IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
Not a member yet
2618 research outputs found
Sort by
Effluent Treatment Technologies in the Iron and Steel Industry - A State of the Art Review
No full textIron and steel industry is the principal driving force propelling economic and technological growth of a nation. However, since its inception this industry is associated with widespread environmental pollution and enormous water consumption. Different units of a steel plant discharge effluents loaded with toxic, hazardous pollutants, and unutilized components which necessitates mitigation. In this paper, pollutant removal efficiency, effluent volume product quality, and economic feasibility of existing treatments are studied vis-à-vis their merits, demerits, and innovations to access their shortcomings which can be overcome with new technology to identify future research directions. While conventional methods are inadequate for complete remediation and water reclamation, the potential of advanced treatments, like membrane separation, remains relatively untapped. It is concluded that integrated systems combining membrane separation with chemical treatments can guarantee a high degree of contaminant removal, reusability of effluents concurrently leading to process intensification ensuring ecofriendliness and commercial viability
Tracing source, distribution and health risk of potentially harmful elements (PHEs) in street dust of Durgapur, India
No full textStreet dust samples from Durgapur, the steel city of eastern India, were collected from five different land use patterns, i.e., national highways, urban residential area, sensitive area, industrial area and busy traffic zone during summer, monsoon, and winter to analyze the pollution characteristics,chemical fractionation, source apportionment and health risk of heavy metals (HMs). The samples were fractionated into ≤ 53 µm and analyzed for potentially harmful elements (PHEs) viz. Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Summer season indicated higher concentrations of PHEs when compared to the other two seasons. Mean enrichment factor (EF), geo-accumulation index (Igeo), and contamination factor (CF) were high for Cd followed by Pb during all the three season in Durgapur. Chemical fractionation was executed in order to obtain distribution patterns of PHEs and to evaluate their bioavailable fractions in street dust samples. Mn was found to be highly bioavailable and bioavailability of the PHEs were in the order of Mn >Zn >Pb >Ni >Cd >Cu >Fe >Cr. Principal Component Analysis (PCA), cluster analysis, correlation analysis indicated the main sources of PHEs could be industrial, especially coal powered thermal plant, iron and steel industries and cement industries and vehicular. Multivariate analysis of variance (MANOVA) indicated that sites, seasons and their interaction were significantly affected by different PHEs as a whole. The health risk was calculated with total metal as well as mobile fraction of PHEs, which indicated that the actual non-carcinogenic risk due to bioavailable PHEs was less (HI<1) when compared to total concentrations of PHEs. Carcinogenic risk was observed for total Cr in street dust (Child: 4.6E-06; Adult: 3.6E-06)
Pore Characteristics of Distinct Thermally Mature Shales: Influence of Particle Size on Low-Pressure CO2 and N2 Adsorption
No full textThe influence of crushed sample particle size on low-pressure gas adsorption and desorption behavior of shales and their measurement is an issue of significant current interest in this new era focused on shale gas and oil resources. Here we study two samples of distinct Indian shales, with different organic contents, ages, levels of thermal maturity, and pore-size distributions crushed to four different particle size ranges [S1 (1 mm to 500 μm), S2 (500–212 μm), S3 (212–75 μm), and S4 (75–53 μm)]. Low-pressure gas adsorption analysis with nitrogen and carbon dioxide gases reveals significant and complex impacts of particle-crush sizes on the measured pore structure characteristics for the two shales. The CO2 results suggest that at the smallest (S4) particle-crush size evaluated, low-pressure gas adsorption measurements record more, finer nanopores (i.e., less than about 8 Å), fewer larger nanopores (i.e., greater than about 8 Å), and a lower overall nanopore surface volume. The N2 results show an overall increase in macro-pore volume at the smallest particle-crush size. The results imply that while more, smaller pores are exposed to gas adsorption at the smaller crush sizes, a significant number of nanopores are in some way altered and are not recorded as part of the measured nanopore-size distribution >8 Å by low-pressure CO2 adsorption analysis. Fractal dimensions of one shale varied across a range of particle-crush sizes, whereas the fractal dimensions of the other shale studied did not. The analyses suggest that low-pressure gas adsorption results conducted with samples of very small particle-crush sizes should be viewed with caution
Safe dismantling of unstable boulder using controlled blasting in the historical Town of Gaya, India
No full textA torrential rain caused displacement of a big size boulder in Brahmayoni Hills which was situated in the historical town of Gaya in India, posing serious threat to many residential houses located below the boulder. The district administration had evacuated more than 70 families who were resided below the unstable boulder. A concrete support was constructed at the base of the boulder for temporary preventive measure and for the permanent solution, it was decided to dismantle the whole boulder using controlled blasting. The boulder was of gneiss granite rock somewhat pyramid in shape with irregular trapezium at the base having 16 m circumference and 8 m height. It was located in very congested area on the hill slope and the nearest residential house was situated at 2.3 m only. No machinery could be deployed for removal of any blasted materials due to unapproachability of the area. The dismantling work of the boulder was carried out in three stages using controlled blasting from top to bottom. Double-layered wire-mesh covering, anchoring with wire rope, double layer fencing below the boulder, conveyor belts and sand bags were used to control flyrock and possible rolling down of the blasted material. The blasthole diameter used was 32 mm drilled with jackhammer and depth of holes in the different stages of dismantling work varied from 1.2 to 1.75 m. The spacing of holes varied from 0.30 to 0.45 m and the explosive charges were distributed in the hole using decked charging to obtain smaller fragment sizes for manual removal of the blasted materials. This paper discusses detailed planning of the dismantling work, protective arrangements made, design of the blast and successful dismantling works of the unstable boulder without causing any harm and damage to the nearby habitant
Mass Balance of Heavy Metals of Fly Ash in Soil and Crops
No full textIn India, coal-based thermal power stations presently share approximately 70% of the total power demand and generate 184 million tons of ash per annum, and this amount is expected to surpass 440 million tons per year in 2030. Due to its high content of plant nutrients and similar physicochemical characteristics, coal ash can potentially be utilized in agriculture, as well as wasteland and acidic soil reclamation. The purpose of this study was to examine the impact of ash on carrot cultivation under controlled conditions because the plant root is the part responsible for the uptake of nutrients from the soil and for the storage of food and nutrients. The current work is focused on carrot crop cultivation in fly ash–treated soil and elemental distribution patterns in soil, coal ash, and plant parts
Hydrodynamic characteristics in a pilot-scale cold flow model for chemical looping combustion
No full textChemical Looping Combustion (CLC) in two interconnected fluidized beds, i.e., the air reactor and the fuel reactor has been recognized to be promising. As the CLC setup design is critical and sensitive to oxygen carrier (OC) materials, it is very much essential to investigate hydrodynamics in a specially fabricated cold model set up for the successful development and operational control of corresponding large-scale hot model. In this study, a pilot-scale cold flow model CLC system has been designed and tested. The riser and fuel reactor were operated at circulated fluidized bed and bubbling fluidized bed conditions, respectively and the control of solid circulation between two reactors was done by two loop seals operated in bubbling fluidized bed conditions. The effect of fluidization velocity in the riser on the voidage profiles, solid circulation rate, and pressure profiles were investigated using Indian ilmenite (150–212 µm) as OC. The stable operation of the system was established under various operational conditions. The results will be useful for the development of ilmenite based hot model CLC system. Moreover, the achievable variations of solid circulation rate in the present study in cold model setup will determine obtainable limit of extent of oxygen transport and thermal energy
Numerical Modeling of Pot-Hole Subsidence Due to Shallow Underground Coal Mining in Structurally Disturbed Ground
No full textStability analysis of underground mining is, generally, complex in nature and is difficult to carry out through analytical solutions more so in case of pot-hole subsidence prediction. Thus, application of numerical modeling technique for simulating and finding a solution is preferred. This paper reports the development of a methodology for simulating the pot-hole subsidence using FLAC3D. This study is restricted to geologically disturbed areas where presence of fault was dominating factor for occurrence of pot-hole subsidence. The results demonstrate that the variation in the excavation geometry and properties of immediate roof rocks play a vital role in the occurrence of pot-hole subsidence
Selective drop breakage studies: a precursor for dry deshaling of Indian non-coking coals
No full textThe coal seams in India are mostly inter-banded, containing stone and hard shales, since such bands cannot be separated during the mining operations; these are mixed with the coal, thereby increasing the ash per cent of the run-of-mine (ROM) coal. In majority of the coalfields, it was found that the nature/character of the coal and stone is such that the stone is harder than the coal. Hence, it may be possible to remove the hard stone by incorporating a rotary breaker at the pithead or coal handling plant. However, before installing a rotary breaker, it is very much essential to understand the breakage characteristics of the coal and stone.
The present investigation includes selective drop breakage tests of coals and stones from variable heights. The differential breakage patterns of this material have been quantified in terms of selective Crushing Index and its dependence on number of drops and heights. Attempts have been made to find a breakage constant with the assumption of drop breakage as a first-order process dominated by volume breakage. Results of the selective drop breakage tests on coal and stone from non-coking coalfields showed that there is a good potential of installing a rotary breaker at the pithead
Evaluation of the Effect of Fault on the Stability of Underground Workings of Coal Mine through DEM and Statistical Analysis
No full textThe rock mass around an excavation is generally traversed by different geological discontinuities such as faults, folds, slips, joints, etc. Fault is one of the major geological discontinuities which creates lot of difficulties during underground winning of coal. Entire stress regime and ground conditions in the formation are altered in and around the faults. Faults also impose detrimental effects by introducing impurities, including clay and various forms of mineral matter into the coal seams; opening of pathways for the influx of water and gas into the underground workings; displacing the coal seams upward/downwards making the coal seams difficult or sometimes impractical to mine. Appropriate evaluation of the effect of the fault on the stability of the underground workings is a requisite for safe design of the underground mining structures. In this paper, a study has been carried out to assess the effect of the fault on the stability of underground coal mines by numerical simulation with distinct element method (DEM). On the calibrated DEM model, parametric study has been performed by varying the selected parameters, the dip and the friction angles of the fault. The analysis of variance (ANOVA) shows that both the factors have statistically significant effect on the strength of the coal pillar. Similarly, the displacement of the immediate roof and the height of the disturbed strata are evaluated by the DEM modelling and statistical analysis when the fault passes through the middle of the gallery. The results of ANOVA for both cases indicate that the both factors have significant effect on the displacement of the immediate roof and the height of the disturbed strata. It is obtained from the study that the low angle fault causes high instability in the immediate roof. The paper has been supplemented with the field observations where instability in underground roadways of a coal mine in India is caused by the fault. It was observed in VK-7 incline mine of Singareni Collieries Company Limited, India that there was sudden failure of immediate roof of a roadway where a low angle fault crosses the middle of the roadway. The findings of the paper help to understand the behaviour of the coal pillar and the surrounding rock mass in the presence of the fault. The study would also help to take appropriate decisions about the unstable regions of the working safeguarding safety in underground coal mines