Yuriy Lytvynyuk, Elkem ASA, Norway

Co-Author:
Antonio De Pretto , Elkem
Bjørnar Larsen, Elkem

Abstract:
A transition of the steelmaking industry towards the green steel making and the reduction of CO2 emissions includes the substitution of the blast furnace route of pig iron production by melting of the Direct Reduced Iron (DRI) in electric furnaces, typically employed in ferroalloy smelting. Two types of furnace designs are presently offered by engineering companies, which operate in either an immersed electrode or brush arc mode configuration, but all of them are based on the application of Søderberg electrodes. Elkem Carbon Solutions, as the inventor of the Søderberg electrode technology, has over a century of experience in the operation of Søderberg electrodes in various pyrometallurgical processes and diverse configurations of electric furnaces. This paper provides an overview of the current features and latest trends in Søderberg electrodes, and their application within ferroalloy smelting, with a focus on the electrode operation under similar conditions to those envisaged for DRI smelters.

Mohammed Alzayer, SABIC, Saudi Arabia

Co-Author:
Mohamed Bahgat Saddik, SABIC

Abstract:
As indicated by the principles of green chemistry, synthesis of materials must be done in a way that avoids hazards. One of the challenges in producing DRI (direct reduced iron) in shaft furnace reactors is ignition of the DRI pellets after discharge. In this study, the oxidation behavior of DRI pellets was examined using different sources of raw iron ore. Each type was reduced in lab using different conditions of reduction temperatures, reducing gas compositions, and pellets’ sizes. After generating reduction curves and comparing the reduction behavior of these pellets, they were exposed to severe oxidizing environment in order to compare how each condition responds to oxidation.

Julia Fogelström, Swerim AB, Sweden

Co-Author:
Du Sichen, Hybrit Development AB

Abstract:
Direct reduction of iron ore using hydrogen is one process that can produce iron from virgin materials and at the same time reduce CO2 emissions. In a shaft furnace, iron ore pellets are loaded at the top while hydrogen is introduced at the lower part. Pellets are slowly passing through the reactor and experience a temperature gradient ranging from low to high, i.e., non-isothermal reduction. Only a handful of studies have been performed to investigate the effect of non-isothermal reduction, and none focus on systematic analysis. Very few comparisons between isothermal and non-isothermal reductions have been made. To better understand the kinetics of non-isothermal reduction for process optimization, a preliminary study including both non-isothermal and isothermal experiments using pure hydrogen is conducted. The reduction experiments are performed in a resistance-heated furnace at 1173 K or between 723-1173 K for the isothermal and non-isothermal experiments, respectively. Non-isothermal reduction is much slower than isothermal reduction, as expected. The heating rate greatly affects the reduction rate, increasing with increasing heating rate. The mechanisms during the isothermal and non-isothermal reductions are discussed and compared. The reduction rate slows down at the later stage of reduction. At this point, the non-isothermal reduction rate is lower compared to isothermal reduction. To further examine the effect of heating rates, the microstructure of reduced samples is studied using a scanning electron microscope. The microstructure develops over time as the pellet is reduced, this is true for both isothermal and non-isothermal reduction. The heating rates have a limited effect on the microstructure. It would be difficult to capture and model the reduction behavior using only isothermal reduction experiments. Thus, studying non-isothermal reduction is needed. When optimizing the reduction in a shaft furnace, considerable attention should be directed toward the effect of the heating rates.

Oscar Hessling, Swerim AB, Sweden

Co-Author:
Du Sichen, Hybrit Development AB
Niklas Kojola, Hybrit Development AB
Julia Brännberg Fogelström, Swerim AB
Johan Martinsson, Swerim AB

Abstract:
Hydrogen reduction of iron ore, to reduce carbon emissions in the steel industry, is a plausible way forward as focus on fossil free production increase. The CO2 byproduct, generated by carbon reduction, is negated and replaced with H2O. In a Hydrogen Direct Reduction shaft, both temperature and pH2O will vary over the shaft height. Lower temperature and higher pH2O found at the top. The reduction reaction with hydrogen is highly dependent on the temperature and pH2/pH2O ratio. Lower temperature and higher pH2O would result in a lower reduction rate. Since only a few systematic studies have been conducted, this work aims to study the effect of pH2O over a temperature range relevant to industrial practice. A resistance heated furnace and a water vapor generator is employed to investigate the 0-15% pH2O range, in the 600 °C – 900 °C temperature range. To produce reliable data, the water content in the gas must be accurately controlled. A system is carefully designed to ensure precise control of the water content in the reaction gas. To further the industrial context, industrially produced iron ore pellets are utilized. Thermal Gravimetric Analysis (TGA) is used to follow the reduction. To understand the reaction mechanisms, SEM is used to study the microstructure of partially reduced pellets. Results suggest the reduction rate is profoundly affected by water at low temperatures, less so when the temperature is increased. The microstructure is highly affected by pH2O at 600 °C, at higher temperatures the microstructure is largely unaffected. Reaction mechanisms are discussed based on the reduction curves and micrographs. The impacts of gas dilution and chemical reaction rate are evaluated.

Theresa Overbeck, VDEh-Betriebsforschungsinstitut GmbH, Germany

Co-Author:
Gregor D. Wehinger, Clausthal University of Technology
Martin Kutscherauer, Clausthal University of Technology
Michael Hensmann, VDEh-Betriebsforschungsinstitut GmbH

Abstract:
Increasing the use of hydrogen as reducing gas in direct reduction changes the reaction and operating conditions of the plant. Particle resolved computational fluid dynamics (PRCFD) offer insights into the surrounding gas flow and the reaction-diffusion mechanisms inside each pellet. As a first step, in this work a three-dimensional model of a single porous iron ore pellet is developed. The model represents the pore diffusion and internal stepwise reduction reactions from iron(III)-oxide to iron with hydrogen and carbon monoxide. The reactions are implemented in the gas and solid species and energy conservation equations. The model is flexible regarding the operating conditions (e.g. temperature), the initial pellet morphology, the initial gas and pellet composition and the gas composition at the pellet surface. The model allows the locally resolved investigation of the reduction progress inside a single porous iron oxide pellet. Radial differences in solid mass fractions go along with a varying porosity of the pellet. The influences of diffusion and reaction kinetics are investigated depending on temperature and gas and pellet composition. Especially, the diffusion of the produced water to the pellet surface can be a limiting factor and is further investigated. We will discuss these results with literature data and own analyzations of direct reduction pellets. In perspective, the model will be used for a PRCFD simulation of different reactor sections.

Noel Ladenthin, RWTH Aachen University , Germany

Co-Author:
Dieter Senk, RWTH Aachen University
Rongrong Wang, RWTH Aachen University
Hannes Drippe, RWTH Aachen University
Alexander Babich, RWTH Aachen University

Abstract:
In order to reduce CO2 emissions and make steel production more sustainable, many steel producers are currently planning to produce metallic iron for steel production using hydrogen-based direct reduction instead of carbon based reduction gas. Melting in electric arc furnaces demands low amounts of gangue in DRI to keep the slag volume low. In respect to this DR pellets with high iron concentration are required. On the other hand highly concentrated iron ore with increased basicity is less available compared to medium iron containing BF pellets with low basicity. IEHK at RWTH Aachen University is characterizing different BF-grade pellets and investigating the influence of texture on reducibility using hydrogen. The characterization is carried out with the aid of chemical analyses of the composition and investigations of the microstructure by microscopy. The reducibility of individual BF-grade pellets is studied in a laboratory furnace using different hydrogen concentrations. In addition, direct reduction tests were carried out using a test plant with a capacity of approx. 20 kg of iron ore pellets. This allows the consideration of mechanisms that may be observed in the reduction of a bulk but not in individual pellets and allows use for upscaling considerations. The results of the investigation can be applied to design further direct reduction processes with low-grade iron ore pellets.

Aidin Heidari, University of Oulu, Finland

Co-Author:
Timo Fabritius, University of Oulu
Mikko Iljana, University of Oulu

Abstract:
The study aimed to compare the reduction behavior of DRI (direct reduced iron) and blast furnace pellets in a CO-H2 atmosphere. The experiments were conducted under controlled conditions to evaluate the effect of temperature and CO-H2 ratio on the reduction process. The reduction rate and final degree of reduction were used as the main parameters to compare the performance of DRI and blast furnace pellets. The results showed that the reduction rate of DRI was much faster than that of blast furnace pellets, and the final degree of reduction was also higher for DRI. This can be attributed to the higher reactivity and porosity of DRI, which facilitates the transfer of gaseous reduction agents and results in a more complete reduction process. The study also found that increasing the temperature and CO-H2 ratio improved the reduction rate for both DRI and blast furnace pellets. However, DRI still showed better reduction performance compared to blast furnace pellets under all experimental conditions. The comparison of the reduction behavior of DRI and blast furnace pellets in a CO-H2 atmosphere highlights the advantages of using DRI as a raw material in the iron and steel industry. The results of this study demonstrate that DRI is a more favorable alternative to blast furnace pellets in the CO-H2 reduction process due to its higher reactivity, porosity, and reduction rate. The findings of this study can help optimize the reduction process and improve efficiency and could have important implications for the iron and steel industry, particularly for the production of high-quality steel products.

Ondrej Baco, Thermo Fisher Scientific Inc., Czech Republic

Co-Author:
Roger Maddalena, Thermo Fisher Scientific Inc.

Abstract:
At the end of the hot rolling process, microalloyed steel will form nanoscale precipitates of compounds such as NbC and TiN. These precipitates have the potential to improve properties by grain refinement and precipitation hardening. Precipitates with smaller size and higher number density typically yield higher strength. The rate of cooling after hot rolling will control the precipitation and coarsening of these particles. One of the challenges is to obtain a statistically meaningful distribution of their size, shape and composition as up to now this has only been possible with tedious, manual analysis. In this study an electron microscopy workflow is presented where the acquisition of images and chemical information is fully automated, even for overnight analysis on large area samples. The automated TEM allowed processing and comparing a statistically relevant number of particles (thousands) of steel lamellae samples from the coil head and coil middle. With these workflows, the time to improve processes and to develop a new steel product can be reduced and R&D manpower can be freed up for new responsibilities.

Seiji Morishige, KOBE STEEL, LTD. , Japan

Abstract:
In the Advanced and Ultra High-Strength Steel (AHSS, UHSS) strip annealing line, press flaws, called “Pick-up”, generated on the strip surface are sometimes caused by hard deposits on the surface of the furnace roll. If “Pick-up” occurs, strip line operation is interrupted for maintenance and an exchange of rolls. The investigation of the “Pick-up” mechanism and its suppression have been invented by using an experimental method in which the reaction of the steel surface-layered powder and the thermal spray layer were considered. However, in this experimental method, the contact state between rolls and steel strip was not reproduced. In the actual conditions, we assume that sliding contact is an important factor in the initial adhesion of pickup. We developed a simulator in which the contact state in the annealing line could be reproduced. The simulator has a mechanism to rotate rolls, while pressing the roll against the steel, and slide horizontally at the same time. In this simulator, a new surface of the strip and rolls can be in contact continuously while reproducing the sliding contact. The atmosphere and temperature of the simulator can be reproduced under the conditions of the actual equipment. The contact pressure between the roll and the steel can be controlled based on the load cell measurement. The test results from the simulator, showed that it was possible to reproduce the same adhesion form as the furnace roll deposit. In addition, it was confirmed that the time to initial adhesion differs depending on the steel grade and the conditions under which the film is changed. By using this simulator, we were able to select the optimum thermal spray layer and introduce it into the actual equipment, achieving an extension of the roll life by avoiding “Pick-ups”.

Nicolae Serban, University Politehnica of Bucharest, Romania

Co-Author:
Mariana Lucia Angelescu, University Politehnica of Bucharest
Vasile Dănuţ Cojocaru, University Politehnica of Bucharest
Elisabeta Mirela Cojocaru, University Politehnica of Bucharest
Irina Varvara Balkan, University Politehnica of Bucharest
Dana Mariana Serban, University Politehnica of Bucharest
Ovidiu Tanase, TURBOMECANICA S.A.
Robert Craciun, TURBOMECANICA S.A.

Abstract:
Shot peening is a very efficient treatment in order to increase fatigue resistance and prolong the life of metal components, while reducing tensile stresses induced by machining and heat treatment processes. The objective of the experimental research presented in the paper is to optimize the technology of mechanical treatment through shot-peening of aircraft parts made of 9310 VAR steel, in order to improve the efficiency of the process and obtain products of increased quality. The influence of the following industrial treatment parameters on the microstructural and mechanical characteristics of the samples was studied: the size of the shot balls, the working pressure and the exposure time. Steel metal balls with different diameters were used: d1 = 0.3 mm (ASR 110, 45-52 HRC) and d2 = 0.6 mm (ASR 230, 45-52 HRC). Also, two values were used for the working pressure (compressed air pressure): p1 = 3 bar and p2 = 5 bar. The exposure time of the samples to the shot-peening treatment varied between 5 - 35 minutes, as follows: t1 = 5 min, t2 = 15 min, t3 = 25 min and t4 = 35 min. The samples resulting from the laboratory experimentation of the designed technology were subjected to an advanced structural and mechanical characterization through XRD analysis, optical microscopy, SEM electron microscopy, microhardness tests and static tensile tests. The tensile strength (σUTS), the yield strength (σ0.2) and the elongation at break (εf) were measured. The results are interpreted and will be used for the fine adjustment of the working parameters and finally for establishing the optimal technological variant of mechanical surface treatment by shot-peening.

Kai K. O. Bär, adphos Innovative Technologies GmbH, Germany

Abstract:
Today mostly thermal metal and especially most surface processes are based on fossil heating systems, whether oil or gas fired. These convection heat transfer driven ovens and driers, build very large, provide limited energy efficiency, little size/width power adjustment and show low dynamic power control characteristics. In addition, a systems inherent CO2-emission footprint of 200 – 300 g per thermal kWh heating energy is generated. The proprietary fully electro-thermal aLITE – (advanced Light Initiated Thermal Emission) Technology, a proprietary high power photonic heating and drying system enables now alternative solutions for a wide range of heating processes (e.g. defined heating, even locally focused up to 1,500 °C, air, special atmosphere, vacuum) and various drying and curing applications (e.g. rinse water, water-based coatings, water/solvent even powder based paints and coatings). The aLITE-processing allows instantaneous on/off and fully defined processes. Dynamic adjustable to mass, size and geometry changes. No need for pre-heating or standby operation. The extreme compact and energy efficient systems operation justifies attractive upgrade/replacement projects. Based on an introduction of the work principle of the aLITE-technology, already realized examples in commercial metal processing lines (e.g. pickling, hot roll, annealing, coil coating) are shown and competitive evaluated with traditional solutions.

Stephan Schirdewahn, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

Co-Author:
Niels Carstensen, Federal Institute of Materials Research and Testing
Kai Hilgenberg, Federal Institute of Materials Research and Testing
Marion Merklein, Fraunhofer Institute for Manufacturing Technology and Advanced Materials

Abstract:
Hot stamping has been established in the automotive industry as a key technology for lightweight construction, regarding the manufacturing of safety-relevant car body components. Hot stamped parts are commonly made out of boron-manganese steel sheets 22MnB5, which are initially austenized and subsequently formed and quenched simultaneously. However, these cyclic thermo-mechanical loads encourage the formation of severe wear and high friction at the blank-die interface, which in turn leads to a time and cost consuming rework of the tool. For this purpose, a promising new approach named laser implantation process has been investigated for improving the tribological behavior of hot stamping tools. This technique enables the generation of highly wear resistant, separated and elevated features in micrometre range by embedding hard ceramic particles into the tool surface via pulsed laser radiation. As a result, the contact area between tool and surface and thus the tribological and thermal interactions are locally influenced. Within first studies, the effectiveness of the laser implantation process has already been proven in laboratory scale by means of modified pin-on-disk tests. However, the transferability of this surface engineering technology with regard to an industry-related deep drawing process has not been investigated in detail yet. For this purpose, a locally modified as well as a conventional die are utilized for hot stamping rectangular cups, in order to qualify the tribological impact of the laser implantation process by using an industry-related tooling system. To evaluate the tribological performance, the maximum punch forces of both tool configurations were compared in order to draw conclusions about the frictional behavior during the forming operation. In addition, hardness measurements were carried out as well as the resulting part geometry was scanned by means of the topometric 3D-sensor ATOS for analysing the mechanical properties and sheet thickness distribution of the hot stamped cups.

Marcia Pereira, Vesuvius Ghlin, Belgium

Co-Author:
Laura Grana Suarez, Vesuvius
Waldemir Moura de Carvalho, Vesuvius
Hervé Tavernier, Vesuvius
Marcia Maria da Silva Monteiro Pereira, Vesuvius

Abstract:
In today’s competitive market, the demand for high-quality, defect-free steel is unprecedented in industry history. Quality standards have been raised worldwide along with increasing market pressure to reduce and control pricing. Perhaps, the most challenging period is associated with the start-up of the continuous casting sequence. Unstable mould conditions will adversely affect the steelmaker’s ability to control this critical stage of casting. This can lead to conditions resulting in poor cast quality, defects, and even breakouts. In order to get a faster and good and stable lubrication state in the mould, and so decrease risks of sticking or cracks formation, a simple solution consists of adding an exothermic powder on top of the steel in the mould, prior to the continuous casting powder. Through the use of computational thermochemistry (Software FactSage) we can explore and study the influence of the different raw materials on the energetic behavior of multicomponent and multiphasic systems, such as the in-mould behavior of the Flux powder. The thermodynamic calculations can be used to identify the reaction products inside a primary metal smelter, to establish overall heat and mass balances of a process, and to generate phase mappings (such as phase diagrams and predominance diagrams). The method is based on identifying the equilibrium state of a system constrained by different conditions of temperature, pressure, volume, chemical potentials, chemical compositions, and more with a short computational time. Consequently, the method allows us to predict the system behavior and quickly adapt the composition of our exothermic powders to the different local working conditions, steel grades, or standard casting flux while keeping the right exothermic behavior.

Johan Richaud, Vesuvius Europe, France

Co-Author:
Anupkumar Nandakumar, Vesuvius India Limited
Soumya Bhattacharjee, Vesuvius India Limited
Rajkumar Gangadharappa, Vesuvius India Limited
Murali Sabhapathy, Vesuvius India Limited
Ganesh L, Hospet Steels Ltd.
Manoj Gupta, Hospet Steels Ltd.
P.L Satish, Hospet Steels Ltd.
Atluri Ratnaprasad, Hospet Steels Ltd.

Abstract:
The production of Re-Sulphurized steel, and other clogging prone grades is a challenge in terms of limited sequence length thus impacting both productivity and sustainability. The efficient production of these grades requires optimized tundish vessel functioning, which has historically been addressed through shaping tundish furniture -impact pad like. Turbostop® pad, dams, weirs and baffles. The design of these refractory components has shown significant impact on steel cleanliness in continuous casting. Tundish to mold steel can also be further improved by modifying flow controlling refractory designs like the stopper. In long product casters, generally argon injection through the stopper nose into the casting channel is avoided to prevent observed boiling in mold, which can cause operational and quality issues. This paper describes the improvement in the flow performance from the tundish to mold. The novel stopper design of Multi-Channel Argon injection through the stopper nose resulted in reduction in clogging occurrences near the stopper regulating surface and the SEN seat. This helps in achieving a stable stopper position throughout the tundish sequence and leading to a significant reduction in the rate of stopper rise required for extended sequence casting. Multiple trials were successfully carried out showing reduction in stopper rise rate as well as reduction of stopper flushing counts compared to conventional stopper design. Thanks to the stopper rise rate reduction, the sequence length could be extended from 2 heats/Tundish to 2.91 Heats/Tundish in average, thus improving productivity and caster yield leading to cost reduction and sustainability improvement - reduced tundish consumption, lower fuel costs. Additionally with this new stopper design quality of the final product also improved.

Maksym Goryuk, National Academy of Sciences of Ukraine, Ukraine

Co-Author:
Anastasiia Semenko, National Academy of Sciences of Ukraine
Yuriy Smirnov, National Academy of Sciences of Ukraine
Oleksiy Smirnov, National Academy of Sciences of Ukraine
Sergii Semiriagin, Scientific and Manufacturing Enterprise Dneproenergostal Ltd.
Vadym Osypenko, Scientific and Manufacturing Enterprise Dneproenergostal Ltd.

Abstract:
The PTIMA NASU proposed new concept of continuous casting of steel for small metallurgical plants. The idea is both reducing capital costs and amount of equipments. This is achieved by excluding “ladle-furnace” aggregate from technology, reducing number of metal overflows, performing in tundish the finishing liquid steel on temperature & chemical composition, and cleaning from non-metallics. As such multifunctional tundish, it is proposed a pilot magnetodynamic (MD) mixer-batcher for cast iron and steel, developed at the PTIMA NASU. This aggregate uses electromagnetic energy for melt heating, stirring and pouring, and constructively combines functions of induction channel furnace and electromagnetic pump. Such tundish, depending on steel grades produced, process productivity and design of continuous casting machine (CCM), can have one or two chambers, induction channels with inductors, electromagnetic devices for metal stirring and pouring, and also it can be additionally equipped with submersible plasmatron for melt refining. The proposed MD-tundish has following advantages: - adjustable induction heating and electromagnetic stirring of melt; - controlled low-pressure electromagnetic pouring of melt with possibility of distributing and stabilizing flow over the width of CCM mold; - possibility for periodic stop/restart at manufacturing small batches of cast ingots with various sections and from different steel grades; - reduction of metal losses and increasing metal yield; - increasing CCM work stability and productivity; - reduction of refractories’ consumption; - energy saving due to rational modes of melt heating and stirring; - exclusion of using special expensive systems for braking steel flows in CCM mold; - improving quality of cast ingots’ surface due to prevention of their cracking and swelling; - reducing porosity and number of non-metallics; - reducing risk of melt breakthroughs; - improvement of working conditions for personnel and ecology due to use of electrical energy, reduction of thermal radiation and harmful emissions.

Tim-Oliver Mattern, Carl Bechem GmbH, Germany

Abstract:
This paper evaluates modern grease technologies available for continuous casters and the impact to bearings and other aspects of maintenance. Grease performance for continuous casters can be largely impacted by the thickener technology, where resistance to water, steam, and high temperatures can degrade the grease. The mobility of the grease in centralized distribution systems can also be influenced by radiant heat before it is ever introduced to the bearing, adding another layer of complexity. Selecting the proper grease will impact the volume of grease consumed, how it behaves in the centralized distribution system, and how well it protects the bearings from this harsh environment.

Mohammad Sharif Sharifian, Hormozgan Steel Company, Iran, Islamic Republic of

Co-Author:
Hamed Jamshidinia, Hormozgan Steel Co
Ayoub Goudarzi, Hormozgan Steel Co
Omid Karami, Hormozgan Steel Co
Abbas Ali Barahimi, Hormozgan Steel Co

Abstract:
Ladle nozzle clogging is a problematic phenomenon in Continuous Casting of Aluminum killed Steels which output of ladle nozzle is reduced. It causes many problems in the production process, such as reducing productivity and increasing casting defects. In spite of extensive research on tundish nozzle clogging, few studies have been done on ladle nozzle clogging, especially in steels deoxidized only by aluminum. In this research, by using scanning electron microscopy analyze, the relationship between the chemical composition of non-metallic inclusions, molten steel and ladle nozzle clogging has been investigated. Due to optimization of calcium treatment in Hormozgan steel company, the number of ladle nozzle clogging and returned molten steel from continuous casting decreased significantly. As a result quantity and quality of produced slab increased.

Johan Richaud, Vesuvius Europe, France

Co-Author:
Sudip Banerjee, Vesuvius India Limited
Paromita Sarkar, Vesuvius India Limited
Roshan Ughade, Vesuvius India Limited
Kamruz Zaman, Vesuvius India Limited
Nagarjuna V L, JSW Dolvi
Sameer Patil, JSW Dolvi
Anil Gargi, JSW Dolvi
Neelesh Pande, JSW Dolvi
Sanjay Gurme, JSW Dolvi

Abstract:
Recent thin slab caster performance enhancements at JSW Dolvi Works with a clear focus to cast long sequences of higher quality grades produced at higher casting speeds, leading to higher throughputs have been possible with the application of the ElectroMagnetic Brake (EMBr). Along with this implementation, the increase in productivity has implied extension of the caster utilization time by reducing the process down time, the major portion of the process downtime is the regular sequence change time. To achieve these challenging conditions, the tundish and mold flow behaviour have been characterized and optimized along with implementation of higher refractories performance related to both their design and their material selection. Extensive numerical and physical simulations have been conducted to determine the different measurable parameters for tundish and mold flow improvements. Increased minimum residence time, improved inclusion floatation and turbulence reduction, better thermal homogeneity in tundish have been obtained after re-designing the internal tundish geometry. A new SEN producing stable meniscus flow and optimal mold temperature distribution allowing longer sequence to be cast in a thin slab caster. In addition to these refractory enhancements, JSW-D has significantly improved their casting parameters and stabilized the processes involved. Due to better co-ordination between the steelmaking & casting shop the casting speed fluctuations have been reduced and higher speeds of over 5.5 m/min corresponding to higher throughputs of above 4 tons/min have been realized on a consistent basis. Stable casting conditions have resulted in better refractory performance. The sequence length has increased by 15% on an average resulting in increasing the productivity of the shop with less unexpected stoppages or reduced numbers in slowdowns. Sustainability improvement has been achieved by increasing the number of heats/tundish and consequently the overall refractory consumption per ton of steel cast as well as the required energy have been reduced.

Jiangshan Zhang, University of Science and Technology Beijing, China

Co-Author:
Yuhong Liu, University of Science and Technology Beijing
Qing Liu, University of Science and Technology Beijing
Haibin Zuo, University of Science and Technology Beijing

Abstract:
Meshing is usually prerequisite and important as a pre-processing step in CFD studies, which determines largely the following convergence speed and simulation accuracy. Herein, we compare three different meshing tools, including two typical commercial ones, ANSYS-ICEM Meshing and FLUENT Meshing, and an in-house meshing tool, Script-Meshing. Commercial meshing tools follow the traditional sub-steps of geometric construction, decomposition and mesh generation; when adjustment in any sub-step(s) is needed, repeated work is required, which is time-consuming and tedious. Script-Meshing is a parameterized mesh generation tool that combines Python scripts with the OpenFOAM blockMesh utility, which can accomplish the geometry, decomposition and mesh generation in one step with controllable parameters; it can adjust the structural parameters and meshing arrangement by just modifying a few lines of code, which can greatly speed up the meshing/remeshing task. The concept of parametric meshing is especially suitable for the meshing of metallurgical vessels, as they normally feature relatively regular internal geometry, and their designs tend to be standardized. In addition, these three meshing tools are demonstrated for meshing of an industrial one-strand continuous casting tundish with an impact pad, weir, dam, long nozzle and stopper. The meshing speed, mesh quality, convergence speed and simulation accuracy are compared between the tools. It is found that Script-Meshing takes an equivalent time with commercial tools to generate hexahedral tundish grid, and the mesh quality is higher using the in-house tool. As a result, the quality mesh can accelerate the convergence speed and obtain results with high fidelity. Script-Meshing shows remarkable performance in structured remeshing, and more than 90% regeneration time can be saved. FLUENT Meshing is good at quickly generating unstructured meshes, however they are not suitable for high-order simulation and the calculation accuracy cannot be ensured.

Mansour Alharbi, SABIC, Saudi Arabia

Co-Author:
Brandao Jr. Renato, Retired
Neeraj Tewari, SABIC
Abdullah H. Kareem , SABIC

Abstract:
The objective of this study was to simulate the fluid flow performance of billet caster tundish using a mathematical model in order to optimize the tundish furniture style and location for best steel quality and/or effective flow control. A six-strand billet caster tundish presents various challenges such as being able to maintain the same casting temperature, homogenous chemistry and similar steel cleanliness in every strand. These challenges make the fluid flow phenomenon in a six-strand tundish more complex. The fluid flow characteristics and tundish performance were derived by performing the Residence Time Distribution (RTD) analysis. The model was developed successfully to simulate the flow characteristic and pattern inside the tundish. The simulation results were validated against the literature. The RTD analysis drove the conclusion that removing the current used flow modifier impact piece would help to enhance the discharging rate and reduce the dead volume zone inside the tundish. This then would enhance maintaining the molten steel temperature homogeneity during casting process.

Javad Gharagouzlou, Hormozgan Steel Company, Iran, Islamic Republic of

Co-Author:
Seyyed Asghar Madani, Hormozgan Steel Co
Mohammad Sharif Sharifian, Hormozgan Steel Co
Ali Keshavarzi, Hormozgan Steel Co
Esfandiar Pourali, Hormozgan Steel Co
Mohammad Molabeyk, Hormozgan Steel Co

Abstract:
Despite the existence of research sources on tundish hot corrosion in silicon killed steel, there are few researches on this issue in aluminum killed steel. In this research, using X-ray Diffraction, the main phases formed as a result of the reaction of slag-tundish mass have been investigated and formation causes of these phases and practical solutions to reduce the corrosion of tundish plaster are presented. According to the obtained results, monticellite phase is the main factor that causes the dissolution of MgO grains in the slag and the corrosion of tundish mass. And the end, the solutions to reducing of tundish mass corrosion in Aluminum killed steel are explained.

Masoud Al-Gahtani, SABIC, Saudi Arabia

Co-Author:
Faisal Al-Ghamdi, SABIC
Vinod Yadav, SABIC

Abstract:
EFFICIENCY OF USING POLLARD-TYPE NITROGEN SHROUD FOR MEDIUM CARBON STEELS ON MINIMIZING RE-OXIDATION DURING CASTING. Masoud Al-Gahtani, Faisal Al-Ghamdi, Vinod Yadav This paper discussed the effect of using pollard-type nitrogen shroud during production of medium carbon steel in order to minimize re-oxidation of the liquid steel. Polar-type nitrogen shrouds protection were mounted to tundsih nozzles at the bottom of the tundish provided an effective protection. The shrouds were designed with flow rate and investigated during production of medium carbon steel billets drawn for low thickness wire rods. Plant trials were used to examine the protection efficiency polar-type nitrogen shroud, and the mechanism of nitrogen entrapment during the casting of medium carbon steel billets was analyzed.

Ion Rusu, BM GROUP POLYTEC S.p.A., Italy

Co-Author:
Ion Rusu, BM GROUP POLYTEC S.p.A.

Abstract:
The paper depicts a robotic cell, which has been ad-hoc developed in order to be installed in the steel shop and support the operators during inspection, cleaning and replacement of the refractory components of the ladle sliding gate. This device is allowing opening the bottom of the ladle so that the liquid steel can run into the tundish of the continuous caster. The developed robotic cell represent an innovative attempt to create a cooperative environment where the technicians and a robot interact in a safe and ergonomic way. This system, which is installed and tested in an Italian integrated steelworks, allows improving both the health and safety condition of the workers and the quality and repeatability of the operations. It automatically manages the sliding gate maintenance, in order to increase safety and operational accuracy, stability in the repetitively and to optimize process times control. This multi-tool robotic cell is equipped with: Extraction/Insertion tool Refractory nozzle extraction tool Tool to remove fixed plate Nozzle cleaning tool

Youn-Bae Kang, Pohang University of Science and Technology , Korea, Republic of

Co-Author:
Jun Hyun Kim, Chosun Refractories Co., Ltd.
Joo-Hyeok Lee, POSCO
Yong-Min Cho, Pohang University of Science and Technology
Dong-Jun Lee, Pohang University of Science and Technology

Abstract:
Continuous casting of liquid steel from tundish to mold is performed by flowing the liquid steel through SEN. However, the inner hole of the SEN is often clogged, and consequently, the casting process is interrupted. The clogging deposit also falls off, enters into the liquid steel in the mold, and eventually appears on the surface of the cast product. Suppressing nozzle clogging is therefore essential to increase the productivity and quality of the cast product. While various origins have been identified for causing nozzle clogging, the present study focuses on the reaction chemistry-based aspect. The initiation of the clogging is due to an interfacial reaction between the inner wall of the SEN and the liquid steel passing through the SEN. In particular, the carbothermic reaction inside the SEN (SiO2(ref.) + 3C(ref.) = 2CO(g) + SiC(s)) generates CO(g), which causes reoxidation of the liquid steel, resulting in clog deposit formation. This initial clog deposit can be a subsequent build-up site for inclusions in the liquid steel. Therefore, it is necessary to suppress the reoxidation. In the present study, the fundamental reaction is discussed in view of thermodynamics, a series of laboratory-scale experiments including in-situ gas analysis in the emitted gas, and proposals to suppress the CO(g) generation. Three approaches will be shown: 1) minimizing SiO2/C ingredients, 2) adding CO absorbers, and 3) replacing SiO2/C ingredients with non-oxide type ingredients (oxynitride-nitride mixture) in the SEN refractory. Significantly improved results were obtained, in terms of suppressing clog deposit growth and casting plant trials.

Mariana Modesto, Vallourec, Brazil

Co-Author:
Edney Arruda, Vallourec
Luis Germano, Vallourec
Stephane Houel, Vallourec
Leno Miranda, Vallourec
Alan Maia, Vallourec
Erica Bandeira, Vallourec
Klaus von Eynatten , EyCon - Steel Plant Technology Consulting

Abstract:
Steel reoxidation during tundish filling represents a significative casting yield loss because the first casted billets are scraped in order to guarantee the product’s internal cleanliness. The present work shows the implementation of Tundish Inertization with argon during the start of casting of round billets in a seamless pipe producer. Several trials were conducted to define the optimal operational and process setups for a Delta-T shape 40ton tundish. The steel inertization capacity was validated through the evaluation of macro, meso and micro cleanliness in the final product. The avoided scrap signalizes expressive yield improvements and savings for the definitive installation, which is being industrialized.

Bernd Kleimt, VDEh-Betriebsforschungsinstitut GmbH, Germany

Co-Author:
Rajko Antonić, Minkon GmbH
Martin Schlautmann, VDEh-Betriebsforschungsinstitut GmbH
Izaskun Alonso Oña, Sidenor Investigación y Desarrollo
Hellai Abdullah, AG der Dillinger Hüttenwerke
Katharina Kortzak-Hojda, VDM Metals GmbH
Robin Jentner, AG der Dillinger Hüttenwerke
Torsten Lamp, Minkon GmbH
David Wappel, RHI Magnesita GmbH
Stefan Eder, RHI Magnesita GmbH
Gernot Hackl, RHI Magnesita GmbH

Abstract:
The control of hydrogen content in steelmaking has always been an important issue, due to the severe quality problems which are caused by too high hydrogen contents in the final steel product. This leads to high demands regarding lowest hydrogen contents at the end of liquid steelmaking, which requires a vacuum degassing treatment of liquid steel and a tight control along the whole liquid steelmaking and casting process route. In the RFCS project HydroPick detailed and comprehensive investigations on all mechanisms of hydrogen pick-up and removal throughout the complete process route of liquid steelmaking and casting were performed. The results were used to derive dynamic process models for through process prediction of the hydrogen content evolution under different process conditions of the involved processes. Regarding the continuous casting process, new and innovative concepts for the tundish with respect to wear lining, preheating, cover powder and fluid flow control of liquid steel were developed, to understand the relevant influencing factors as well as to control and limit the hydrogen pick-up during the casting process. Also, a new system for continuous measurement of the hydrogen content dissolved in liquid steel was developed and applied for monitoring the hydrogen content evolution in the tundish during casting. Finally the predictive process models were used to build a through process on-line advisory system for monitoring and control of the hydrogen content evolution, in combination with new measurement strategies, for reliable and effective achievement of the target values. The hydrogen pick-up is predicted and as far as possible limited, and the process parameters of hydrogen removal during vacuum degassing are controlled, so that the quality-dependent hydrogen target values for liquid steelmaking can be reliably achieved. The investigations and developments were performed at the steel plants of Dillinger and Sidenor in cooperation with BFI, RHIM and Minkon.

Pedro Cardoso, Vesuvius Sp.z o.o., Brazil

Co-Author:
Lucio Mascarenhas, Vesuvius
Eduardo Duarte, Vesuvius
Paulo Teixeira, Vesuvius
Franz Ramstorfer, Ternium
Giovani Delfim, Ternium
Moises Miranda, Vesuvius

Abstract:
In the light of the Industry 4.0, the Robotic Process Automation (RPA) is being considered as new wave of the future technologies, connecting several fields of engineering as mechanical, electronic and automation. Following this trend, the human processes in the steelmaking plants, whose level of danger is one of the highest in the industrial sector, are beginning to be oriented towards being automated. The main advantages in the use of robot manipulators in this industry are the increase in the safety of the operators, in the quality of the process and in the production. However, the implementation of robot manipulators in the steel industry has several challenges that result in the low rate of use of this system in this segment of the industry, as an example, exposure to high temperatures, high concentration of dust and particulates and adaptation to the original layout of the machine, whose system will interact. It's shown the increase of productivity, safety and product quality of robotized tundish operations in continuous caster operation1. The objective of this paper is to present the implementation and the results of the robotized tundish operations focused on the ladle exchange operation, in which it is notably the most critical moment of the continuous casting. In addition to ensuring the operator's safety, the increase in quality is proven by the reduction of N2 pickup2 in operations using the robotized tundish compared to conventional operations.

Johan Richaud, Vesuvius Europe, France

Co-Author:
Anil Kumar Rauta, Vesuvius India Limited
Akanksha Kumari, Vesuvius India Limited
Krushna Chandra Panda, Vesuvius India Limited
Murali Sabhapathy, Vesuvius India Limited
Thayappa Hosahali, JSW Vijayanagar
Sankar Ananthan, JSW Vijayanagar
Anil Kumar, JSW Vijayanagar
K. Ravi Shekar, JSW Vijayanagar

Abstract:
The CRNO steels are mainly used as core materials in electrical motors and transformers as they are the group of electrical steels with Isotropic Magnetic properties, meaning magnetic properties are practically same in all directions of magnetization in the plane of material. The essential magnetic properties requirement for these steels are low core loss values and high permeability. Thin gauge, clean steel and optimum grain size are required to achieve the desired magnetic properties in CRNO steels. Electrical steels with Si ranging less than 1% showed significant variation in permeability (B50), where it varied from 1.69 to 1.77 T and average core loss value was 5.48 (W15/50). Since the permeability and the core loss depends on the steel cleanliness detailed investigation was carried out to find the factors primarily influencing it, and it was found that the presence of inclusion size above 10 μm resulted in lower permeability and higher core loss. Hence in this grade use of Tundish Gas Diffuser (TGD) and an Inert working lining (OBL™) was experimented for forced flotation of inclusions through argon bubbling inside the tundish and to prevent generation of inclusion by reaction of the steel with the tundish working lining. Extensive numerical and physical simulations have been conducted to determine the position and the flow of argon thru the TGD. Average inclusion size reduced from 12 μm to < 8 μm in HR coil with the use of diffuser and the inert working lining. The permeability variation has reduced from 0.08T to 0.05T (i.e 1.72 to 1.77 T) and the Average core loss value reduced to 5.32 (W15/50). In addition to these refractory enhancements, JSW V has significantly improved and stabilized the various processes involved from steel making to casting.