Modeling of Steelmaking Processes

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If the address matches an existing account you will receive an email with instructions to retrieve your username. Full Paper. Yuriy Lytvynyuk Corresponding Author E-mail address: ylitvinyuk gmail. Read the full text. Tools Request permission Export citation Add to favorites Track citation. Share Give access Share full text access. Share full text access. Please review our Terms and Conditions of Use and check box below to share full-text version of article. Abstract A new model for the simulation of the converter steelmaking process was developed after the detailed study of existing thermodynamic and kinetic models and approaches.

Citing Literature. Volume 85 , Issue 4 April Pages Danieli Corus developed the Steel Plant Model to optimize logistics in both existing and new steel plants. The SPM simulates any operational scenario in any steel plant realistically and accurately, in 3D and real time. All objects, including equipment, cranes and ladles, communicate. The SPM simulation includes process time deviations, maintenance and breakdowns.


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Thanks to Smart Cranes interaction, transportation movements are simulated very realistically as well. Molten steel with desired composition, cleanliness, and temperature is finally transformed into solid products through continuous casting. Present-day steelmaking process routes involve two dominating technologies namely, oxygen steelmaking BOS and electric steelmaking EAF steelmaking.

Typical steelmaking process routes are illustrated schematically in Figure 1. Furthermore, all the secondary steelmaking processes may or may not always be integrated into the production circuitry. These processes gener- ally depend on the grade of steel being produced and are customer driven. A brief summary of primary and secondary steelmaking together with casting processes are presented in the following sections. More elaborate description is available in standard texts [57].

Notes: The composition of hot metal and steel depends on the quality of raw material and the process route. Some variations in composition and cleanliness are therefore possible from one practice to another. Alloys Crud l e ste e stee el Crud. Steelmaking, Modeling, and Measurements 7. The former is ensured by blowing oxygen through molten steel while the latter by maintaining a highly basic slag, i. Refining is carried out in a pear-shaped vessel, traditionally termed as a converter i. The vessel is lined with basic refractories made from magnesite, dolomite, etc. Oxygen is injected at supersonic speed into molten iron through a water-cooled, multihole lance.

This readily dissolves in liquid steel and starts oxidizing and eliminating impurities dissolved in blast furnace iron. The dissolved impurities in molten iron, excepting sulfur, have extremely high affinity for oxygen. Thus, dissolved oxygen and carbon readily react together pro- ducing gaseous carbon monoxide, which is eliminated easily from the system. In addition to that, Si, Mn, and P also readily oxidize and form their respective oxides which being acidic in nature forms a chemically stable slag by reacting with dissolved lime.

Generally, a part of the sulfur is also removed during oxygen steelmaking. Dissolved lime helps eliminate the two most harmful impurities in iron namely, sulfur and phosphorous. The following are key chemical reactions in steelmaking:. Converter mouth Taphole. Slag layer Trunnion Metal bath ring Refractory lining. With oxygen injection, impurity oxidation, lime dissolution, and slag formation start practically simultaneously. A large amount of heat is released due to the oxidation reactions Equations 1.

Indeed, the surplus heat produced allows for incorporation of a reasonably good amount of scrap in the process. Furthermore, chemical heat in CO gas produced via reaction Equation 1. This paves the way for introduction of even more scrap than is normally possible. During the blow, oxygen flow rate and the lance height are adjusted to control the rate of oxidation of the impurity elements. Simultaneously, samples are also collected through a sublance a melt sample collector device to exactly know the instantaneous state of melt composition and temperature.

Such monitoring helps operator decide the end blow strategy in advance and results in a final melt with correct temperature and compositions. Dynamic monitoring helps eliminate any reblow that is known to offset productivity of a steel melt shop. Once the blow is terminated, the converter is emptied into a ladle a cylindrical-shaped, refractory-lined vessel for further refining of steel.

Modeling of Steel Heating and Melting Processes in Industrial Steelmaking Furnaces

Due care is always taken to minimize slag carryover from BOF to ladle, as converter slag is rich in FeO, i. Subsequently, converter lining is inspected and repaired, slag splashing for protection of lining and submerged tuyeres is carried out and the converter is made ready for the next heat. A wide size range of BOFs are used in the industry typically, between 60 and ton and the overall duration of refin- ing tends to vary with converter size, initial melt composition, etc.

The sequence of chargingblowingsampling and tapping operations is illustrated through a set of schematics in Figure 1. Arc furnace steelmaking gained momentum after the World War II. This is a solid charge-based process and uses steel scrap and direct reduced iron as opposed to molten iron in a basic oxygen process as the chief iron-bearing material. The extent of refining required in an EAF is generally less than that in a BOF, since less amount of impurity is required to be eliminated in the former.

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The impurities present in DRI and other charge materials e. Steelmaking, Modeling, and Measurements 9. Charging scrap 2. Charging hot metal. Main blow 4. Tapping 6. Slag off. The reactions between various dissolved impurities and iron ore, in contrast to those with dissolved oxygen, do not produce enough heat to make EAF steelmaking autogeneous. Energy required for melting solid charge, dissolution, and subsequent refining of the bath is provided by electrical energy. Graphite electrodes, ultrahigh power transformers, etc. The total energy required to make 1 ton of liquid steel in EAF is approximately 6.

The level of agitation in an EAF is not much and therefore the refining rate is low. To expedite the rate of chemical reactions, oxygen is often injected through one or more lances. In many modern EAFs, supersonic jets of oxygen are delivered using the Co-jet technology.

Eccentric bottom tapping. Basic steelmaking is more frequent in EAFs since this allows effective removal of sulfur and phosphorous. Periodic chemical analysis of melt helps determine the state of refining and prepare the operator for taping the furnace. Modern day EAFs are equipped with eccentric bottom tapping technology to facilitate easy tapping. A schematic of an EAF is shown in Figure 1. Significant amount of oxygen also remains in steel in the dissolved state. The solubility of oxygen in liquid steel is appreciable and in oxygen steelmaking, the solubility often exceeds 0.

Dissolved oxygen, if left as it is, seriously impairs mechanical properties of steel and must therefore be removed from the melt before casting. The economics of steelmaking necessitates that removal of oxygen as well as subsequent adjustment of composition and temperature is carried out in a vessel beyond the primary steelmak- ing furnace such that the latter can be used solely for the production of crude steel maximizing productivity.

Deoxidation or removal of oxygen is generally facilitated by the addition of elements like Al, Si, Mn, etc. Typically, lump additions of deoxidizer elements are made to the bath almost simultaneously with tapping as is illustrated in Figure 1. Alternative modes of additions are also used at times for better utilization of such additives. Tapping stream Addition chute. Alloys Air entrainment Slag. FeMn lumps. Adapted from Guthrie, R. The requirements of a deoxidizer are high reactiv- ity with dissolved oxygen, minimal residual contamination, and production of a deoxidation product that is easily separable from molten steel.

These are referred to as endogenous inclusions.


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Their presence makes steel as it is loosely termed, dirty and therefore, it is desirable that contamination from such foreign oxides is mini- mal. Worn-out refractory pieces remaining entrapped in steel, on the other hand forming exogenous inclusions, are also unwanted. Extreme care and control are necessary to produce steel devoid of nonmetallic inclusions, which tend to seri- ously impair mechanical properties of steel. With state-of-the-art technology, high performance interstitials free IF and extra deep drawing EDD grades, virtually free of inclusions and dissolved impurities are routinely produced in many steel mills around the globe.

During deoxidizer addition, some silica and lime are also added such that an adequate ladle slag e. Such slag helps absorb nonmetallic inclusions as they float up due to buoyancy. In addition, ladle slag also provides a protective cover over the melt thereby minimizing radiation losses and contamination from the ambient i.

Composition and cleanliness control invariably follow primary steelmak- ing owing to the increased demand of a diverse range of high-quality steels. Chemical opera- tions carried out in ladles as well as holding and transportation of molten steel often cause substantial drop in liquid steels temperature. Adequate corrective measures are required to compensate for such lost heat. Accordingly, a multifaceted activity generally follows beyond primary steelmaking operations.

These are collectively referred to as secondary steelmaking and help bring versatility to composition and associated mechanical properties of steel. The total duration of secondary steelmak- ing i. Secondary steelmaking techniques are generally concerned with one or more of the following:. Composition adjustment: These include alloying additions for adjustment of melt chemistry, powder injection for desulfurization, vacuum treatment for removal of dissolved gases, and production of ultralow carbon steel.

Cleanliness control: This is concerned with the production of clean steel and involves synthetic slag preparation for better inclusion absorption, cre- ating correct flows in tundish and molds to aid inclusion float out and injec- tion techniques to modify morphology and composition of oxide and sulfide inclusions. Temperature control: Melt heating is done through electrical energy. An arc is produced between graphite electrodes and this generates enough heat increasing the temperature of the melt.

Secondary steelmaking operations are carried out in a ladle furnace LF , which is a refractory lined typically magnesite , cylindrical-shaped vessel see Figure 1. The gas rising through the liquid induces a turbulent recirculatory motion, which provides the necessary bath agitation for exacerbat- ing the rates of various heat and mass transfer controlled processes viz. Depending on the end requirement, a wide range of gas flow rates is applied. Intermediate flow rates are used during chemistry adjustment and arc heating. More than required gas injection increases the possibility of atmospheric reoxida- tion, erosion of electrodes and ladle refractory, etc.

Argon flow rate is an important process variable in secondary steelmaking and is controlled effectively to achieve superior process performance. A schematic of gas injection operation in a ladle is. Otherwise, the pores tend to get blocked making gas injection difficult.

8th International Conference on Modeling and Simulation of Metallurgical Processes in Steelmaking

Steelmaking, Modeling, and Measurements Stopper-rod assembly. Refractory lining Refractory Steel lined wall Steel shell. Porous plug Porous plug Argon a b. From Mazumdar, D. Typically alloying additions are made over the eye of the surfacing plume, as shown in Figure 1. The additions melt, dissolve, and disperse in the melt under the influence of convection current induced through gas injection.

The composi- tion of the melt is closely monitored by collecting samples and analyzing these. Occasionally, it is desirable to remove additional sulfur from the melt to meet cus- tomer requirement. Typically, a basic, synthetic ladle slag is prepared and argon is bubbled at a high rate to promote slag metal mixing, facilitating desulfurization according to Equation 1. Slagmetal contact area and the intensity of bath agita- tion influence the rate of ladle desulfurization most. Their presence in the final product seriously impairs the performance of steel.

It is therefore desirable to regulate such unwanted elements within their acceptable limits. This is accomplished via vacuum processes com- monly termed as degassing operations. Many degassing techniques are available on a commercial scale. These are schematically shown in Figure 1. Of these, two types of degassing processes, namely tank and circulation degassing are fre- quently used in the industry. During treatment of melt under vacuum, the dissolved gases tend to escape to the ambient, which is thermodynamically favorable.

Apart from a low operating pressure 1 mbar or so , a good level of bath agitation is very. The quality of steel achieved during one stage can be completely lost during a subsequent transfer operation, if the latter is not regulated properly. Transfer operations are of immense importance to steelmakers and their engineering is vital to fully exploit the benefits of primary and secondary steelmaking processes.

Alloy feeding hoppers Tapping ladle Vacuum Vacuum Alloys pipe pipe. Vacuum tank Heating element Vacuum chamber. On the other hand, in tank degassing, the injected argon aids in stirring of the melt. For larger volume ladles, circulation degassing is relatively more effective than tank degassing.

There are also other vacuum techniques available for adjusting steel chemistry and most notable among these are the vacuum oxygen decarburiza- tion VOD and vacuum argon decarburization VAD processes. These are used in the production of ultralow carbon steel. The vacuum shifts the CO equilibrium favorably aiding removal of carbon to produce low-carbon steel.


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  • Steel cleanliness is adversely affected by the presence of alumina and sulfide inclusions, which influence mechanical properties of steel. This is also true with any entrapped slag particles. Alumina inclusions pose many problems, such as noz- zle clogging, during transfer operations leading to operational hazards.

    Present-day steelmakers, therefore, aim to produce steel with practically negligible contamina- tion from alumina and sulfide inclusions. While it is easier to float and remove relatively larger inclusions, this is not so with inclusions of size 50 m or less. To aid removal of alumina and sulfide inclusions, calcium is injected into steel in the form of CaSi and CaFe wire.

    Dissolved calcium reacts with oxide and sulfide inclusions, and changes their state solid liquid , morphology, shape, and size to facilitate their removal producing clean steel. Recovery of calcium is extremely poor in steelmaking environments and this tends to offset economic benefits. Alloy addition, injection, and vacuum treatments involve endothermic processes and consume heat. These in turn lead to a substantial drop in melt temperature, to compensate which it is not desirable to maintain a significantly higher superheat in. The temperature over and above the liquidus temperature is customarily termed as superheat.

    Electrodes Fume extraction Powder injector. Alloy chute Wire feeder. The plug is seldom placed directly beneath the elec- trodes. While electrodes are confined in a region close to the central axis of the vessels, the plug on the other hand is generally displaced toward the wall and placed at 0. This is to minimize, what is known in the industry as electrode hunting to prolong latters life.

    It is therefore often required to compensate the lost heat before continuous casting such that premature freezing is avoided and casting com- mences at correct temperature i. Heating of melt during secondary processing is carried out in a LF, operated in a manner similar to an electrical arc furnace described in Section 1. Depending on the ladle size and power ratings, the temperature of the melt can be increased by about 0. Figure 1. During arcing, a refractory-lined roof is used as a protective cover to minimize radiation losses.

    More details and the science and technology of secondary steelmaking are available in Ref. Traditionally, molten steel used to be cast through the ingot-casting route wherein individual molds are filled with molten steel to produce steel ingots. The ingots were subsequently rolled to flat, long, and round products. Slag Covering material. Covering Slag material. In continuous casting, a ladle is placed over a tundish, which feeds one or many molds beneath through a submerged entry nozzle SEN as shown in Figure 1. The tundish, traditionally a buffer vessel, now helps improve steel cleanliness fur- ther through floatation of inclusions, aided by inserting appropriate flow control devices at strategic locations.

    Depending on the section cast, the speed of casting as well as the number of molds beneath tundish varies. Typically continuous casting produces three different kinds of products namely slab, bloom, and billet. Specialty products like beam blanks are also occasionally produced. The relative section sizes and typical casting speeds are summarized in Table 1. Thus, a tundish equipped with a billet caster would feed many molds and casting would proceed at a relatively higher speed.

    Similarly, a tundish equipped with a slab caster would feed typically one or two molds and cast steel at a somewhat lower speed. The biggest challenge in continuous casting is to cast steel continuously without strand breakouts and other interruptions with the minimum of external and internal defects i. More information on the same is available in Ref. The mold in continuous casting is made from copper and is water cooled.

    A part of the superheat is removed in the mold by circulating water. This facilitates the formation of a solid thin shell of steel that supports the strand below mold exit. The mold is oscillated to prevent the solidifying casting from sticking to mold wall.

    Suitably designed mold powders also termed as mold fluxes are added to foster lubrication between mold wall and the descending strand. The strand is continuously withdrawn by the guide and pinch rolls while the bending rolls serve to gradually bend the strand upon its emergence from the mold. Immediately below the mold, the strand meets a series of water-mist sprays that help extract a significant portion of heat from the moving strand, thereby solidifying steel completely. Beyond the sprays, as the solid strand is further cooled by radia- tion to the ambient, it is cut into required lengths by oxyacetylene torches or shear- ing machines.

    Cut sections of billets, blooms, and slabs are subsequently processed in rolling mills and supplied to the customers in required forms and sizes. Continuous casting machines perform vital thermal and mechanical functions. These are required to be controlled effectively and optimized such that defect-free steel can be produced on a sustained basis. Apart from conventional continuous casting process described above, thin slab and strip casters have also been com- mercialized in recent years. Thin slabs i. Ability to cast steel continuously in the form of strips helps eliminate subsequent processing operations e.

    Continuously cast slabs, blooms, and billets undergo various hot and cold working processes whereby a range of long, flat, and round products are pro- duced. A given mill may not always produce all different kinds of products. The final product range from continuous casting is illustrated in Figure 1. Conventional beam blanks. The repre- sentation can be either physical or mathematical. In the former, the actual process or phenomenon is represented via a physical system while in the latter, via mathematical expressions or equations.

    More specifically, in physical modeling, a given phenom- enon is investigated in a replica of the actual industrial unit while in mathematical modeling a given phenomena is investigated by representing the latter via a mathe- matical equations or expressions. Modeling is a well-established scientific technique with demonstrated capabilities and finds widespread application in engineering process analysis, design, control, and optimization. The key objective in physical modeling is to measure and visualize one or many characteristics of the real system, rather inexpensively and conveniently.

    Physical modeling studies of high-temperature steelmaking provide useful insight into the system, which is practically impossible otherwise. For example, it is dif- ficult, if not impossible, to observe the subsurface trajectory of deoxidizer and alloy- ing additions in a steel melt following their projection into a ladle during tapping. On the other hand, one can conveniently get a reasonable idea of such trajectories by projecting representative, similar shaped, solid particles in an appropriately scaled water model system. Besides, many a time, physical modeling is carried out to measure the characteristic of the system that can then be applied to validate a mathe- matical model.

    This has become a popular approach in steelmaking process research and hence, physical modeling and mathematical modeling are frequently applied in conjunction, as it is generally difficult to derive validation dataset from industrial- scale operations. The term model as opposed to law implies that the relationship employed in the mathematical expressions may not be quite exact and therefore, the predictions derived from them may only be approxi- mate.

    The adequacy and appropriateness of a mathematical model largely depends on how rigorously the model has been formulated i. Steelmaking is a complex process and involves multiphase turbulent flow, heat, and mass transfer as well as chemical reactions among slag, metal, gas, and solid. Accordingly, numerous idealizations are applied to formulate reasonably realistic process models in steelmaking. Classical mathematics is rarely useful for solving model equations and numerical techniques are invariably applied.

    Without robust software and powerful digital computers, there would be little hope of predicting many phenomena of practical interest. In recent years, major breakthroughs in math- ematical modeling have been possible because of efficient solution algorithms and user-friendly, powerful computational softwares as well reasonably priced high- performance computers.

    Mathematical modeling offers many distinct advantages [13] and the following are notable among them. Remarkable speed: A researcher can study the implications of hundreds of different configurations via a mathematical model in a very short time. In contrast, detailed experimental observations which are also not possible many a time involve many man months. Simulation of real conditions: In a computational procedure, there is very little difficulty in having a very low or high temperature, large or small vessel dimensions, etc.

    Thus, a full-scale system with liquid steel as the fluid can be modeled as conveniently as a reduced scale model with water. Complete information: Results can be derived throughout the domain of interest. There are no inaccessible locations in a computer simulation. Similarly, there is no counterpart of flow disturbance caused by a probe. Various types of mathematical models are applied in steelmaking process analysis, design, optimization, and control.

    These include. Computational fluid dynamics based models for simulation of reacting turbulent flows and transport 2. AI-based models for process control and optimization 3. Thermodynamic models for equilibrium calculation 4. Reduced order models for automation and control in the shop floor. In addition to those models, altogether different modeling approaches are adapted to simulate processing beyond solidification including mechanical working, micro- structural and textural evolution, etc.

    It is not possible to cover all such topics in reasonable details in a singular work. Accordingly, the present chapter primarily emphasizes 1 and 2. Process analysis and optimization involve mathematical modeling primarily in an off-line fashion. In contrast, process control requires modeling and prediction in real time.

    Models in category 1 are in general far too complex and therefore, not suited for real-time applications in steelmaking process control. Online control requires simpler models and in such context, reduced order models have made it to the shop floor. Popularly used methods in the latter category include.

    Big River Steel's Water Model for Casting

    Heat and material balance 2. Lagrange response rate analysis 3. Predictor-corrector controller 4. Statistical self-learning. Instead, pilot-scale trials are conducted, provided resources are available. Unlike physical modeling, the mate- rial used is essentially the same as those in the full-scale system. Pilot-scale systems are expensive to build and operate, and conducting trials on these particularly at elevated temperatures, are as cumbersome as in full-scale systems.

    Nonavailability of low-cost measuring probes capable of working in high-temperature environment on a sustained basis poses additional problems. Physical and mathematical model- ing, although useful, do not alone constitute the requisite framework, particularly if the ultimate objective of modeling is to do the following [14]:. Develop altogether a new process 2. Carry out measurements and modifications which, hitherto, are difficult in an existing process 3.

    Mathematical modeling. Complete process knowledge. Physical Pilot-scale modeling trials. Adapted from Szekeley, J. Indeed, in the development and commercialization of many iron and steelmaking technologies, from sponge iron making to thin strip casting, an integrated approach embodying physical modeling, mathematical modeling, and pilot-scale experimen- tations has been applied. A rigorous approach in steelmaking process analysis and design must embody the three above-mentioned components, as is illustrated in Figure 1. In the absence of such approaches, engineering of steelmaking per se involves conducting large-scale experimentation in actual steel processing units.

    As desired performance can be arrived at through many trials, involving several man months and exorbitantly high costs, there is a definite need for effective and time-intensive research and development efforts. While many early developments in iron and steel- making were the results of direct high-temperature trials of course on smaller scales , more recent developments, on the other hand, owe their success and commercialization to an approach that embodies a judicial blend of modeling and high-temperature trials.

    It is certainly not desirable to begin any exploratory work on process optimization, control, or design in full-scale or pilot-scale vessels. Its relevance to steelmaking is readily appreciated since visual opacity, high operating temperature, and relatively large size of steel processing ves- sels often preclude direct observation. However, without companion measurements, modeling is incomplete and unsatisfactory. Measurements allow us to observe the reality. The most reliable information about any aspect of steel processing can only be acquired through measurements.

    Models and measurements are naturally there- fore regarded as interdependent components of a process investigation.

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    A diverse range of off-line and online measurements are routinely carried out in the industry. These are used to monitor, automate, and control steelmaking pro- cesses. Composition Thermoanalytical, Converter, LF, vacuum Melt, slag, off gas, solid spectrophotometry, solid degassing charge, etc. Pressure Pressure transducers Converter, ladle, LF Gaseous and solid injectants, spray cooling Position Laser-based devices Converter, tundish, mold Lance height, melt level, etc.

    Weight Load cell Converter, ladle, tundish Melt, slab, etc. Phases Accelerometers, lasers Furnaceladle transfer Slag carry over. Various types of measurements and measuring devices commonly used in the steel industry are summarized in Table 1. The major challenge in measurements is the design of low-cost probes i. Rapidity and reproducibility of industrial-scale measure- ments are also important issues in such context.

    Measurements and their relevance to BOF process control are illustrated in Figure 1. Parallel to the above, various types of measurements and measuring devices are used in room temperature studies of steelmaking. Although described later in detail in Chapter 3, a summary of these is presented in Table 1. Indeed, sophisticated, modern, liquid steel production systems that enable various adaptations to meet present-day economic and ecological requirements, have outgrown, the originally very simplistic LD process. In this remarkable journey, models, sensors, computers, and softwares have played crucial roles in practically every aspect of steelmaking.

    Higher productivity and superior product quality are interlined with efficient process control. The latter ensures shorter tap-to-tap time, correct end composition and temperature, better steel cleanliness, defect-free casting, etc. Nearly 50 years back, LD heat i. Experience of Off gas Measurements through Sublance operator analysis submerged tuyere. Turn down: Temperature, Off gas volume, Online: temperature, sample, [O], [C] temperature temperature, sample manually and chemical chemical composition composition.

    Currently, the same is carried out by a static process model, which is significantly more precise and extensive. Furthermore, any deviation in real practice is addressed through a dynamic or an online process model used to evaluate corrective measures needed to achieve correct end blow point i. To achieve satis- factory results, it is essential to have proven methods of direct and continuous mea- surements of temperature and composition of the bath. The future years will witness. Environmental aspects were and have been a serious challenge for steelmakers.

    Large volume of gases and dust are generated during various stages of steelmaking oxygen steelmaking, tapping, desulfurization through carbide injection, LF opera- tions, and alloy additions and in this, the converter steelmaking assumes a preemi- nent position.

    Efficient gas cleaning plants or dedusting systems are required such that clean converter gas, practically free of dust and sulfur, that can replenish energy sources in steel plants can be produced. Converter off gases, dust and slag, etc. Similarly, human involvement in risk-prone area and hazardous environment should be as little as possible. Serious efforts in robotics and automation are therefore called for.

    If steel has to remain competitive, efforts related to better productivity and prod- uct quality must culminate with a smaller specific energy requirement particularly, EAF, rolling mill operation, etc. Modeling will be a key player in many futuristic developments on these fronts. In the foreseeable future, EAFs and oxygen steelmaking will continue to domi- nate the steelmaking scenario, as no new technology is presently in sight. Although increased productivity through enhanced process performance, reduced yield losses, etc.

    Consistent productivity and quality 2. Zero emission 3. Reduced specific energy consumption. As we march ahead toward an era of automated, efficient, and green steelmaking, there is an increasing need for superior process control strategies in order to achieve consistent product quality coupled with maximum yield, optimum cost, minimum impact on the environment, smaller specific energy consumption, etc. In such efforts, modeling is likely to play pivotal roles and embraced in the industry as well as research and development on an ever-increasing scale. Successful new strategies are expected to evolve from a knowledge-based foundation encapsulating models, measurements, and steelmaking principles and practices, as already illustrated in Figure 1.

    Finally, Continuous casting process together with emerging casting technologies is briefly mentioned. Following such, an introduction to models and measurements, as two interdependent components of a steelmaking process investigation, is presented. The role of models, sensors, and computers in futuristic developments concerning emission, recycling, energy consumption, etc. It is emphasized that a sound understanding of the fundamental aspects of steelmaking, modeling, and measurements is a prereq- uisite to any serious research and development efforts in steelmaking.

    Rewrite erroneous statements correctly. Mechanical properties of steel can be affected only over a limited range through composition and grain size control. The world steel production currently exceeds mmt and is increasing. Aluminum and silicon have greater affinity toward oxygen than that of iron and are employed as deoxidizers in steelmaking. Slag splashing is the primary reason for significantly enhanced BOF lining life.

    Residual oxygen in BOF steelmaking is generally much greater than that in electric steelmaking. High-temperature steelmaking processes are generally chemically con- trolled rather than mass transfer controlled. Removal of sulfur and phosphorous is facilitated equally in oxygen steelmaking. Generally, less than 1 ppm hydrogen is required in final steel since hydro- gen is known to induce embrittlement in steel.

    Deoxidation and composition adjustment, gas injection, vacuum treatment are all endothermic processes and are associated with a drop in melt tem- perature in ladles. In an unstirred ladle, the content is more prone to thermal stratification. Most of the deoxidizers are still added in the BOF following refining. With the current technology, a BOF can work for several years without having to go for relining.

    The size, shape, and composition of endogenous inclusions can be suitably modified through calcium injection. Endogenous inclusions are generally much larger in size than exogenous inclusions. In a LF, the porous plug located at the base is directly placed under the electrodes. Water modeling is by far the most popular technique in physical model studies of steelmaking. A mathematical model employed in process control and automation performs in real time and is therefore considerably simplified.

    It is desirable to augment physical and mathematical modeling with pilot or full-scale investigation for complete understanding of steelmaking. Recycling of steel is not significant. Support your answers with numbers and sketches, wherever appropriate. What are the key reasons for the popularity of steel as an essential material in the present-day society? What are the two dominant routes of steelmaking? How do they compare in terms of productivity and specific energy consumption?

    What are the key reasons for Bessemer and hearth steelmaking processes to loose ground against oxygen steelmaking? What are the two key parameters monitored dynamically in BOF for accu- rate end point control?


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