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Correlating Textural Parameters with Joint Roughness for Himalayan Schist and Gneissic rocks
No full textThe shear strength characteristics of jointed rock masses are interrelated to the roughness of joint
surfaces. These joint surfaces are characterized by mineral grains and their textural arrangements
such as orientation, size, shape, degree of grain linking, and relative quantities of grains and matrix
in a rock which varies accordingly. Textural Coefficient (TC), a dimensionless quantitative
measure, is often used to quantify the intrinsic textural characteristics of rocks. The Joint roughness
coefficient (JRC) is a metric that is frequently used to characterize rock mass roughness in the field
that inherently controls the inter-block shear strength of jointed rock masses. This parameter has
significant importance in the indirect assessment of rock mass strength to be used in a variety of
rock engineering projects and has a direct association with the inherent textural parameters.
Therefore, in the present work, we have made observations on the Himalayan schist and gneissic
lithologies to quantify the potential control of textural characteristics (TC) on joint roughness
(JRC). The JRC for studied rock types were measured in field and then statistically derived from
the 2D surface profiles using the root means square of the first derivative of the profile outline (Z2).
The TC values for studied rock types were estimated using microphotographs of respective joint
surfaces. The statistical analyses suggest two groups of data correlation controlled by a threshold
TC value of 1.1. Both the groups showed a strong linear correlation between JRC and TC for the
studied lithologies signifying the control of textural characteristics on joint roughness. As a result
of the study, empirical equations have been proposed to quantify the JRC from Z2 as well as usin
Environmental and economic benefits of single-atom catalysts in energy conversion and storage
No full textSingle-atom catalysts (SACs) have gained significant popularity in heterogeneous catalysis owing to their high activity and stability. The predominant focus of current research is centred around the dispersion of SACs onto a support medium, aiming to enhance the efficiency of energy conversion and storage systems. The utilization of these catalysts has been associated with environmental and economic benefits. This perspective article provides an overview of the latest advancements in SACs used for energy conversion and storage applications, with an emphasis on their potential environmental and economic benefits. It also provides insights into the future applications of SACs in energy conversion and storage. In addition, the article investigates emerging opportunities for energy conversion and storage systems. Furthermore, the article provides a comprehensive analysis of the key benefits, challenges, and potential factors that may influence the advancement of energy conversion and storage technologies
Significance of organo-mineralogical constituents on pore distribution, fractals and gas sorption mechanism of Permian shale beds in Korba sub-basin of the Son-Mahanadi Valley, India
No full textIn this study, shale samples obtained from the Korbasub-basin of Central India have been evaluated for the significance of organo-inorganic constituents in terms of their source potential of gas genesis, pore-matrix setup, and gas adsorption and desorption. The samples were analysed for various properties, such as megascopic features, lithological variations, depositional facies, and sources of organic and inorganic sediments. Also, maceral content, mineralogical constituents, kerogen type, pore distribution, pore structure, fractal characteristics and gas storage capacity were examined. The analysis revealed a trend of alternating bands of carbonaceous matter, silts, intercalations, and fluvial bedding lithofacies patterns indicating that the sediments were deposited under fluvio-terrestrial-lacustrine depositional conditions. Ternary facies analysis of maceral composition and van Krevelen diagram suggested the evolutionary path of type IV kerogen and are thermally matured source material located within the dry hydrocarbon generation window. Evaluation of pore types and pore structures using BET sorption plots (hysteresis H3 and isotherm type IV) revealed the presence of cylindrical, slit and combined cylindrical-slit pores with two distinct fractal characteristics. The discrete macerals underwent partial decomposition during transportation and mixing with inorganic components (clay and minerals), which influenced organic matter preservation, gas genesis, pore fractals and storage mechanism. The chemical index of alteration (CIA – 88.36 to 91.97), weathering (CIW – 96.60 to 98.80) and compositional variation (ICV – 0.31 to 0.70) demonstrated the influence of partial decomposition and strong weathering patterns on the organo-inorganic matter. A significant correlation was observed between pore fractals and elemental composition, particularly related to the resistance of weathering elements such as MgO, Al2O3, Fe2O3, SiO2, P2O5, TiO2, etc., which partially contributed to the formation of pore rugged surfaces. Microscopic and XRD analyses were employed to determine the mineral type, grain shape and size, and their amount leading to the development of the shales brittleness index (MBI). The importance of brittle characteristics, governed by minerals and clays within the shale, is discussed in relation to the hydro-fracturing technique for permeability enhancement. The results of high-pressure methane sorption indicated a moderate gas storage potential. The variation in sorption capacity (VL – 6.65 to 8.25 cc/g) is described through relationships with the ICV, pore diameter, pore volume, liptinite and total maceral content. Fractal dimensions D1 (2.4571–2.5611) and D2 (2.5804–2.7529) exhibited a direct relationship with adsorption properties, indicating the presence of rugged surfaces associated with meso- and macro-scale pores, which primarily control gas storage in shale. This research offers detailed insights into shale gas, providing valuable information for CBM and petroleum operators engaged in methane gas exploration and production. While commercial CBM production has been ongoing in India for over a decade, the exploration and understanding of shale gas reservoir characteristics are still in progress. This investigation adds significant value and highlights the extensive opportunities for research and potentially commercially recovering shale gas in the Korba sub-basin
A comparative review on thermal behavior of feedstocks during gasification via thermogravimetric analyzer
No full textWith increasing initiatives on “clean power plan” and “carbon neutrality,” gasification is one of the most promising ways toward cleaner energy production using a diverse range of feedstocks. However, prior to gasification, the feedstock must be thoroughly analyzed. The characteristics of various feedstocks, including coal, biomass, petcoke, municipal solid waste (MSW), and their blends, are studied using thermogravimetric analysis (TGA). TGA is widely employed to examine the effect of various parameters, such as time, temperature, heating rate, residence time, pressure, gas composition, and particle size, on the gasification reactivity and kinetics of different carbonaceous feedstocks. Since it is realistic, rapid, reliable, and cost-effective, it is a widely used technique. This review details various thermal analysis techniques, including TGA, differential thermal analysis, and derivative thermogravimetry that can be used for feedstock characterization. The objective of this review is to compare and analyze the reactivity and kinetics behavior of various feedstocks during gasification using TGA. It was observed that the reactivity of biomass is found to be greater than that of MSW, coal, and petcoke with their activation energy in the range of 56–230 kJ mol−1, 100–275 kJ mol−1, 58–250 kJ mol−1, and 120–640 kJ mol−1. This paper will also help in predicting the suitability of different feeds for gasification as well as selecting/designing suitable gasifier. It does highlight different feedstocks used in gasification, along with several thermal analysis techniques. Additionally, in this overview directions of future progress are anticipated for its sound development
Bio-coke: A sustainable solution to Indian metallurgical coal crisis
No full textCoal is the predominant global energy source, where its consumption as metallurgical coke from fast-depleting
prime coking coal is vital. In India, the complete depletion of prime coking coal and ultimate dependence on low-
grade low-volatile coking coal reserves are the primary concern, so the need to explore alternative fuels, pref-
erably with less climatic concern. Accordingly, a process for the synthesis of bio-coke, a novel product, using
varying blending ratios (90:10, 80:20, 70:30, 60:40, and 50:50) of such inferior grade coal and biochars (derived
at 550◦C) of coconut shell (CSC), groundnut shell (GSC), sawdust (SDC), and sugarcane bagasse (SBC) in the
presence of starch and molasses binders was developed via carbonization (at 800–1100◦C). Obtained bio-cokes
from coal and biochars with molasses possess better strength and plastic properties for metallurgical applications
than those prepared with starch, and can be a sustainable substitute for metallurgical coke
Multi-elemental analysis of Indian coals and its gravity fraction based on ICP-OES
No full textInorganic elements in coal are often regarded as a nuisance being responsible for most of the problems arising during coal utilization. Commonly found group of minerals in coal are major (quartz, pyrite, clays, and carbonates), minor and rare earth elements. Three Indian coals were subjected to gravity fractionation to study the association of major, minor, and rare earth elements. It showed that concentration of elements like Al, Ca, and Fe is much lesser in lighter gravity fraction than the heavier gravity fraction. Elements like Fe and Mn were higher at 1.50 gravity fractions with respect to its nearby gravity, while Co content was little higher in lighter fraction. Major toxic elements such as As, Pb, and Cr can be reduced by almost 3–4 times by washing coal. The rare earth elements Y, Lu, Ce, Dy, and La are embedded with mineral matter of the coal. Gravity fractionations, distributing the ash content, and elements link with organic materials. This study showed that along with coal beneficiation, separation of valuable elements in different gravity fractions to be monitored so that the coal beneficiation could be a win-win strategy for upgradation of coal quality and pave the route for extraction of economically important elements
Numerical simulation study on stability analysis of crown pillar—a case study
No full textThe transition from an open-pit to an underground space is inevitable to exploit deposits from greater depth. Crown pillar, a remnant ore usually left in between open-pit to underground mining that supports the terrain and aids in carrying out underground mining operations safely and its stability is vital. The design of crown pillar is majorly influenced by its thickness, span, slope angle, ore dip, depth of open-pit mining, rock mass quality, cohesion and friction angle. When the crown pillar is situated near the surface (shallow depth), it is synonymously named as the surface crown. The behaviour of the crown pillar is different from the surface crown due to variation in geo-mining conditions. As underground mining progresses, displacements around the crown pillar are generated and stresses reorients around it. This can be assessed through numerical simulation. To have a better understanding, this paper concentrates on crown pillar’s stability and geometrical parameters influence on its stability. The field study is carried out at Ramrama manganese ore mine, where the transitioning takes place at shallower depth and FLAC3D 5.0 is used for numerical simulation work to analyse the behaviour of the crown pillar. From the results interpreted, it is found that the maximum amount of principal stresses decreases for the lower span, 8 m, of crown pillar with increase in slope angle and for the larger span as in case of 22 m span; the stresses generated are reduced in case of 38° slope angle and increased for 45° slope angle. Higher dip of orebody generates high amount of stresses in the pillar and with an increase in the depth of mining, high amount of displacements and stresses are observed around the crown pillar
Mechanical behaviors of deep pillar sandwiched between strong and weak layers
No full textA variety of coal room and pillar mining methods have been efficiently practiced at depths of up to 500 m with least strata mechanics issues. However, for the first time, this method was trialled at depths of 850–900 m in CSM mine of Czech Republic. The rhomboid-shaped coal pillars with acute corners of 70°, surrounded with 5.2 m wide and 3.5–4.5 m high mine roadways, were used. Pillars were developed in a staggered manner with their size variation in the Panel II from 83 m × 25 m to 24 m × 20 m (corner to corner) and Panel V from 35 m × 30 m to 26 m × 16 m. Coal seam inclined at 12° was affected by the unusual slippery slickenside roof bands and sometimes in the floor levels with high vertical stress below strong and massive sandstone roof. In order to ensure safety, pillars in both the panels were continuously monitored using various geotechnical instruments measuring the induced stresses, side spalling and roof sagging. Both panels suffered high amounts of mining induced stress and pillar failure with side-spalling up to 5 m from all sides. Heavy fracturing of coal pillar sides was controlled by fully encapsulated steel bolts. Mining induced stress kept increasing with the progress of development of pillars and galleries. Instruments installed in the pillar failed to monitor actual induced stress due to fracturing of coal mass around it which created an apprehension of pillar failure up to its core due to high vertical mining induced stress. This risk was reduced by carrying out scientific studies including the three-dimensional numerical models calibrated with data from the instrumented pillar. An attempt has been made to study the behavior of coal pillars and their yielding characteristics at deeper cover based on field and simulation results