IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Nano-scale physicochemical attributes and their impact on pore heterogeneity in shale
No full textHeterogeneity in shale due to distribution of mineral and organic matter controls the disposition of pores in them. While the effect of vertical anisotropy is accounted for most cases of porosity estimation, the effect of bedding parallel heterogeneity is often ignored. This study dives deep into the shale fabric using bedding parallel sections, and the pore volume distribution is estimated in shales of varying thermal maturity and organic carbon content (2.6% − 38.2 %). Three among the five shales used in this study are early mature (Tmax: 439–444 ◦C), whereas the remaining two are over-mature, signified by very high S4Tpeak (670–685 ◦C). The higher thermal maturity indicates thermal alteration induced by igneous intrusion. The pore volume, functional groups, and organic matter distribution are systematically derived in different positions of the bedding parallel section using a combination of 3D imaging, spectroscopy, small-angle scattering and low-pressure gas adsorption techniques. These spot-specific properties are further compared with bulk properties to quantify the extent of heterogeneity. It is observed that the over-mature shales with higher aromaticity contain 150–200% more bulk accessible pore volume than the lesser-mature shales. It is also evident that the smaller mesopores (~10 nm pore width) are more inaccessible compared to their coarser (~20 nm pore width) counterparts. Higher matured shales show increased inaccessibility of mesopores up to 228 % due to bitumen deposition in pores during thermal maturation, resulting in a sharp decline in mesopore surface fractal dimension. The uniformity of the functional group and organic matter distribution in different parts of the shale depends on the maturity, and reflects the extent of variation in pore volume across the specimen. The 3D tomography-derived spatial abundance of organic matter in over-mature shales show higher deviation (±15-20%) from the average than lesser mature shales (5–10%). This study proposes a multiscale methodology which can evolve and develop as a protocol for systematic, reservoir-scale maturity-dependent heterogeneity quantification in gas-shales
Explicit dynamics based numerical simulation approach for assessment of impact of relief hole on blast induced deformation pattern in an underground face blast
No full textThe breakage of rock mass by blasting has many challenges. The optimal breakage in an underground development face/tunnel blast is dominantly dependent on the relief area provided to the blast holes. The cut portion in the burn cut face blast is significantly important to achieve the controlled deformation due to the blast. This paper has discussed the impact of the number and diameter of the relief holes on the breakage pattern of the rock. The numerical simulation with varying numbers and diameter of relief hole was carried out for this purpose. Finite element modeller explicit dynamics of Ansys-Autodyn was used for the simulation work. The isosurface of non-deformed zone was plotted to compare the extent of deformation under varying conditions of relief holes. The analysis shows that the higher number of relief holes with optimum diameter gives more controlled deformation than single relief hole with larger diameter. The nearfield vibration was also recorded by placement of seismograph. The waveform analysis of the recorded vibration was carried out. The redesigning of the blasting pattern was done using the results of numerical simulation and waveform analysis. The redesigned pattern consists of four relief holes of 115 mm diameter. The blasting output with the revised design has resulted into the considerable improvements in the pull and reduction of overbreak. The revised pattern has addressed the issue of the socket formation at the site
Morphometric Analysis of Baner, Neogal and Awa River Basins, Himachal Pradesh, India
No full textThe present study aims at evaluating the morphometric parameters of Baner, Neogal and Awa river basins in Himachal Pradesh, India for making important assessments about the morphometric characteristics and geo-hydrological conditions of these watersheds. Georeferenced Survey of India toposheets, Cartosat-DEM are the datasets used in ArcGIS software for the delineation of watersheds and calculating important morphometric parameters along with the preparation of relief, slope, aspect and drainage basin asymmetry maps. The results show that the Neogal and Awa rivers are of 6th order whereas Baner river is of 7th order. The basins are of elongated shape and the drainage is mainly of sub-dendritic to dendritic type. In the northern regions of these river basins, the slopes are very steep and the relief is very high that results in rapid runoff and increases the intensity of erosion. High drainage density (>2.8) and fine drainage texture (>9) indicate moderately permeable subsurface material that causes groundwater deficit. These watersheds have developed asymmetrical drainage and their high ruggedness values (>12) refers to the rejuvenated stage of their geomorphic development. The study concludes that erosion-prone areas with rapid runoff are present in the area and adequate measures will assist in the sustainable management of land and water resources
Study of Micro-structures and their Relation with Occurrence of Mineral Matter in Ramagundam Coals, Godavari Basin, India: Implications on Coal and Hydrocarbon Industries
No full textThis paper is an attempt to study the relationship between coal microstructures and mineral matter in Ramagundam Gondwana coal of Godavari basin. For this purpose, the occurrence and distribution of mineral matter in different lithotypes and microlithotypes have been investigated and their association with organic matter has been studied. The work has been accomplished through detailed petrography, SEM-EDS and XRD studies. Presence of clay minerals and pyrite, along with trace amounts of apatite, ankerite, hematite, calcite, dolomite and quartz has been revealed from the study. The lithotypes and bands have variable concentrations of mineral matter which occurs associated with different microstructures in coal. Optical microscopy reveals that mineral matter occurs maximum in dull-coal but it is almost equally distributed in dull-banded coal and banded-bright coal. The study also incorporates the nature of fracture and phyteral pores and their association with mineral matter. Vitrain is characterized by cleats, micropores and microfractures which are often filled up partially or completely with mineral matter; fusain has well preserved tracheids with open pits and partially homogenized cell structure filled with mineral matter. In durain and clarain lithotypes, the minerals are intimately intergrown with the organic constituents
Proceedings of Geotechnical Challenges in Mining, Tunneling and Underground Infrastructures ICGMTU, 20 December 2021
No full textThis book consists of selected papers presented at the International Conference on Geotechnical Challenges in Mining, Tunneling and Underground Infrastructures (ICGMTU), held as a virtual conference on December 20, 2021. The papers represent the research work in the related fields of underground mining, ground control, mining geotechnics, geo-instrumentation, mine tunnelling, and underground structures. It focuses on the latest technology being implemented including artificial intelligence and machine learning applications to solve challenges in mining tunneling and geotechnical structure engineering. It also highlights the state-of-the-art technologies adopted by the civil and mining industry for their commercial as well as environmental benefits. The papers are presented by an international pool of academics, research scientist, and industrial experts and therefore cater to the global audience from the field of underground engineering
Preparation of formed-coke using devolatilized inferior coal and its mechanical properties
No full textCoke plays multiple roles in blast furnace operation. Preparation of formed coke from inferior coal provides an alternate way to utilize inferior coal for metallurgical uses. In this process briquettes of coal, char were prepared to produce similar properties to the conventional coke and sufficient strength to maintain the shape during transport, storage and utilization. In this study formed coke was prepared using devolatilized coal at different temperature. The effect of use of this devolatilized coal was studied in terms of point crushing strength. In general, it was observed that higher devolatilization temperature (550 °C) and longer duration (3 hr) increases the point crushing strength and fixed carbon. Fast volatilization process during carbonization significantly decreases the coke mechanical strength. The use of devolatilized coal reduces the volatile matter content and in turn reduces the fast volatilization which increase the point crushing strength
Organic petrography and stable isotopic characteristics of Permian Talcher coal, India: Implications on depositional environment
No full textThe depositional environment of coal generally controls its chemical composition, physical properties, and utilization potential. Therefore, the present study investigates the depositional environment of the Talcher coal, which represents the single largest coal reserve in India, based on proximate, ultimate and petrography analyses, as well as on the determination of stable carbon (δ13C) and nitrogen (δ15N) isotopic composition. The Talcher coal is classified as sub-bituminous to high volatile bituminous rank based on the vitrinite reflectance (0.40–0.59%), volatile matter (43.0–55.1%), and carbon content (71.2–79.3%). The ash yield varies from 12.4 to 39.3%. Petrographically, the coal is dominated by vitrinite (48.4–64.2%) followed by inertinite (21.4–36.2%) and liptinite (10.0–16.8%). The mesotrophic to rheotrophic water conditions in the palaeomire is deciphered by the vitrinite to inertinite ratio (V/I) and the groundwater index (GWI). The coal was formed in a telmatic environment where forested vegetation prevailed. The recorded TPI values (>1) indicate a high tree density. The δ13C and δ15N values of Talcher coal range from −23.7‰ to −21.7‰ and +0.6‰ and +3.4‰, respectively. The total organic carbon to total nitrogen ratio (TOC/TN) of the coal lies between 20 and 40, which reflects the dominance of vascular higher terrestrial plants as the source vegetation. The δ13C composition of coal corresponds to that of the C3 land plants. Both δ13C and δ15N composition of Talcher coal falls within their respective global coal values. The δ13C composition of the palaeoatmospheric CO2 (δ13Cair) is found to be −3.7 ± 0.5‰ and − 2.6 ± 0.5‰ applying Arens and Gröcke equations, respectively, and they are in agreement with the global Permian δ13Cair (−5.6 to −2.3‰)
Pyrolysis and combustion behavior of few high-ash Indian coals
No full textIn this study, three high-ash Indian sub-bituminous coals of different thermal maturities from three different open cast mines of Raniganj basin, eastern India, were studied to understand their combustion and pyrolysis behavior. The combustion analyses were performed under three different heating rates (5°C, 10°C, and 15°C/min). From the thermograms of TG-DTG pyrolysis curves, it was observed that the overall pyrolysis reaction can be deduced into four different temperature regions with each region showing unique properties, and those regions are inherent moisture loss, prior to primary pyrolysis, primary pyrolysis, and secondary pyrolysis regions. The main pyrolysis reaction occurs in the primary pyrolysis region for all the samples but a significant devolatilization has also been seen for the early oil window mature noncoking coal in the secondary pyrolysis region. The kinetic parameters were also evaluated for both combustion and pyrolysis analysis. X-ray diffraction revealed that this sample consists of a significant amount of siderite and pyrite, and consequently showed distinct behavior. It was observed that the pyrolysis properties and kinetics were closely related to their complex mechanisms and reactions. Rock-Eval pyrolysis also confirmed the presence of siderite in the sample, which decomposed simultaneously with the organic-matter during pyrolysis
Preheating upto Tarrification Point and Compaction: A Promising Way for Coke Quality Enhancement
No full textCoke producers are facing a tough challenge to produce good quality metallurgical coke at reasonable price due to decreasing availability and increasing cost of good quality hard coking coal.The use of alternative carbon source like non-coking bituminous coal, heat altered coking coal (Jhama), petcoke can be a way to address the problem. In this article, the effect of preheating and stamp charging of coal on coke quality parameters were studied and compared with the properties of coke produced in top charging and stamp-charging process. The effect of coal preheating before compaction on the properties of resulting cokes has been studied using five different types of coals. Five coal samples with different coking properties have been selected for the study. The Coal samples have been preheated to their tarification level and then stamped for compaction to higher bulk density before carrying out high-temperature carbonization. The most significant differences between cokes from preheating then compaction were observed in terms of CRI and CSR value. Significant differences of properties have been observed between coke samples produced in preheating followed by stamp-charging and the coke samples produced in top charging and normal stamp-charging technique
Biochar washing to improve the fuel quality of agro-industrial waste biomass
No full textLow energy density and low ash melting temperatures of agro-industrial waste biomass are bottlenecks for their sustainable use in combustion utilities. Torrefaction at low temperature (350 °C for 30 min) for energy density enhancement followed by very simple aqua-washing technique to remove soluble mineral matters from biochar (BC) samples have been employed in this research work to investigate possible improvement of combustion performance of tobacco stalk (TS), sugarcane bagasse (SB), and poultry litter (PL) biomasses (BM). Though the energy density of the BC was significantly higher than their respective BM, the propensity for slagging was also higher, particularly in TS-BC and PL-BC. On char washing, ash content as well as the slagging and fouling tendencies were estimated to be decreased. Energy densification ratio (as compared to biomass) as well as GCV were further increased in washed biochar (WBC). As per the DSC-TGA investigations, combustion reactivity of BC was improved by washing. The significant advantages of BC washing were observed in TS-BC and PL-BC due to the removal of a large amount of soluble materials from respective BCs. As the water extracted material from SB-BC is insignificant, unwashed SB-BC having sufficiently high GCV (20.6 MJ/kg), energy densification ratio (1.5), carbon content (66.7%) can be directly used without washing. Water washing of BC is highly beneficial for TS and PL in respect of combustion performance and a valuable potassium-rich fertilizer material was obtained on evaporation of the leachate depicting unique value-addition of entire process