IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Genesis and Characteristics of Coal and Biomass Ash
No full textThe coal ash and biomass ash produced from their respective combustion are widely variable in terms of their physical and chemical properties. Thorough understanding of their properties is a prerequisite for their possible utilization at different sectors. In this chapter we discuss different physical and chemical parameters, viz., particle size distribution, surface area and porosity, major oxide composition, percentage of unburned carbon, and micro-morphology of several ash samples from India. Presence of unburnt carbon, that is, non-combusted or partially combusted organic matter in ash, can cause potential damage when used in concrete structures, as it induces adsorption of air-entraining agents (or AEAs) and thereby limits their role in resisting freeze-and-thaw in concretes. Consequently, knowledge on unburnt carbon, surface area, and porosity of ashes can be critical. Similarly, the chemical composition of the ashes is significantly important, and depending upon their composition, the ashes can be used in relevant sectors. The coal ashes were observed to be marked by higher SiO2 + Fe2O3 + Al2O3 contents, while the biomass ashes were observed to be marked by higher Na2O, K2O, MgO, and P2O5 contents
Comparison of steel and fiber-reinforced polymer rebars for mining applications: A numerical approach
No full textUnderground mines offer various non-favourable environmental conditions, one among them is the presence of corrosive elements which are not suitable for conventional materials such as steel. This problem can be avoided to a certain extent by using glass reinforced polymer (GRP) rebars. GRP rebars show high tenacity and excellent corrosion resistance compared to conventional steel which extends these materials application to constructions roofing supporting and columns. Thus this paper aims to carry out a comparative study of between steel and GRP rebars strength under tensile, compressive and bending forces using LS-DYNA. Numerical analysis results showed that the stresses generated under tensile and compressive loading are 25% and 37.25% higher for GRP rebars when compared to steel but within the safe limits. Similarly, deformation under tensile and compressive loading for GRP rebar is 62.16% and 87.12% higher compared to steel, respectively. However, load carrying capacity of GRP rebar of GRP rebar is the almost same as steel. Since both the materials showed no sign of damage under 40 kN, thus GRP rebar could be used as a replacement material instead of steel in roof supporting and column in mines
Strength development and microstructural investigation of lead-zinc mill tailings based paste backfill with fly ash as alternative binder
No full textThe increasing popularity of paste backfilling demands alternative binder optimisation and bulk waste disposal. This study investigates the efficacy of fly ash (FA) as partial replacement of ordinary portland cement (OPC) for paste backfill application in underground mines. The effect of FA addition on uniaxial compressive strength (UCS) and cohesion of paste backfill are demonstrated. The strength development was correlated with microstructural evolution using scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDS). The study revealed that the rate of strength development in paste backfill slowed down when OPC was substituted by FA. However, the targeted 28 days' UCS of 1.1 MPa for the backfilling stope of lead-zinc mine was achieved with binder dosages of 8 wt% OPC, 7 wt% OPC, 6 wt% OPC, 7 wt% OPC +1 wt% FA and 6 wt% OPC +2 wt% FA. Thus, FA is a suitable binder substitute and up to 25% of OPC (8 wt%) can be replaced with FA. Analysis of microstructural evolution in paste backfill revealed that calcium silicate hydrate (C–S–H) did not develop in OPC-FA binder based paste backfill at its early days’ of curing and gypsum was found only in samples with OPC as sole binder. The multiple linear regression analysis on interaction effects of OPC, curing time, FA replacement percentage for 8 wt% and 5 wt% binder groups indicated that the UCS development is more sensitive towards FA replacement. The obtained results would help in better understanding and design of paste backfill for lead-zinc underground mines
Estimation of Mine Water Quantity: Development of Guidelines for Indian Mines
No full textThere are no available guidelines in India for estimating the quantity of mine water in an operational mining pit. Based on multiple case studies, procedures to determine water quantities have been developed for Indian geo-mining conditions, which varies with season and pit depth, India’s monsoonal rainfall pattern, aquifer conditions (local and regional), and groundwater fow directions have been considered. These guidelines can be used for scientifc assessments in surface pit mines, and for planning dewatering. Groundwater movement in underground mines is predominantly lateral, coinciding with the water table, and recharged by leakage from overlying aquifers, so water estimation can be based on volume and the size of voids/ openings created underground. These guidelines should be useful for planning mine production and water management
Oral bioaccessibility of potentially toxic elements (PTEs) and related health risk in urban playground soil from a medieval bell metal industrial town Khagra, India
No full textIn vitro oral bioaccessibility assay (simple bioaccessibility extraction test) was used to assess bioaccessible PTEs (As, Cd, Co, Cu, Fe, Mn, Ni, Pb, Sn, and Zn) in 16 playground soils of Khagra, which is a medieval bell metal industrial town at Murshidabad district, West Bengal, India. The aim was also to establish levels of potentially toxic elements (PTEs) in soil, their origin, and human health risk, particularly on children. The average pseudo-total PTEs content in playground soil samples was in the decreasing order of Fe (18,988 mg kg-1) > Zn (1229 mg kg-1) > Cu (999 mg kg-1) > Mn (343 mg kg-1) > Pb (181 mg kg-1) > Sn (132 mg kg-1) > Co (8.63 mg kg-1) > As (5.21 mg kg-1) > Cd (0.88 mg kg-1). The pollution indices indicate significant enrichment of Cd, Cu, Pb, Zn, and Sn in the playground. The bioaccessible percentage of PTEs in the 16 playground soils ranged from 0 to 80.25%, where the range of percentage of bioaccessibility was 13.24-62.50, 0-61.46, 16.82-28.79, 5.05-73.06, 0.96-6.14, 2.28-38, and 0-80 for As, Cd, Co, Cu, Fe, Ni, and Zn, respectively. The order of percentage of bioaccessibility was As > Mn > Zn > Sn > Cu > Co > Pb > Cd > Ni > Fe. PCA extracted two major factors indicating the anthropogenic (Cd, Cu, Ni, Pb, Zn, and Sn) and geogenic (Co, Fe, and Mn) source. Stepwise multiple regression analysis exhibited that the oral bioaccessibility of PTEs did not correlate with physicochemical parameters like pH, EC. In contrast, Sn had a significant correlation with that of organic matter. The health risk for pseudo-total as well as bioavailable fraction in playground soil depicted that children were more vulnerable to ingestion of soil contaminated with PTEs, particularly for Cu and Pb. A risk management plan with the bioaccessible data involving detailed site-specific exposure factors to indicate the importance of the study in terms of child health safety is required
Potassium Influencing Physiological Parameters, Photosynthesis and Sugarcane Yield in Subtropical India
No full textPotassium plays an important role in the metabolism of plants, growth, development and yields. Worldwide, KCl is commonly used as source of K fertilizer in agricultural crops. The present experiment was taken up to assess the response of various sources of K on physiological attributes, yield and quality parameters of sugarcane. Treatments were no K application, potassium ammonium sulphate (H4KNO4S-9:0:30:20, NPKS ratio), slow release K fertilizer (0:0:45:0), sulphate of potash/potassium sulphate (K2SO4-0:0:50:17.5), muriate of potash (KCl-0:0:50:0) and muriate of potash (KCl) + elemental S @ 40 kg ha−1. Application of K2SO4 recorded 15.8% improvement in tiller population (during peak tillering stage) and 22.2% improvement in dry matter accumulation (at the harvest stage) over the KCl. About 12.33–24.16% increments in crop growth rate and the highest net photosynthetic rate (19.91 µmol m−2 s−1) were also recorded with application of K2SO4. Application of K fertilizers improved the availability of potassium in soil by 8.17% (254.2 kg ha−1). Potassium uptake in sugarcane crop ranged from 245 to 347 kg ha−1. The highest individual cane length (311 cm) was measured with application of K2SO4. Application of K2SO4 brings forth about 23.8% increments in millable canes, 14% in cane weight and 33.8% in cane yield over no K. Application of K also increased mean sucrose content in juice by 0.58 unit (17.0 pol per cent juice) over no use of K. Overall effect of K application on increasing sugarcane yield and sucrose content simultaneously brought forth improvement in commercial cane sugar (CCS) by 29.43% (10.50 t/ha) over no use of K. However, application of K2SO4 also improved CCS by 25.89% (11.67 t/ha) over the application of KCl
Source rock properties and pore structural framework of the gas-prone Lower Permian shales in the Jharia basin, India
No full textThis paper examines the source rock potential and pore structural framework of Lower Permian shales belonging to Barren Measures and Barakar Formations of Jharia basin, eastern India. The Jharia basin contains prolific coking-coal reserves and, consequently, the organic-matter in this basin tends to be mature. Open system pyrolysis analysis reveals that the Barakar Formation shales are thermally more mature and organic-rich than the Barren Measures Formation. Analysis reveals that shales of the Barren Measures possess “fair” to “good” oil generation potential. The more mature shales of the Barakar Formation are gas prone. Detailed pore scale distribution and fractal metrics determined by low-pressure N2 gas adsorption are observed to be higher for the Barren Measures Formation than the more mature and organically rich Barakar Formation shales possibly due to the inability of N2 gas to access the ultrafine components of the complex pores in the Barakar Formation shales. Substantial concentration of pores, organic-rich character, and thermal maturity levels indicates that the studied horizons have unconventional source rock properties
Comparison of CO2 gasification reactivity and kinetics: petcoke, biomass and high ash coal
No full textIt is desirable to exploit biomass energy along with coal and petcoke through gasification, and understanding the differencesbetween petroleum coke (petcoke), coal and biomass gasification behaviour becomes very essential. Consequently, presentinvestigation compares gasification components of petcoke, sawdust and high ash coal with their physico-chemical propertiesunder isothermal conditions in CO2atmosphere in the temperature range of 1173–1623 K. Physico-chemical characterisationincludes proximate and ultimate analyses, porous structure analysis by Brunauer-Emmett-Teller (BET) surface area from nitro-gen (N2) adsorption isotherm, ash composition analysis and ash fusion temperature. The effects of temperature and nature ofdifferent solid fuels on gasification reactivity have been discussed. Gasification kinetics has been investigated using two nth-order kinetic models, such as homogeneous model (HM) and shrinking core model (SCM). Influence of diffusion resistance ongasification behaviour of different solid fuels is also reported. Thus, the present study will be helpful to realise the effects of highash in gasification behaviour as well as in designing and modelling of the suitable gasifier and to establish optimum gasificationconditions for petcoke, biomass and high ash coa
Underground extraction methodology of contiguous coal seams ensuring the safety of the parting and the surface structures
No full textIn India, the coal seams are called contiguous, when the thickness of the parting formation between two coal seams is within 9 m. When the extraction is carried out in one seam, it not only disturbs the stress regime of the current working and its adjoining mined out areas but also alters the stress regime of the overlying and underlying formations. The interactions among coal seams become more pronounced when the thicknesses of the partings are lesser. If the parting between two coal seams collapses during their extractions, there may be a chance of casualty. The extraction of the contiguous seams becomes more difficult if the surface structures are present above the seams. If the seams are situated at a shallow depth of cover, the effects of the contiguous seams working easily reach to the ground surface. Therefore, the contiguous coal seams require suitable extraction methodology to ensure safety. In this study, a methodology is designed for safe extraction of the contiguous coal seams under surface structures. The safety of the parting is assessed by the analytical models, the numerical simulations and field investigation. The support system is designed to ensure the safety of the parting during the extraction of the coal seams. To assess the impact of mining on the surface structures, subsidence parameters are evaluated which are found to be within the permissible limits. Thus, this extraction methodology and the safety control measures can be applied for safe extraction of the contiguous coal seams having similar geomining conditions
Interactive effects and competitive shift between Triticum aestivum L.(wheat) and Chenopodium album L. (fat-hen) under ambient andelevated ozone
Get PDFThe aim of this study was to evaluate the impact of ambient and elevated O3 (ambientþ20 ppb) under
the competition between a crop plant Triticum aestivum L.cv. HD 2967 and a weed, Chenopodium album L.
(fat-hen) grown singly and in mix-culture (1:1) using open-top chambers. The competition posed a
relatively lesser effect on the growth of fat-hen as compared to the wheat under ambient O3 at both the
sampling time, however, the effects of stress factors (competition and O3) were more pronounced at the
reproductive stage on both the plants. Fat-hen possess a stronger antioxidative potential against elevated
O3 (eO3), irrespective of competition, making it more resistant against the existing stress factors. Significant
stimulation in the activities of CAT, POX, GR and SOD in fat-hen and non-enzyme antioxidants
(AsA, thiols, and total phenolics) might have helped the plants to pose a superior ROS scavenging potential
under competition þ O3. Strong stimulation of flavonols (kaempferol and quercetin) and phenolic
acid (p-coumaric acid and ferulic acid) in fat-hen not only helped the plants to withstand the oxidative
damage under eO3 but also might have influenced the allelopathic interaction (competition þ O3). Yield
loss in wheat was observed to be larger under competition þ O3 (33.1%) followed by O3 (20.5%) than only
under competition (16.3%). The study suggests stringent weed management strategies to be established
recognizing the existing threat from O3 to the productivity of a staple crop-wheat