IR@CIMFR - Central Institute of Mining and Fuel Research (CSIR)
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A study on the interdependence of heavy metals while contributing to groundwater pollution index
No full textThe contribution of heavy metal to the groundwater pollution index (m-HPI) is dependent on other heavy metals present in it. This contribution may be synergistic or anti-synergistic (antagonistic) depending upon the constituent matrix. Both heavy metal type and its concentration are important. m-HPI, a variant of heavy metal pollution index in water, may be calibrated against USEPA hazard index (HI) using a generic multivariate non-linear regression (MVNLR) model. Excellent correlation may be obtained between HI and m-HPI through optimization of normalized weightage factors of constituent metals that contribute to m-HPI. MVNLR model was employed on groundwater samples of ten sites having different heavy metal matrix. The synergistic/antagonistic contribution of heavy metals to m-HPI was well discernible at each site. This study clearly showed that the individual contribution of a particular heavy metal to pollution index might be altered (enhanced or reduced) in the presence of other heavy metals. A calibrated MVNLR model was successfully used for predicting the hazard index (HI) of water samples
Organo-Lithotype Controls on Cleat/Fractures, Matrix-Associated Pores, and Physicomechanical Properties of Coal Seams of Raniganj Coalfield, India
No full texthe organo-lithotype properties of Barakar and Raniganj Formation coal seams have been investigated to assess the process of cleat origin, occurrence, and their influence on strength properties. Coal cleats have wide applications in coalbed methane gas recovery, underground mine strata mechanics, beneficiation, and pulverization. However, there is very limited information available on the cleat occurrence and controlling parameters of Indian coals. In this view, a total of 31 coal samples were retrieved from eight exploratory boreholes intersecting coal-bearing formations like Barakar and Raniganj in the Raniganj Coalfield. We identified four distinct lithotypes in coal seams: (i) B, bright coal; (ii) Db, dull banded coal; (iii) Bb, bright banded coal; and (iv) Bd, banded coal. The abundance of bright-band-associated lithotype indicates organic matter that attained the early anoxic conditions after deposition. The cleat system in Barakar coal is comparatively better than in Raniganj coal controlled by the lithotype, type of organic matter, thermal maturity, and gelification extent. The carbon enrichment process in coal mainly controls the megascopic cleat genesis pattern. The positive trend of cleat intensities with the depth of coal seams as determined by megascopic, microscopic, and scanning electron microscope (SEM) studies postulates that the macro- to nanocleats are interdependent and developed during devolatilization due to loss of plasticity. The field emission scanning electron microscopy (FE-SEM) photographs have shown intricate microfractures and pore structures owing to the epigenetic characteristics. Vitrinite bands indicate that it comprises the partially deformed planer cleat system. The resistance to quartz weathering nature attributed to coal brittleness properties also contributed to cleat genesis. The total clay content exhibits an inverse relationship with different cleat intensities, suggesting that hydrous clay swells due to its inherent ultrafine characteristics, thus not supporting the cleat construction. However, it ropes the development of the irregular crack when organo–inorganic matter achieves the dry thermal conditions. The microfractures linked with different pore structures in studied coals can be classified into seven types: (i) vitrite-associated regular open-slit pores, (ii) vitriinertite-char allied irregular pores, (iii) irregular fracture-pore partially filled with clay, (iv) fissile pores along bedding planes of clay, (v) organic pores evolved due to external heat received from intrusives, (vi) deep organic pores evolved during compaction and thermal transformation, and (vii) pore fractures blocked by boghead algae. The clay content showed a positive relationship with physicomechanical properties, signifying the cementing characteristics of clay holding fractures and pores. There is significant variation in the strength properties of Barakar and Marren measures coal influenced by thermal maturity, lithotype characteristics, and organo–inorganic content
Insights into membrane crystallization: A sustainable tool for value added product recovery from effluent streams
No full textWorldwide waste valorization and recovery of non-utilized components/unreacted compounds/ side streams/ byproducts are being researched upon. These are indispensable for environment protection, process economics and emerging technology development concepts like zero liquid discharge. Existing techniques suffer from problems like secondary contamination, complex design, costly raw materials, and extreme process conditions. Membrane crystallization offers a robust and simple solution for sustainable recovery of valuables from effluent streams. This review was undertaken to critically assess efficacy of membrane crystallization for value-added product recovery integrating the basic principles of process intensification: economics, efficiency, and sustainability. Processes like membrane distillation integrated crystallization, osmotic membrane crystallization, concentrative pressure-driven crystallization were analysed with respect to selective separation, byproduct recovery percentage, and viability. Several approaches on process intensification and comparative performance evaluation were discussed. Integrative technology options combining conventional methods like precipitation, evaporative crystallization as well as standalone versions were explored in detail to ascertain techno-commercial viability. It was concluded that membrane crystallizers provides an efficient and eco-friendly means for value added product recovery from diverse waste streams. This critical review on insights aims to formulate concrete guidelines towards applicability of membrane based crystallization for value added product recovery
Mineralogical studies of Mahanadi Basin coals based on FTIR, XRD, and Microscopy: A Geological Perspective
No full textThis paper is a attempt to investigate the mineral matter constitutents in Permian coal of Mahanadi basin, India. Twenty two bulk samples from the working mines have been selected for the study. Analytical techniques such as X-Ray diffraction, Fourier transform infracred spectroscopy coupled with coal microscopy have been used in this study for rapid characterization. The chief mineral phases are quartz, kaolinite, orthoclase, muscovite and chlorite in order of increasing abundance in all the samples. Petrographic analysis reveal the mominance of Vitrinte (36.17%) followed by the Inertinite (32.33) , Liptinite (14.30%) groupt of macerals and mineral matter (17.18%) . Mineral matter in the voids and cell lumens is common mode of occurence in the coals which can be attributed to syngenetic and epigenetic types. The proximate analysis suggest the coals have high ash yield (8.37%) to 38.46 on air dried basis) with hgih volatile matter (10.8% to 35.51% on air dried basis) making it suitable for thermal power plant
Empirical Approach Based Estimation of Charge Factor and Dimensional Parameters in Underground Blasting
No full textBlasting with the aim to reduce oversize boulders in underground has many hurdles due to limited accessibilities and poor site conditions. Optimized drilling and blasting parameters can help to achieve this objective. The major challenges of the blast designers lie within deciding blast geometry, namely drill hole diameter, burden, and spacing. The general approaches covered worldwide to determine burden-spacing are based on various rules of thumb, which are based on previous experiences of blasts and the associated outcomes. However, many parameters influencing optimum burden-spacing to achieve desired fragment size are site specific. Sometimes drill geometry is decided based on associated blasting hazards rather than rock fragmentation. The Kuz–Ram model is a worldwide accepted rock fragmentation predictor. The parameters associated with this predictor also include burden-spacing for a blast. Back calculation of burden-spacing from the Kuz–Ram model can be used to achieve desired fragment size. This paper deals with burden-spacing determination by using an empirical approach for the underground stope ring blasting
CFD modeling of a typical fluidized bed column
No full textThe hydrodynamic behavior of a 2-D gas–solid fluidized bed has been studied using computational fluid dynamics (CFD) software package ANSYS Fluent. The modeling results were validated using the experimental data carried out in a lab-scale perspex column based fluidized bed having a diameter of 0.1 m and height of 0.62 m. The modeling studies showed a very good resemblance with the experimental observations. Studies were carried out by using 0.0003 m biomass fine powder having a density of around 1242 kg/m3 at different inlet gas velocities. Eulerian-Eulerian model approach along with the kinetic theory of granular flow is used for simulating the gas–solid fluidization behavior. In the present work, the effects of inlet gas velocity, pressure drop and bed expansion ratio was studied. The minimum fluidization velocity condition was predicted by using the simulated contour plot of the computational software. The momentum exchange coefficients were calculated using Syamlal-O’Brien functions. The comparison study showed that the CFD simulation of a gas–solid fluidized bed can be used effectively for the designing and operation of a lab-scale fluidized bed column. Moreover the simulation studies would also help in the scaling up of the fluidized bed further for industrial usage
Blast Vibration and Fragmentation Control at Heavily Jointed Limestone Mine
No full textThe presence of structural inhomogeneity in a rock mass in the form of joints, fractures, bedding planes is a very common phenomenon. These discontinuities have a great influence on rock fragmentation as explosive energy is significantly affected by it. The extent of these discontinuities also has a great influence such as the thickness of the joint interfaces which varies from very tight joints to open ones. The amount of energy (or stress) generated by explosives, transmitted through the joints and energy can be passed over the interface resulting in poor fragmentation. The paper is based on the challenges faced during the study at Sangmania and Birhauli limestone mines to achieve the desired fragmentation as the rock formation of the area is dominated by joints and layered bedding. Experimental practices viz. drilling of holes, drill pattern designs, delay intervals and charging of explosives (with or without deck) have been performed to achieve desired fragmentation. Fifty blasts have been conducted at different quarries of Sagmania and Birhauli mines to determine the effect of both joint spacing and orientation on rock fragmentation. Two hundred thirty-six ground vibrations data have been recorded and compared for different prediction equations for better control on ground vibration. The in-hole velocities of detonation of explosives were monitored and optimal deck length and deck types were optimized to improve the fragmentation. The in-situ block size and blasted block size were determined to evaluate the efficiency of blasting
Wireless paging system for underground mines
No full textUnderground working in different horizons with intricate haulage and traveling roadways is very complex in nature. Wired communication is presently the most adopted technology in Indian underground mines. Also, the cellular network cannot be used for communication due to the non- availability of the coverage link. So, addressing of key-personnel to pass on the information and assign task becomes a challenge for mine management. Implementation of wireless paging systems with routers and/or repeaters at strategic locations can instruct manpower for the jobs as well as obviate the impending mishap, if any, at remote locations of the mine. This paper presents a design of a wireless paging system for underground mines which consists of a two-way alphanumeric paging system operating on a ZigBee based wireless network and a paging terminal software. This paging system can be used to unicast or broadcast messages to all the pagers working in the RF network. A successful field trial of the same is also conducted to devise a node placement strategy for the routing units with prototype pagers in the shaft and traveling roadways at 400 and 500 m horizon of a deep underground coal min
Utilization of Iron Ore Tailings for Brick Manufacture from Donimalai Mines of Karnataka, India
No full textThe iron tailings were mixed in various proportions with different combinations of cement, sand, and sodium silicate to obtain or value-added product out of iron tailing waste which is suitable for use in the construction industry. Bricks were made using a variety of compositions of iron tailings, Ordinary Portland Cement, sodium silicate, and sand in cuboid mould (9″X 5″X 3″). The bricks were dried for 24 hours, and then kilned at 115 ± 10°C for 24 hours. Mechanical features such as water absorption, compressive strength, and efflorescence are tested. The maximum compressive strength rating of 8.58 N/mm2 was recorded with ratios of 8:2 (Iron tailing and cement). However, in process of making it economical, the ratio of 9:1 has opted and this ratio complies with the requirement of the Indian standard (IS: 1077:1992) of the common burnt clay building bricks. Water absorption for the proposed bricks is less than that of burnt clay bricks. The lower capillary pore can prevent the formation of efflorescence. This process, with the same parameters, can be exchanged commercially, and a large number of wastes of iron ore can be used to make bricks. Therefore, the technological processes identified in this paper can convert large amounts of hazardous waste into the environment into value-added products. Iron tailing can be seen as a stable addition to clay soils, its use when restricted to making bricks. This research helps to open a new area of research
Facets of coalbed methane reservoir in East Bokaro Basin, India
No full textThe East Bokaro Basin of the Damodar valley is a potentially prospective CBM (coalbed methane) play having significant cumulative coal seam thickness, in-situ gas content, vitrinite percentage, and adequate thermal maturity. Successful CBM recovery needs a detailed understanding of the organic content, pore structures/networks, storage properties and gas flow mechanism. The present work attempts to systematically investigate East Bokaro coal for organo-petrographic controls on gas content and generation, variations in sorption capacity and saturation, pore mechanisms, cleat intensity, cleat aperture distribution and spacing. The values of in-situ gas, sorption capacity and methane concentration (C1) vary from 3.52 to 30.93 cc/g (dry ash-free basis), 15.40–32.40 cc/g (dry ash-free basis), and 66–93 vol%, respectively. The atomic ratios H/C and O/C indicate that thermally matured coal seams contain type III-IV kerogen positioned in the dry gas window. The decrease of hydrogen-containing liptinite with increasing depth reveals the function of thermal gradient on the cracking of liptinitic compounds with successive evolution of hydrocarbons and the development of a carbon-rich pore matrix. The H/C ratio is also influenced by the increasing content of vitrinite and reflectance values of deeper coal. More than 63 % of desorbed gas was determined from desorption measurement and low sorption time (τ, mainly <10 days). This demonstrates good diffusion characteristics of the studied coal. It shows the tendency of desorbed gas diffusion from pores reaches to cleat-fractures with negligible influence of secondary mineral infillings. The high-pressure sorption studies of methane on various samples indicate substantial open-pore characteristics, supporting adsorption, diffusion and gas release. The relationship of C3/C1 and C2/C1 ratios demonstrates that the hydrocarbons in coal primarily originated from the thermogenic transformation of organic matter. Such an assessment is also supported by the stable isotope (δ13C1) value that ranges between −22.70 ‰ and −57.30 ‰. However, some of the lighter isotope values (<–50 ‰) indicate a mixed origin of gases, which may be due to the influx of fresh-water to coal associated aquifers carrying bacteria received from local drainage. Geochemically and thermally altered dissolved and partially filled pores, shown by SEM photographs, negligibly influence gas sorption, diffusion, and flow mechanism in coalbeds. The pore network model signifying that the studied coal seams are microstructurally different comprises a lateral difference in pore and cleat/fracture