IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Stability assessment of heightened rib/snook during extraction of a thick coal seam by continuous miner in single lift
No full textContinuous miner (CM) of 4.6 m working height is adopted to extract 6.0 m thick coal seam in single lift at GDK 11 Incline mine. Nine panels of this mine with their depth variation between 150 and 310 m have been satisfactorily depillared using CM. Field observations found that the different sizes (we/h = 0.92–2.23) of remnants (ribs/snooks) of pillar were intact even when their position is shifted in goaf during 4.6 m extraction height in the initial two panels with average depth variation between 277 and 295 m. It provided an opportunity to further extract the 2 m thick floor coal bottom which were left-out inside the goaf during extraction in the previous two panels. Numerical modelling studies for assessing the competency of 6.0 m heightened remnants supported extraction of full thickness of the seam in single lift. These were further verified with the observations of strata monitoring during extraction of 6.0 m thick coal seam using the same CM of 4.6 m cutting height. Extraction of thick coal seam up to 6.0 m in subsequent panels of the seam experienced safety factor of heightened snook (we/h = 0.69–1.52) ranging from 0.27 to 0.47 between 160 and 254 m depth of cover. Discussing site conditions of the mine, this paper presents design of rib/snook for safe and efficient extraction of a thick coal seam in single lift
CoSe2 grafted on 2D gC3N4: A promising material for wastewater treatment, electro catalysis and energy storage
No full textDespite several efforts in the past, the availability of stable and scalable multifunctional catalysts for water
treatment and energy storage applications is very sparse. This research work addresses the above concern by
grafting CoSe2 nanorods onto 2D gC3N4 using a simple hydrothermal process. The catalytic activity of the
synthesized material has been determined by its ability to degrade bisphenol A-an endocrine disruptor and a
carcinogen. The photocatalytic results showed 92.37% bisphenol A degradation within 210 min mediating
CoSe2-gC3N4. The pollutant mineralization was verified by carrying the total organic carbon (TOC). The CoSe2-
gC3N4 catalyst exhibited 90.31% pollutant mineralization, whereas it was found to be 41.65% and 35.12% for
bare CoSe2 and gC3N4, respectively. The catalyst was characterized using XRD, XPS, DRS and HR-TEM. Further,
the catalyst large electrochemical active surface area demonstrates a higher potential of 380 mV at a current
density of 50 mA/cm2 (oxygen evolution reaction, OER) and − 210 mV at 50 mA/cm2 (hydrogen evolution reaction, HER). The remarkable specific capacitance of 153F/g at 0.5 A/g (retention of > 80% after 9000 cycles) is
evidence of the multifaceted applications of CoSe2-gC3N4 catalyst for energy storage/harvesting concomitant
with water remediation
Impact of Particle Crush-Size and Weight on Rock-Eval S2, S4, and Kinetics of Shales
No full textThe Rock-Eval technique in the last few decades has found extensive application for source rock analysis. The impact of shale particle crush-size and sample weight on key Rock-Eval measurements, viz. the S2 curve (heavier hydrocarbons released during the non-isothermal pyrolysis-stage) and the S4 curve (CO2 released from oxidation of organic matter during the oxidation-stage) are investigated in this study. For high and low total organic carbon (TOC) samples of different thermal maturity levels, it is apparent that particle crush-size has a strong influence on the results obtained from Rock-Eval analysis, with the effect being stronger in high-TOC samples. In comparison to the coarser-splits, S2 and pyrolyzable carbon (PC) were found to be higher for the finer crush sizes in all the shales studied. The S4CO2 oxidation curve shapes of Permian shales show contrasting signatures in comparison to the Paleocene-aged lignitic shale, both from Indian basins. A reduced TOC was observed with rising sample weight for a mature Permian shale from the Jharia basin, while the other shales sampled showed no significant reduction. The results indicate that the S4CO2 curve and the S4Tpeak, are strongly dependent on the type of organic-matter present and its level of thermal maturity. Sample weight and particle size both influence the S2-curve shapes at different heating rates. With increasing sample weights, an increase in S2-curve magnitude was observed for the shales of diverse maturities. These differences in the S2 curve shape lead to substantially different kinetic distributions being fitted to these curves. These findings are considered to have significant implications for the accuracy of reaction kinetics obtained from pyrolysis experiments using different sample characteristics
Air Quality Impact Assessment and Management of Mining Activities Around an International Heritage Site in India
No full textA comprehensive field study has been carried out to measure the background air quality status and identify the air pollution sources from opencast mines around a heritage site in India. Air quality modeling has been carried out to envisage dust concentration due to the existing and closed mines in the region. The predicted total PM10 and PM2.5 levels at the selected receptor locations ranged from 86.39 to 194.89 and from 34.82 to 99.55 μg m−3, respectively. The air quality modeling exercise predicted that levels of PM10 and PM2.5 might increase from 3.2 to 23.1 and from 2.1 to 8.9 μg m−3 respectively due to mining activities when some of the closed mines will be operated in the region without the controlled emission. Hence, adequate measures have been suggested to control air pollution from mining activities. An intelligent dry fog system has been designed to suppress dust emission efficiently from mineral processing plants and opencast mines. The developed system has special features for facilitating eco-friendly mining
Application of MR and ANN in the prediction of the shovel cycle time, thereby improving the performance of the shovel- dumper operation - A case study
No full textLoading and hauling of ore and waste are the key operations of an opencast coal mine and entail a high operational cost. The productivity of a mine can be increased by reducing the cycle time of loading equipment as well as utilizing dumpers optimally. In this paper we discuss the impact of rock type, bucket fill factor, rock fragmentation, the height of the cut, and angle of swing of the bucket on shovel performance. A time study is conducted on shovels in an opencast coal mine with experimental blasts of rocks to assess the impact of different factors on the performance of the shovel. Based on the data, the authors applied multiple regression (MR) and artificial neural network (ANN) techniques to develop different models for the prediction of the shovel cycle time. Developed models are validated by comparing the predicted data with actual field data. With the help of the best model, the plausible fleet size is determined in order to utilize the shovel and dumper optimally and to improve the performance of shovel-dumper operation
Sulphur in Jharia and Raniganj coalfields: Chemical fractionation and its environmental implications
No full textIn coal, total sulphur content is not the only important factor for the industry, but also the forms of sulphur and their distributions should be considered before utilizing any coal for a particular use. In Jharia and Raniganj coalfields, sulphur is present in the forms of organic sulphur (OS), pyritic sulphur (PS), and sulphate sulphur (SS). In this perspective, the present study aims to know the different forms of sulphur in coking and non-coking coals of Jharia and Raniganj coalfields. Twenty samples were collected from both the mining areas. The total sulphur content in coking coals varied from 0.28% to 0.55% and in non-coking coals it varied from 0.33% to 0.54%. The distribution pattern of sulphur showed that PS and OS are dominating in both the coalfields. The OS in Jharia field varied from 0.13% to 0.47%, and in Raniganj coalfield it varied from 0.19% to 0.41%. This depicts that both the coalfields were formed under freshwater condition. Similarly, PS varied from 0.01% to 0.21% and from 0.06% to 0.29%, and SS varied from 0.0052% to 0.01% and 0.005%–0.02% in the above fields, respectively. It is noticed that the content of sulphate sulphur is less than 0.1 wt%, which is lower than other forms of sulphur. In the past two decades, sulphur emission has increased with the increase of thermal power plants due to more demand for power, which is one of the causes of global warming. During coal combustion, H2S and SOx, are produced and that can react with O2 and H2O to form H2SO3, H2SO4 or H2S. Thus, sulphur release can respond within the ecosystem in the form of acidic precipitation that may acidify and affect lakes and streams, sub-surface water and historical monuments. In India, coal consumption and ecological contaminations are increasing day by day due to the rapid energy consumption. Therefore, special attention should be given to adopt clean coal technologies though the coal contains less sulphur
Unearthing Underground Mining-Induced Strata Disturbance by Electrical Resistivity Tomography Interpretation
No full textThe focus of the study was to evaluate the rock strata transformation above an underground mine panel during pre-and-post mining based on an electrical resistivity tomography (ERT) geophysical technique. The data were acquired using two electrode arrays (i.e., pole-dipole and Wenner-Schlumberger [WS]) with electrode spacing of 6 m up to 570 m in length. The resistivity data were digitally processed through RES2DINV software. The formation of fractured rock in the overburden caused by underground mining operations was clearly distinguished by resistivity anomalies observed using the pole-dipole array. Variation in the hydrogeological condition in the strata was also assessed during the pre-and-post mining conditions. The impact of compression and tension generated in the strata as a result of extraction of coal and subsidence in the overburden rock was observed through prominent resistivity variations observed in an inversion modelling of the WS true resistivity profile. The influence of surface topography in the near surface top weathered rock was also distinctly outlined by the resistivity measurements. ERT is a strong tool capable of providing valuable information regarding strata deformation caused by mining
Analysis of factors and suggestions for improving labour productivity in underground metal mines
No full textDespite the new age of industrial mechanization, the mining industry across the globe has been using a large number of labourers to achieve organizational objectives. Improvement of productivity becomes an important goal of any mining industry to achieve price competitiveness. The challenges for the industry are to identify areas of waste, meet the market demand and improve the net revenue. The most effective way of increasing productivity in the mine is the effective utilisation of mineworkers. In this paper, the effective working hours of workers in the underground mine were determined and the causes of delay in completing the single cycle of operation starting from face marking for blasting to rock bolting for support were analysed. It was found that the effective utilization of manpower is 70.8% in a single shift. Hence, one of the important factors affecting the mine’s productivity is the effective management of manpower. As a result, various suggestions were provided for improving the productivity in the mine
Partitioning of Rare Earth Elements (REEs) from Coal to Coal Fly Ash in Different Thermal Power Stations (TPSs) of India
No full textRare earth elements (REEs) have been a topic of profound interest for several decades especially in the present age of electronic and digital revolution. India has the world’s richest beach sands with REEs, yet it imports some strategic REEs to fulfil its demand. It’s high time to explore alternative sources to meet its demand and coal ash from Thermal Power Stations (TPS) can be a very good alternative resource. In the present study, coal and coal fly ash (CFA) from seven Indian TPSs have been evaluated for estimation of REEs and variations in minerals compositions. Mineralogy of the samples is estimated using X-Ray diffraction (XRD) technique. Coal samples mostly consist of quartz and kaolinite however phase transformations of minerals occurred due to high temperature treatment during combustion. CFA mostly contains quartz and mullite. REEs have been determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and considerable occurrence of any specific REE is not observed. Among the studied TPSs, Pr has the highest concentration among REEs in ash, reaching up to 63 ppm. The Outlook Coefficient (Cout) of REEs is in the range of 0.3–4.5 and 0.1–1.2 for coal and CFA respectively. In this research paper, Enrichment Coefficient (Δe) has been introduced to see the enrichment of REE in CFA with respect to the mother coal and a graph of Δe vs glassy phase has been plotted to observe the partitioning of REEs. Occurrence of Light REEs is more prominent than Heavy REEs