IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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Environmental Effects of Coal and Biomass Ash Generation
No full textThere are apprehensions of presence of potentially toxic organic and inorganic substances in coal and biomass ash. Potentially toxic elements, PAHs, PCBs, and radioactive elements are some of the environmental concerns associated with the handling, utilization, and disposal of these ashes. During combustion in the power plant, volatile toxic elements are released from the coal and significant part of the element gets adsorbed on the ash particles at cooler zones of the furnace. These surface-associated metals are easily mobile and may get dispersed into the environment. Inorganic elements in the ash could be associated with the water-soluble phase, glass phase, bound to metal oxides or silicate matrix. The release of the elements is measured by leaching test. The concentration of elements in the leachate is compared with the values provided by regulatory authorities to evaluate the environmental acceptability of the ash. Weathering of ash or its interaction with water and CO2 and other reactive liquids in the disposal or utilization sites leads to decomposition of glassy phase and formation of new clay phases. These new clay phases fix the potentially toxic elements in immobile pools. Thus, the pond ash or weathered ash has fewer risks than the fresh ash. Depending on the presence of unburnt carbon, halides, and the prevailing combustion conditions in the furnace, some ashes have considerable amount of PAHs, PCBs, and different dioxins. But studies with these organic pollutants are relatively less. Construction materials prepared from ash could exhibit radiation hazard, however, most of the studies showed radiation levels within the permissible limits. All these potential hazards from ash depend on the nature of the ash, so judicious screening and adoption of appropriate abatement techniques has to be followed while utilizing the ashes for different gainful purposes
Nondestructive Evaluation of Track and Haulage Ropes of Aerial Ropeway Installation in India—A Case Study
No full textAbstract—The wire ropes in steel material are generally used in harbours, on ships, haulage applications in mine winders, aerial ropeway carrying, haulage/track ropes for transportation of passengers
and in many industrial fields. The properties of high axial strength and flexibility in bending, convert
wire ropes into imperative load transmission components for many industrial applications. The
exhaustive usage of these ropes deteriorates with its use over the course of period. The conduct of wire
rope inspection has make one’s way expeditiously over the past few decades. To perform nondestructive tests of rope is a way how to analyse the real condition of ropes during their running operation. It
became very necessary to evaluate ropes during their live condition in the interest to facilitate substitution of the rope in stipulated period and also for strengthening risk-free duration of working when
discard requirements failed to attained. Available magnetic rope flaw detectors are now became much
easier to set off and yield a paramount component of steel wire ropes verification or evaluation. The
results of tests from these equipment’s capable of providing certain appraises of safety concern regarding steel wire rope parameters such as loss of metallic cross-sectional area and localised faults. It also
provides further accurate baseline in establishing the state and rest duty period of a wire rope. A conducted research result depicts the level and the wide range of flaws, distribution pattern of localized
defects such as concentrated or dispersive broken wires. This technical paper on nondestructive evaluation work being sponsored by Indian industry, illustrates the method of nondestructive testing
applied and analysis of condition of haulage and track ropes including safety recommendations for further continuance in service
Theoretical and experimental examinations to substantiate the structure ofcoal derived asphaltene by formation of complex with o-chloranil
No full textThe structure of coal derived asphaltene (CDA) proposed by Mullins et al has been corroborated through theoretical and experimental examination by the virtue of its electron donor property. Here, o-chloranil has been used as an electron acceptor. Investigation of o-chloranil/CDA complex in gas phase has been performed by density functional theory (DFT) methods. The Charge transfer (CT) transition energy of the complex in gas phase was calculated by the time-dependent density function theory (TD-DFT) using the ground state optimized geometry at the respective levels of theory. For this, the three semi empirical methods AM1, PM3 and PM3MM were computed under the MPW1PW91, B3PW91, PBE1PBE, BPV86 and RCIS formalism. It is found that the two formalisms MPW1PW91 and PBEPBE under PM3 and PM3MM reproduced values close to the experimental one. However, all of them provide lower charge transfer (CT) transition energy values than that has been experimentally determined. Experimentally, FTIR spectra of the donor, acceptor and the complex further supported the understanding of complex formation and demonstrated close similarity with the theoretically determined CDA frequencies. These findings support the validity of the CDA structure to an extent
Coal fly ash‐derived mesoporous SBA‐15 as support material for production of liquid hydrocarbon through Fischer–Tropsch route
No full textThe supernatant solution of silicate species extracted from coal fly ash (CFA) by NaOH fusion is used under acidic conditions with surfactant pluronic P‐123 to prepare the mesoporous silica (SBA‐15). Structural properties of prepared SBA‐15 are found close to those prepared by pure chemicals. Furthermore, the synthesized mesoporous silica (SBA‐15) from CFA is used as support in Fischer–Tropsch synthesis (FTS). The obtained mesoporous material has a surface area of 643 m2/g and a pore size of 8.24 nm. Co–Fe bimetallic catalyst containing 15 wt% of cobalt and 5 wt% of iron is prepared by incipient wetness impregnation of cobalt nitrate and iron nitrate salts over CFA‐derived SBA‐15. These mesoporous support and catalyst are characterized by X‐ray diffraction (XRD), N2 adsorption–desorption, H2‐temperature‐programmed reduction (TPR), NH3‐temperature‐programmed desorption (TPD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). FTS experiment is showing 65.53% of C5+ selectivity. The results indicate that the nanosubstrate material derived from CFA may be used as support for FTS activity with further improvements
Directional controlled blasting technique for excavation of unstable slopes along the Konkan Railway route
No full textThe paper presents an innovative directional controlled blasting (DCB) technique for excavating unstable slopes along the Konkan railway in India without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw were developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3, irrespective of the actual free face, was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle was changed from 80–82 to 45– 47 degrees, and possible wedge, planar and toppling failures were eliminated. No incident of rockfall and slope failure
along these slopes has been observed after the stabilization
Utilisation of lead–zinc mill tailings and slag as paste backfill materials
No full textPaste backfilling is an incipient underground mine backfill technology in India. It facilitates maximum use of mill tailings with enhanced stability of the underground workings and minimises rehandling of water, as well as provides bulk disposal of mining solid waste. Binder type and dosage plays an important role in paste backfill performance. This paper highlights environmentally friendly utilisation of solid wastes like lead–zinc mill tailings and lead–zinc smelter fuming furnace slag (FFS) as paste backfilling for an underground metalliferous mine. Various experiments were conducted to study the effect of use of FFS as a fractional replacement for ordinary portland cement (OPC) in paste backfilling. The physico-chemical properties of both the lead–zinc mill tailings and fuming furnace slag (FFS) have been examined. In the first set of experiments, raw slag (FFS) was used for paste backfill preparation and experimentation for uniaxial compressive strength (UCS) development, whereas in the second set of experiments, FFS was crushed to -75 μm (80 wt%) and used for the study. Multiple regression analysis of strength development was also conducted up to fifth order. The regression analysis is in accordance with the strength development and justifies the significance of OPC, crushed fuming furnace slag (CFFS) and waste chemistry on the strength gain with curing time. Use of crushed fuming furnace slag as OPC replacement in paste backfill showed encouraging results of strength development in contrast to raw FFS. Also, the economic analysis revealed that the paste backfilling cost per tonne reduced significantly with slag replacement in the binder phase
धात्विक अयस्क के भूमिगत उत्खनन में हाल की तकनीकियों में प्रगति
No full textFaster excavation of the mineral deposits from underground means is the need of the hour to meet the increasing mineral demands of the country, this has been achieved in several Indian underground mines to exploit the mineral deposits by significant advancements in planning and execution of the technologies. The advancements in development face and production blasting techniques is a part of this whole operational changes. The advancements in the face blasting techniques have lead to pull increment with deeper hole drilling using jumbo drills as well as reduction of overbreak from the final line of extraction. The production blasting with large consumption of explosives has also been developed in the recent days. The issues of vibration control near surface and underground structures, hole collapsing for deeper hole drilling and problems with discontinuous strata having shear zones were dealt using the recent analytical methods. Following paper have dealt with some of the advancements in drilling & blasting operation for face blasting and production blasting. The advancements in scientific approach to cope up with the challenges from the large scale excavations have also been dealt in the pape
Directional Controlled Blasting for Extraction of Composite Strata in An Indian Coal Mine
No full textExtraction of thin coal seam and associated overburden using drilling and blasting is a cost expansive task. In such scenario,
the separate excavation of each stratum needs blasting of shallow deep holes. The shallow deep hole blasting comes with many
associated safety and productivity threats such as – flyrock ejection, frequent marching of machinery, extra manpower effort etc. The
simultaneous excavation of thin strata with overburden can be an alternative to this problem. However, simultaneous excavation may
lead to the problems of dilution. Accordingly, a directional controlled blasting is a need to restrict the throw of the blasted material
from each stratum within the desired distance. This paper has dealt with the methodology to excavate two numbers of coal seams
with two layers of associated overburden simultaneously. The scientific methodology consisting of near field vibration assessment and empirical formulation based approach was used to design the blast. The optimal burden and charge factor estimation were
carried out for different strata using this approach. The charging quantification and delay sequence arrangements were designed to suit the requirements of material movements. The blast for the excavation of composite strata was conducted using the devised blasting patterns. The blasting outputs were excellent in terms of the throw of the blasted materials and fragmentation
Roadheader – A comprehensive review
No full textMechanical excavators are preferred to conventional drilling and blasting as blasting poses several regulatory and operational issues. The roadheader is a machine for excavating rock in mining and civil construction projects. It is a hybrid machine, with better manoeuvrability than that of tunnel boring machines. It can cut rocks even up to 160 MPa, if laminated or fractured, in different tunnel profiles and adapts easily to changing operational conditions. A comprehensive survey of literature pertaining to varied aspects of the roadheader is presented in this paper. This review classifies literature on roadheaders into multiple classes and sub-classes and identifies important parameters that define roadheader efficiency and the risk factors involved in its deployment. We also provide an account of recent technological additions that help collect data on roadheader performance during operations. Such data has the potential to rapidly improve roadheader design
Evaluation of the Fuel Value and Soil Application Potential of the Cadmium Contaminated Biochar Obtained after Water Treatment
No full textSpent biochar obtained after water treatment especially metal adsorption could be used as a solid fuel. In this study, soil application potential and fuel value of cadmium contaminated biochar was investigated. Biochar prepared from Parthenium (PBC) and the thermally modified biochar (MPBC) was artificially contaminated with different concentrations (1, 10, 50, 100 and 200 mg/l) of Cd solution. The contaminated PBC-Cd and MPBC-Cd was applied to a red soil, and their impact on soil biological activity, maize growth and Cd bioaccumulation was assessed. Maize growth was retarded due to the contaminated biochar. Soil and plant Cd concentrations increased significantly. The soil dehydrogenase (DHA) and fluorescein diacetate hydrolases enzyme activities were adversely affected. DHA reduced from 324 to 97 mg TPF/kg/24 h in MPBC-1 to MPBC-200, while in PBC-1 to PBC-200, DHA decreased from 422 to 112 mg TPF/kg/24 h. Cd contaminated biochars obtained after waste water treatment could not be used for soil application. Fuel values of contaminated biochar were analysed by the higher heating value of biochars and their fusibility indices. The high heating value of the biochar is comparable with the lignite. Raw biochar contains significant amount of alkali elements that affected their use as a fuel. However after adsorption, the washing of the biochar alkalies significantly improved the fuel properties, especially the propensity for slagging and fouling. Biochar used for treatment of contaminated waste water could be sustainably used as a solid fuel; however further studies are needed to manage the metal enriched ash generated after combustion of these contaminated biochar