Subjects -> METALLURGY (Total: 58 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access  
Advanced Device Materials     Open Access   (Followers: 3)
American Journal of Fluid Dynamics     Open Access   (Followers: 47)
Archives of Metallurgy and Materials     Open Access   (Followers: 8)
Asian Journal of Materials Science     Open Access   (Followers: 5)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 20)
Complex Metals     Open Access   (Followers: 1)
Corrosion Communications     Open Access   (Followers: 5)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 19)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 10)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 3)
International Journal of Metals     Open Access   (Followers: 6)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 8)
International Journal of Mining and Geo-Engineering     Open Access  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 4)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 23)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 32)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 7)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 1)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 18)
Journal of Metallurgical Engineering     Open Access   (Followers: 2)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Engineering     Open Access  
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 42)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 31)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 6)
Metallurgy and Foundry Engineering     Open Access  
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 33)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Rare Metals     Hybrid Journal   (Followers: 1)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access  
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 4)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 1)
Stainless Steel World     Full-text available via subscription   (Followers: 17)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 4)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 1)
Welding in the World     Hybrid Journal   (Followers: 4)
Welding International     Hybrid Journal   (Followers: 7)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Metallurgical and Materials Transactions B
Number of Followers: 31  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1543-1916 - ISSN (Online) 1073-5615
Published by Springer-Verlag Homepage  [2469 journals]
  • A Sulfur Emission-Free Route for the Synthesis of Mo and Mo2C via
           Carbothermal Reduction of MoS2

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      Abstract: In this work, the sulfur-free emission route for the synthesis of Mo and Mo2C via carbothermal reduction of MoS2 was proposed. The internal MoS2-C mixture is wrapped by an external desulfurization layer composed of CaO and C. In the internal layer, MoS2 reacted with carbon black and generated Mo, Mo2C (or their mixture), as well as S2, CS2 and CS gas. Both experiments and thermodynamic calculations show that the main gaseous product should be CS2. The sulfur-containing gas produced can be completely captured by the desulfurization layer in the form of CaS. This strategy can avoid the emission of S-containing gas compared with the traditional route. In addition, after removing the unreacted desulfurizer and gently breaking the desulfurization product layer, the molybdenum-containing product can be collected. For the raw material with a MoS2:C molar ratio of 1:1, after reacting at 1600 °C for 4 hours, Mo with carbon and sulfur contents of 0.053 and 0.050 pct is acquired. In addition, Mo2C-dominant product can be obtained after reacting at 1600 °C for 4 hours at a MoS2:C molar ratio of 1:1.52, with the carbon and sulfur contents of 5.878 and 0.049 pct. The above shows that this strategy has the advantages of high-efficiency desulfurization and simple separation of desulfurization product, which is an environment-friendly method for the production of molybdenum additives.
      PubDate: 2022-02-01
       
  • Asymptotic Model of Refractory and Buildup State of the Blast Furnace
           Hearth

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      Abstract: Wear of the hearth refractory and buildup (“skull”) formation play important roles for the life length of the ironmaking blast furnace. The extent of these factors during the campaign can be estimated by solving a sequence of inverse heat-conduction problems, but this requires thermocouple measurements in the lining and the effect of liquid flow is often disregarded. The model developed in the present paper aims at providing a theoretical estimation of the asymptotic inner profile of the hearth by a CFD-based approach that estimates both the iron flow and the refractory erosion and possible skull. The profile, shaped by the flowing hot metal, solidified skull, and remaining refractory, is obtained through an iterative process based on the calculated fluid flow and temperature distribution in the domain. The paper presents the assumptions behind the model, its main equations and the solution procedure, as well as a set of illustrative examples that show the versatility of the approach. The results of the model can be used to estimate the potential strengths and weaknesses of a specific hearth design and also how the lining state would be affected by changes in the boundary conditions.
      PubDate: 2022-02-01
       
  • Electrochemical Performance of Carbon Anodes Made of Bio-pitch as a Binder

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      Abstract: Bio-pitch is considered as a promising candidate to replace fossil coal-tar-pitch used in carbon anodes. The electrochemical performance of the carbon anode is affected by the properties of its constituents and replacement of coal-tar-pitch with bio-pitch requires that the electrochemical performance is not significantly reduced. In this work the impact of the bio-pitch on the electrochemical behavior of carbon anodes was investigated using different electrochemical methods including, electrolysis under constant current, cyclic voltammetry and electrochemical impedance spectroscopy in a laboratory scale electrolysis cell. The electrochemical behavior of the bio-pitch anodes was compared to that of the reference anodes made of coal-tar-pitch. The bio-pitch anodes demonstrated slightly improved electrochemical performance, compared to the reference anodes. The reaction overpotential decreased while an increase in the double layer capacitance, which referrers to the interfacial contact between the anode and the molten electrolyte, was noticed upon using the bio-pitch as a binder. The finding of this work proved the potential of using the bio-pitch, as a binder, which can even be beneficial for the electrochemical performance of carbon anodes.
      PubDate: 2022-02-01
       
  • Interfacial Reactions Between Al and Ni During Compound Casting

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      Abstract: The formation of bonding between Ni and Al during the compound casting and a subsequent heat treatment is investigated. The preventive effect of the surface oxide layers was partially eliminated and the bonding between the metals started immediately after the compound casting. The bonding between the metals progressed rapidly during the heat treatment at 973 K and was almost complete after 10 minutes. The first intermetallics formed between the two metals were AlNi3, AlNi, and Al3Ni2. The first two transformed to Al3Ni2 by the reaction with the liquid Al on the interface during the heat treatment. A part of Al3Ni2 was also subsequently transformed to Al3Ni. Al3Ni also formed as eutectic and proeutectic phases during the solidification of the Al. Comparison of the results obtained in this study with those published previously in the literature for Ti/Al, Fe/Al, and Al/Al bimetals suggests that the difference between the Gibbs free energy of formation of oxides covering the two bars determine the rate of bonding between the two metals.
      PubDate: 2022-02-01
       
  • Surface Tension, Interfacial Segregation, and Graphite Shape in Cast Irons

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      Abstract: Using literature data on iron melts, an expression of the surface tension of cast iron melts as a function of temperature and composition was obtained. Its predictions were satisfactorily compared with reported experimental results. Then, an analysis of experimental information of sessile drop experiments with cast iron melts onto graphite substrates showed a strong adhesion between these two phases when sulfur is present and its dramatic decrease when the sulfur activity is reduced by the addition of spheroidizers such as Mg and Ce. Finally, analysis and discussion of results on the segregation of impurities and trace elements at the graphite matrix interface in cast irons led to the proposal of a scheme for their effect on graphite shape.
      PubDate: 2022-02-01
       
  • Hydrodynamic Modeling of Two-Phase Flow in the Industrial
           Ruhrstahl–Heraeus Degasser: Effect of Bubble Expansion Models

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      Abstract: In an industrial Ruhrstahl–Heraeus (RH) degasser, gas bubbles can expand rapidly due to heating by the melt as well as to the significant pressure drop when they rise in the melt. A suitable model for the bubble expansion is, therefore, essential for the accurate numerical prediction of argon–melt hydrodynamics in an RH degasser. This study focuses on the evaluation and comparison of different bubble expansion models available in the literature based on a coupled computational fluid dynamics–population balance model. The simulation results show that compared with the measured results, the modified Szekely–Martins model demonstrates the suitability for treating the bubble expansion behavior and thereby simulating the argon–melt hydrodynamics in an industrial RH degasser. The flow field and bubble expansion, breakup, and coalescence phenomena are then investigated.
      PubDate: 2022-02-01
       
  • Inhibitory Effect of MgO, FeO, CaF2, and Al2O3 Additives on the
           Dissolution Behavior of Ca from Silicate Mineral Phases into Water

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      Abstract: The inhibitory effect of MgO, FeO, CaF2, and Al2O3 additive on the dissolution of Ca into water from 10 quasi-ternary silicate mineral phases was studied according to the silicate crystal structure. After adding MgO or FeO, the dissolution ratio of Ca decreased by Ca2+ substitution with Mg2+ or Fe2+. In the CaF2-added silicate phase Ca4Si2O7F2, non-existence of the face-sharing type of linkage between CaOx polyhedrons could be a reason for the low dissolution ratio of Ca. In Al2O3-containing silicates, Al atoms could form [AlO4]5− and [AlO6]9− polyhedrons linked to [SiO4]4− tetrahedrons to form a complicated silicate network structure with a higher polymerization degree, which helps suppress the dissolution of Ca. The dissolution ratio of Ca is also inversely correlated to the overall polymerization degree in the silicate network structure. Using multivariate analysis, the dissolution ratio of Ca was predicted utilizing factors internal to the silicate structure (corrected basicity, polymerization degree of silicate network structure, lattice energy, and average nearest neighbor Ca–O distance). For both quasi-binary and quasi-ternary systems, the overall polymerization degree of silicate network strongly affects the dissolution of Ca, while the other factors only make slight contributions.
      PubDate: 2022-02-01
       
  • Sn-Aided Joining of Cast Aluminum and Steel Through a Compound Casting
           Process

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      Abstract: Obtaining a strong bond between aluminum and steel is challenging due to poor wettability between aluminum melt and steel and brittle intermetallic phases forming in the interface. In this research, a novel coating method, namely hot dipping of Sn, has been developed to treat the steel insert surfaces. Results show that without preheating the mold or Sn-coated insert, a thin, crack-free, and continuous metallurgical bonding layer was achieved in the A356 aluminum/steel compound castings. Intermetallic structures forming in the interface have been characterized in detail. The Sn-coating layer completely melted and mixed with the liquid aluminum during the casting process. The reaction layer at the aluminum/steel interface is composed of ternary Al–Fe–Si particles and a thin layer of binary Al5Fe2 phase with thickness less than 1 µm. A small fraction of dispersed Sn-rich particles was observed distributing in the reaction layer and adjacent to eutectic Si particles in the A356 alloy. A sessile drop wetting test showed that Sn-coated steel substrates can be well wetted by aluminum melt. The improved wettability between A356 alloy melt and steel was attributed to the penetration and breaking of the aluminum oxide layer at the surface of the aluminum droplets by liquid Sn. Graphic
      PubDate: 2022-02-01
       
  • Microstructure Simulation of the Nonuniform Shell for the Round Billet
           Continuous Casting

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      Abstract: To study the effect of nonuniform heat transfer on the grain structure of shells in molds, a micro and macroscopic model coupling heat transfer with dendritic growth was established based on the measured heat flux. Dendritic growth was modeled by using a cellular automaton technique and by considering solutal transport. The quasi-instantaneous nucleation model was introduced to address heterogeneous nucleation, which might occur at the mold wall and in the bulk of the liquid. The temperature field of the billet under the measured heat flux in the mold was calculated, and the initial solidification process and grain structure evolution of four domains at different angles from the inner arc were simulated. The effect of circumferential nonuniform heat transfer on the grain structure of the chill zone and columnar grains of the shell was discussed in detail. The relationship between the distribution of the primary dendrite spacings in different domains and locally measured heat flux was analyzed.
      PubDate: 2022-02-01
       
  • Electrical Conductivity and Melt Structure of the CaO–SiO2–Based Mold
           Fluxes with Different Basicity

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      Abstract: External fields, such as magnetic and electric, are applied to the continuous casting mold to improve the quality of casting products. The performance of the mold flux should also be impacted when these external fields are applied in the mold. The extent of the impact is associated with the electrical conductivity. So, in this study, the electrical conductivity of the mold fluxes with various basicity was measured using the AC four-electrode method. The results show that the electrical conductivity of the mold flux increased while its activation energy decreased with the increase of basicity from 0.8 to 1.1, at 1423 K to 1573 K. In addition, the analyses of Fourier-transform infrared (FTIR) and Raman spectroscopies show that the complex structural units, such as Q3(Si), Si–O–Si, Si–O–Al, and Al–O0, reduced with the increase of basicity. So the melt structure of the mold flux was simplified by the addition of CaO and reduction of SiO2. From the variations of electrical conductivity and melt structure, it can be concluded that it is due to the simplification of melt structures of the mold flux by the increase of basicity, which promotes the diffusion of ions/ionic groups, and then leads to the increase of electrical conductivity.
      PubDate: 2022-02-01
       
  • Modeling Inclusion Removal when Using Micro-bubble Swarm in a Full-Scale
           Tundish with an Impact Pad

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      Abstract: Gas was injected into the upper part of a water model ladle shroud, producing micro-bubbles by the shearing action of the high-speed entry flow of water, combined with subsequent bubble breaking actions of turbulence. An impact pad was used in favor of a standard turbulence inhibitor, to maintain the integrity of the micro-bubbles, and assure their wide distribution within the tundish. The effects of these two systems on removing small inclusions were investigated, and a numerical model was developed to simulate the motion behaviors of bubbles in the tundish, considering bubble coalescence. Both the turbulence inhibitor and the impact pad performed similar on flow improvement, but the impact pad effectively restrained coalescence between bubbles, leading to a 55.3 pct drop in the average bubble size within the tundish, and generating a 53.9 pct reduction in the residual numbers of inclusions below 51 μm diameter, by contrast with the turbulence inhibitor data. The impact pad fits well with gas bubbling for deep cleaning the liquid steel in tundish.
      PubDate: 2022-02-01
       
  • The Flow Behavior of Molten Steel in an RH Degasser Under Different Ladle
           Bottom Stirring Processes

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      Abstract: The effects of the ladle bottom stirring flow rate and the number of argon plugs on the circulation flow rate and mixing time in an RH degasser were studied using a physical simulation method. The flow field in the RH ladle was studied using particle image velocimetry (PIV). The results show that applying the ladle bottom stirring process has a great influence on the flow field in the RH ladle. When only stirring under the upleg, the circulation of the RH ladle was enhanced. The velocity of molten steel circulation was accelerated, the RH circulation flow rate was increased, and the mixing time was decreased. When the lifting gas flow rate is 133.3 m3 h−1 and the ladle bottom stirring rate is 166.7 L min−1, the circulation flow rate increases by approximately 25 pct, and the mixing time decreases between 36 and 40 pct compared with that without ladle bottom stirring. Stirring in the argon plug below the downleg is not conducive to improving the circulation flow rate but is beneficial to reducing the molten steel mixing time. Double-ladle argon plug stirring can improve molten steel activity on both sides of the snorkel at the upper part of the RH ladle, but this can negatively affect the original vessel circulation. To ensure that the circulation flow is not reduced during double-ladle bottom argon plug stirring, the snorkel upleg lifting gas flow rate must be greater than 133.3 m3 h−1 for the system studied in this work.
      PubDate: 2022-02-01
       
  • Soft-Sensing Model for Submerged Arc Furnace Electrode Current Based on
           Machine Learning

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      Abstract: Electrode current plays a significant role in control of submerged arc furnaces. However, it is difficult to measure the values directly. Recent studies have expanded the available information on current distribution of submerged arc furnaces, thus enabling the soft-sensing model for submerged arc furnace electrode current to be constructed. The present study aimed to establish a soft-sensing model for submerged arc furnace electrode current. The study consisted of the establishment of the mechanism model, identification of the mechanism model parameters, compensation of the mechanism model errors, and update of the soft-sensing model. The main conditions considered in the mechanism model include operating resistance, short network resistance and inductance, and electrode depth. The innovation of this study is that a dual particle swarm optimization algorithm with information exchange is proposed to ensure the speed and accuracy of mechanism model parameter identification. The experimental results demonstrate that the soft-sensing model can predict the electrode current with high accuracy. Compared with the traditional method using the transformation ratio of the transformer and the primary current, the prediction accuracy of the electrode current is improved by about 12 pct. The model update strategy can improve the adaptability of the model.
      PubDate: 2022-02-01
       
  • Effect of Microstructure Evolution of Iron-Rich Intermetallic Compounds on
           Mechanical Property of Al–7Si–0.3Mg Casting Alloy with Low Iron
           Content

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      Abstract: In this study, the effects of microstructure evolution of iron-rich intermetallic compounds on mechanical properties in Al–7Si–0.3Mg cast alloys with low iron content (0.1 to 0.3 wt pct) were investigated. A series of characterization methods was utilized to observe the microstructure of iron-rich intermetallic compounds. The results indicate that the dominant iron-rich intermetallic compounds change from π-AlMgFeSi phase with a script-like morphology to β-AlFeSi phase with a needle-like morphology as Fe content increased. Besides, the 2D/3D morphology of Fe-rich intermetallic compounds significantly changes with the increase of Fe content. In 0.3 wt pct Fe alloy, the π-AlMgFeSi phase with a layered structure and seaweed-like morphology forms on the surface of the β-AlFeSi phase with a platelet-like morphology, and the crystallographic orientation relationships were \(\left[ {1100} \right]_{\pi } \parallel \left[ {111} \right]_{\beta } \,{\text{and}}\,\left( {\overline{1} 10} \right)_{\beta } \parallel \left( {1\overline{2} 10} \right)_{\pi }\) . In addition, the β-AlFeSi phase tends to nucleate in 0.2 wt pctFe alloy, while the growth of β-AlFeSi phase is boosted in 0.3 wt pctFe alloy. The sufficient growth of β-AlFeSi phase leads to the formation of the π-AlMgFeSi phase. Furthermore, the formation of the π-AlMgFeSi phase improves the mechanical properties of alloys. The microstructure morphology of π-AlMgFeSi phase formed on the surface of the platelet-like β-AlFeSi phase enhances the adhesive strength between the β-AlFeSi and the matrix and reduces the negative effects of Fe-rich intermetallic compounds on mechanical properties of Al–7Si–0.3Mg cast alloys.
      PubDate: 2022-02-01
       
  • Study of Peritectic Phase Transition in High-Mn Steel Using Phase-Field
           Method

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      Abstract: A multi-component multi-phase-field model was conducted to simulate the solidification process of Fe-Mn-C-Al high-Mn steel with different solidification modes, especially that with the peritectic phase transition. The evolution of the microstructure and solute distribution during the solidification process was analyzed. In addition, the influence of the C content, cooling rate, and thermal undercooling was discussed. The results reveal that the area of interfaces and solute distribution influence the evolution of phase fractions. The amount of initial ferrite phase, the solute distribution formed by the initial ferrite phase, and the nucleation position of austenite phase are key factors affecting the microstructure morphology and microsegregation. The microstructure and microsegregation have an interactive effect. Increasing C content changes the solidification mode, leading to different microstructure and microsegregation. For all the steel with different C contents, the cooling rate and undercooling do not influence the phase transition sequence, while they affect the microstructure and microsegregation. The cooling rate and thermal undercooling have more influence on the solidification process of hypo-peritectic high-Mn steel than hyper-peritectic steel. The present study contributes to providing significant reference for the process control of the microstructure morphology and microsegregation of peritectic high-Mn steel.
      PubDate: 2022-02-01
       
  • Modeling of Fluid Flow and Bulk Liquid Mixing Phenomena in a Mechanically
           Agitated Ladle

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      Abstract: Fluid flow and mixing phenomena were investigated in a cylindrical-shaped, mechanically agitated water model ladle (D = 0.30 m) both computationally and experimentally. Embodying the dynamic/sliding mesh approach in ANSYS Fluent (version 18.0), appropriate flow models were formulated via the realizable k–ε turbulence model as well as LES (large eddy simulation) and, based on this, flow and mixing times were predicted in the water model system as a function of impeller speed. In parallel, while distributions of axial and rotational components of flow at different locations in the system were mapped via a Laser Doppler Velocimeter (LDV), electrical conductivity measurement technique was adopted to determine 95 pct bulk mixing times experimentally. Reproducible measurements, obtained under different experimental conditions, were applied to directly assess the relative adequacy of the two flow calculation procedures. Comparison between numerical predictions and experimental measurements indicates that LES provides considerably more accurate estimates and thus outperforms the realizable k–ε turbulence model. In general, the realizable k–ε model is found to overestimate flow recirculation rate leading to expeditious mixing or shorter mixing times in the system. The implications of the present findings, with reference to industrial-scale simulation of mechanically agitated, high-temperature systems, such as the Kanabara (KR)™ reactor, are also briefly addressed in the text.
      PubDate: 2022-02-01
       
  • Ecofriendly Selective Extraction of Vanadium from Vanadium Slag with High
           Chromium Content via Magnesiation Roasting–Acid Leaching

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      Abstract: Conventional vanadium (V) extraction methods for vanadium-bearing slags create high chromium content discharge Cr(VI)-containing hazardous wastes. In this article, an ecofriendly magnesiation roasting-acid leaching method is proposed to selectively extract V from the slag. In the near-zero discharge process the generation of Cr(VI) is eliminated. Cr present as (Fe0.6Cr0.4)2O3 in the leach residue in association with Fe2O3 and SiO2 can be directly smelted to produce ferrochrome. From the obtained leach liquor, V, Mg and Mn are recovered successively. At pH 3.0, V precipitates as ammonium polyvanadate, which is calcined to V2O5 (99.14 pct pure) with a total recovery rate of 94.10 pct. Meanwhile, the NH3 gas produced during calcination is recycled for pH adjustment. At pH 8 to 9, Mn precipitates as hydroxide and is calcined to produce a MnO by-product (91.10 pct pure; recovery rate 47.96 pct). Subsequently, at pH 10 and above, dissolved Mg is precipitated as Mg(OH)2 and calcined to obtain MgO (purity = 99.12 pct; recovery = 90.47 pct). The calcine MgO is recycled as a roasting additive. The evaporation of residual solution yielded (NH4)2SO4 crystals and condensed water, which are recycled in vanadate precipitation and acid leaching, respectively. Graphical abstract
      PubDate: 2022-02-01
       
  • Effect of Different Methods for Removing Bifilm Defects from A356 Aluminum
           Alloy

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      Abstract: Individual and simultaneous effect of three factors of flux, mechanical stirring of the melt, and holding the melt under reduced atmospheric pressure on the removal of bifilm defects from the A356 and A356 + 0.1 wt pct Sr melts have been investigated using a reduced pressure test technique. The results showed that in the first place, holding the liquid metal under a reduced atmospheric pressure and then using a suitable flux on the melt surface had the most significant effects on the removal of bifilms from the melt. The presence of Sr in the melt caused an increase in the porosity of the samples in 30 minutes, but also healed the crumpled bifilms and prevented them from unfurling. Mechanical stirring of the melt was found to have the least significance in the removal of bifilms. However, to reduce the bifilm content of the melt as much as possible, stirring the melt while using flux and a reduced pressure was found to be essential.
      PubDate: 2022-02-01
       
  • Investigation of the Influence of Slag Basicity on Metal Droplet
           Dephosphorization

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      Abstract: As a part of ongoing work on metal droplet dephosphorization, this study specifically investigated the effect of slag basicity (V ratio) by employing time lapse sampling while monitoring simultaneous decarburization using a constant volume pressure increase technique (CVPI) with X-ray fluoroscopy. The dephosphorization kinetics of droplets with two different initial carbon concentrations (2.51 and 0.007 wt pct), were tracked by quenching and analyzing droplets after different reaction times. The reaction kinetics were further elucidated by combining the decarburization rate of the droplet, measured via CVPI with the bloating behavior of droplet observed in-situ by X-ray fluoroscopy. The results showed that for high carbon droplets the dephosphorization rate increased with increasing slag basicity largely due to the increasing droplet decarburization rate, which enhanced mass transport of phosphorus by CO bubble stirring. Further increasing slag basicity increased the peak decarburization rate, but did not appear to further increase droplet dephosphorization. In low carbon droplets, the dephosphorization rate was also increased with increasing slag basicity because of the higher phosphorus partition ratio and larger mass transfer parameter \(kA\) resulting from the faster oxygen transfer in the slag causing an increase in the interfacial area for reaction.
      PubDate: 2022-02-01
       
  • Formation of NO and SO2 in the Sintering Process of Iron Ores

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      Abstract: Nitric oxide (NO) and sulfur dioxide (SO2) are the major environmental pollutants being generated in the steel industry. More than half of NO and SO2 are emitted from sinter plants. Due to the catalytic effect of CaO in the sinter mix on the formation of NO and SO2, it might differ from that in the combustion of raw coals. In the combustion of raw coals, both NO and SO2 were formed in the temperature range of 473 K (200 °C) to 1623 K (1350 °C). In the case where the content of endogenous CaO in coal ash was high, the formation of SO2 was significantly reduced below 1473 K (1200 °C). In the case of the sinter mix, NO was formed in the temperature range of 473 K (200 °C) to 1173 K (900 °C) and the conversion of N to NO was increased by the catalytic effect of CaO in the sinter mix. Most of the SO2 was formed above 1473 K (1200 °C). The CaO present in the sinter mix reacted with the SO2 generated below 1473 K (1200 °C) to form CaSO4, the stability of which was maintained until 1473 K (1200 °C); thus, the conversion of S to SO2 was reduced. Based on the coal composition and functionalities of nitrogen and sulfur in coals, the indices of NO and SO2 were proposed to predict the conversion of N to NO and S to SO2, respectively. The increased heating rate shifted the formation temperature range of NO to higher temperatures and increased the formation of SO2 by the thermally activated decomposition of CaSO4.
      PubDate: 2022-02-01
       
 
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