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The present paper illustrates an innovative steel processing route developed by employing hydrogen direct reduced pellets and an open slag bath furnace. The paper illustrates the direct reduction reactor employing hydrogen as reductant on an industrial scale. The solution allows for the production of steel from blast furnace pellets transformed in...
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Since the European Union defined ambitious CO2 emission targets, low-carbon-emission alternatives to the widespread integrated blast furnace (BF)—basic oxygen furnace (BOF) steelmaking strategy—are demanded. Direct reduction (DR) with natural gas as the reducing agent, already an industrially applied technology, is such an alternative. Consequently...
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... To reduce the operational costs of an electric smelter, the electrode technology is important. The well-proven Søderberg technology is an option for a DRI smelter, based on experience with high-current operations and electric smelters in general, it is expected that a prospected DRI smelter can operate with Søderberg electrodes as well (LÖTTER, 2021;LYTVYNYUK, 2023;CAVALIERE, 2022;RUDGE, 2023). ...
One of the biggest challenges in the 21st century is the reduction of anthropogenic emissions of greenhouse gases. A contributor up to date is the iron and steel industry due to the usage of fossil carbon sources as fuel and reducing agents. The conventional blast furnace and basic oxygen furnace steelmaking route still relies on coal and metallurgical coke, despite countless innovations and improvements in the past. An alternative to lower the specific CO2 footprint of steel production is the replacement of the blast furnace with a combination of a direct reduction (DR) unit like a direct reduction shaft furnace and an electric smelter. This article focuses on a continuous and reducing smelting unit to produce green hot metal suitable for usage in a basic oxygen furnace for green steel production. Similar electric furnaces are already in use in the ferroalloy industry. However, due to differences in metal, slag, and raw material properties, it is not possible to transfer the state-of-the-art ferroalloy production technology entirely to the innovative hot metal smelter. Therefore, similarities and necessary adjustments to existing smelting furnaces are presented in this article on a way to a decarbonized integrated steelwork.
... Now, the pellets reduced via pure hydrogen are carbon free leading to an increase in the melting temperature of the sponge iron (1538 • C). As a consequence, carburization is needed [51,52]. DR under CO atmosphere is often accompanied by carbon deposition due to an inverse Boudouard reaction at temperatures <1000 • C. ...
... It remains the leading technology due to its undoubted advantages in productivity and liquid steel composition control. According to the experts' forecast, it has all the prerequisites to remain the leading method even with the transition to hydrogen metallurgy [1][2][3][4][5]. According to the statistical report of the World Steel Organization, in 2021, the total production of converter steel was 73.2% of the total [1]. ...
Introduction. The BOF technology is the leading one in the production of structural steel due to its undeniable advantages.Problem Statement. In the conditions of most Ukrainian converter shops, when the blowing parameters change significantly during the campaign (temperature of the lining, dimensions of the workspace, quality of scrap metal, temperature and composition of iron), and the bath is blown at a constant flow rate with conventional Laval nozzles, sometimes it is impossible to ensure a stable purging process with high rate of post-combustion of CO up to CO2. Therefore, one of the main problems of oxygen conversion is the improvement of the designs of blowing devices, in particular, the nozzles.Purpose. The purpose of this research is to study the possibility of using nozzles of the coherent type for the top oxygen blowing of the converter.Material and Methods. In the research, we have used samples of coherent-design laboratory nozzles having different central part-to-periphery ratio under fixed equal general conditions of jet output (percentage of the annular gap to the total area of the nozzle, %: 75, 65, 50, 45, 35, 25). They have been studied by calculating the jet momentum, through weighing and taking shadow shots when the gas flow velocity reaches 2 M. The results have been compared with those for the cylindrical nozzle.Results. When the gas is supplied at 2 M, the coherent-type nozzles with a fraction of the outer part of 65—75% contribute to the formation of 1.5—1.6 times wider jets as compared with the cylindrical nozzle, with a multinode structure. It helps to increase the jet momentum by 45—55%.Conclusions. The design of a coherent type nozzle with an outer part share of 75% can be recommended to be used as the second tier or the second level nozzles of the top oxygen lance for post-combustion in an oxygen converter due to an increase in the surface area of the jet contact. The efficiency of post-combustion of CO from waste converter gases is expected to increase due to the increasing reaction surface area of additional oxygen jets.
... Note, however, that even though some limited pilot experiments were carried out by Tenova [34], there are no industrial references yet of using that technology in connection with an H 2 -DR shaft. ...
There is an explosion of publications and of various announcements regarding the use of hydrogen in the steel sector as a way to arrive at Net-Zero steel production − particularly in Europe. Most of them describe process technologies on the one hand and commitment to implement them quickly in the steel sector in the form of roadmaps and agendas, on the other hand. The most popular process technology is H 2 Direct Reduction (H 2 -DR) in a shaft furnace. Available technical literature, as abundant as it may be, is still fairly incomplete in making the pathway to Net-Zero explicit and credible. This paper tries to identify important issues which are not openly discussed nor analyzed in the literature, yet. Process-wise, open questions in technical papers are: (1) what are the best-fitted iron ores for H 2 -DR, (2) what downstream furnace, after H 2 -DR, can accommodate various raw materials, (3) how and how much carbon ought to be fed into the process, (4) what is the best design for the shaft, (5) should it be designed for both natural gas and H 2 operations, or simply for H 2 , (6) how should the progress of R&D be organized from pilot plants up to full-scale FOAK plants and then to a broad dissemination of the technology, (7) what kind of refractories should be implemented in the various new reactors being imagined, etc. Cost issues are also widely open, as a function of green hydrogen, green electricity and carbon prices. How is hydrogen fed to the steel mill and what exactly is the connection to renewable electricity? Is the infrastructure that this calls for planned in sufficiently details? What is still missing is a full value chain picture and planning from mining to steel mills, including electricity and hydrogen grids. Two years after our last review paper on hydrogen, the overall picture has changed significantly. Countries beyond Europe, including China, have come up with roadmaps and plans to become net-zero by 2050, plus or minus 10 years. However, they do not rely as much on H 2 alone, as Europe seems to be doing. What is most likely is that several process routes will develop in parallel, including, beyond H 2 -DR, Blast Furnace ironmaking and NG Direct Reduction with CCS, electrolysis of iron ore and scrap-based production in EAFs fed with green electricity, which would single-handedly support the largest part of production by the end of the century; as more and more scrap is to become available and be actually used. There is also a question for historians. The influence of Climate Change on Steel has been discussed continuously for more than 30 years. Why has the commitment to practical answers only solidified recently?
... The electric arc furnace (EAF) slag is composed of SiO2-CaO-MgO-Al2O3-FeO [1,2] system with a temperature of up to 1756K [3]. The electrical conductivity of the slag in the EAF is important in the industrial process and directly affects the quality of the final product and energy consumption [4]. ...
Electrical conductivity is of fundamental importance in electric arc furnaces (EAF) and the interaction of this phenomenon with the process slag results in energy losses and low optimization. As mathematical modeling helps in understanding the behavior of phenomena and it was used to predict the electrical conductivity of EAF slags through artificial neural networks. The best artificial neural network had 100 neurons in the hidden layer, with 6 predictor variables and the predicted variable, electrical conductivity. Mean absolute error and standard deviation of absolute error were calculated, and sensitivity analysis was performed to correlate the effect of each predictor variable with the predicted variable.
... The online tests carried out show that the calculation, optimization, and control architecture can lead to promising and satisfying results. In Cavaliere et al. [3], an innovative steel processing route developed by employing direct hydrogen reduced pellets and an open slag bath furnace is illustrated. The paper illustrates the direct reduction reactor employing hydrogen as a reductant on an industrial scale. ...
In the recent past, ironmaking and steelmaking saw the incorporation of various new processes and technologies that can be operated and organized in different combinations depending on the properties of raw materials and the required quality of the final products [...]
... Several approaches were used to develop these solutions, whose overview is provided in Figure 1. [6]. ...
... Pimm et al. improved the MIDREX process to use renewable energies to satisfy the energy needs Figure 1. Direct reduction methods have been developed extensively [6]. ...
... Today these processes provide for more than 70% of the overall production of DRI and hot briquetted iron (HBI). Natural gas is transformed into reducing agents, mostly carbon monoxide and hydrogen, which operate as iron oxide reducers [6]. The shaft furnace is divided into three main parts: (i) reduction zone, (ii) transition zone, and (iii) cooling zone. ...
The direct reduction process has been developed and investigated in recent years due to less pollution than other methods. In this work, the first direct reduction iron oxide (DRI) modeling has been developed using artificial neural networks (ANN) algorithms such as the multilayer perceptron (MLP) and radial basis function (RBF) models. A DRI operation takes place inside the shaft furnace. A shaft furnace reactor is a gas-solid reactor that transforms iron oxide particles into sponge iron. Because of its low environmental pollution, the MIDREX process, one of the DRI procedures, has received much attention in recent years. The main purpose of the shaft furnace is to achieve the desired percentage of solid conversion output from the furnace. The network parameters were optimized, and an algorithm was developed to achieve an optimum NN model. The results showed that the MLP network has a minimum squared error (MSE) of 8.95 × 10−6, which is the lowest error compared to the RBF network model. The purpose of the study was to identify the shaft furnace solid conversion using machine learning methods without solving nonlinear equations. Another advantage of this research is that the running speed is 3.5 times the speed of mathematical modeling.
... This combination has proven succesful in processing ilmenite-or titanomagnetite-based sponge iron, e.g., in South Africa or New Zealand [14][15][16][17]. Moreover, the smelter is capable of producing hot metal based on prereduced iron (PRI) from lower-grade iron ores [18][19][20]. The flowsheet in Figure 1 highlights the differences between the two routes. ...
... Finally, the possibility of introducing a potential process route beyond the DR-EAF route can be speculated. In a recent study, 17 an alternative steelmaking route of the DR-OSBF (open slag bath furnace)-BOF route was proposed. OSBF is a type of smelting furnace similar to the SAF (submerged arc furnace), where additional reduction of unreduced ores is possible with additional carbon reductants during subsequent melting. ...
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Wanho Kim is the representative of “TheHighest” company, South Korea. He develops solutions for reducing CO2 emissions in various technological fields based on chemical metallurgy. He holds a doctoral degree from Yonsei University in materials science and engineering and has worked as a principal researcher at POSCO to reduce CO2 emissions in steel processing. He has been developing alternative processes using hydrogen to reduce CO2 emissions in iron and steelmaking and has also participated in the development of related national projects. He currently provides comprehensive consulting in developing sustainable green technologies for various metallurgical industries.
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Il Sohn is professor at the Materials Science and Engineering Department in Yonsei University, South Korea. He holds a doctoral degree from Carnegie Mellon University in materials science and engineering and has worked extensively in the steel-related industry and academia for more than 2 decades. He engages in fundamental research of steelmaking and recycling and process optimization. He serves as a member of the National Academy of Engineering of Korea and several editorial boards of renowned metallurgical journals including Metallurgical and Materials Transactions. His profound hope is to make an impact for the sustainability of the industry.
... Although this accounts only for a small share of the global crude steel production, it is a widely used steelmaking strategy, particularly but not exclusively, in NG-rich countries [16,17,[20][21][22][23]. Besides the EAF, processing sponge iron into pig iron using a submerged arc furnace (SAF) might be a second option [24,25]. These aggregates are typically used to produce ferroalloys [26][27][28][29][30] and process DRI made from ilmenite-or titanomagnetite-based ores into hot metal [31][32][33]. ...
Since the European Union defined ambitious CO2 emission targets, low-carbon-emission alternatives to the widespread integrated blast furnace (BF)—basic oxygen furnace (BOF) steelmaking strategy—are demanded. Direct reduction (DR) with natural gas as the reducing agent, already an industrially applied technology, is such an alternative. Consequently, the melting behavior of its intermediate product, i.e., direct reduced iron (DRI), in either an electric arc furnace (EAF) or a submerged arc furnace (SAF), is of great interest. Based on the conditions in these aggregates, a test series to experimentally simulate the first few seconds after charging DRI was defined. DRI samples with different carbon contents and hot briquetted iron (HBI) were immersed in high- and low-carbon melts as well as high- and low-iron oxide slags. The reacted samples were quenched in liquid nitrogen. The specimens were qualitatively evaluated by investigating their surfaces and cross sections. The dissolution of carbon-free DRI progressed relatively slowly and was driven by heat transfer. However, carbon, present either in the DRI sample or in the melt, not only accelerated the dissolution process, but also reacted with residual iron oxide in the pellet or the slag.
