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Recycling of Nd-Fe-B Magnets to Reclaim Nd Salt and Pigment
Get PDFHard disk of computers is the most essential part, which plays significant role for
programming the computers. Hard disk contains permanent Nd-Fe-B magnet as a most powerful
magnet, these magnets become waste rapidly by reaching its end-of-life, therefore the metallic content
(Nd, Pr, Dy) in it is also act losses which is present in limited stock in nature therefore recycling of
these waste is necessary to get the metallic content from it and also preserve the natural resources. This
study provide a proper technique and development of hydrometallurgical process to extract REMs
from Nd Fe B magnets, which includes general flow chart such as manual dismantling,
demagnetization (300 °C, 3h), crushing to get the material in its homogenous form, leaching (2M
H SO , 100 g/L, 25 °C, 1h), solvent extraction of REMs (pH~2, 15 min), air sparging to remove iron
from the solution (pH~3.5, 50-60 °C, 1h), etc. about >95% of rare earth metals were recovered by this
techniques and remaining metals left in the liquor can be recovered by further hydrometallurgical
processes
Business opportunities to reclaim metals by urban mining
Get PDFIn the modern world, changing requirements of advanced and latest features of electronic devices in each sector have created the generations of huge amounts of e-waste. On the other side, the depletion of limited metal reserves, illegal recycling, and business opportunities by organized sectors
compelled the researchers to develop environmental and feasible processes for the recycling of these e-wastes to reclaim different non-ferrous (Cu, Ni, Al, Pb, and Sn), precious (Au, Ag, Pt and Pd), rare (Li, Co, In) and rare earth metals (Nd, Ce, La, Y and Eu). Since, the last 15 years CSIR-NML, Jamshedpur, India has been actively involved in the development of the process Know-how to recycle waste electrical and electronic equipment (WEEEs) to recover metals and materials. At first, the WEEEs were
classified, dismantled, and pre-treated to isolate plastics, ceramics, rubber, epoxy, iron casing, and metallic fractions. Further, the metallic concentrate was treated using hydrometallurgical technique i.e. dissolution of metals by aqueous processing, solvent extraction, adsorption, and electro-winning for maximum recovery of metallic values. Various flow sheets developed for the recycling of WEEEs are discussed for the processing and extraction of metallic values, which strictly complies with
environmental rules and regulations
Corrosion behavior of AlCuFeMn alloy in aqueous sodium chloride solution
No full textMedium Entropy Alloy AlCuFeMn possesses high room temperature strength and oxidation endurance. In present work, the aqueous corrosion resistance of the as-cast as well as low temperature oxidized AlCuFeMn alloy in 3.5 wt% NaCl solution, is explored. Equimolar proportions of high purity copper, manganese, iron, and aluminum were arc melted and cast in a copper mold. The alloy primarily consists of a face-centered cubic and a bodycentered cubic phase. Potentiodynamic polarization tests on the alloy after low temperature surface oxidation reveal an aqueous corrosion resistance comparable to AISI 304 steel and CoCrFeMnNi high entropy alloy. The Xray photoelectron spectroscopic studies confirmed that the free surface in the as-cast alloy is in partially oxidized state. The same completely oxidizes after low-temperature surface oxidation. Such low temperature surface oxidation improves pitting corrosion resistance in AlCuFeMn alloy due to increased metal/oxide layer resistance. The electrochemical impedance spectroscopy tests coupled with microscopy confirmed that the principal corrosion mechanisms in the alloy are of the uniform and pitting type. The energy dispersive spectroscopy experiments indicate that a copper oxide enriched layer is formed on the surface oxidized specimen during corrosion
Nanocrystallization and Core-loss properties of Fe-rich FeSiBPNbCu nanocrystalline alloy
No full textThe present work investigates the structure, soft-magnetic and core-loss properties of 25 mm wide Fe83Si2B9P4Nb1Cu1 nanocrystalline ribbons. The melt-spun precursor ribbons of the thickness of 22 and 28 mu m were prepared using commercial raw materials under ambient atmosphere. The XRD and DSC results show predominantly amorphous and hetero-amorphous structure for 22 and 28 mu m ribbons in the as-quenched state. Further, the partial crystallization annealing leads to thickness dependent nanocrystallization process, wherein the thinner 22 mu m ribbon shows sluggish primary(alpha-Fe(Si)) and delayed secondary(Fe-3(B0.8P0.2)) crystallization process compared to 28 mu m ribbons. The difference is explained through as-quenched precursor matrix structure and selective solute re-distribution of the intergranular region during nanocrystallization. Moreover, the higher crystallite size (D) and volume fraction(V-cr) of alpha-Fe(Si) nanocrystallites are observed for the 28 mu m ribbon in the optimal annealing window. Under optimal annealing conditions, the 28 mu m nanocrystalline ribbon (733 K) shows better AC soft-magnetic properties including B-800 of 1.62 T, H-c of 15.7 A/m, B-r/B-s ratio > 0.8 compared to B-800 of 1.59 T, H-c of 17 A/m and B-r/B-s ratio > 0.7 of 22 mu m (743 K) ribbon. The 28 mu m ribbon shows a low core loss (P) of 0.34 W/kg under 50 Hz, 1.5 T compared to P > 0.65 W/kg for 22 mu m ribbons. The lower core-loss behaviour of thicker 28 mu m in the sub-kHz frequency regime has been explained based on the nanocrystalline microstructure and loss coefficients (hysteresis and eddy current). The work compares the AC core-loss properties with reported Fe-rich nanocrystalline alloys and also discusses the scope of improving B800 beyond 1.65 T for the present alloys
Quantification and analysis of slag carryover during liquid steel tapping from BOF vessel
No full textThe amount of slag carryover (SCO) during the liquid steel tapping from the basic oxygen furnace (BOF) vessel has been estimated using a thermodynamic model that ensures the matching the predicted bath silicon with that of experimentally measured silicon in ladle furnace. FactSage 6.4 has been used for thermodynamic analysis. A simple correlation has also been established to estimate SCO immediately after the tapping process using the readily available plant data. Viscosity, interfacial tension of the slag, impurities in the liquid steel, and the tapping temperature has been found to have a profound effect on the amount of SCO. The advantage of the present method of SCO estimation compared to the other methods and the industrially viable control measures for minimising SCO is discussed in light of clean steel practices. Further, industry trials have been conducted to validate the control of SCO by tuning the BOF slag properties
Weibull parameter based probability distribution for predicting creep life of power plant materials: A non-destructive approach
No full textThe knowledge of remaining useful life and the probability of failure at any point of time in the life cycle of any power plant component is an important information for the plant operators to take preventive action. This paper focuses on life data evaluation of creep-exposed power plant material based on statistical probability distribution through Weibull analysis. The probability distribution was obtained considering the change in non-linear ultrasonic (NLU) parameter measured in P92 steel at different creep test conditions. The material was creep tested at 650 degrees C for three different applied stresses. The NLU parameter (beta), which indicates the extent of damage, is the ratio of the amplitude of the fundamental frequency of the transmitted signal to the square of the amplitude of the second harmonic of a sinusoidal wave propagated into the material. The two-parameter based Weibull distribution function was adopted for evaluating the cumulative distribution function and failure rate. A sudden increase in NLU parameter was observed at similar to 80% of creep damage followed by a drop in its value indicating the specimen failure. With increase in applied stress, failure rate increase was also observed. Microstructural observations revealed that with creep progress, the growth and coarsening of precipitates, micro crack formation and their coalescence were the major cause for increase in failure rate. Therefore, application of this technique can be useful for evaluating the creep life and probability of failure of any plant component in a non-invasive way. Copyright (C) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Third International Conference on Recent Advances in Materials and Manufacturing 2021
Atomistic structural transformation of iron single crystal under bi-axial stretching using classical molecular dynamics simulation
No full textThe exploration of mechanical properties and formation of various crystal structures under the mechanically stressed condition has numerous uses for the design of engineering components for electronic instruments, automotive, aerospace, etc. In order to diagnose the stress-strain behaviour and growth coalescence of crystalline structures in single-crystal iron during bi-axial tensile deformation, classical molecular dynamics (MD) simulation has been employed. Two-stage atomistic structural transformations in single-crystal iron are observed. First-stage transformation corresponds to body-centred cubic (bcc) to face-centred cubic (fcc) crystal, whereas the second-phase transformation corresponds to fcc to bcc. To gain further insights, multiple MD simulations have been performed by varying the strain rate of the tensile deformation. Common neighbour analysis, dislocation analysis and stress-strain analysis have been used to precisely characterize the simulation trajectories during simulations. Outcomes of our work will provide additional insights for improved design of engineering components
Recycling of Valuables from Spent Lithium-Ion Batteries for Sustainable Development in Energy Storage Systems
No full textIn the past several years, lithium-ion batteries (LIB) have been widely used in portable electronics ubiquitous. Due to technological advancement and as an alternate source of the stored energy system, lithium-ion batteries or rechargeable batteries become the most promising to use in electric vehicles. In the coming decades, a huge number of electric vehicles are predicted to be on the road worldwide. As a result, a large number of lithium-ion batteries will be produced. As per the current trend of handling spent batteries hold, most of those batteries may end up in landfills. Currently, a few numbers (<5 percent) of spent Li-ion batteries are being recycled. Extensive research works are being carried out worldwide to develop electrode materials for rechargeable batteries. Many electric vehicle industries are engaged to develop high-efficiency rechargeable batteries. It is important to note that the industrial revolution created cradle to grave system. However, for sustainable development in energy storage systems and the corresponding resources management, cradle to cradle system is highly desirable. Recycling plays a crucial role in sustainable resource management for the future generation. The cathode and anode electrode materials in lithium-ion batteries contain valuables that can be recycled and reused in new battery manufacture. Cathode material contains mixed oxide reaches in valuable elements such as lithium, cobalt, manganese, nickel, and the anode material contains valuables such as copper and graphite. We studied the zero waste valorization of spent lithium-ion batteries for sustainable development in energy storage systems
Extraction of REEs from Blast Furnace Slag by Gluconobacter oxydans
No full textGranulated blast furnace slag (GGBFS) is a potential resource of rare earth elements (REEs), and due to the complex mineralogy, extraction by conventional hydrometallurgical process makes it an acid-consuming method. Bioleaching is thus investigated using a chemo-organotrophic bacterium Gluconobacter oxydans (DSMZ 46616) for REE extraction from GGBFS containing 157 ppm Ce, 90 ppm La, 71 ppm Nd and 40 ppm Er, hosted in a Ca-Al-Si matrix. The gluconic acid generation by G. oxydans was assessed for its role in REE extraction from GGBFS. With 5% (w/v) GGBFS using a mixture of a non-adapted and a GGBFS-adapted culture, a maximum solubilization of 67% and 88% Nd was observed after 12 and 40 days of incubation, respectively. The total amount of gluconic acid excreted by the bacteria increased with leaching duration, which contributed to a rise in metal extraction. Scanning electron microscope-energy dispersive analysis (SEM-EDAX) analysis of the solid residue showed bacterial cells in corrosion pits, and thereby assisting in metal solubilization