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The influence of furnace length on several key performance indicators of a reheating furnace such as the fuel consumption, thermal efficiency and through-thickness temperature uniformity of a discharged slab was investigated. Energy balance equations of radiation set up by the zone method were solved by coupling them with the heat conduction equations of the slab. The zone model was validated by actual data collected during an instrumented slab trial. The simulation results showed that the model predictions were in good agreement with actual measurements. Under the premise that the throughput rate and the total fuel consumption were fixed, every additional meter of the preheating zone length increased the slab discharge temperature by about 10.75 °C and decreased the exhaust temperature by about 13.29 °C, but made no change in the section temperature difference in the slab at discharge; every additional meter of the soaking zone length decreased the section temperature difference in the slab at discharge by about 2.88 °C, but made a somewhat gentle change in the slab discharge temperature and exhaust temperature. For the existing furnace, the actual length was not suitable to be changed, so the relative length was defined as representing the actual length, which could be indirectly changed by adjusting the current fuel consumption. After optimization, the relative lengths of the preheating zone and soaking zone increased by five meters and one meter, respectively, while the relative lengths of the first and second heating zones decreased by five meters and one meter, respectively, and the section temperature difference in the slab at discharge, exhaust temperature and fuel consumption simultaneously decreased. [ABSTRACT FROM AUTHOR]

In order to improve the heat transfer characteristics of the air impingement freezer, an impingement freezer experimental table was designed as the research object in this paper. Numerical simulation technology was used to simulate the impingement freezer experimental table on the basis of test verification. When the other structural parameters in the impingement freezer experimental table were constant, the effect of the inclination angle of the orifice plate (θ = 60°, 65°, 70°, 75°, 80°, 85°, and 90°) on the heat transfer characteristics of a steel strip surface was analyzed by two aspects, the average Nusselt number and the heat transfer uniformity. The results showed that with the increase in the inclination angle of the orifice plate (60° ≤ θ ≤ 90°), the average Nusselt number of the steel strip surface was increased by 19.39%, and the heat transfer uniformity index was decreased by 33.69%. When θ = 90°, the average Nusselt number on steel strip was the maximum, which was 263.68, and the heat transfer uniformity index was the minimum, which was 0.2039. Therefore, the heat transfer intensity and heat transfer uniformity in the air impingement freezer could be improved when the inclination angle of the orifice plates was 90°. This helps to improve the output of the air impingement freezer, reduce energy consumption, and improve the quality of frozen food. [ABSTRACT FROM AUTHOR]

The quality of the bloom will be impacted by the non-metallic impurities in the molten steel in the tundish, which will reduce the plasticity and fatigue life of the steel. In this research, a mathematical model of a six-flow double-channel T-shaped induction heating tundish was established, the effects of induction heating conditions on the removal of inclusions in the tundish were investigated, and the impact of various inclusion particle sizes on the removal effect of inclusions under induction heating was explored. The results show that the Residence Time Distribution (RTD) curve produced through numerical simulation and physical simulation is in good agreement. The reduction of inclusion particles in the channel is made affordable by the dual-channel induction heating technique. As the diameter of inclusion particles increases from 10 μm to 50 μm, the probability of inclusion particles being removed from the channel gradually decreases from 70.9% to 56.1%. [ABSTRACT FROM AUTHOR]

Waste PCBs the core of e-waste is rich in copper, tin, zinc, iron, and nickel. Leaching base metals from PCB used to be done in toxic, corrosive acidic/alkali mediums. In this work, an environmentally friendly method for leaching metals from thermally treated PCBs (TPCBs) of mobile phones was proposed using choline chloride based deep eutectic solvents (DES). DES selectivity and solubility of metals from metal oxides were the main screening criteria. FA-ChCl had the maximum solubility of Cu, Fe, and Ni, while Urea-ChCl had high Zn selectivity and solubility. Oxalic acid has high selectivity for Sn. FA-ChCl extracted Cu and Fe best at 16 h, 100 °C, and 1/30 g/mL. Urea-ChCl extracted Zn (90.4±2.9 %) from TPCBs at 100 °C, 21 h, 1/20 g/mL, and 400 rpm. Oxalic acid (1 M) removed 92.3±2.1 % Sn from TPCBs in 1 h at 80 °C and 1/20 g/mL. The shrinking core model-based kinetic investigation of FA-ChCl for Cu extraction showed a diffusion-controlled process. The proposed method is greener than mineral acids utilized for metal extraction., (© 2024 Wiley-VCH GmbH.)

Ladle metallurgy is an important steelmaking technology in high-quality steel production. The blowing of argon at the ladle bottom has been applied in ladle metallurgy for several decades. Until now, the issue of breakage and coalescence among bubbles was still far from being solved. In order to have a deep insight into the complex process of fluid flow in the gas-stirred ladle, the Euler–Euler model and population balance model (PBM) are coupled to investigate the complex fluid flow in the gas-stirred ladle. Here, the Euler–Euler model is applied to predict the two-phase flow, and PBM is applied to predict the bubble and size distribution. The coalescence model, which considers turbulent eddy and bubble wake entrainment, is taken into account to determine the evolution of the bubble size. The numerical results show that if the mathematical model ignores the breakage of bubbles, the mathematical model gives the wrong bubble distribution. For bubble coalescence in the ladle, turbulent eddy coalescence is the main mode, and wake entrainment coalescence is the minor mode. Additionally, the number of the bubble-size group is a key parameter for describing the bubble behavior. The size group number 10 is recommended to predict the bubble-size distribution. [ABSTRACT FROM AUTHOR]

Single Snorkel Furnace (SSF) vacuum refining furnace is a novel external refining equipment for high clean steel production. RH is a molten steel refining technology developed by Rheinstahl-Heraeus company. Compared with the traditional RH furnace, the SSF furnace has the advantages of a simple structure, high refining efficiency, and low production cost. However, because the upward flow and the downward flow are in a single snorkel, the flow phenomenon is more complex than that in the RH device. Therefore, the gas–liquid two-phase flow law in SSF furnaces plays an important role in improving equipment efficiency and accurate control. In addition, the evolution and movement behavior of bubbles have an important influence on the two-phase flow. In this study, the Population Balance Model (PBM) model is employed to study the bubble properties, taking into account the effect of bubble coalescence and breakup on the flow field. The simulation results with this model are consistent with the experimental values, and the comparison with the results of the model without the PBM is revealed to be closer with less error. The results show that with the PBM model the flow field is more homogeneously distributed, the flow velocity is more stable, and the area distribution of the upward flow and downward flow in the snorkel is more symmetrical. In the case of this study, as the fluid level rises, the bubble diameter will increase due to the decrease in hydrostatic pressure. [ABSTRACT FROM AUTHOR]

In order to conduct more thorough research on the structural characteristics of the atmosphere and the distribution and transmission of atmospheric pollution, the use of remote sensing technology for multi-dimensional detection of the atmosphere is needed. A light-weight, low-volume, low-cost, easy-to-use and low-maintenance mini Infrared Lidar (mIRLidar) sensor is developed for the first time. The model of lidar is established, and the key optical parameters of the mIRLidar are optimized through simulation, in which wavelength of laser, energy of pulse laser, diameter of telescope, field of view (FOV), and bandwidth of filter are included. The volume and weight of the lidar system are effectively reduced through optimizing the structural design and designing a temperature control system to ensure the stable operation of the core components. The mIRLidar system involved a 1064 nm laser (the pulse laser energy 15 μJ, the repetition frequency 5 kHz), a 100 mm aperture telescope (the FOV 1.5 mrad), a 0.5 nm bandwidth of filter and an APD, where the lidar has a volume of 200 mm × 200 mm × 420 mm and weighs about 13.5 kg. It is shown that the lidar can effectively detect three-dimensional distribution and transmission of aerosol and atmospheric pollution within a 5 km detection range, from Horizontal, scanning and navigational atmospheric measurements. It has great potential in the field of meteorological research and environmental monitoring. [ABSTRACT FROM AUTHOR]

A large-eddy simulation (LES) based meshless model is developed for the three-dimensional (3D) problem of continuous casting (CC) of steel billet. The local collocation meshless method based on radial basis functions (RBF) is applied in 3D. The method applies scaled multiquadric (MQ) RBF with a shape parameter on seven nodded local sub-domains. The incompressible turbulent fluid flow is described using mass, energy, and momentum conservation equations and the LES turbulence model. The solidification system is solved with the mixture continuum model. The Boussinesq approximation for buoyancy and the Darcy approximation for porous media are used. Chorin's fractional step method is used to couple velocity and pressure. The microscopic model is closed with the lever rule model. The LES model is compared to the two-equation Low Re k − ε turbulence Reynolds Averaged Navier–Stokes (RANS) model in terms of temperature, velocity and computational times. The LES model resolves transient character of vortices which RANS-type turbulence models are unable to tackle. The computational cost of LES models is considerably higher than in RANS. On the other hand, it results in a much lower computational cost than the direct numerical simulation (DNS). The paper demonstrates the ability of the method to solve realistic industrial 3D examples. Trivial adjustment of nodal densities, high accuracy, and low numerical diffusivity are the main advantages of this meshless method. [ABSTRACT FROM AUTHOR]

(1) Background: Cultivating resistant rootstocks is an effective way to mitigate apple replant disease (ARD), and we developed superior apple rootstock line 12-2 (self-named), which shows improved ARD resistance. (2) Methods: We used ARD-associated pathogen Fusarium proliferatum MR5 (MR5) to test the fungal infection in the 12-2 line. Seedlings of the 12-2, T337, and M26 rootstock lines were planted in a substrate with potato dextrose broth and MR5 spore solution, and aboveground physiological indicators were measured. (3) Results: MR5 had the greatest effect on the leaf growth of T337 and M26. The incidence rates of infectious symptoms in the T337 and M26 lines were 68 and 100%, respectively. MR5 significantly affected the leaf chlorophyll content, ETR, and NPQ of T337 and M26, as well as Pn and Tr of M26. MR5 tended to reduce the leaf photosynthetic parameters of T337, but the decreases were not significant. The leaf reactive-oxygen-species levels of T337 and M26, the leaf antioxidant-enzyme activities of M26, and the superoxide-dismutase activity of T337 were significantly affected by MR5. MR5 also had a significant effect on the leaf malondialdehyde, proline, and soluble-sugar contents of T337 and M26. None of these aboveground physiological indicators were affected by MR5 in the 12-2 rootstock. (4) Conclusions: The 12-2 rootstock was more resistant to ARD-associated MR5 and could serve as an important test material for resistant-apple-rootstock breeding in China. [ABSTRACT FROM AUTHOR]

The corner defects in the casting slab greatly influence the product quality. These defects may extend during the heating and rolling process and even result in the discarding of the rolled plate as scrap. A corner cleaning equipment based on the scarfing machine is proposed to eliminate the defects in slab corners for producing high-quality steel. Unlike the flat surface scarfing process, the flame jet and the shape of the molten pool have an essential impact on the effectiveness of the flame cleaning in the corner of the casting slab. A three-dimensional fully coupled model for the flame cleaning nozzle is developed to simulate the flow pattern of the flame jet, Oxygen concentration distribution, and temperature field in the corner of the slab. The simulated flame jet flow field and temperature results agreed well with the factory trial results. Additionally, a three-dimensional thermal model for simulation of the molten pool formed by flame cleaning in the corner of the casting slab has also been developed. For the sake of simplicity, the 2D elliptic and 3D Gauss heat source models are used to simulate the flame heating on the upper and right surfaces of the slab corner and the reaction heating between oxygen and heated iron along the corner, respectively. The simulation results show that the length is 58.1 mm and 57.9 mm on both sides and the corner melting depth is 29.9 mm. The error is 7.04%. The numerical simulation results showed good agreement with the factory trial results, indicating that the proposed models of the flame jet and the heat sources analysis are feasible to study the flame cleaning process of the slab corner, it provides the scientific theoretical basis for the design and practical application of corner scarfing machine. [ABSTRACT FROM AUTHOR]

Argon gas injection into a continuous casting mold facilitates many factors related to smooth and long casting sequences by reducing nozzle clogging, improvements in steel cleanliness by inclusion floatation, etc. However, an unoptimized gas flow rate may deteriorate the cast slab quality through mold slag exposure, slag entrapment into the solidifying shell, etc. Formation of mold slag open eyes (MSOE) removes the protective slag layer to invite the issue of liquid steel reoxidation. Different MSOE formations were observed at varying flow conditions through physical modeling experiments. Total MSOE area helps in determining the extent of reoxidation. This study aims to predict the dimensionless MSOE area by developing a macroscopic mechanistic model which results in a model equation in terms of a "densimetric Froude number (FrD,m)" and two unknown arbitrary constants. To close this equation, FrD,m is obtained by evaluating its unknown characteristic, i.e., mold plume velocity (Ump). It was calculated at different gas flow rates (Qg) using shadow-imaging technique applied on a 1:7 scale water model. Average velocity of bubbles (approximated as Ump) in plume was estimated by individual bubble tracking using an ImageJ macro validated against the manually calculated Ump. Then, FrD,m was calculated using both manual and automatic Ump values. In separate water modeling experiments, total MSOE areas at same Qg values were obtained. Then, dimensionless MSOE area was calculated by dividing this total MSOE area by total plume area. Dimensionless area was correlated with manual and automatic FrD,m. This correlation is compared with the model equation, and arbitrary constants were obtained to close the model equation. Finally, a zone-wise mean bubble size analysis was introduced to strengthen the assumption regarding the probable location of MSOE. [ABSTRACT FROM AUTHOR]

Reducing the volume of distributing chamber by shortening its width is one of the ways to obtain good metallurgical effects for a large two-strand induction heating tundish. A multi-field coupling numerical model was established to figure out the effect of distributing chamber volume on the flow field, temperature field of molten steel, and removal of inclusions. Three tundishes with distributing chamber widths of 1.216 m (tundish A), 0.838 m (tundish B), and 0.606 m (tundish C) were modeled. The results indicated that reducing the width of the distributing chamber from 1.216 m to 0.838 and 0.606 m could improve the fastest heating rate from 0.4 K/min to 0.6 and 0.8 K/min and reduce the energy consumption from 476 kWh to 444 and 434 kWh. The temperature fluctuation of molten steel in the distributing chamber rose with the decrease in distributing chamber volume during the continuous casting process. Besides, tundish B performs the best temperature uniformity. The flow field in the distributing chamber was no longer symmetrical, and a short-circuit flow appeared when the width was reduced to 0.606 m. As a result, the floating ratio and removal ratio of inclusions decreased and the ratio of inclusions flowing into the mold sharply increased in tundish C. When the width was reduced from 1.216 to 0.838 m, the floating ratio of inclusions had little change and the removal ratio increased slightly. The floating efficiency increased with the decrease in the volume of distributing chamber, and the removal efficiency is the highest in tundish B. Taken together, tundish B should be adopted. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Mold slag entrainment during the continuous casting process presents a late stage source of non-metallic inclusions (NMI) with a high likelihood of ending up in the final product. The reaction between the entrained slag phase and surrounding liquid steel in the continuous casting mold affects the inclusion morphology and properties. However, there is a lack of information on the kinetics of the NMI-steel reaction. A novel approach, utilizing controlled synthetic inclusion/metal samples, has been developed to study the reactions between free inclusion-slag droplets and steel. The technique combines High-Temperature Confocal Scanning Laser Microscopy (HT-CSLM), X-ray Computed Tomography (XCT) and advanced electron microscopy techniques offering rapid controlled heating performance and extensive characterization of the samples. This method offers the ability to observe the size, shape and composition of an unconstrained reacting inclusion and to investigate the interface between the materials with respect to reaction time. This study interrogates a low aluminum steel (0.04 wt pct) and a high aluminum steel (1 wt pct) in contact with an inclusion-slag phase with a starting composition aligned to a typical mold slag. It was found that the reaction between silica and aluminum across the interface of the two phases provided a driving force for spontaneous emulsification to occur. Products of such emulsification will have a significant effect on the inclusion size distribution and potentially the prevalence of inclusion retention in molten steels solidifying in the continuous caster (for example if emulsified buoyancy forces are reduced to near zero) and hence in the subsequent solid product. [ABSTRACT FROM AUTHOR]

In the current study, the transient fluid flow pattern in steel continuous casting molds with varied dimensions was evaluated using nail board measurement and onsite top flux observation. Effects of steel throughput, argon flow rate, submergence depth of the submerged entry nozzle, and mold dimension on the flow pattern inside the mold were investigated. The top flux under lower steel throughput, higher gas flow rate, and shallower submergence depth of the submerged entry nozzle were easily swept away by argon bubbles so that the molten steel was exposed to the air, called exposed eyes. Linear fitting equations between the steel throughput and the gas volume percentage for the transient flow pattern were performed. The critical linear relationships of the double roll flow pattern transformed to the complex flow, and the complex flow transformed to the single roll flow pattern. Flow pattern regimes were plotted with the results of the industrial measurements. The present work aimed at providing an operating interval of the steel throughput and the gas volume percentage to maintain the double roll flow pattern inside the mold for the regular casting practice. [ABSTRACT FROM AUTHOR]

Electroslag remelting (ESR) technology has been adopted to recycle the rejected electrolytic manganese metal scrap. In this study, a transient 3D coupled numerical model accounting for the electromagnetism, multiphase flow, heat transfer, and solidification was elaborated and used to simulate the evaporation behavior of the molten manganese metal (MM) during the ESR process. The volume of fluid approach was employed to capture the interfaces between the gaseous manganese, molten slag, and molten MM. The evaporation rate of the molten MM was defined by applying the Lee model, while the enthalpy-porosity formulation described the solidification. An industrial experiment via a commercial-scale ESR furnace was conducted for the model validation. The research findings indicate that the molten MM's evaporation occurs during the droplet falling and in the metal pool. Then, gaseous manganese bubbles ascend to the molten slag-free surface, thus promoting the melt movement, especially the slag-metal pool interface fluctuation. The evaporation rate of the molten MM is promoted by the increased applied current and the reduced ambient gauge pressure. The recycling ratio drops from 81.75 to 71.79 pct with the applied current increase from 3000 to 4000 A and drops from 78.19 to 73.71 pct with the ambient gauge pressure reduction from 0 to − 1000 Pa. [ABSTRACT FROM AUTHOR]

Slag entrainments in a continuous casting mold result in serious defects in steel products. Most previous studies concentrated on the magnitude of meniscus velocity or transient roll cell motion to investigate the cause of slag entrainment. However, slag entrainment is more directly connected with the meniscus vortex, which accompanies a meniscus deformation (e.g., vortex dimple or core). Most previous numerical studies on the meniscus vortex were conducted using a single-phase flow analysis; thus, the effect of meniscus deformation was never examined. This study conducts a multiphase flow simulation by employing a free-surface-capturing technique, and succeeds in reproducing the meniscus vortex core in the mold. The core depth and onset condition for the meniscus vortex obtained by the present numerical study show good agreements with the experimental results. The vorticity distribution on the mold meniscus and meniscus vortex patterns according to flow asymmetry are also dealt with herein. [ABSTRACT FROM AUTHOR]

The general flow characteristics of the molten steel and the behavior of molten steel and liquid slag interface (level fluctuation) in the mold with a new type of electromagnetic brake, freestanding adjustable combination electromagnetic brake (FAC-EMBr), was investigated by numerical simulation. The influences of the magnetic induction intensity, the submerged entry nozzle (SEN) immersion depth, the SEN port angle, and casting speed on the effect of FAC-EMBr are investigated. The results show that electromagnetic field formed by FAC-EMBr can cover the jet flow impact region, the upward backflow region, and the meniscus region simultaneously. With the increase of magnetic flux density, the jet flow impact intensity and the molten steel velocity in the upward and downward backflow regions are effectively suppressed, the meniscus wave height also decreases gradually, and the level fluctuation tends to be stable. For the influence of SEN port angle and SEN depth on the effect of FAC-EMBr mold, the results show that the molten steel velocity in the three main influence regions are all effectively depressed with increase of the value of SEN port angle and SEN depth. Even though under the condition of high casting speed (VC = 2.2 m/min), the application of FAC-EMBr can achieve effective braking effect. [ABSTRACT FROM AUTHOR]

POSCO's advanced CASting Technology (PoCAST) is an innovative molten mold flux feeding technology which has been developed to ensure quality of continuously-cast Twinning-Induced Plasticity (TWIP) steel and Ultra-low carbon steels (ULCSs). Stable qualities of ULCS slabs could be achieved by reducing mold flux entrapments by optimizing the range of slag pool depth; this result matches well with entrapment characteristics during 0.6 scale water model tests. Also, uniform solidification at the meniscus with shallower depth of oscillation mark and subsurface hook depth was performed in optimum range of slag pool depth. Thermal plasma melting furnace feeding facility has been developed to control the slag pool depth in the mold by increasing the melting rate. The proposed optimized range of slag pool depth was verified in a commercial trial by realizing thickness control of slag pool depth during ULCS production. [ABSTRACT FROM AUTHOR]

The distribution of surface macro-inclusions is an important parameter that can directly influence the surface quality of IF steel sheets. In the present work, macro-inclusions > 100 μm within a 20-mm zone from the slab surface across the whole slab width were characterized by step machining methods, and the total analyzed area was 3,300,000 mm2. Three kinds of macro-inclusions were detected: bubbles (including single and aggregated), alumina associated with bubbles and refractory-related alumina. The three-dimensional distribution of surface macro-inclusions across the whole slab width was reconstructed, which showed macro-inclusions along the thickness direction almost concentrated 8 to 20 mm from the slab surface, corresponding to the center of the upper roll zone and stagnant zone below the submerged entry nozzle bottom according to the full-scale water mold model simulation. An inclusion stability model was established that indicated that increasing the flow velocity sharply decreased the stability degree at the solidification front because of the washing effect. The calculated results by this model agree with the fact that macro-inclusions were mainly concentrated in the slab center because of the low flow velocity at this location. The present work indicates that increasing the flow velocity at the solidification front as well as eliminating the stagnant zone is a potential way to improve the surface quality of IF steel slabs. [ABSTRACT FROM AUTHOR]

Multi-hole ceramic filter is regarded as an effective and cheap method of additional flow control device in tundish. In order to evaluate the performance of the ceramic filter, a transient three-dimensional (3D) comprehensive numerical model has been developed to study the flow pattern, temperature distribution and residence time of the molten steel, as well as the elimination of inclusion in a full size two-strand tundish. One-way coupled Euler–Lagrange approach with random walk model was adopted to track the inclusion motion trajectory. The gravity, buoyancy, drag, virtual mass, lift, pressure gradient, and rebound forces were included. The inclusion Reynolds number was utilized for the judgment of the inclusion separation at the slag-steel interface and the internal surface of the filter hole. Besides, the residence time distribution curve has been analyzed for figuring out the macroscopic mixing of the molten steel. The results indicate that the ceramic filter increases the flow resistance of the molten steel in the tundish, resulting in a longer residence time and a higher temperature drop. Except removed by the covering molten slag, the inclusion could also be trapped by the filter hole when the molten steel travels through the ceramic filter. The elimination of the smaller inclusion is significantly improved. The removal ratio of the 1 μm inclusion in the tundish without ceramic filter is only 59.3 pct, while the value is improved to 65.3 pct if we apply the ceramic filter with slenderness ratio of 3 to the tundish. And with the slenderness ratio changing from 3 to 5, the removal ratio of the 1 μm inclusion increases from 65.3 to 72.0 pct. Additionally, the ceramic filter could counteract certain side effects of the increasing inclusion density on the removal, especially for the smaller inclusion. With the inclusion density increasing from 3990 to 5000 kg/m3, the removal ratio of the 1 μm inclusion decreases by 14.5 pct in the tundish without ceramic filter, and after using the ceramic filter, the removal ratio decreases by 13.0, 7.4, and 5.0 pct with the slenderness ratio varies from 3 to 5. [ABSTRACT FROM AUTHOR]

In order to recognize the dripping and the carburizing behaviors of the molten iron within the coke packed bed in the flash ironmaking process, a transient three-dimensional numerical model was developed. The volume of fluid (VOF) approach is used to describe the movement of the molten iron and the argon gas. The porous medium module is employed to define the momentum, heat, and mass transfer between the coke packed bed and the molten iron. Moreover, a factor is introduced to consider the influence of the ash film on the carburization process. A reasonable agreement between the experiment and simulation is obtained. The results indicate that the molten iron flows downward from the upper crucible to middle crucible. After entering the middle crucible, the molten iron spreads around within the coke packed bed and simultaneously moves downward. The carbon is, therefore, transferred from the coke to the molten iron. With the 47-mm-height coke packed bed, the carbon content in the molten iron after the carburization decreases from 3.19 to 1.97 pct, while the coke diameter ranges from 2 to 5 mm. With the 2-mm-diameter coke, the carbon content in the molten iron after the carburization increases from 2.84 to 4.81 pct, while the coke packed bed height increases from 37 to 97 mm. [ABSTRACT FROM AUTHOR]

Scale-adaptive simulation (SAS) of the transient gas-liquid two-phase flow in a laboratory-scale continuous-casting mold is presented. The main objective is to investigate the applicability of the scale-adaptive unsteady Reynolds-averaged Navier-Stokes turbulent model (URANS SAS) for predicting the transient multiscale turbulent structures in a two-phase flow. Good quantitative agreements with the experimental data and the large eddy simulation (LES) results are obtained both for the time-averaged velocity field and for the transient turbulent characteristics. The introduction of the von Karman length-scale into the turbulence-scale equation allows the SAS model to dynamically adjust to the resolved turbulent structures. The LES-like pulsating behavior of the air gas and the large-scale liquid eddy magnitudes in the unsteady regions of flow field are captured by the SAS model. The classical − 5/3 law of power spectrum density (PSD) of the axial velocity is kept properly for the single-phase turbulent flow. For two-phase flow, the decay of PSD is too steep at the high-frequency region; the predicted PSD obtained with SAS is damped stronger than that estimated by LES. The SAS model offers an attractive alternative to the existing LES approach or to the other hybrid RANS/LES models for strongly unsteady flows. [ABSTRACT FROM AUTHOR]

Gas injection into a ladle shroud is a practical approach to produce micro-bubbles in tundishes, to promote inclusion removal from liquid steel. A semi-empirical model was established to characterize the bubble formation considering the effect of shearing action combined with the non-fully bubble break-up by turbulence. The model shows a good accuracy in predicting the size of bubbles formed in complex flow within the ladle shroud. [ABSTRACT FROM AUTHOR]

In continuous casting of steel, argon gas is often injected to prevent clogging of the nozzle, but the bubbles affect the flow pattern, and may become entrapped to form defects in the final product. Further, an electromagnetic field is frequently applied to induce a braking effect on the flow field and modify the inclusion transport. In this study, a previously validated GPU-based in-house code CUFLOW is used to investigate the effect of electromagnetic braking on turbulent flow, bubble transport, and capture. Well-resolved large eddy simulations are combined with two-way coupled Lagrangian computations of the bubbles. The drag coefficient on the bubbles is modified to account for the effects of the magnetic field. The distribution of the argon bubbles, capture, and escape rates, are presented and compared with and without the magnetic field. The bubble capture patterns are also compared with results of a previous RANS model as well as with plant measurements. [ABSTRACT FROM AUTHOR]

An innovative method for separating non-metallic inclusions from a high temperature melt using super gravity was systematically investigated. To explore the separation behavior of inclusion particles with densities less than that of metal liquid under a super-gravity field, a Fe-Al-O melt containing AlO particles was treated with different gravity coefficients. AlO particles migrated rapidly towards the reverse direction of the super gravity and gathered in the upper region of the sample. It was hard to find any inclusion particles with sizes greater than 2 μm in the middle and bottom areas. Additionally, the oxygen content in the middle region of the sample could be reduced to 0.0022 mass pct and the maximum removal rate of the oxygen content reached 61.4 pct. The convection in the melt along the direction of the super gravity was not generated by the super-gravity field, and the fluid velocity in the molten melt consisted only of the rotating tangential velocity. Moreover, the motion behavior of the AlO particles was approximatively determined by Stokes' law along the direction of super gravity. [ABSTRACT FROM AUTHOR]

Poly(vinyl chloride) (PVC) is one of the major thermoplastics and many scientific and technological efforts have been performed by the incorporation of different additives. The main purpose of this work is the design, fabrication, and experimentally characterization of PVC ternary composites. Acrylonitrile-butadiene-styrene (ABS) core-shell rubber particles and nano-CaCO3 particles were employed to modify hard PVC simultaneously. Transmission electron microscopy (TEM), scanning electron microscope (SEM), and mechanical test were used to evaluate the properties of the composites. Mathematical models for the mechanical properties of PVC ternary composites were investigated by using a method combining design of experiments (DOE), Kriging surrogate model, and data analysis to investigate the various weight ratios addition of nano-CaCO3 and ABS on the mechanical properties of compounded PVC and predict mechanical properties associated to the studied composites. Benefiting from the proposed strategy, more reliable results and accurate predictions of mechanical properties of the nanocomposites can be extracted from Kriging surrogate model. POLYM. ENG. SCI., 56:1109-1117, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The deformation behavior of isotactic polypropylene (iPP) spherulites with uniaxial stretching was investigated at different drawing temperatures via in situ polarized optical microscope (POM) observation. The iPP spherulites were prepared by two procedures: cooled to the room temperature from melt and annealed at 135, 140, and 145°C for 3 h. It was found that the crystallization conditions dominate the crystalline morphology and even the tensile properties of iPP. For iPP which crystallized during cooling progress, the spherulites were imperfect and the boundaries of the spherulites were diffuse, displaying good toughness at various drawing temperatures. For iPP annealed at high temperatures displayed the brittle fracture-modes and the crack happened between spherulites, which due to the large and perfective spherulites have thick lamellas and weak connection at interspherulitic boundary. The shape and size of the iPP spherulites formed at 140 and 145°C are affected with uniaxial stretching till to the fracture of the samples at different drawing temperatures. The spherulites obtained at 135°C are deformed along the drawing direction at 100°C but not affected at low drawing temperatures, indicating the toughness increased with the increase of the drawing temperatures. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Arca subcrenata Lischke is a marine traditional Chinese medicine. The study investigated the antitumor effects of P2, a polypeptide fraction from A. subcrenata, and its toxicity in vitro and in vivo. The results showed that P2 could inhibit the proliferation of seven tumor cell lines, especially in HeLa and HT-29 cell lines. The IC50 values were 11.43 µg/mL for HeLa and 13.00 µg/mL for HT-29 treated by P2 for 48 h. P2 had little cytotoxicity on normal liver cells (L-02). The maximum tolerated dose (MTD) of P2 on KM mice was 1000 mg/kg by i.p. or i.v. The tumor growth inhibitory ratios of P2 were 26.4%, 41.4% and 46.4% for H-22, and 34.0%, 45.8% and 60.1% for S-180 tumor-bearing mice. The results demonstrated that P2 might be a potential antitumor agent with high efficiency in dose-dependent and time-dependent manners and low toxicity. [ABSTRACT FROM AUTHOR]

The incorporation of carbon nanotubes (CNTs) is expected as an effective path for tailoring mechanical properties of polymer blends. In this study, acid-modified multiwalled CNTs (A-MWCNTs) were introduced into polystyrene/maleic anhydride- g-(styrene-ethylene-butadiene-styrene) (PS/SEBS-MA) blends. By altering the mass ratio of PS/SEBS-MA from 80/20 to 60/40, the biphase structure of blend was changed from sea-island-like type to quasi co-continuous structure, of different mechanical behaviors. In 80/20 mass ratio, the impact strength was improved while the tensile strength was unchanged with increasing A-MWCNTs content, whereas a simultaneously toughening and strengthening effect was achieved for the compound with 60/40 mass ratio. Scanning electron microscopy, polarized light microscopy, dynamic mechanical analysis, and rheological measurements were carried out to detect the distribution of A-MWCNTs in the blends. The results demonstrated as increasing the nanotube loading from 0 to 3 wt%, A-MWCNTs might gradually migrate into continuous PS phase in 80/20 mass ratio, due to the low content of SEBS-MA, while they were totally packed in SEBS-MA region within the entire loading range used in 60/40 mass ratio due to its high content of SEBS-MA. This study provides guidance on the design and preparation of high performance ternary polymer/elastomer/inorganic filler composites. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the effects of the processing parameters that were applied to a twin screw extruder on the morphology and impact strength of poly(butylene terephthalate) (PBT)/acrylonitrile-butadiene-styrene (ABS) blends. The study found that increased feed rate decreased ductile brittle transition temperature (DBTT) and increased room temperature impact strength (RTIS). It concluded that the variation of DBTT between PBT/ABS can be correlated to the variation of the degree of rubber particles distribution.

In the present work, the flow field in a slab continuous casting mold with thicknesses of 180 and 250 mm are compared using high temperature quantitative measurement and numerical simulation. The results of the numerical simulation are in agreement with those of the high temperature quantitative measurement, which verifies the accuracy and reliability of the numerical simulation. Under the same working conditions, the velocities near the mold surface with the thickness of 180 mm were slightly higher than those of the mold with the thickness of 250 mm. The flow pattern in the 180 mm thick mold maintains DRF more easily than that in 250 mm thick mold. The kinetic energy of the jet dissipates faster in the 250 mm thick mold than in the 180 mm mold. For double-roll flow (DRF), as the argon gas bubbles can be flushed into the deeper region under the influence of strong jets on both sides, the argon bubbles distribute widely in the mold. For single-roll flow (SRF), as the argon bubbles float up quickly after leaving the side holes, the bubble distribution is more concentrated in the width direction, which may cause violent interface fluctuation and slag entrainment. The fluctuation at the steel-slag interface in the mold with 180 mm thickness is greater than that in the mold with 250 mm thickness but less than 5 mm. The increase of mold thickness may lead to a decrease of the symmetry of the flow field in the thickness direction and uniformity of mold powder layer thickness. In summary, the steel throughput should be increased in the 250 mm thick mold compared with that in the 180 mm thick mold. [ABSTRACT FROM AUTHOR]

A comprehensive transient model is developed to study the effect of electrode rotation on the evolution of metal pool profiles and the solidification quality of ESR ingots. Magnetohydrodynamic flow, heat transfer, solidification, and electrode melting are considered simultaneously in the model. The growth of the ESR ingot is predicted using the dynamic layering method. The numerical results show that the productivity reaches a maximum of 15.97% at the rotating speed of 40 rpm without increasing power. With the increasing rotating speed, the maximum temperature of the melt decreases, and the temperature distribution becomes more uniform. Compared with the static one, the pool profiles are flattened by −1.19%, −8.52%, and 12.44% at the rotating speeds of 20, 40, and 60 rpm, respectively. The metal pool profile was improved remarkably, but only at the higher speed (i.e., 60 rpm). The effect of rotating speed on the metal pool profile depends on the competition between the melting rate and slag temperature. Meanwhile, the local solidification time and the secondary dendrite arm spacing are slightly improved at lower rotating speeds but are significantly worse at higher rotating speeds. [ABSTRACT FROM AUTHOR]

In this paper, the rod deflection method was applied to quantitatively measure velocity near the mold surface at high temperatures and the k-ε model coupled with a discrete phase model (DPM) was adopted to simulate the flow field in the mold. The calculated results match very well with the measured results under all the present conditions. Under the conditions of the large mold width of 1800 mm, 1.1 m/min casting speed and 140 mm submerged entry nozzle (SEN) immersion depth, the velocity near the mold surface decreases with increasing the argon gas flow rate. When the argon gas flow rate is 6 L/min, the flow pattern is the double roll flow (DRF). When the argon gas flow rate is increased to 10 L/min and 14 L/min, the flow pattern is the single roll flow (SRF), and the risk of slag entrainment increases. With an argon gas flow rate of 10 L/min, and an immersion depth of 160 mm, the velocity near the mold surface sensitively increases with increasing the casting speed. When the casting speed is 1.1 m/min, an intermediate flow (IF) is formed with the intensified mold surface fluctuation, which can easily result in slag entrainment defects. When the casting speed is only increased to 1.2 m/min, the velocity near the mold surface changes drastically and is close to the upper limit velocity of 0.4 m/s. When the casting speed is 1.1 m/min, and the argon gas flow rate is 10 L/min, the velocity near the mold surface is obviously increased with increasing the immersion depth. When the immersion depth of the nozzle increases from 140 mm and 160 mm to 180 mm, the flow pattern changes from SRF or IF to DRF. When the bottom shape of the SEN changes from mountain to well, the velocity near the mold surface decreases. We suggest adopting the well-bottom nozzle to reduce the risk of slag entrainment. [ABSTRACT FROM AUTHOR]

A mathematic model considering the bubble coalescence and breakup using the Euler-Lagrange approach has been developed to study the effect of the initial bubble size on the distribution of bubbles captured by the solidification shell. A hard sphere model was applied for dealing with the bubble collision. Advanced bubble coalescence and breakup models suitable for the continuous casting system and an advanced bubble captured criteria have been identified established with the help of user-defined functions of FLUENT. The predictions of bubble behavior and captured bubble distribution agree with the water model and plant measurements well respectively. The results show that the number of small bubbles captured by solidification shell is much higher than that of large bubbles. What is more, the number of captured bubbles at the sidewalls decreases with the distance from the meniscus. For the case of large gas flow rate (gas flow fraction of 8.2%), the initial size of bubbles has little effect on bubble captured distribution under various casting speeds. When the gas flow rate is small (gas flow fraction of 4.1%), the number density of captured bubbles increases as the initial bubble size increases, and the effect of initial bubbles size on captured bubble number density is amplified when the casting speed decreases. The average captured bubble diameter is about 0.12–0.14 mm. Additionally, for all cases, the initial bubble size hardly affects the average size of captured bubbles. [ABSTRACT FROM AUTHOR]

Carbon source precursors for high-grade, clean, and low-carbon refractories were obtained by in situ exfoliation of flake graphite (FG) and phenol–formaldehyde resin (PF) composites with three-roll milling (TRM) for the fabrication of graphite nanoplatelets. In addition, by using Ni(NO3)2·6H2O as a catalyst in the pyrolysis process, multidimensional carbon nanostructures were obtained with coexisting graphite nanoplatelets (GNPs), glassy carbon (GC), and carbon nanotubes (CNTs). The resulting GNPs (exfoliated 16 times) had sizes of 10–30 μm, thicknesses of 30–50 nm, and could be uniformly dispersed in GC from the PF pyrolysis. Moreover, Ni(NO3)2·6H2O played a key role in the formation and growth of CNTs from a catalytic pyrolysis of partial PF with the V–S/tip growth mechanisms. The resulting multidimensional carbon nanostructures with GNPs/GC/CNTs are attributed to the shear force of the TRM process, pyrolysis, and catalytic action of nitrates. This method reduced the production costs of carbon source precursors for low-carbon refractories, and the precursors exhibited excellent performances when fabricated on large scales. [ABSTRACT FROM AUTHOR]

This paper reviews the current state of the art in the application of electromagnetic forces to control fluid flow to improve quality in continuous casting of steel slabs. Many product defects are controlled by flow-related phenomena in the mold region, such as slag entrapment due to excessive surface velocity and level fluctuations, meniscus hook defects due to insufficient transport of flow and superheat to the meniscus region, and particle entrapment into the solidification front, which depends on transverse flow across the dendritic interface. Fluid flow also affects heat transfer, solidification, and solute transport, which greatly affect grain structure and internal quality of final steel products. Various electromagnetic systems can affect flow, including static magnetic fields and traveling fields which actively accelerate, slow down, or stir the flow in the mold or strand regions. Optimal electromagnetic effects to control flow depends greatly on the caster geometry and other operating conditions. Previous works on how to operate electromagnetic systems to reduce defects are discussed based on results from plant experiments, validated computational models, and lab scale model experiments. [ABSTRACT FROM AUTHOR]