IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
Not a member yet
2618 research outputs found
Sort by
Optimum Utilization of Continuous Miner for Optimization of Production in Board and Pillar Mining Method in Indian Underground Coal Mines
No full textIn present contest with the past, production optimization has become important goal for industries. With reference to past few decades’ underground coal mining operations uses continuous mining technology to extract coal reserves from the underground coal seams. Matching with the continuous miner shuttle cars are used to transport the coal from the face to a feeder breaker. After that, coal is generally tilted over the conveyor system in underground that transport to the surface for distribution to consumers most of power generation plant of India. The availability of coal and methods of mining plays the key role, but in this area of continuous technology, miner feels a safe and environment-friendly path for increasing the overall production. Technology suits for obtaining the target production according to Indian coal seams occurrence as per geological structures. Productivity may improve by effective management of breakdown of the using machineries. This paper is purpose to identify the various factor and problems affecting the productivity of the underground coal mine
Revision of country specific NCVs and CEFs for all coal categories in Indian context and its impact on estimation of CO2 emission from coal combustion activities
No full textThis paper highlighted the need for periodic change in country specific NCVs and CEFs of solid fuels. Accepted India specific NCV/CEF values of coking coal, non-coking coal and lignite were worked out during the India’s Initial National Communication’2004 taking 1994 as the base year. Those values continued to be in use in CO2 estimations done by sectoral/national/international agencies and also in estimations related to India’s Second National Communication’2012 to UNFCCC. In present investigation fresh estimations taking base year as 2007 were done considering large numbers of relevant post 2006 coal-quality data for each Indian coal category and as a result NCV of non-coking and coking coal diminished by 6.6% and 2.1% respectively. The changes happened due to cumulative effect of slow changing quality of coking, non-coking coals and their grade-wise production pattern over the years. Using new NCV-CEF values, reduction of CO2 emission by 53.4 Tg, solid fuel (coal and lignite) emission by 5.4%, total fossil fuel emission by 3.8%, sectoral emissions by 2.7%–5.9% were observed. The relevance of new NCV-CEF values were examined in present context and the new values should be used for accurate estimation of CO2, which indicates energy efficiency and clean use of coals
Insights from Rock-Eval analysis on the influence of sample weight on hydrocarbon generation from Lower Permian organic matter rich rocks, West Bokaro basin, India
No full textAmong the different Rock-Eval parameters, the hydrocarbons released under the S2 peak of Rock-Eval is of significance as it indicates the residual hydrocarbon content of the rock. Further, through its relationship with total organic carbon (TOC) content, it helps in calculating hydrogen indices (HI) which helps in understanding the type of organic matter present in a rock [HI= (S2/TOC)*100]. The present study documents the role of sample weight/amount used for analysis on the Rock-Eval S2 parameter for unconventional source-rock characterization. For the purpose of this study, a vitrain band sample type (manually isolated from a coal), a high-TOC shale sample type, and a carbonaceous shale sample type were analyzed at two different particle sizes (viz. 1 mm-500 μm and 212-75 μm) and different sample weights (5–15 mg for organic matter rich rocks and 30–60 mg for shale) using a Rock-Eval basic cycle (heating rate at 25 °C/min). Although S2 is reported as mg hydrocarbon (HC)/g rock, with increase in sample weight, an increase in hydrocarbons released under the S2 peak of Rock-Eval was observed for all three sample types for both the particle sizes. The observations were further validated using a Norwegian geochemical standard (JR-1). Further, all samples were reanalyzed by conducting pyrolysis experiments at a lower heating rate of 5 °C/min. The impact of sample weight on S2 and HI was observed to be more pronounced for the JR-1 standard (higher hydrocarbon yield) than the Van Krevelen Types III-IV organic matter-bearing rocks. It thus calls for interpreters to be aware of the influence of mass of organic matter on hydrocarbon generation, and to monitor the maximum S2 values of organic matter-bearing rocks, within the flame ionization detector (FID) detection limits. Further, it is recommended that for Type III organic matter-bearing rocks with TOC content>20 wt %, elemental analysis should be used to derive atomic H/C and O/C ratios for Van Krevelen diagram-based kerogen typing
Assessment of the Strength of Inclined Coal Pillars through Numerical Modelling based on the Ubiquitous Joint Model
No full textThe inclined coal pillars, formed during the underground extraction of the inclined coal seam, are different from the flat coal pillars due to the high strength anisotropy of the inclined bedded rock, and the asymmetrical stress distribution. To ease the manoeuvring of the men and machinery in the inclined coal mine, the pillars are developed along the apparent dip. Thus, the pillars become rhombus-shaped with acute-angled corners which crush rapidly due to the high stress concentration. No suitable formula is found to estimate the strength of the inclined coal pillar that incorporates all these factors. Thus, the use of the available coal pillar strength formulae may endanger the extraction of the inclined coal seams. This study elucidates the procedures to estimate the strength of the inclined coal pillars by the numerical modelling technique. The ubiquitous joint model is used to simulate the shearing characteristics of the inclined strata. The parametric study shows that the strength of the inclined coal pillars decreases with the increase of the dip of the coal seams. It is also obtained that the strength of the pillars decreases with the decrease of the value of the acute angle of the corners. The peak stress distribution and the strain accumulation over the inclined pillars at the time of failure are plotted in three-dimensional graphs which show the asymmetrical characteristics of the inclined coal pillars. The analysis of variance shows that the dip of the coal seams and the acute angles of the corners have a statistically significant effect on the strength of the inclined coal pillars. Based on the results of the simulation, the best fit relation is established by the multivariate non-linear regression technique to estimate the strength of the inclined coal pillars. The coefficient of determination (R2) and the root mean square error of the model are obtained as 0.92 and 0.065, respectively. The validation of the developed model has been carried out by the stable and failed inclined pillar cases of different underground inclined coal mines in India. Comparisons of the safety factors, obtained from the developed model and the flat pillar strength formula, indicate that the flat pillar strength formula overestimates the strength of the inclined coal pillars. The developed model can be used to design the inclined coal pillars for safe extraction of inclined coal seams
Health risks from PAHs and potentially toxic elements in street dust of a coal mining area in India
No full textPolycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) (Ba, Zn, Pb, Cu, Cr, Ni, As, Co) were determined in the road dusts of a coal mining area (Dhanbad, India) to assess their content and potential human health risks. Dust samples were collected from sign boards of the heavy traffic road connecting Dhanbad and Sindri. The total PAHs (∑PAHs, all values in mg/kg) content in the road dust samples varied from 3.98 to 13.1, with carcinogenic PAHs content of 14.8–34.4% of the ∑PAHs. Phenanthrene (2.72), fluorene (0.715) and pyrene (0.575) are the major PAHs. Principal component analysis revealed that these PAHs are probably originated from pyrogenic (coal combustion and traffic emission) and petrogenic (coal dust, tyre and road particles) sources. Among the PTEs, the mean content was higher for Ba (293 mg/kg) followed by Zn (224), Pb (128), Cu (52.6), Cr (45.2), Ni (22.0), As (17.5) and Co (8.11). The overall pollution load index varied from 0.43 to 1.0. Source analysis showed that PTEs in the road dust of the study site were derived from traffic emission (Zn, Fe, Mn, Co and Pb), coal dust (Cr, As and Ni) and soil (K, Mg, Ba, Sr and Ca). In general, the PTEs are lower, but the PAHs contents were elevated in the road dust samples. Although the exposure risks from PTEs are low, the risk to children (expressed as hazardous quotient) for As and Pb is near to the permissible limit of 1.0. Cancer risk from PAHs for adult (4.8 × 10−6) and child (5.3 × 10−6) has exceeded the acceptable limit of 10−6
Caveability Assessment of a Hanging Overlying Massive Deccan Trap and its Effect on Underground
No full textEfficient and safe extraction of coal from underground mines require regular/smooth caving of the hanging overlying strata in goaf which is intended to fall. Sometimes presence of extremely difficult to cave massive strata (EDTCMS) having higher strength and thickness as immediate roof delays the natural caving and affect adversely the depillaring operation in underground mines. Such EDTCMS are found globally (India, China, United States, Czech Republic) with thickness varying to hundreds of meters characterised as igneous/sedimentary formations. It is found to be lying either just immediately above or after a certain parting from the coal seam. The latter is found more frequent to the former in coalfields of the world including India. Bulking factor plays a major role in filling the void by the falling of the partition between coal seam and EDTCMS. When a large overhang of EDTCMS is created in the void then their sudden breakage may generate issues like dynamic weighting, floor heaving, pillar spalling, coal bump/rock burst, goaf encroachment/pillar failure and air blast in and around the face. Dynamic weighting by a dolerite sill in the roof destroyed the integrity of almost half of the chock shields in less than 4 second at Churcha West Colliery, India. Various techniques have been adopted worldwide to deal with the issues due to EDTCMS like their pre-fracturing, induced blasting, leaving wider barrier pillars at the face, back filling and injection of grouting material into the mining-induced overburden. This paper presents a case study discussing issues of spontaneous heating and pre-mature collapse of pillars due to EDTCMS at Mathani Underground Mine
Heavy metals in eggs and chicken and the associated human health risk assessment in the mining areas of Singhbhum copper belt, India
No full textMetal contamination was studied in locally rearing chicken and eggs in the environs of mining areas of Singhbhum copper belt. Concentrations of metals were below Indian standards except for Cu, Ni and Zn in the case of chicken at some locations. Estimated daily intake (EDI) and target hazard quotient (THQ) suggested that the metals did not pose risk individually. However, considering the geometric mean of the metals, hazard index (HI) was above unity. Cu, Pb and Co were the key components contributing to a potential noncarcinogenic risk. The HI varied from 0.62 to 1.66 among the locations indicating a considerable heath risk to the consumers of locally reared chicken and eggs around the mining areas. Higher HIs were found at the locations in close vicinity to copper mining and processing units compared to other locations
Influence of Joint Conditions and Blast Design on Pre-split Blasting Using Response Surface Analysis
No full textBlasting is a major method of excavation in mining, civil construction and infrastructure projects. The integrity of the rockmass of the final wall after excavation is important for the stability and economics of the operation. Perimeter blasting achieves a planned surface of the rockmass. The pre-split is one such technique, deployed when there is no free face and, thus, involving several interactions of rockmass properties, including strength, joint spacing and joint orientation, with respect to blastholes, blast design, explosive configuration, blasthole deviations and other variables. The mechanism and models of the pre-split are perfunctory, particularly in defining interactions of pre-splitting variables. The basis of pre-splitting vis-à-vis dominant variables affecting performance is, accordingly, discussed here. Since the half cast factor, generally used for damage assessment, has its limitations, the index of blast damage has been compared while modelling performance. Models using response surface analysis for pre-splitting, for both blast damage index and half cast factor, were developed using historical data. The angle of the blasthole with respect to the major joint orientation, spacing of the joints, blasthole spacing, drill deviation, linear charge concentration and compressive strength has been used to compare the above-mentioned damage criteria. Blast damage index has been found to be a better predictor for determining rockmass damage due to blasting. The desirability of the variables deployed has been determined using optimization procedures. A fresh impetus to pre-split studies is expected to provide a ground for future research, particularly studies using advanced computational and numerical algorithms
Extraction of Deep-Seated Coal Deposits Using Emerging Underground Mining Methods
No full textThe average depth of the underground coal workings has increased considerably due to the exhaustion of coal deposits near surface. Nevertheless, the coal extraction at depth is overwhelmed with geomining issues due to high in-situ stresses, dynamic behaviour of rockmas, large dilation in mine openings, etc. Therefore, to extract coal from deep mine safely, this paper assesses the geomechanical issues and the mining challenges of deep mining and emerging methods to manage these issues eectively for Indian mining conditions. The geo-mechanical issues have been assessed based on the basic rock mechanics of deep mines. The mining challenges are analyzed focusing on stable working face, roadways, transportation, etc. The comprehensive survey and critical studies of the emerging underground mining methods are done to nd out the prospective methods of underground mining which can negotiate the complexities of deep-seated coal deposits in India. The selection of mining methods suitable to the characteristics of coal deposits has been discussed and suggested for mining at greater depth. The works presented in this paper are highly pertinent to Indian mining industry and would provide an insight to select greener, economical and safe mining method to extract deep-seated coal deposit
Comparative pore structural attributes and fractal dimensions of Lower Permian organic-matter-bearing sediments of two Indian basins: Inferences from nitrogen gas adsorption
No full textPore structural framework of Lower Permian shales from two Indian basins is investigated using a low-pressure nitrogen adsorption–desorption technique. Specific surface areas (SSA) of shales are controlled by their thermal maturity. Thermally mature shales are marked by lower average pore sizes, diminishing pore size distribution style from the finer to the coarser pores, and higher fractal dimension D2, relative to the less mature shales. D2 (pore structural fractal dimension) showed a positive relationship with SSA and maturity and a negative correlation with pore sizes. The fractal-distinguishing parameter ∆S was higher for the mature shales. With increasing maturities, pore structures become complex and the fractal dimensions become more distinct