IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
Not a member yet
2618 research outputs found
Sort by
Specific surface area and pore size distribution in gas shales of Raniganj Basin, India
No full textUnderstanding of multiscale transports of shale gas is important for shale gas exploration and exploitation. Traditional porosity determining approaches normally underrate the shale gas transport capacity as these techniques do not include adsorb gas in nanometer-sized slit pores. Silty shale, carbonaceous shale, claystone and ironstone shale unit of Barren Measures Formation was examined to understand the pore system at various scales. The pores are intergranular, intragranular, interlayer, dissolved pore and fracture pores where gas molecules are present as free state and/or adsorbed gas in the internal structure of the pores and at the edge of their structures. Here, we used the Brunauer–Emmett–Teller technique with scanning electron microscopy for considering the adsorption mechanism to understand the gas transport in micro and nano pores in shales. The adsorption parameters between organic wall and grain surface were observed to be controlled by clay mineralogy. SEM, X-ray diffraction and BET manifest significant information about role of clays, organic matter and mineral composition in development of pore network, which also governs the gas storage and transport properties. A large portion of pores in Barren Measures shales ranges between 20 and 55 nm and the pore size diameter ranges from 5.49 to 29.75 nm
Performance of a coal Pillar at deeper cover: Field and simulation studies
No full textExhaustion of coal reserve, extractable by conventional longwall method of working at Czech mines, provided an opportunity to try modified Room and Pillar (R&P) method to extract high grade coal locked-up in larger shaft protection pillar at around 900 m depth. The shaft pillar is divided into various R&P panels and the development process in a panel followed a constant gallery width of 5.2 m and 3.5 m height. This development in the shaft pillar by bolter miner resulted oblique and inclined pillars of 860–1225 m2 area. Stability of these pillars is realised to be vital for optimum recovery of high-grade coal from these panels. No empirical formulation is found suitable for the design of pillars at such a depth. Therefore, an attempt is made to select a better representing one through comparative study of the available formulation. CMRI formula is found to be an alternative solution for designing pillars at this depth as it contains depth of cover as a design parameter. This parameter in the formulation is included to take care of the in situ stress conditions and compactness of the material at higher depth of cover. Further, a number of geo-technical instruments are installed in two pillars of Panel V for an analysis of their stability during the development. An attempt is made to develop a strainsoftening based numerical modelling approach, calibrated by field studies and CMRI empirical formulation, to assess pillar performance at deeper cover. This development is found to be helpful in pillar stability analysis, when the installed instruments ceased to work. Further, an apprehension of pillar failure by extrapolation of field results is not confirmed on simulated models. This paper briefly presents a discussion of difficulties involved in pillar design at higher depth followed by results of field and simulation conducted for the deep Czech mine
Presplit blasting for stabilization of highwall slopes and productivity enhancement in a trench-mining project
No full textStabilization of highwall slope by implementing presplit blasting and productivity enhancement by improving the powder factor using controlled blasting at Sharda project of South Eastern Coalfields Ltd. (SECL) was the endeavour of the research team of CSIR-CIMFR in the first trench highwall mining of India. Good fragmentation was achieved through improved rock-explosive interactions and redefined design parameters in the trench which had restricted width and lesser initial powder factor (in m3/kg) due to varying rock-geologic and rock-explosive characteristics. Through systemic analysis of blast-results and implementation of scientific theories combined with the usage of rock parameters and its physico-mechanical properties, it could possible to achieve around 2.0 m3/kg powder factor instead of 1.3-1.4 m3/kg maintaining stable highwall benches with 700or more slope angle. The work led to huge cost benefits in explosive consumption for the company i.e. M/s Cuprum Bagrodia Ltd. and also markedly reduced the environmental implications from production blastsduring day-to-day operations
Microbial removal of sulphur from petroleum coke (petcoke)
No full textPetroleum coke (pet coke) is a carbonised heavy residual product obtained from petroleum processing. Pet coke contains between 1 and 10% w/w sulphur as both inorganic and organic forms. The removal of organic sulphur from pet coke is desirable to reduce the environmental harm of its combustion emissions but the elevated temperatures and pressures needed result in a lower fuel-value. The removal of sulphur by microbial attack involving acidophilic bacteria is an alternative approach and is the subject of this study. Single and mixed cultures of Thiobacillus thiooxidans (isolated from natural hot sulphur spring) and Thiobacillus ferrooxidans (isolated from an existing culture) were investigated for total sulphur removal from pet coke. Batch leaching experiments showed a reduction in total sulphur of 92% over 28 days. A combination of Thiobacillus species performed better than the single bacterial culture
Predictions of Gross Calorific Value of Indian Coals from their Moisture and Ash Content
No full textIndia, the world’s third largest coal producing country, is expected to maintain strong dependency on coal for the coming few decades. The gross calorific value (GCV) of coal is a key yardstick for many end users purchasing coal from suppliers, as it provides a clear measure of the useful energy content of a coal. Several methods are available to predict GCV using either moisture content and/or ash yield or using entire proximate and ultimate coal analysis data. These correlations and machine learning prediction tools tend to be too complex and hence are of limited utility for the end-user. For Indian coals, the most widely used simple correlation, based only on moisture content and ash yield, proposed by Mazumdar (1954), is less applicable to the coals being mined today, which have higher ash yields. This and other existing correlations used to predict GCV of Indian coals from moisture content and ash yield is linear in nature. Here the application of non-unitary exponents to the ash yield and moisture content terms and introducing other non-linear terms to the equation to provide empirical correlations with improved prediction accuracy for local and national application is evaluated. This evaluation is achieved in Excel using its built-in optimizer “Solver” to evaluate a generic equation and optimize its coefficients when applied to a dataset of 756 coals from three Indian coal basins and to locally focused subsets of that dataset
Design Methodology for Cutting Drum, Power Rating and Operational Control of Surface Miner under Varied Rock Conditions—An Approach
No full textSurface miners are being increasingly used in opencast mines owing to their ability to excavate thin bands selectively. Even-minor variations in intact rock and rock mass parameters can adversely affect the performance of surface miner in terms of production and pick consumption. Power utilization both by rotary motion of cutting drum and linear motion of surface miner has been taken into account for arriving at suitable cutting speed and depth of cut. Cutting speed of surface miner, cutting force developed by individual pick and number of active picks coming in contact with the rock in respect to depth of cut under varied tensile strength can be determined through these studies. This will help the end user to decide suitable parameters for operational control. It is essential to optimize the operating parameters of machine (cutting speed and depth of cut) for a given rock mass condition with available machine power. The present study covers the 2.2 m wide drums of surface miner. Distribution of power available to the components of the machine has been arrived based on technical specifications of each component, taking power loss due to sleep occurs in belt power transmission mechanism
Stability Assessment of Old Underground Coal Mine Openings for the Safety of Overlying Railway Tracks
No full textThis paper presents the stability assessment of a century old coalmine situated under a railway track. The mine openings may lead to the surface subsidence which can endanger the track safety. To assess the stability, this paper presents a unified approach of observational, empirical, and analytical methods. Observational approach monitored the immediate roofs with geotechnical instruments during a period. In empirical approach, the coal pillar safety factors were assessed using rock mass classification. Finally, the analytical study was performed using numerical simulation. All these studies found that the openings and the coal pillars are stable for the track safety
Design, analysis and comparison of methods to increase time tE of increased safety motor for hazardous area
No full textHigh Tension (HT) increased safety (Ex e) motors are being designed for safe operation in the hazardous area. The motor time tE for increased safety motor is prime safety parameter. The higher value of time tE means insulating system of Ex e motor is able to withstand the locked condition for long time so motor will be more safe for long duration during in abnormal condition in hazardous area. The research work shows that the time tE of Ex e motor can be increased by increasing the mass of rotor bar or by increasing the stator coil pitch. Low speed and a high speed HT Ex e motor were selected to redesign with increasing rotor bar mass and stator coil pitch. The time tE and other parameters of redesigned motors have been compared with standard design of Ex e motor. It is anticipated that this study will be of immense benefit to Ex e HT motor designers
Study on the influence of initiation system on blast induced ground vibration in dragline operations
No full textDuring blasting, only a small portion of the total available energy of explosive reaction gets consumed in breaking up the rock while most of remaining energy gets dissipated in the form of ground vibration and air overpressure. These side effects of blasting operation not only reduce the powder factor but also prove to be a nuisance for the nearby human settlements and structures, both belonging to and not belonging to the owner of the mine. However, to fulfil the expanding production targets of large opencast mines the deployment of high capacity machines and consequent requirement of deep hole blasting with high amount of explosive consumptions is obvious. In such circumstances, the evaluation of the ground vibration parameters and development of new controlled blasting designs are the needs of the hour. Choice of better initiation system to reduce ground vibration is a major step in this direction. For this, an experimental study was conducted to understand the influence of initiation system on blast induced ground vibrations. In the study, 21 production blasts - 10 using detonating fuse and 11 using electronic detonators, were monitored for ground vibration measurement. The blasts were conducted at the dragline benches of Jayant opencast project. The results obtained from the study revealed that the percentage reduction in ground vibration levels, by using electronic detonators instead of detonating fuse, ranges from 33% to 9% for varying distance from the blast site ranging from 100 m to 1500 m
Significance of lithotypes for hydrocarbon generation and storage
No full textThis paper examines the hydrocarbon generation and storage potential of lithotypes, macerals, kerogen type relative to thermal maturity. To investigate authors had collected lithotype (vitrain, durain and fusain) samples from the high volatile sub-bituminous coal of Barjora area, SE of Raniganj coal basin, India. Relevant analyses viz. Rock Eval pyrolysis (REP), total organic carbon (TOC), micropetrography, vitrinite reflectance (Romv) and Fourier Transform Infrared Spectrometry (FTIR) were carried. The geochemical analysis indicates that the studied lithotypes have excellent potentiality of generating hydrocarbon in respect of TOC and S2 (under Rock-Eval pyrolysis) and it increases from vitrain to durain to fusain. Also, the free hydrocarbons which was recorded under S1 curve of Rock Eval pyrolysis, was observed to be highest within the fusain lithotype (21.73 mg HC/g rock). Further, the thermal maturity (Tmax: 418–423 °C) and mean vitrinite reflectance (Romv: 0.42–0.56%) indicate the samples are immature in nature. However, ↑Vt60 (vitrinite grains having a reflectance greater than 0.60%), indicates that thermogenic gas generation was occurring to some degree in almost all the samples. Moreover, comparison between geochemical and petrographical analysis it has been inferred that storing capability of hydrocarbons also increases from vitrain to durain to fusain. The higher capability of hydrocarbons within the fusain (in comparison to durain and vitrain) may be due to presence of large amount of fusinite and semifusinite macerals. The production index (PI) also shows similar trend with increasing S1 value. The FTIR study demonstrates that the fusain has higher intensity of aliphaticity than that of vitrain and durain. The higher intensity of aliphaticity in the fusain may be due to presence of considerable amount of bituminite and other liptinites within the cavities/cell lumens. All the observation suggests that fusain has the highest hydrocarbon generation and storage potentiality, whereas durain has less and vitrain has least generation potentiality in comparison to fusain