scholarly journals Diffusive steel scrap melting in carbon-saturated hot metal—phenomenological investigation at the solid–liquid interface

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1358 ◽  
Author(s):  
Penz ◽  
Schenk ◽  
Ammer ◽  
Klösch ◽  
Pastucha ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Carbon Concentration ◽  
Steel Production ◽  
Production Optimization ◽  
Steel Scrap ◽  
Process Conditions ◽  
Hot Metal ◽  
Scrap Melting ◽  
Solid Liquid Interface ◽  
Solid Liquid

The oxygen steelmaking process in a Linz-Donawitz (LD) converter is responsible for more than 70% of annual crude steel production. Optimization of the process control and numerical simulation of the LD converter are some of the current challenges in ferrous metallurgical research. Because of the process conditions and oxidation of impurities of the hot metal, a lot of chemical heat is generated. Therefore, steel scrap is charged as a coolant with the economical side aspect of its recycling. One of the more complex aspects is, among others, the dissolution and melting behaviour of the scrap in carbon-saturated hot metal. Heat and mass transfer act simultaneously, which has already been investigated by several researchers using different experimental approaches. The appearances at the interface between solid steel and liquid hot metal during diffusive scrap melting have been described theoretically but never investigated in detail. After an experimental investigation under natural and forced convective conditions, the samples were further investigated with optical microscopy and electron probe microanalysis (EPMA). A steep carbon concentration gradient in the liquid appeared, which started at an interface carbon concentration equal to the concentration on the solid side of the interface. Moreover, the boundary layer thickness moved towards zero, which symbolized that the boundary layer theory based on thermodynamic equilibrium was not valid. This fact was concluded through the prevailing dynamic conditions formed by natural and forced convection.

scholarly journals Investigation of Peritectic Solidification Morphologies by Using the Binary Organic Model System TRIS-NPG

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 966
Author(s):  
Johann P. Mogeritsch ◽  
Mehran Abdi ◽  
Andreas Ludwig
Keyword(s):  
Growth Conditions ◽  
Model System ◽  
Process Conditions ◽  
Competitive Growth ◽  
Diffusive Growth ◽  
Β Phase ◽  
Α Phase ◽  
Peritectic Solidification ◽  
Solid Liquid Interface ◽  
Solid Liquid

Under pure diffusive growth conditions, layered peritectic solidification is possible. In reality, the competitive growth of the primary α-phase and the peritectic β-phase revealed some complex peritectic solidification morphologies due to thermo-solutal convection. The binary organic components Tris-(hydroxylmenthyl) aminomethane-(Neopentylglycol) were used as a model system for metal-like solidification. The transparency of the high-temperature non-faceted phases allows for the studying of the dynamic of the solid/liquid interface that lead to peritectic solidification morphologies. Investigations were carried out by using the Bridgman technic for process conditions where one or both phases solidify in a non-planar manner. Different growth conditions were observed, leeding to competitive peritectic growth morphologies. Additionally, the competitive growth was solved numerically to interpret the observed transparent solidification patterns.

scholarly journals Process Improvements for Direct Reduced Iron Melting in the Electric Arc Furnace with Emphasis on Slag Operation

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 402
Author(s):  
Marcus Kirschen ◽  
Thomas Hay ◽  
Thomas Echterhof
Keyword(s):  
Steel Production ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Raw Material ◽  
Steel Scrap ◽  
Process Conditions ◽  
Arc Furnace ◽  
Process Improvements ◽  
Direct Reduced Iron ◽  
Arc Furnaces

Steelmaking based on direct reduced iron (DRI, and its compacted derivative hot briquetted iron, HBI) is an anticipated important global alternative to current steel production based on FeOx reduction in blast furnaces due to its lower specific CO2 emission. The majority of DRI is melted and refined in the electric arc furnace with different process conditions compared to the melting of steel scrap due to its raw material composition being rather different. We provide data and analysis of slag composition of DRI charges vs. steel scrap charges for 16 industrial electric arc furnaces (EAFs). Suggestions for optimized slag operation and resulting process improvements of DRI melting in the EAF are given. A dynamic mass and energy model of the DRI melting in the EAF is introduced to illustrate the implications of the adapted slag operation on the EAF process with DRI charges.

scholarly journals Investigation on Peritectic Solidification Morphologies by Using the Binary Organic Model System TRIS-NPG

2020 ◽  
Author(s):  
Johann P. Mogeritsch ◽  
Mehran Abdi ◽  
Andreas Ludwig
Keyword(s):  
Beta Phase ◽  
Growth Conditions ◽  
Model System ◽  
Process Conditions ◽  
Competitive Growth ◽  
Solutal Convection ◽  
Diffusive Growth ◽  
Peritectic Solidification ◽  
Solid Liquid Interface ◽  
Solid Liquid

Under pure diffusive growth conditions, layered peritectic solidification is possible. In reality, the competitive growth of the primary alfa-phase and the peritectic beta-phase revealed some complex peritectic solidification morphologies due to thermo-solutal convection. The binary organic components TRIS-NPG were used as model system for metal-like solidification. The transparency of the high-temperature non-faceted phases allows studying the dynamic of the solid/liquid interface which lead to peritectic solidification morphologies. Investigations were carried out by using the Bridgman technic for process conditions where one or both phases solidify in a non-planar manner. Different growth conditions were observed which led to competitive peritectic growth morphologies. Additionally, the competitive growth was solved numerically to interpret the observed transparent solidification patterns.

Impact of Thermal Transport on Silicon Carbide Formation/Engulfment During Directional Solidification of Si

2012 ◽  
Author(s):  
Xu Ma ◽  
Hui Zhang ◽  
Lili Zheng
Keyword(s):  
Directional Solidification ◽  
Carbon Concentration ◽  
Thermal Transport ◽  
Solidification Rate ◽  
Carbon Accumulation ◽  
Carbide Formation ◽  
Melt Convection ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Sic Particle

This paper investigates thermal transport on SiC formation and engulfment in directional solidification of crystalline Si. A comprehensive computational model is developed which is capable of describing fluid and thermal transport, SiC particle formation/transport, and its pushing-engulfment near the solidification interface. It is found that the impurity of carbon concentration in the melt is affected by melt convection; the concave interface leads to the carbon accumulation in the central region near the interface; the size of the SiC particle when engulfed into solid Si is mainly determined by the solidification rate. The distributions of carbon concentration and SiC particles are determined by both melt convection, interface shape and solidification rate. The low solidification rate is not desirable for high quality Si crystal growth when the solid/liquid interface is concave.

scholarly journals Numerical Simulation of the Melting Behavior of Steel Scrap in Hot Metal

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 678
Author(s):  
Nanyang Deng ◽  
Xiaobin Zhou ◽  
Moer Zhou ◽  
Shiheng Peng
Keyword(s):  
Carbon Concentration ◽  
Vertical Direction ◽  
Bath Temperature ◽  
Melting Behavior ◽  
Melting Rate ◽  
Middle Part ◽  
Steel Scrap ◽  
Low Carbon ◽  
Carbon Distribution ◽  
Hot Metal

The current study focuses on the melting behavior of a scrap bar with low carbon content in hot metal which contains high carbon concentration by applying experiments and mathematical modelings. The experiments suggest that higher temperature is favorable for the melting of the bar and the melting rate of the bar is initially high while decreased to a relative stable level after 90 s in the current conditions. It can be found from the mathematical results that the bar temperature is increased near to bath temperature in about 20 s after it was immersed into the bath, and the temperature in the axis of the bar is not distributed evenly during the temperature increase stage. Moreover, the mathematical results shows that a bath circulation flow would be formed in the bath under the effects of temperature and carbon distribution during the melting process. The bath flow near the melting interface would influence the carbon concentration of the molten phase, in turn, affects the melting rate of the bar in the vertical direction. Both the experimental and mathematical results show that the melting rate in the upper part, which is in the upstream of the bath flow, is higher than that of the middle part, followed by the down part of the bar in the downstream of the flow, in which the carbon concentration is much lower than that of the bath. At this period, the main factor that dominate the bar melting is not the temperature but the carbon distribution at the melting interface after the bar temperature is increased to the bath temperature.

scholarly journals Scrap melting model for steel converter founded on interfacial solid/liquid phenomena

2017 ◽  
Vol 115 (2) ◽  
pp. 201 ◽  
Author(s):  
Ari Kruskopf ◽  
Lauri Holappa
Keyword(s):  
Mass Transfer ◽  
Process Model ◽  
Melting Rate ◽  
Phase Changes ◽  
Interface Model ◽  
Hot Metal ◽  
Scrap Melting ◽  
Carbon Mass ◽  
Steel Converter ◽  
Solid Liquid

The primary goal in steel converter operation is the removal of carbon from the hot metal. This is achieved by blowing oxygen into the melt. The oxidation of carbon produces a lot of heat. To avoid too high temperatures in the melt cold scrap (recycled steel) is charged into the converter. The melting rate is affected by heat and carbon mass transfer. A process model for steel converter is in development. This model is divided into several modules, which are fluid dynamics, heat- and mass-transfer, scrap melting and chemical reactions. This article focuses on the development of the scrap melting module. A numerical model for calculating temperature and carbon concentration in the melt is presented. The melt model is connected with the solid scrap model via solid/liquid interface. The interface model can take into account solidification of iron melt, melting of solidified layer, a situation without such phase changes, and scrap melting. The aim is to predict the melting rate of the scrap including the properties of the hot metal. The model is tested by calculating the melting rates for different scrap thicknesses. All of the stages in the interface model were taking place in the test calculations.

Analyses and Calculation of Steel Scrap Melting in a Multifunctional Hot Metal Ladle

2018 ◽  
Vol 90 (3) ◽  
pp. 1800435 ◽  
Author(s):  
Shuai Deng ◽  
Anjun Xu ◽  
Guang Yang ◽  
Hongbing Wang
Keyword(s):  
Steel Scrap ◽  
Hot Metal ◽  
Scrap Melting ◽  
Hot Metal Ladle

scholarly journals Analysis of Solid-Liquid Interface Behavior during Continuous Strip-Casting Process Using Sharp-Interface Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Changbum Lee ◽  
Wooyoung Yoon ◽  
Seungwon Shin ◽  
Jaewoo Lee ◽  
Hee-eun Song
Keyword(s):  
Liquid Interface ◽  
Strip Casting ◽  
Sharp Interface ◽  
Optimum Process ◽  
Process Conditions ◽  
Reconstruction Method ◽  
Interface Behavior ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Continuous Strip

Continuous strip casting (CSC) has been developed to fabricate thin metal plates while simultaneously controlling the microstructure of the product. A numerical analysis to understand the solid-liquid interface behaviors during CSC was carried out and used to identify the solidification morphologies of the plate, which were then used to obtain the optimum process conditions. In this study, we used a modified level contour reconstruction method and the sharp-interface method to modify the interface tracking, and we performed a simulation analysis to identify the differences in the material properties that affect the interface behavior. The effects of the process parameters such as the heat transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface are estimated and also used to improve the CSC process.

Atom-probe analysis of the solid-liquid interface

1995 ◽  
Vol 53 ◽  
pp. 676-677
Author(s):  
J.A. Panitz
Keyword(s):  
Molecular Level ◽  
Selective Adsorption ◽  
Electronic Devices ◽  
Atom Probe ◽  
Chemical Agent ◽  
Hostile Environment ◽  
Solid Interface ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Chemically Selective

The first few atomic layers of a solid can form a barrier between its interior and an often hostile environment. Although adsorption at the vacuum-solid interface has been studied in great detail, little is known about adsorption at the liquid-solid interface. Adsorption at a liquid-solid interface is of intrinsic interest, and is of technological importance because it provides a way to coat a surface with monolayer or multilayer structures. A pinhole free monolayer (with a reasonable dielectric constant) could lead to the development of nanoscale capacitors with unique characteristics and lithographic resists that surpass the resolution of their conventional counterparts. Chemically selective adsorption is of particular interest because it can be used to passivate a surface from external modification or change the wear and the lubrication properties of a surface to reflect new and useful properties. Immunochemical adsorption could be used to fabricate novel molecular electronic devices or to construct small, “smart”, unobtrusive sensors with the potential to detect a wide variety of preselected species at the molecular level. These might include a particular carcinogen in the environment, a specific type of explosive, a chemical agent, a virus, or even a tumor in the human body.

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