indian coalfield may be classified into four different clusters, viz. very highly/extremely susceptible (Tgign 320 ℃). The field observations and TGA/DSC experiment results with the following statistical analysis substantiate a similar assessment
Investigation on mercury flow and emission in integrated primary iron production process
No full textThe Minamata convention addresses the issue related to mercury poisoning and aim to reduce mercury pollution, as mercury is one of the major concerns for human health. Globally Steel industry is an important source of anthropogenic mercury release. India being one of the largest steel producing country need to look after into details of mercury emission from steel industry. The raw materials like iron ore, coal contains small amount of mercury, which released during steel production. In this study, field studies have been conducted for estimation of mercury input and release from an integrated steel plant in India. Various raw materials, products and wastes are collected for mercury analysis. Mercury mass balances for individual processes were estimated and sinter, coke production processes are found to be significant contributor. Overall mercury mass balance of the plant shows 31.9% of mercury is released through flue gas in various process along with that coke oven gas and Blast furnace gas are also significant contributor. The mercury emission factor for the studied plant found to be 0.057 g Hg/tonne of hot metal production
Deep convolutional neural network based secure wireless voice communication for underground mines
No full textA secure wireless voice communication system for underground miners is an essential gadget for efficient and safe mining. Voice over internet protocol is a proven solution for wireless communication in underground mines where other cellular and satellite networks cannot be deployed. However, the wireless network's security is the major issue for the reliable operation of the system. A secure voice communication system has been developed by integrating voice over internet protocol system and deep convolutional neural network (DCNN) based trained model. Experimental results indicated that voice recognition accuracy of the DCNN based developed model was 93.7% for the noiseless environment. In contrast, it was 82.1 and 79% for the existing K-nearest-neighbour (KNN) and support vector machine (SVM) algorithms, respectively. Voice recognition response time of the DCNN, KNN, and SVM algorithms was 178, 220, and 228 ms, respectively. Thus, deployment of the developed secure and robust voice communication system would improve safety and productivity in underground mine
Fugitive dust emission control study for a developed smart dry fog system
No full textAir pollution due to dust emission is continuously increasing day by day in mining and allied industrial areas. Mining operations contribute a substantial amount of dust emission at the crushing, screening, and bulk material handling in loading areas. The ambient suspended dust particles create a severe nuisance to workers and local dwellers. For effective controlling of positive dust emission, an innovative automated dry fog dust suppression system (DFDSS) has been developed using hybrid nozzles, sensors, actuators, controllers, screw compressors, air receivers, pumps, motors, and water arrangement with filtration facility. The DFDSS was installed in a crushing and screening plant of an iron ore mine in India. Performance study indicted fugitive dust emission concentration values ranged from 354 to 7040 μg m− 3 , which was reduced to 91–300 μg m− 3 after installation of DFDSS. The reduced values were within the permissible limit of 1200 μg m− 3 at a distance of 25 ± 2 m in the predominant downwind direction. The installed DFDSS added a meager addition of moisture content of 0.032% in the handling iron ore material, which was below the acceptable limit of 0.1%. The DFDSS precisely regulated fugitive dust emission from various mining activities without affecting the minerals processing performance. Thus, the DFDSS can be implemented effectively in different mining and allied industries where there is a dust emission problem
Parametric study to design competent irregular-shaped remnants in mechanised depillaring
No full textMechanised depillaring (MD) has been proved to be a panacea for faster extraction of the developed pillars which is blocking access to deeper deposits and locking more than 3200 Mt of coal, developed by Bord and Pillar mining method in Indian coalfields. Depillaring of these square/rectangular-shaped developed pillars by continuous miner creates irregular-shapedribs/snooks. Stability assessment of such ribs/snooks becomes a challenging task due to various issues faced in estimation ofload acting upon it and their strength. Area-based approach for the design of rib/snook is found to be the most suitable criteriaduring MD. Field investigations supported for parametric investigation for a competent size of rib/snook with varying nature of roof and depth of cover. Taking help from previous studies to design such ribs/snooks on numerical models using FLAC3D,aparametric study is carried out using 3DEC. Strength of such ribs/snooks and load acting upon them is calculated with the help of calibrated numerical models in order to estimate their factor of safety. This paper presents a review of the previous researches and a novel numerical simulation technique for estimation of a competent size of rib/snook in a given geo-mining condition
Phytostabilization of coal mine overburden waste, exploiting the phytoremedial efficacy of lemongrass under varying level of cow dung manure
No full textA pot study was performed to assess the phytoremedial potential of Cymbopogon citratus (D.C.) Staf. for reclamation of coal mine overburden dump wastes, emphasizing the outcome of amendment practices using cow dung manure (CM) and garden soil mixtures on the revegetation of over-burden wastes (OB). Wastes amendment with cow dung manure and garden soil resulted in a significant increase in soil health and nutrient status along with an increment in the phytoavailability of Zn and Cu which are usually considered as micronutrients, essential for plant growth. A significant increment in the total biomass of lemongrass by 38.6% under CM20 (OB: CM 80:20) was observed along with improved growth parameters under amended treatments as compared to OB (100% waste). Furthermore, the proportionate increases in the assimilative rate, water use efficiency, and chlorophyll fluorescence have been observed with the manure application rates. Lemongrass emerged out to be an efficient metal-tolerant herb species owing to its high metal-tolerance index (>100%). Additionally, lemongrass efficiently phytostablized Pb and Ni in the roots. Based on the strong plant performances, the present study highly encourages the cultivation of lemongrass in coal mining dumpsites for phytostabilization coupled with cow-dung manure application (20% w/w)