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Carbon dioxide sequestration by mechanical activation of Linz-Donawitz steel slag; the effect of water on CO2 capture
No full textMineral carbonation, a process of carbon-dioxide (CO2) captured from the atmosphere or flue gases, is a way to sequestrate CO2 safely and permanently. In this technology, CO2 is chemically reacted with calcium, magnesium, sodium, and iron-containing materials. The procedure is analogous to natural weathering processes, to form thermodynamically stable and environmentally harmless carbonate minerals. Our research was focused on simultaneous mechanical activation and CO2 capture and storage (CCS) on Linz-Donawitz steel slag dominantly composed of Ca-silicate and oxide phases. The experiments were carried out in a planetary ball mill under 5 bar CO2 pressure in dry and wet (deionized H2O) conditions. The primary objective of the experiments was to observe the role of H2O in the reactions. The presence of H2O in the system leads to a finer particle size distribution but, at the same time, reduces the number of active sites·H2O also acts as a carbonate reaction promoter, it is expected to initialize silicate (Windt et al. 2010) surface protonation and enhancing Ca leaching. The latter of the two processes was predominant so that in wet condition (0,246 kgCO2/kg), almost three times as much calcite is produced as in dry condition (0,083 kgCO2/kg). The combination of nano milling and wet media carbonation is a promising process to reduce energy requirement through increasing the reaction rate and promotes the use of Ca-silicate wastes otherwise underperforming in CCS
Prediction of hot metal temperature in a blast furnace iron-making process using multivariate data analysis and machine learning methodology
No full textThe feed-forward back propagation neural (FFBPN) network method and multivariate data analysis are used to present a new approach for predicting the health of a blast furnace in the form of hot metal temperature (HMT), which is a crucial parameter to control the stable flow of hot metal production while avoiding major danger incidents during the ironmaking process. The health status also appears to predict the performance level of BF at a premature time, allowing the operator to take necessary steps to avoid BF deterioration. The BF's health status designates the stability or instability of the BF, which may arise during the manufacturing process of hot molten iron, and is used to find the fault. In this paper, the health status of BF was determined with the help of a FFBPN and correlation matrix. This was done with Matlab (Version 2018Rb) software that uses data pre-processing, variable reduction, and a selective attribute of a data set. The FFBPN model has been trained, tested, and validated, and it has got 96% correlation coefficient of HMT prediction of a combination of all data sets. The predicted HMT using several actual process data sets has helped identify the process irregularity in BF
Thermo-mechanical property enhancement of rigid polyurethane foam composite using low-cost, environment-friendly fly ash over silica particles
No full textLow-cost and environment-friendly fly ash particles and silica particles were used as additives in the rigid polyurethane foam composite. The usage of fly ash will decrease the need for its handling and exposure to the environment. FTIR spectra show the absence of hydrogen-bonded urea which indicates no aggregation of hard urea domains in the soft polyurethane matrix after the addition of silica/fly ash. The composite loaded with a 20-weight percentage of fly ash had the highest glass transition temperature. At the 10-weight percentage of the additive, the gross calorific value in the fly ash-loaded composite decreased by 12% when compared with the composite loaded with silica. The introduction of fly ash into the foam composite up to a certain weight percentage (10 wt%) enhanced the compressive strength of the rigid polyurethane foam composite. The percolate particle concentration was at 10 weight percentage of the additive. The addition of fly ash increased the compressive strength up to 21% compared to the foam composite loaded with silica. The addition of fly ash in the foam composite resulted in a decrease of water absorption up to 23% in comparison to the composite loaded with silica. Hence, low-cost and environment-friendly fly ash is a suitable additive that can be loaded into rigid polyurethane foams for superior enhancement in mechanical and thermal properties
Flotation of Low-Grade Graphite Ore Using Collector Derived from Low-Density Polyethylene Waste
Get PDFPolymorphs of carbon ranges from soft, blackish graphite to hard, transparent diamond. From the early fifteenth century itself graphite was widely used as it shows the properties of both metal and non-metal, has an extraordinarily low specific gravity, incredibly soft and cleaving with noticeably light pressure, exceptionally heat resistant and inert when in contact with other materials. That is why it is called as a "Mineral of Extremes" [1]. Crystalline forms of natural graphite have small flake size and as metamorphic grade increases it leads to microcrystalline forms. These flake graphites are graded based on the graphitic carbon content and flake size. Hexagonal crystal structure is the thermodynamically stable form of graphite which results in tremendous properties. The properties of graphite vary from place to place as the geography of the mined area play a crucial role in metamorphism.
Among various beneficiation techniques, froth flotation is more suitable for treating fines and naturally hydrophobic ores. Flotation is a surface phenomenon based on the surface hydrophobicity of the mineral surfaced to be separated [2-4]. Due to the natural hydrophobicity of graphite, this technique is adopted for beneficiation. The hydrophobic mineral particles which are attached to air bubbles floats on top as froth and is separated, while the remaining hydrophilic gangue particles that attach with water molecules stay in liquid [2-6]. Nanobubbles can be produced by ultrasonication, but this doesn't have any effects on the floatation performance of graphite [7]. Ultrasonic-assisted flotation has effects on floatability which enhances the recovery flaky graphite from low-grade graphite ore [8]. The particle size has crucial roles in the overall multi-stage grinding-regrinding-flotation steps [9]. Selective adsorption of particular reagents on the mineral surface depends on the particle size of the mineral present in the pulp [10]. Controlled grinding is very important to achieve ideal cost-effective separation [11]. Surface chemistry can be affected by flotation. The purity of single graphite particles, on the other hand, is rarely compromised. Flotation reagents, viz., collectors, frothers, etc., are added to transform the mineral-water mixture suitable for flotation by controlling the relative hydrophobicity of particles and maintain froth characteristics [12]. These chemicals have critical role and importance in the entire process as they involve complex interactions. Graphite has natural affinity towards air bubbles. The chemical reagents commonly used in graphite flotation increase the selective hydrophobicity and a variety of nonpolar hydrocarbon-based oils such as kerosene, diesel, and fuel oil are generally used collectors in combination with frothers such as pine oil, Methyl Isobutyl Carbinol (MIBC) or higher alcohol [13-15]. A jump-in phenomena exist between non-polar collectors and the hydrophobic surface, indicating the existence of an attractive force. Polar collectors form hydrogen bonding with water results in a weaker adhesive force. Jump-in distance, jump-out distance, friction force, and adhesion force are greater and play crucial role in the interaction of collectors with graphite surface [16]. Diesel oil as collector and MIBC as frother was found to yield best results in graphite flotation comparing other hydrocarbon oils like dodecane, kerosene, pine oil, iso octonal in terms of total carbon content and total carbon recovery of the rougher concentrate of graphite [13, 17]. In graphite flotation, the selectivity index between collector and graphite increases as the average droplet size of collector emulsions (e.g., Kerosene) lowers [18]. Conventional reagents are not economic when used in industrial scale due to the continuous price escalation of fuel oils.
Synthetic plastic, the world's most used polymer, whose disposal poses the utmost threat to environment as it is not readily bio-degradable and uses non-renewable resources as key ingredient in manufacturing of plastics. Around 12. 7 tonnes per year of plastic waste is produced around the world which pollutes the entire ecosystem.
The present work evaluates the flotation performance efficacy of the oil ( collector PE) derived using LDPE, i.e., low-density polyethylene waste as collector in combination with MIBC as frother and compares with the conventional reagent combination of diesel and MIBC for flotation of low-grade graphite ore (run-of-mine) from Tamil Nadu
Recycling of Cathode Material from Spent Lithium-Ion Batteries for Energy Application
No full textLithium-ion batteries have been widely utilized in portable electronic devices such as laptops, mobile phones, and other handheld electronic devices since their commercialization in the early 1990s. Extensive use of lithium-ion batteries has been seen in the past three decades. Nowadays, lithium-ion batteries are considered to be the most promising energy storage and green power source for electric vehicles. Like portable electronic devices, it is predicted that lithium-ion batteries are also going to be exploited in the electric vehicle sectors in the coming years. As a result, a large number of spent lithium-ion batteries will be generated. Spent batteries are not only concerned with environmental issues but, it is also concerned with resource management and sustainability. The cathode material in lithium-ion batteries is made of mixed metal oxide. The cathode part in spent lithium-ion batteries contains valuable metals such as Li, Ni, Mn, and Co. However, most of the spent lithium-ion batteries may end up in landfills. Hence, in the view of worldwide electric car revolution and a large number of spent lithium-ion batteries generation, recycling cathode material from spent lithium-ion batteries for energy applications is highly desirable to overcome the environmental issues and resource management for sustainable utilization of energy storage materials. We studied the recycling of cathode material from spent lithium-ion batteries and its characterization for energy storage applications
A novel Fe-rich non-equiatomic medium-entropy alloy with superior mechanical properties
No full textA cost-effective iron-rich non-equiatomic Fe50Mn20Al15Ni10Co5 medium entropy alloy (MEA) was synthe-sized by vacuum induction melting. The as-cast alloy exhibits a multiphase microstructure with the ordered B2 (a= 2.90 +/- 0.01 angstrom), disordered body-centred cubic (BCC) (a= 2.89 +/- 0.01 angstrom) and face-centred cubic (FCC) (a= 3.61 +/- 0.02 angstrom) phases. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to confirm the structure of the evolved phases. The columnar dendrites having a width in the range of 120-300 gm were observed in the as-cast structure. The formation of Ni-Al rich B2 precipitates in the BCC matrix was confirmed based on detailed microstructural characterization using scanning electron micro-scope (SEM) and TEM. The phase separation in the form of modulated structure of ordered B2 and dis-ordered BCC phase was related to the spinodal decomposition. The formation of the FCC phase at and near the grain boundaries is linked to simultaneous nucleation and growth mechanisms, which occur during the solidification. The as-cast alloy has shown an average compressive yield strength of similar to 1250 MPa and ulti-mate strength of similar to 1675 MPa, along with a compressive strain of similar to 42%. The optimum balance of strength and ductility is achieved due to the formation of the hard (B2, BCC) and soft (FCC) phases and their interplay during the deformation process. These encouraging results of the alloy in the as-cast state have provided the direction to design and develop such economically viable alloys, which could be produced at industrial scale.(c) 2023 Elsevier B.V. All rights reserved
Effect of flue gas constituents on boiler tube failure of a captive power plant
No full textWater leakage was reported from one of the superheater tubes of the boiler during operation. The power plant is a part of the copper ore smelting and refining industry. It was observed, that the leakage took place through a cracked region of the tube, which was severely damaged due to a chemical attack. Damage occurred due to a reaction between the flue gas and the outer wall of the superheater tube. Inefficient treatment of flue gas resulted in the retention of metal particles, SO2 gas, and particulate within the same in substantial concentration. When the same flue gas was used in the boiler, SO2 reacted with the tube surface at elevated temperatures. The incident led to wall thinning and
deep pit formation over the tube surface. Metal particles were fused, adhered to the tube surface, and
triggered secondary cracking during operation. Gradual wall thinning, increment in pit size, and crack propagation through thickness resulted in the ultimate failure of tube material
Failure Investigation of Boiler Tube: A Root Cause Analysis
No full textIn a thermal power plant, water wall boiler tube
made of Cr–Mo low alloy steel, failed during operation.
Post failure investigation revealed ‘fish mouth’ opening
accompanied by thick scale formation, significant wall
thinning and de-shaping of circular cross section of tube
material. All the evidence indicated temperature rise over a
period, for which martensitic transformation, matrix grain
growth and globulerization of carbide precipitate occurred
within microstructure of the alloy. The temperature rise
was due to the over-firing of burner and the sudden change
in flue gas constituents. Wall thinning due to oxide scale
formation and plastic flow of material at elevated temperature tentatively below upper critical temperature, reduced the load bearing ability of component. The tube material ultimately failed due to overload during service
Influence of rare earth metals on inclusion modification of dual phase steel
No full textInclusions are very critical in advanced high-strength steels as they are used in automobile and
aerospace industries in which modification of inclusions is required. In this investigation, Rare
Earth Metals (REM) have been used to control and modify the inclusions in the steel. With the
addition of REMs, the total sulphur content present in the steel has been reduced by 22%. An
inclusion study has been performed using the inclusion classifier and ISO-4967 method. Total
inclusions and the number of inclusions at higher indexes (severity) are reduced by adding REM.
The chemistry of the modified inclusions, such as oxides, sulphides and oxysulphides of REM, is
compatible with the steel matrix and does not have harmful effects. With the addition of REM,
the global cleanliness index value at 1.5, 2, 2.5 and 3 indexes are decreased. This may be
attributed to the REM breaking down the stringers. Whereas value has been increased at 0.5
and 1 indexes after the addition of RE metals, inclusions sizes are reduced, which is not harmful
to the properties of the steel.
Les inclusions sont très importantes dans les aciers avancés à haute résistance, puisqu’ils sont
utilisés dans les industries automobile et aérospatiale dans lesquelles la modification des
inclusions est requise. Dans cette étude, on a utilisé les métaux de terres rares (REM) pour
contrôler et modifier les inclusions dans l’acier. Avec l’ajout des REM, la teneur totale en soufre
présente dans l’acier a été réduite de 22%. On a réalisé une étude d’inclusion à l’aide du
classificateur d’inclusion et de la méthode ISO-4967. Les inclusions totales et le nombre
d’inclusions aux indices (de sévérité) plus élevés sont réduits en ajoutant des REM. La chimie
des inclusions modifiées, comme les oxydes, les sulfures et les oxysulfures de REM, est
compatible avec la matrice en acier et n’a pas d’effets nocifs. Avec l’ajout de REM, les valeurs de
l’indice global de propreté aux indices de 1.5, 2, 2.5 et 3 sont diminuées. On peut attribuer cela
aux REM qui désagrègent les inclusions linéaires. Alors que la valeur a été augmentée aux
indices de 0.5 et 1 après l’ajout des métaux de RE, les tailles d’inclusions sont réduites, ce qui
n’est pas nuisible aux propriétés de l’acier
CSIR-NML Annual Report 2022-2023
Get PDFIt contains the statement of R&D works undertaken, achievements made, and the expenditure by the laboratory during the financial year 2022-2023