IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Design of blasting patterns to induce effective caving in continuous miner depillaring panel – a case study
No full textAn innovative scheme of induced caving by blasting was adopted in the depillaring continuous miner panel CM1 of Jhanjra Colliery of Eastern Coalfields Limited, a subsidiary of Coal India Limited. Initially, the blasting pattern was designed with respect to underground workings and later with respect to the surface, vertically above the panel, to facilitate effective caving. The natural caving was delayed due to the presence of three hard-rock beds of more than 5000 cavability index in the immediate roof of the R-VI seam in addition to the oversized left-out standing pillars kept during coal extraction in the panel, which provided extra supports to the hanging roof-rock in the goaf. To mitigate the situation, the design parameters were meticulously planned and implemented for successful blasting operations, which led to effective caving in the goaf and enabled successful extraction of the coal from the panel maintaining the required level of safety and productivity
Utilization of Waste Lubricant Oil in Fuel Phase of ANFO Explosives: Its Field Applications and Environmental Impact
No full textDisposal of used lubricant oil in an ecosystem is a serious environmental threat. In this context, recycling waste lubricant oil into a valuable product has an immense commercial and environmental significance and is a challenging area of research. In this article, we have demonstrated the use of waste lubricant oil as a partial replacement of diesel oil of ammonium nitrate fuel oil (ANFO) explosives. Moreover, the effect on detonation properties and rock fragmentation patterns by the use of lubricant oil based ANFO in blasting operation has also been studied. The field trial experiments were carried out with lubricant oil based ANFO explosive to demonstrate the real applicability of the prepared explosive composition at Nimbeti Limestone open-pit mine of Shree Cement Limited, India. These explosive compositions revealed effective detonation performance. Importantly, air quality was analyzed during blasting operations to indicate that the emitted toxic fumes such as CO, NOx, and fine dust particles (PM2.5 & PM10) were found within the permissible limit at the mining area by the use of lubricant oil based explosives. Further, rock fragmentation analysis indicated that ANFO explosive compositions with 20 %, 30 %, and 40 % (w/w) lubricant oil in diesel oil revealed good rock fragmentation as compared with normal ANFO in the conducted experimental blas
The tunnel wall collapse and pothole creation on the hilly terrain surface: a case study of stabilization
No full textAn approximately 2-km-long tunnel is located in the heart of the Bailadila hills in India and is used for the transportation of iron ore excavated from nearby mines. A portion measuring 2 m height and 5 m width of the Reinforced Cement Concrete (RCC) wall of this tunnel was severely ruptured and caved in bringing a lot of debris and the slush. This caused subsidence on the hilly terrain surface exactly overlying the affected tunnel portion. Various stabilization measures consisting of cement grouting in tandem with chemicals were undertaken to strengthen the failed concrete lining as well as the rock and soil mass of tunnel walls and roof in and around the collapsed portion. Additional stabilization measures were also undertaken to back-fill the cavity/pothole formed on the hilly terrain surface. Further, monitoring of the stabilized zone was carried out by installing mechanical type convergence indicators in the tunnel walls and roof. Also, the efficacy of grout was estimated using an ultrasound sonic tester and through Schmidt hammer rebound tests. The paper presents this case study along with the conclusions and recommendations, which were drawn based on this study
Evaluating the sustainability of a hydropower project in the Himalayas: A case study for resolving legal disputes in tribunals
Get PDFLand use controversies often dog the construction of hydroelectric projects. Many important projects are
battling in the tribunals because of Geo-environmental concerns. The paucity of scientific studies
objectively investigating the litigations further aggravates the un solvability of the disputes.
The SawraKuddu Hydroelectric project, India, became a subject of litigation when project affected
persons filed a suit in the National Green Tribunal questioning the sustainability of the built environment. The litigants petitioned that the additional adit's blasting vibrations can trigger the landslide of slip
zone, and Thana village situated above it. The petitioners further claimed that vibrations had cracked the houses. They also asserted degradation in the apple cultivation due to tunnel construction. The tribunal
took a stern note of the petition and banned the construction activities. The tribunal further ruled that a scientific investigation must be conducted to ascertain the cause of petitioners' claims.
The study results revealed that the vibrations originating from adit excavation are insignificant and
cannot destabilize the slip zone. The high fluctuation of annual rainfall and tectonic strain were deemed
responsible for the differential settlement of foundations and cracks in the houses. The horticulture study indicated that the physiological processes of apple crops were normal. The study's findings convinced the
tribunal, and construction activities were resumed, resulting in the disputed 111 MW project's
commissioning. Many run-of-the-river hydroelectric projects in the world are battling similar litigations
addressed in the present study. A similar objective methodology is a need for the hour to resolve other
hydroelectric projects' sustainability issues. The study findings will pave the path for the swift resolution
of land disputes related to similar project
Evaluating production behaviour of CBM wells from Raniganj Coalfield through reservoir characterization under constrained field data conditions
No full textThere remains a good level of uncertainty in peak gas rate and the time to reach the peak for coalbed methane (CBM) wells owing to reservoir heterogeneity. The novelty of the present study lies in predicting the production behavior of wells in the emerging CBM block of Raniganj through extensive reservoir characterization coupled with reservoir simulation and validation. Ten regional (R–I to R-X) and two local seams intercepted in the six exploratory boreholes drilled in Raniganj Coalfield were investigated. The reservoir characterization approach was used for uncertainty analysis of the key parameters viz. isotherms, gas content, permeability and porosity, and their impact on the production behavior of the CBM wells. Low, mid and high cases of the parameters were determined through regression analysis.
Isotherm and gas content data were experimentally determined while in situ permeability data were obtained from the pressure transient analysis of injection/fall-off test. Reiss model was used for porosity-permeability transformation and Corey's model was used to define the range of relative permeability. The experimental values of Langmuir volume varies between 17.4 and 29.8 cc/gm (daf); Langmuir pressure 2451–7827 kPa; gas content 2.07–13.03 cc/gm (daf); and fracture permeability 0.79–7.12 mD. The model was set up in CMG-GEM simulator to represent a single well producing under commingled completion strategy for all the 12 seams being perforated. Production profiles of both gas and water show a wide range of variation up to 56,201 m3/day and up to 129.84 m3/day, respectively. Data analysis reveals that Raniganj coals are having a wide range of saturation distribution (between 27% and 100%) with a huge upside potential going towards 100% saturation case. Gas content and permeability are found to be the two key factors controlling the CBM production in Raniganj Coalfield. The model results were validated with actual well performance
Probabilistic stability analysis of failed and stable cases of coal pillars
No full textThe conventional design criterion of the safety factor for pillar stability is a deterministic approach characterised by non-random and exact values of its input parameters i.e. strength and stress. The integrity of pillars often jeopardized when some fluctuations or deviations occur in their strength and stress due to uncertainties in field conditions. To counter these unknown fluctuations or deviations, the coal pillars are designed with safety factors greater than unity and their exact values are selected based on local geomining factors. This practice does not guarantee stability against the geomining uncertainties and consequently lock-up the coal in the bigger size of the pillars. Therefore, to assess the variability in the input parameters in pillar design, this paper presents a probabilistic approach to analyse the stability of coal pillars considering the cases of stable and failed pillars in Indian coalfields. The databases of input design parameters are collected for stable and failed coal pillars from different Indian coal mines. The probabilistic distribution fittings of strengths, stresses and safety factors of stable flat, stable inclined, failed flat and failed inclined pillar cases are derived to know their means and standard deviations. The Monte Carlo Simulation and the First Order Reliability Method have been implemented to solve the limit state functions. The failure probabilities estimated for stable flat, stable inclined, failed flat and failed inclined cases are 0.29, 0.28, 0.56, and 0.99 respectively. The analysis recommends the safety factors of corresponding threshold failure probabilities of stable flat pillars as 1.61 and for stable inclined pillars as 1.41 in Indian mines with the ranges of design parameters considered in their databases. Therefore, the probabilistic stability analysis can provide an additional design criterion to select the optimum safety factor of pillars for improved recovery rates in coal mines
Ore and Backfill Dilution in Underground Hard Rock Mining
No full textThe ore dilution is generally defined as the degradation of economical and valuable ore with the addition of the unwanted host rock, failed backfilled material and or ore material considered below the cut-off the grade. The importance of ore dilution on the profitability of a mining operation is very well known and also well documented, since, it adds to the cost of mining, hauling, transportation, milling and processing etc. It also differs from one mining operation to another, the ore type being extracted, the type of the host rock present and type of mining method applied, type of backfilling method and material used, including other mining parameters. The ore dilution is generally expected at all stages of mining operation including the very first step of stoping in the case of hard rock mining, where, the low-grade ore is extracted un-intentionally or intentionally to insure the safe mining environment including excavation stability and or towards the easy movement of men and machineries. It is well known that the numerous parameters including mining and rock mechanics influence the occurrence of ore dilution in the case of underground hard rock mining. Herewith, through review study, the problem of ore dilution, various factors affecting dilution, its measurement and possible control measures is discussed
Establishing fluidization parameters of different size of coal ash particles in bubbling fluidized bed
No full textThe Fluidization behavior of coal ash particles was studied to establish fluidization parameters in a cylindrical bubbling fluidized bed. A series of experiments were carried out with different sizes of irregular coal ash particles ranging from 1 mm to 3 mm at different bed heights at atmospheric pressure and room temperature (ca. 28 °C). Fluidization regimes of all selected coal ash particles were studied by varying flow rates of fluidization medium i.e., air. The change in bed height and pressure drop across the bed was carefully analyzed to see the effects of particle size and superficial gas velocity during fluidization. The minimum fluidization velocity (Umf), minimum bubbling velocity (Umb) and fluidization index for different sizes of ash particles in cold conditions were calculated. The validation of experimental values was supported by theoretical calculations. It was observed that the Umb is 1.5–1.8 times higher than the Umf at different bed heights (Hbed). No substantial deviation was found in Umf with the variations of Hbed at a particular mean particle diameter (dp). Finally, the fluidization index between 1.58 and 1.78 for coal ash particles of Geldart-D type (dp> 1000 µm) shows an ideal condition for fluidization
Study on the Trend of Accidents due to explosives in Indian Mining Industry and the Future Challenges
No full textThe cases of accidents in indian coal and non-coal mines during 2001-2009 were studied and analysed from the various available annual reports and standard notes. The study reveals that there is an overall decrease in number of accidents due to usage of explosives in the mines. The number of accidents due to use of explosive in indian mines was 15 in 2001 which has been reduced to 8 in 2009. Based on analysis of the trend lines plotted for fatal and serious accidents during the period it is clear that these declining trends are insignificant and not encouraging. The slope of the trend line for decrease in fatal accidents in non-coal mines is 8.280 whereas for coal mines, it is 6.200 only. The various challenges for future and need of the hour to mitigate the accidents due to explosives usage in mine s have been discussed and presented in this paper