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Study of mineralogy and distribution of rare earth elements in coal block of Eastern Coalfield, India
No full textCoal by-products are continuing to be explored as secondary resources for extraction of rare earth elements (REEs). Nevertheless, the knowledge of their geological abundance is still scarce compared to the high global demand. The present investigation aims to study the distribution of REEs in coal samples acquired from Eastern coalfield, India. A total of 27 samples collected from two boreholes (RGCF-1and RGCF-2) were thoroughly analyzed. The average REE concentration in RGCF-1 was 724 ppm, while for RGCF-2, it was 658 ppm with a distribution pattern of Ce>La>Nd>Y>Pr>Sc>Sm>Gd>Dy>Yb>Er>Eu>Ho>Tb>Tm>Lu. Quartz, feldspar, sanidine, magnetite, hematite, anatase/titanate and illite were deduced to be the major mineral phases in these coal ash samples prepared at 815 degrees C. In RGCF-1, REEs were associated with magnetite, whereas in RGCF-2, they were primarily with aluminosilicate and titanate minerals. The overall concentration of critical REEs varied from 122.5 to 387.8 ppm with an outlook co-efficient (C-outl) of 0.58-1.26, indicative of the suitability of the chosen coal block for future exploration. Such an exploration-based investigation on abundance of REEs in the Indian subcontinent coupled with the knowledge of their mineralogical association is beneficial in not only understanding their enrichment but also coining a suitable extraction strategy for these valuables
Fine Size Dry Iron Ore Beneficiation Using Thin Bed Air Fluidized Dry Separator
No full textIron ore beneficiation is generally done through a wet processing route. The areas of water scarcity and owning to issues like slurry generation make wet processing route application a tougher one. At different stages of wet beneficiation, nearly 1 m(3) of water is required for processing one tonne of iron ore. Processing the iron ore through a dry processing route may be considered an alternative method where the air is used as fluid media instead of water, which reduces the slurry generation. In the present study, iron ore feed with a size range of - 1mmto + 0.1 mm with an assay of 58.28% Fe is subjected to dry processing on a thin/shallow bed air fluidized dry separator (TBAFDS). This unit is a gravity-based separator that utilizes the difference in minimum fluidization velocities of heavier and lighter particles. Airflow rate, frequency of deck vibration, and side tilt are three parameters that were considered for the experimentation. Iron ore processed in a single stage, nearly 4.5 to 5% enhancement of Fe content was achieved in heavy stream products of TBAFDS. The middling and light stream of the first stage is processed further in multistage on TBAFDS to increase the yield% of high Fe content product. At the end of the third stage, a product stream of 62.25% Fe content with a yield of 53.56% was achieved
Analysis of Vortex Stability During the BOF Tapping Process
No full textThe present work discusses the numerical simulation of the tapping process to validate the earlier postulates related to the influence of BOF vessel shape on vortex formation. Numerical experiments were conducted by varying the initial filling flow rates (FR 40 and 20 lpm), dwell times (DT 90 and 30 seconds), nozzle diameters (ND 2.14 and 1.04 cm), and initial liquid height (LH 14 and 11 cm). It was earlier reported that the vortex formation is mainly dependent on the nozzle diameter and the stability of the vortex relay on the residual motion in the draining liquids. The present numerical study provides insight into the vortex stability and elucidates the role of residual motion in the draining liquids under different process conditions. The delay in vortex formation for the case of higher residual motion is due to a delay in acceleration and alignment of angular momentum at the nozzle axis vicinity. Further, it is also observed from the numerical experiments that the vertical velocity component's magnitude exceeds the curl velocity's horizontal velocity component to establish the stable vortex. The findings of simulated results are in good agreement with the experimental results reported earlier. It also supports the theory of controlling the vortex formation in BOF vessels (by tilting front/back) without using an external device, such as a dart, a device to arrest the slag entering the ladle at the tapping end
Influence of Tensile Stress Annealing on Soft Magnetic and Core Loss Properties of Nanocrystalline Fe83Si2B9P4Nb1Cu1 Alloy
No full textMinimization or tailoring of magnetic anisotropies in the order of magneto-crystal, magneto-elastic and external field-induced anisotropies are effective way of improving soft-magnetism in nanocrystalline alloys. The recently developed Fe-rich nanocrystalline alloys have been found to exhibit positive magnetostriction behaviour and magnetic coercivity twice that of FINEMET alloys, after optimal annealing. This makes uniaxial tensile-stress annealing a promising method to improve the soft-magnetism of these alloys. In that direction, the present study investigates the influence of tensile stress annealing on structure, soft-magnetic, magnetostriction and core-loss properties of Fe-rich Fe83Si2B9P4Nb1Cu1 nanocrystalline ribbons. The samples were uniformly annealed at 480 degrees C for 4 min with varying uniaxial tensile stress ranging from 0 to 180 MPa. The XRD results showed that all annealed ribbons had a uniform nanocrystalline microstructure consisting of a BCC alpha-Fe(Si) phase with an average grain size of less than 20 nm, irrespective of the applied stress. However, the magnetic properties were highly sensitive to the magnitude of the tensile stress during nanocrystallization annealing. The optimal tensile stress ranging from 90-140 MPa resulted in the best combination of soft-magnetic properties (11-12 A/m) and high squareness ratio (0.8-0.9). These ribbons also depicted longitudinal anisotropy (K-u 24 A/m) and transverse anisotropy behaviour (K-u > 0). The transformation of tensile stress-induced anisotropy from longitudinal to transverse was characterized by the reduction of the magnetostriction constant and change in the magnetization process. The core-loss plots (50-1000 Hz) showed a reduction for optimal stress-annealed (90-140 MPa) ribbons and a drastic increase for 165-180 MPa ribbons. The study highlights the beneficial role of controlled tensile stress annealing in improving the soft-magnetism of Fe-rich nanocrystalline alloys with positive magnetostriction
Creep strain prediction in power plant material via ANN modelling of nonlinear ultrasonic test results
No full textReliable and accurate prediction of the creep life of power plant components is crucial for both economic and safety reasons. Existing prediction models, based on creep test data, can be complex and time-consuming. Nonlinear ultrasonic (NLU) is a widely-accepted non-destructive testing (NDT) technique for evaluating damage progression in crept specimens. The information from NLU measurements alone is insufficient to forecast the life of any component. In real-time applications, intelligent NDT protocols are needed to enable fast and accurate life prediction of such components. A methodology for creep life prediction using artificial neural networks (ANN) has been introduced based on NLU test results of crept P92 steel specimens. The technique involved creep tests of P92 specimens exposed to a temperature of 625SUPERSCRIPT ZEROC with applied stress ranging from 120MPa to 160MPa, NLU measurements at each step load, and prediction of creep life of the material with a ANN trained with creep strain and NLU test data. The technique involves prediction from previously generated historical data, thus saving both cost and time of conducting continuous experiments. This approach for ANN modeling of NLU data can be considered a reliable, time-saving, and effective technique for assessing creep damage progression in power plant components
Solar-driven methanol to formate conversion coupled with energy-efficient hydrogen production through Cr dopant-induced charge transfer modulation at the in-situ formed FeOOH/FeCo-LDHs interface
No full textThe goal of developing efficient electrocatalysts that can effectively accelerate both the hydrogen evolution reaction (HER) and the methanol oxidation reaction (MOR) is essential. Additionally, overcoming the sluggish anodic oxygen evolution reaction (OER) also presents a considerable challenge for achieving energy-efficient hydrogen (H2) production. Herein, we report the synthesis of self-supported hierarchical FeOOH/Fe0.5CoCr0.5LDHs as an advanced electrocatalyst by employing simultaneous engineering strategies for producing the formate from MOR at the anode while simultaneously generating H2 at the cathode. Both the experimental and theoretical studies demonstrate the superior charge transfer enabled by the in-situ formed heterostructure. Additionally, electronic modulation due to Cr intercalation, and the presence of a superhydrophilic hybrid surface morphology promote the remarkable electrocatalytic activity and stability of the FeOOH/Fe0.5CoCr0.5-LDHs electrocatalyst. The overall water splitting process required a cell voltage of 2.01 V to achieve a current density of 50 mA cm- 2, whereas a lower cell voltage of 1.76 V was sufficient for overall methanol oxidation. Remarkably, a solar-driven system prototype, consisting of a commercial Si cell combined with a methanol splitting electrolyzer comprising FeOOH/Fe0.5CoCr0.5-LDHs electrodes, achieved a photocurrent density of 8.1 mA cm-2 over 2 h. This work demonstrates the capability of earth-abundant elements-based electrocatalysts for sustainable and selective electrochemical synthesis. As a result, it enables the energy-efficient generation of clean H2 and valuable chemicals byproducts
Relative influence of microsegregation and structural unit size on the strength-impact toughness properties of an armor grade steel
No full textThe present study highlights the comparative interplay between microsegregation of alloying elements and structural unit size on the strength and impact toughness properties of a medium carbon low alloy armor grade steel. Interestingly, despite possessing finer substructural unit (Bain width), the sample austenitized at a lower temperature (800 degrees C) exhibits inferior impact toughness. This emanates from centerline fissure cracking assisted by severe segregation-induced tensile residual stress at the mid-thickness region. On the other hand, coarse Bain width reduces toughness at the higher temperature (1200 degrees C). Therefore, austenitization at an intermediate temperature (1000 degrees C) imparts excellent impact toughness (similar to 45 J at - 40 degrees C) combined with a commendable yield strength (similar to 1090 MPa). This is attributed to the fine Bain width along with moderate segregation, indicating the significance of austenitization temperature to get an optimized microstructure for achieving a striking balance between strength and impact toughness in a chemically inhomogeneous armor steel structure
γ-FeOOH Nanosheet with Enormous Cationic Defect: Efficient and Durable Bifunctional Electrocatalyst Suitable for an Industrial-Scale AEM Electrolyzer
No full textAnion exchange membrane (AEM)-based electrolysis of alkaline water using a transition metal electrocatalyst is supposed to be the effective route for next-generation pure green hydrogen production, but development of a suitable electrocatalyst is challenging. Herein, we report the development of a simple and scalable protocol to grow a highly aligned ultrathin iron(III) oxyhydroxide (lepidocrocite, γ-FeOOH) nanosheet on nickel foam (γ-FeOOH-NS-NF) at room temperature (RT) through controlled simultaneous oxidation and hydrolysis in the presence of hydrazine. During synthesis, hydrazine plays crucial multiple roles, one of which is the generation of enormous Fe vacancies (VFe). The synthesized γ-FeOOH-NS-NF showed superior bifunctional water splitting activity because of its thin sheet microstructure and enormous cationic defect. Particularly at high current density, it showed an exceptionally low overpotential of 320 at η1000 and a Tafel slope of 29 for the OER, and 309 mV at η1000 and 65 mV dec–1 for the HER in aqueous 1 M KOH solution. For overall water splitting, a 10 mA cm–2 current density was observed at a low potential of 1.6 V. It showed 98% Faradaic efficiency and excellent stability for continuous operation over 100 h at 500 mA cm–2 current density. More importantly, a membrane electrode assembly (MEA) having γ-FeOOH-NS-NF in both the anode and cathode in a prototype anion exchange membrane (AEM) electrolyzer (4 cm2) showed outstanding water splitting performance and stability. The experimental results evidenced that the ultrathin sheet microstructure grown on NF and the generated VFe are primarily responsible for the efficient water splitting. Thus, the scalable and robust synthetic technique, direct usability in an AEM electrolyzer, and the correspondingly high AEM activity and excellent electrode stability make it suitable as an industrial-scale AEM electrolyzer for green hydrogen production
Environmental Impact Assessment in the Entire Life Cycle of Lithium‑Ion Batteries
No full textThe growing demand for lithium-ion batteries (LIBs) in smartphones, electric vehicles (EVs), and other energy storage devices should be correlated with their environmental impacts from production to usage and recycling. As the use of LIBs grows, so does the number of waste LIBs, demanding a recycling procedure as a sustainable resource and safer for the environment. This review paper analyses and categorizes the environmental impacts of LIBs from mining their constituents, their usage and applications, illegal disposal, and recycling. Compared to recycling, reusing recovered materials for battery manufacturing would lessen the environmental footprints and reduce greenhouse gas emissions (GHG) and energy consumption. Thus, to prevent pollution and safeguard the environment, it is necessary to consider recycling spent LIBs and improving production and disposal methods. The present study offers a comprehensive overview of the environmental impacts of batteries from their production to use and recycling and the way forward to its importance in metal replenishment. The life cycle assessment (LCA) analysis is discussed to assess the bottlenecks in the entire cycle from cradle to grave and back to recycling (cradle)
Use of Additives as Internal Heat Sources in Hematite Ore Pellets- A Review
No full textMagnetite ore pellets oxidize to hematite during their induration in a mild oxidizing atmosphere of strand
which produces internal heat in the pellet and enhances diffusion bonding. Hematite ore pellet does not
have such oxidation. Therefore, hematite pellets require a much higher induration temperature
(>1300°C). To reduce the induration temperature requirement (maximum temperature of the strand) of
hematite pellets, investigators have added several additives, namely, coke fines, coal fines, charcoal,
anthracite, Jhama coal, blast furnace flue dust, etc. as carbon sources. Carbon in these materials oxidizes
in the mild oxidizing atmosphere of the strand and provides in-situ exothermic heat which helps in the
bonding of pellets. Investigators have also added lower iron oxides containing materials for this purpose,
namely, magnetite ore, mill scale, and sludge which oxidize and provide diffusion bonding and exothermic
heat. However, each of the above materials has a different character of reaction based on its
chemistry, particle size and shapes, surface morphology, distribution, and concentration. Therefore,
they affect differently on the pellet properties. Several studies reported so far on the effects of each
material, their optimum requirement, advantages, and disadvantages are discussed along with their
comparative analysis. This will help identify the appropriate additive and their amount of requirement in
hematite pellets