IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Mechanical wear of cutters in tunnel boring machines – a comprehensive review
No full textFactors that determine the selection of method to excavate a tunnel depend upon the geology, economy and site conditions, but when it comes to the economics of tunnelling then it has to be chosen correctly as per the methodology. Cutters are an integral part of a tunnel boring machine and its performance depends largely on these. In order to ascertain various factors of cutters that influence the performance of the machine, a comprehensive study of literature was carried out. The method involved referencing the citations to a particular publication from which the importance of factors responsible for cutter wear in TBM were decided. In order to categorise the impact of different variables on cutter wear, the references were divided into wear, mechanical, geological and engineering categories based on citations reviewed and observed. Cutting conditions of disc cutters has been reviewed and evaluated based on findings of different authors
Application of CFD Techniques to Assess Spontaneous Heating/Fire during Extraction of Thick Coal Seam Using Blasting Gallery (BG) Method
No full textSpontaneous combustion is one of the key issues in the blasting gallery (BG) method of coal mining. Earlier most of the BG panels have been sealed due to the occurrences of spontaneous heating during the extraction of the panel. This research paper describes a study on spontaneous heating/fire mechanism in depillaring panels of thick seam mining using laboratory experiments, calculating goaf ignition temperature, field investigation and computational fluid dynamics (CFD) techniques. The laboratory study, i.e. Proximate analysis, ultimate analysis, Sulphur analysis, CPT study, DSC study indicated that coal is prone to spontaneous heating. The CFD simulation study reveals that spontaneous heating of leftover coal in goaf areas alone cannot be responsible for the fire in the BG panel. It indicates that an increase in temperature of the goaf is proportional to the amount of coal left in the goaf region. CFD study for roof fall in leftover coal in the goaf region along with spontaneous heating establishes that temperature rise in goaf is proportional to roof fall area of the panel. The laboratory, field and CFD simulation study clearly verify that spontaneous heating/fire in BG panel is due to the combination of spontaneous heating in leftover coal, and frictional heat generated due to roof fall
IoT Based Multimode Sensing Platform for Underground Coal Mines
No full textReal-time information of the underground environment plays a vital role for underground coal mines. For this purpose, a number of systems have been developed by earlier researchers. However, the application of IoT is very limited due to the nonexistence of TCP/IP in underground coal mines. Therefore, attempts have been made to develop an IP based multimode sensing platform for realizing the vision of IoT in underground coal mines. In the present development, a Zigbee based wireless sensor network (WSN) has been initially established and extended to IoT with IP enabled gateway. In addition, the data discard mechanism has been used to address the life span of the sensor network. A dashboard has been designed to access the data at the confluence of WSN and the gateway. Further, an android app has been developed for retrieving the data using the corresponding IP address. The data have also been visualized by the web browser in the same fashion. Finally, the full-scale IoT system has been tested and it is evident from the obtained results that the response of the system is in agreement
Adsorption of hazardous dye crystal violet from industrial waste using low-cost adsorbent Chenopodium album
No full textThe present article describes the use of Chenopodium album ash (wildly growing weed) as effective adsorbent for the removal of a hazardous dye, crystal violet, from its aqueous solutions. This paper presents an experimental study and discussion of the adsorption characteristics of this dye on the plant ash. Two techniques, that is, batch and column operations have been used to explain the removal process. Column capacity is found to be lesser than the batch adsorption capacity. Batch adsorption studies were conducted as a function of adsorbent dose, equilibrium pH, contact time, initial dye concentration, kinetics and Freundlich isotherms. Extent of adsorption has been found to be greater at neutral pH. Kinetic studies indicate that the overall adsorption process is best described by pseudo-first-order kinetics. The adsorption data were fitted to linearly transformed Freundlich isotherm with R2 (correlation coefficient) 0.999. Values of Freundlich parameters n and Kf have been found to be 1.642 and 14.253, respectively. These results indicate that ash of Chenopodium album can be used as an effective and low-cost adsorbent for the treatment of wastewaters contaminated with organic dye crystal violet
Energy saving integrated membrane crystallization: A sustainable technology solution
No full textAn integrated membrane system for crystallization has been studied experimentally. Performance of two membrane based processes; Osmotic Crystallization (OC) and Ultrafiltration (UF) were compared by using different membrane configurations (flat sheet and hollow fibre). Possibility of reduction in crystallization time by antisolvent addition was also explored. Different process combinations were developed for comparative performance analysis. For macromolecular feeds, it was seen UF see was more viable; though FO was attractive with respective to operation at ambient temperature and pressure. Integrated membrane based antisolvent crystallization did not affect the purity of the crystals as is evident from the X-Ray Diffraction analysis of the obtained crystals. The integrated membrane system showed an energy saving of 33.33% while antisolvent addition decreased energy consumption by 16.7%. Combination of membrane based and antisolvent crystallization further lowered the energy consumption by a whopping 36%. This was accompanied with a proportional reduction of 17% of crystallization time with respect to conventional evaporative crystallization. The competitive flux and energy saving quotient makes the system techno-economically viable
Evaluation of Measured Digital Output of Gas Sensors During Spontaneous Heating of Coal
Get PDFSpontaneous heating is the major cause of unintentional coal burning in the underground coal mine.
It is responsible for releasing a number of combustible gases. For measuring the concentration of
these gases, the role of gas sensors becomes very important to plan efficient preventive measures.
In general, the outputs of sensor produced in digital format after processing through the microcontroller
platform. However, the sensor data need to be displayed in a standard format. Therefore, a
tool is needed to convert the digital output of the sensors to the standard format (PPM or %) in
actual environmental condition. Hence, in the present paper, mathematical expressions have been
deduced for each sensor to produce the output in a standard format for test environmental condition
and the same were compared simultaneously with the handheld gas analyzer. The results were
found in agreement
Challenges in flattening of hill by blasting for construction of international airport at Navi Mumbai, India
No full textExcavation of rock by blasting in densely populated area is a challenging work in terms of its adverse effect. Blasting operation involves the interactions of blast design parameters and rock properties with explosives parameters. Optimization of blast design parameters for civil construction site plays a vital role to control the adverse effects of blasting. This paper deals with optimization of blast design parameters for flattening and Demolition of cliffs of Ulwe Hill by controlled blasting techniques which was surrounded by densely populated area. More than 5000 blasts including almost 50 challenging cliff blasts were conducted at different locations of the Navi Mumbai International Airport (NMIA) construction site in order to flatten the Ulwe hill height from 92 mRL to 8 mRL. Blast designs were developed and executed in order to achieve the desired fragmentation level i.e. 300 mm to 700 mm for preparation of stable runway foundation with minimum blast induced ground vibration level. The excavation has been completed about 60 % of the total volume of rock till August 2019. The Ulwe hill was surrounded by 10 villages and most of the villages have been shifted to another locality. However, controlled blasting operations are being carried out nearby two villages and High Tension line which are the major issue now a days. The study involved designing, planning and supervision of the total drilling and blasting operations, suggestions/modifications in blast design parameters, monitoring of blast-induced ground vibrations, noise/air overpressure, quality test of explosives and its accessories in order to process to achieve the desired objectives of the project. Rock fragmentation analyses were carried out for each blast using photo-analysis system and subsequently blast designs were modified to get desired fragment size for land development work. The sequence of detonation, rock movement and stemming ejection during the trial blasts were recorded in each blast
Exploring Rock-Explosive Interaction Through Cross Blasthole Pressure Measurements
No full textThe detonation of the explosive in a blasthole generates pressure to the tune of several giga-pascals that in turn drives the breakage of rockmass in several complex ways. However, nature and the interactions of such pressure with the surrounding rockmass are not explicitly known. This is primarily due to the destructive and rapid nature of the process that hinders measurements in or around the blasthole. Accordingly, such tests are quite cumbersome, complex and costly. The instrumentation has to have standard specifications with several mega-samples per second monitoring capacity. Also, the sensors deployed for the purpose should have a steep rise time because of the fact that the event is transitory in nature. This may be one of the reasons that the focus of researchers has been on determination of energies involved in the process by indirect means. There have been attempts to understand the blasthole pressure and its interactions with the nearby rockmass but due to expensive nature of testing, the progress is not as anticipated. This study attempted the cross blasthole pressure measurements by placing pressure sensors at a distance from the blasthole. The paper presents some examples of cross borehole pressures measured in varied type of rock masses with a good range of acoustic impedance of the rockmass and its joint spacing. Attempt has been made to explain the pressure traces with the aim that further studies in this domain will lead to better understanding of rock–explosive interaction. The method is quite in infancy and it is expected that future studies shall aid in standardisation of the method thus developed
Black carbon aerosols from the coal seam of eastern India: A real-time analysis with statistical validation
No full textUnderground coal seam fire is one of the serious problems caused by coal mining activities. Hence, the present study is focused on investigating the potential emission of black carbon (BC) and its dispersion from the fire-affected area located in the Jharia coal field, Dhanbad district of the Jharkhand state of India. The real-time BC concentration measurements in the active fire area and the adjacent neighbouring urban area were studied and reported. Results showed an average concentration of BC was 12.54 μg m−3 in the fumes/smokes emitting from the surface cracks and vents at the fire-affected zone. The continuous probability distribution functions, i.e., lognormal, gamma and Weibull, were used to fit the BC data individually, and among these lognormal fits, the best were for the medium-range values. Furthermore, the robustness of the obtained BC concentration was also explained by these models. All fitness was in good agreement, in the studied area, with the coefficient of regression ranging between 0.84 and 0.96. Both the experimental and predicted results clearly indicated the contribution of the BC that discharged from the coal seam fire as a source of particulate pollutant. Spatial modelling was also performed to validate the experimental consistency of BC concentration while the model was in good agreement with the underground coal fire zone as compared to the rest