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Progress of steelmaking technology in Japan over the last 100 years is overviewed covering hot metal pretreatment, primary steelmaking with open hearth furnaces, converters and electric arc furnaces, secondary refining of steel with degassers and ladle furnaces, and ingot- and continuous-casting.
Key issues that contributed considerably to the prog...
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... of the acidic Bessemer converter was much greater than the BOH (Fig. 1), 6) but the slopping loss of met-© 2015 ISIJ al out of the converter mouth and erosion wear of the bottom tuyeres resulted in 8% lower metal yield on ingot basis and 3.4% higher cost of production. In addition, the Bessemer converter could not make P content lower than about 0.1% with the acidic lining, and hence the application of ...
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... aforementioned advantages combined with financial support by MITI on the second rationalization program of Japanese steel industry prompted other steel companies to install LD converters (Fig. 2, 16) upper left). The share of LD steel production started around 5% in 1958, surpassed BOH steel share in 1965 to reach 55%, and achieved in 1970 a high 79% with a production of 73.51 million tons, top in the world. New installations of LDs and conversion of BOHs to LDs, and revamping and merger of obsolete LDs to build new LDs continued ...
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... 1988, Nagoya commercialized a HMPT process, named Optimizing Refining Process (LD-ORP) 39) with mixed blowing BOF (Fig. 10, top). 40) DeS hot metal was subject to deSi and deP together with scrap melting in the BOF. Slag rich in P was separated at tapping from steel which is subsequently decarburized in LD-OB. Inflow of slag containing P and S to LD-OB was minimized, and hence reversal of P at deC blowing was suppressed, amount of slag reduced, and smelting ...
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... minimized, and hence reversal of P at deC blowing was suppressed, amount of slag reduced, and smelting reduction of Mn in LD-OB was carried out favorably. Nippon Steel produced nearly 30% of total crude steel with LD-ORP in 2009. 40) Similar process to the above with BOF was industrialized by Sumitomo Metal in 1990 as Smart Refining Process (SRP, Fig. 11). 41) Hot metal preliminarily treated for deS and deSi, leaving 0.1%P and 0.1%Si at 1 300°C was blown with O 2 in the 1st mixed blowing BOF with an addition of 16 kg/ton iron ore and 4 kg/ton CaF2 to get 0.032%P melt which was sub- jected to deC and deP in the 2nd mixed blowing BOF with 10 kg/ton CaO as flux to reach 0.012%P. Slag from ...
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... 2000, Nippon Steel commercialized Multi-Refining Converter (MURC, Fig. 10 bottom) 42) as a variant of BOF based HMPT. Hot metal was subject to deS with KR or Mg- CaO injection, and charged into a mixed blowing BOF with scrap for deP blow. After tilting the BOF for slag removal, deC blow was carried out in the same BOF. De-P is promot- ed with the mixed blowing BOF, and the slag left in the BOF after deC blow is ...
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... the balance among the phases, helped by optimized power control and operator guidance system. Coherent burners for highly efficient scrap melting have got popular too, to avoid the harm of hot spot formation. Recent developments in the technology for the equipment and operation of EAF in Japan followed the trajectory of the European predecessors (Fig. 12). 45,46) Productivity of EAF is influenced by the choice of mixed raw materials (hot metal, scrap, DRI, HBI etc), furnace capacity, scrap preheating, machine and practice for charg- ing, efficiency of melting practice, and sequence matching with the preceding and succeeding processes (LF, CC). Efforts have continued to maximize the ...
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... early 1970s when continuous casting machine (CCM) was introduced in its infancy, steel melt was cast into ingots, soaked, subjected to roughing and supplied to down- stream rolling for billets, blooms or slabs (collectively semis). The ingots were classified in the order of deoxidation degree into rimmed-, semi killed-or killed-steel ingot (Fig. 13). 47) ...
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... tubular bub- bles started growing about 40-50 mm from the surface of ingot, the distance being controlled by the composition, cooling rate, pouring rate of the melt and the amount of minor addition of Al to the melt. The solidified shell layer from the ingot surface to the end of the tubular bubbles, called rim layer, was negatively segregated and clean, and the ingot was named rimmed ingot since it was surrounded by the rim layer (Fig 13, left). ...
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... later, VLB CCMs were introduced successfully in 1976 at Keihin (SMI-Concast make), Kimitsu in 1980 (Hitachi Zosen-Demag make), and Fukuyama where circu- lar CCM was converted by Hitachi Zosen-Demag to VLB in 1980. Since then, new installations of VLB CCMs (Fig. 14) 84) were many in other steel plants in Japan. In Europe and USA, it took longer time for the implementation, but recently, the installation has been increasing, following the one at Dillinger. To deal with more demanding qualities, ...
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... super clean steel grades, a solution has been provided by Chiba in 1996 in the form of Centrifugal (CF) tundish (Fig. 15). 59) It consists of a cylindrical front chamber where inclusions in the melt from ladle are separated to the central concave cavity of the melt generated with progressive circu- lating electromagnetic field set around the cylinder chamber. Cleaned steel flows out of a bottom opening of the cylinder chamber into rectangular rear chamber ...
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... development, H-shape tundish, has been made at Nagoya in 2000. It consists of two rectangular chambers connected side by side with bottom through hole to form H- shape tundish (Fig. 16). 60) Two ladles for preceding heat and succeeding heat can be teemed into the 1st chamber simul- taneously, without causing the harmful lowering of the melt in the chambers at the ladle change. 2nd chamber is equipped with DC arc heating guns to compensate for tem- perature drop of the melt within. At the bottom of the through hole, Ar ...
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... addition, electromagnetic devices to control the melt flow in mold have been industrialized (Fig. 17) 61,62) such as In-Mold Electro-Magnetic Stirrer (M-EMS) pioneered in 1980 at Hirohata, followed by Electro Magnetic Brake (EMBR) of ABB at Mizushima, later developed into Flow Controlled Mold (FC-Mold) 85) of Kawasaki Steel, and LMF of Nippon ...
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This paper analyzes the effect of new technology for steel refining -- the basic oxygen furnace -- on productivity growth using the productivity decomposition method. I employ a technique that decomposes productivity growth into four factors: operational improvement, within- and between-technology reallocation, and entry-exit effects. I demonstrate...
Citations
... (0.15 on average), with optimal values in the range 0.25-0.30 were proposed by [38] while Emi [39] suggests values in the range of 0.3-0.4, Weng and Wang [40] recommend an optimal value of 1.5 to maximize sulfur partition with basicities greater than 6. ...
... Furthermore, especially in the case of aluminum killed steels, it is important to consider the increase in alumina content in the slag during the desulfurization+deoxidation process. [38] [33] [39], often described in a "compact" way by the molecular reaction shown in equation (4) � ...
... Considering the low calorific value and long impurity removal time generated by CO 2 participating in the oxidation reaction, it is necessary to use electric energy to heat the system during the steelmaking process. The CIDSVS process has a good application prospect in the electric furnace steelmaking process [38] and has positive economic and environmental effects. ...
A novel method for CO2 injection direct smelting vanadium steel (CIDSVS) is proposed. Achieving selective oxidation of phosphorus is essential for the applicability of the suggested process. Under the guidance of thermodynamics, the mechanisms of CO2 injection dephosphorization and vanadium retention were investigated with CO2 flow rate and dephosphorization slag composition as experimental variables. The results indicate that CO2 as an oxygen source can remove 73.8% of phosphorus, while the oxidation rate of vanadium is 17.5%. The dephosphorization process can be divided into two stages: FeO- and CO2-dominated experimental processes. In the initial stage of slag feeding, [V] and [P] undergo fast oxidation, and the oxidation amount is positively correlated with the initial FeO content. The high basicity (CaO/SiO2 ratio) reduces the activity of V2O3 in the slag and promotes the oxidation of [V]. Under the experimental conditions of 1,400°C, the optimal conditions were determined to be a CO2 flow rate of 1.5 mL·g⁻¹·min⁻¹, a FeO content of 40%, and a basicity B of 2.5. Following the CIDSVS steelmaking operation, 80% of the vanadium is retained, and the impurity elements fulfill the specifications for steel. This method enhances vanadium utilization and is environmentally friendly.
... Secondary refining line at a steel mill is a common integration of the RH (Ruhrstahl-Hausen) vacuum degasser and LF (ladle furnace), to have the mass production of high-purity steel after removing impurities like nitrogen and hydrogen from molten steel, by lowering the partial pressure. Sometimes top-blowing oxygen is injected at the surface of the ruffling liquid steel to remove carbon [1][2] . There are two snorkels assembled under the bottom of RH degasser and immersed into the molten steel of a ladle. ...
Magnesia-chrome refractories are appropriate to work under cyclic temperatures or atmospheric conditions because some oxides of chrome ore readily release oxygen (are reduced) upon heating and pick up oxygen (are oxidized) upon cooling or upon changing the atmosphere. They have been ideal lining materials for RH degassers for many years, despite challenging of Cr 6+ disposal issue after using. The varieties of magnesia-chrome refractories depend on their raw materials and burning temperatures, which could be well demonstrated by their microstructures. But Indian chrome concentrate cannot be directly used in the production of magnesia-chrome bricks because of reducing sintering density. Silicate bonded magnesia-chrome bricks are produced with low purity magnesia after burning at relatively lower temperatures, resulting in liquid film forming as silicate bond around chrome ore particles. Direct bonded and rebonded fused-grains magnesia-chrome refractories are made of high purity magnesia or fused magnesia-chrome grains, forming euhedral and intergranular secondary chromite spinels as the main feature. The amount of secondary spinel increases with the rising burning temperature, leading to increasing hot modulus of rupture and overall hot properties as well. It is important to burn magnesia-chrome bricks under weakly reducing atmosphere. The oxygen content of burning atmosphere from 800 °C to 1 650 °C would better controlled below 0.5% to increase the burnt strength and to avoid inner cracks and loose bonding of magnesia-chrome bricks, while the atmosphere contains 3%-6% O 2 under most economical firing condition.
... Burgeoning metallurgical technology has been leading the continuous casting owing to high efficiency and low energy consumption gradually among the existed casting technologies [1][2][3][4]. In the continuous casting process, submerged entry nozzle (SEN) is a key functional refractory connection between the tundish and mold. ...
The corrosion mechanisms that occurred between the slag-line and mold flux under the applied external electric field are studied. The results show that the slag-line can be effectively protected when the slag-line is connected to the negative electrode, and the graphite as an auxiliary electrode is connected at positive potential. Under the applied negative electric field, a thick protective adhesion layer is formed on the surface of the slag-line due to the electrochemical reactions. Additionally, the slag-line material is further reacted with surface of the formed protective layer and generates another interface reaction layer. Under the effect of double protective layers, the slag-line can be perfectly devoid of corrosion attack under the negative electric field. The performance of the slag-line and the production time of the whole continuous casting can be improved. The external electric field is expected to be a new technical approach to alleviate corrosion of the SEN.
... Oxygen-converter is a unit for steelmaking by oxygen blowing of liquid iron, which ensures the oxidation of iron impurities (silicon, manganese, car bon, etc.) and their subsequent removal from the melt. Currently, it is the main way of steel production in the world metallurgical practice [1][2]. ...
... There are several ways of oxygen blowing in the converter: top blowing, bottom blowing and a combination of these two methods with blowing through the bottom by oxygen covered with a natural gas or neutral gas [1][2]. Despite a long period of oxygen converter process research and development, today there are several issues that can be solved by physical methods. ...
Introduction. The process of oxygen conversion, despite the existing improvements, can be supplemented by physical methods of influence, including the unconventional method of applying low-voltage potential developed at the Iron and Steel Institute of the NAS of Ukraine.Problem Statement. The studies of the method of low-voltage potential application on 60, 160 and 250 ton converters have shown that the technology intensifies thermophysical and hydrodynamic processes in the gasslag-metal system and increases the converter process efficiency.Purpose. The purpose of this research is to study the features of the influence on the reaction zones of the low voltage potential application at four blowing options with the use of high-temperature physical model.Materials and Methods. A physical model that simulates the top, bottom and combined oxygen blowing under low-voltage potential application of different polarity on the lance has been used. An insert of a transparent quartz plate is made in one of the walls for visual observation and video recording. The top blowing is conductedwith two nozzle lance (nozzle diameter 1.7 mm with an angle of 30 ° to the lance). The bottom blowing is conducted with a bottom tuyere with a 1.5 mm diameter central nozzle. Combined blowing is realized by a combination ofthese options.Results. The visual observation of the reaction zones with different blowing options has shown that the highest temperature and the largest dimensions of the brightest parts of the bath correspond to the combined blowing, while the lowest ones are reported for the bottom blowing. While applying the low-voltage potential method it has been established that the reaction zone is longer at the positive polarity on the lance, during the period of silicon oxidation, and at the negative polarity on the lance, during the period of intense carbon oxidation. The video of gas bubbles flotation, probably CO, has shown that the bubbles are formed more intensively in thecase of negative polarity on the lance.Conclusions. The applied technique has allowed estimating the influence of low-voltage potential application on the geometric parameters of the reaction zone.
... DC furnaces have not replaced AC ones, but their number has been growing. For instance, in Japan, there are 22 DC furnaces in operation now, with capacities from 30 to 429 tons [5]. They include one of the biggest arc furnaces worldwide, a DC furnace with a capacity of 420 tons, equipped with a 170-MVA power transformer, at the arc voltage of 600 V and the rated current of 280 kA. ...
... This practice definitely improves the quality of the steel manufactured, increases productivity, and at the same time maximizes cost-efficiency of the production process. The reduction of tapping temperature and making all the refining operations beyond the EAF allows the tap-to-tap time to shorten, which reduces heat losses and the consumption of refractory materials [5]. ...
... This calls for attention to gauge the entire progress that the global steel industry has made on GHG mitigation. Most of previous investigations have been limited to specific production technologies 24,26,27 where the interplay between material flows and supply-side technical efficiency was widely overlooked. Such lack of understanding could prohibit the development of strategies that are more effective for steel industry toward future GHG emission mitigation. ...
... This step began with a literature review on global steel production technologies and routes change. Some of the literature, especially that on the historical development of ironmaking 27 and steelmaking 26 technologies, provides important information for our analysis, helping us define system boundaries, identify key technologies for global steel production and track technology progress in quantifying production activities and emission trends (details in Section S1). (2) Material flow analysis. ...
Steel production is a difficult-to-mitigate sector that challenges climate mitigation commitments. Efforts for future decarbonization can benefit from understanding its progress to date. Here we report on greenhouse gas emissions from global steel production over the past century (1900-2015) by combining material flow analysis and life cycle assessment. We find that ~45 Gt steel was produced in this period leading to emissions of ~147 Gt CO2-eq. Significant improvement in process efficiency (~67%) was achieved, but was offset by a 44-fold increase in annual steel production, resulting in a 17-fold net increase in annual emissions. Despite some regional technical improvements, the industry’s decarbonization progress at the global scale has largely stagnated since 1995 mainly due to expanded production in emerging countries with high carbon intensity. Our analysis of future scenarios indicates that the expected demand expansion in these countries may jeopardize steel industry’s prospects for following 1.5 °C emission reduction pathways. To achieve the Paris climate goals, there is an urgent need for rapid implementation of joint supply- and demand-side mitigation measures around the world in consideration of regional conditions. The effectiveness of large historical efforts for decarbonizing steel production is unclear. Here, the authors show that such efficiency gains were offset by a booming steel demand increase. This has led to a stagnating decarbonization progress over past decades, which jeopardizes realization of future climate targets.
... By performing the tasks elaborated on the basis of the mathematical models and by optimizing the parameters of the main processes in the elaboration and casting of the high strength mechanical steels, their properties can be improved. The steel industry has responded to current requirements by developing new steel brands that can be used in different industrial sectors and which have a common set of characteristics These steels are called HSLA -high strength microalloyed steels [1]. All these features are found in high strength microalloyed steels, which are produced and developed under different brands by the major steel producers around the world [2]. ...
... In a LD converter with combined oxygen and argon blowing, Fig. 2, the basic reactions that take place are oxidation, and the movement of the metal bath is mainly generated by the energy transmitted by the oxygen jet hitting the metal bath and by the blowing energy, due to carbon monoxide (CO) formation and release [6]. [1,8] In the initial phase of the process when the silica oxidation takes place, the formation of CO remains less intense. In the main decarburization phase, the formation of CO in the reaction areas of the oxygen jets and in the immediate vicinity is extremely pronounced. ...
... Fig. 1. General presentation of the technological flows of making and casting steel[1,4] ...
The paper presents the processes of elaboration and casting that favourably influence the properties of microalloyed steel.
High strength microalloyed steel used to manufacture main oil and gas pipelines must meet, in addition to special technical conditions, economic conditions, which contribute to the protection of the environment. Secondary treatment in LF and RH installations as well as automatically controlled continuous casting can also help improving the physical, mechanical and corrosion properties of the products obtained from these steels. The making of X70 steels at OLD1-(Liberty Steel Group), according to existing technology, is the peak of performance at the current stage.
Blowing oxygen and argon into the converter is done according to a Blowing Pattern that takes into account the gas flow and the distance from the head of the blowing lance to the surface of the metal bath. Deoxidation and microalloying of the X70 steel take place in the casting ladle and during the secondary treatment in LF and RH.
For deoxidation and microalloying, some ferro-alloys which have strictly limited content of harmful elements (P, S) are used. LF microalloying materials such as: Mn-99%, Al-99%, FeTi-70%, FeV-80%, FeNb-65%, Ca-99% or SiCa60/30% are introduced into the steel as tubular ferro-alloys and not chunks. In this way, a superior assimilation and homogeneous diffusion of the elements into the metal bath are achieved.
Secondary treatment of the X70 steel for chemical and thermal homogenization of the metal bath is achieved by advanced metal bath desulfurization using synthetic slag, lime and bauxite. Vacuum degassing with RH procedure is done to reduce hydrogen from 8-9 ppm to less than 2 ppm. At the continuous casting of these steel types, the bubbling is not used because it is intended that the floating of inclusions be easier on the surface of the metal bath.
... Most sulphur will initially react with magnesium to form MgS. The lime will mostly prevent the resulphurisation via reaction (9). With magnesium/lime co-injection, sulphur concentrations below 0.001% (10 ppm) have been reported in the literature [29][30][31][32] . At the plants of Tata Steel IJmuiden and Port Talbot a significant amount of heats had a measured final sulphur concentrations below 0.001% with co-injection. ...
... The KR is widely applied in Asia (especially Japan). With the KR, sulphur concentrations below 0.001% (10 ppm) have been reported in the literature 28,31 . ...
Sulphur removal in the ironmaking and oxygen steelmaking process is reviewed. A sulphur balance is made for the steelmaking process of Tata Steel IJmuiden, the Netherlands. There are four stages where sulphur can be removed: in the blast furnace (BF), during hot metal (HM) pretreatment, in the converter and during the secondary metallurgy (SM) treatment. For sulphur removal a low oxygen activity and a basic slag are required. In the BF typically 90% of the sulphur is removed; still, the HM contains about 0.03% of sulphur. Different HM desulphurisation processes are used worldwide. With co-injection or the Kanbara reactor, sulphur concentrations below 0.001% are reached. Basic slag helps desulphurisation in the converter. However, sulphur increase is not uncommon in the converter due to high oxygen activity and sulphur input via scrap and additions. For low sulphur concentrations SM desulphurisation, with a decreased oxygen activity and a basic slag, is always required.
... While production efficiency was dramatically improved, the phosphorus flowed not to the slag, but to the final steel product, as shown in Fig. 1C. Because this process involved higher smelting temperatures (1600-1800°C) than the puddling process (1300°C), the phosphorus oxide in the acidic slag was reduced into elemental phosphorus, resulting in its dissociation into the molten steel (Emi, 2015). To avoid this, the Bessemer process required the utilization of low-phosphorus pig iron, which was known as Bessemer pig iron. ...
... After the end of World War II, the LD converter, which uses pure blown oxygen, was developed. As shown in Fig. 1F, this process was characterized by high production efficiency and the production of two different slags, with the phosphorus concentrated in one of them (Emi, 2015;Inazumi, 2009;Wolf, 1997). Unlike the Bessemer converter, where air is blown into the process, the LD converter process creates a large exothermic reaction, allowing the use of pig iron with fewer exothermic elements such as phosphorus and silicon. ...
This article will outline the historical transition in the flow of phosphorus in steelmaking technology, and examine the current and future phosphorus flow in steel production and the peripheral steelmaking processes. History provides many instances of innovative changes in steelmaking processes driven by various issues associated with raw materials which emerged over time, such as supply, quality and cost issues. The major steel countries with a long history, including Sweden and Japan, have shown flexibility in their ability to adapt to the changes in the value of resources and geopolitical conditions over times, and have enacted survival resource utilization measures over many centuries, leading to improvements in their respective steelmaking processes. Considering these success stories, it stands to reason that the ideal state of steelmaking is one with a clear stance with regard to resource policy.
