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To develop more sustainable purification and recovery processes, it is critical to accurately determine inorganic impurities of natural graphite (NG) and valuable elements present in low concentrations in steelmaking slag. This study applied three microwave-assisted acid digestion methods for basic oxygen furnace (BOF) slag, NG, and NG ash. Nitric acid (HNO3), hydrochloric acid (HCl), and hydrogen fluoride (HF) were used in method 1. In method 2, method 1 was followed by microwave-assisted boric acid (H3BO3) digestion. In method 3, acids (HNO3, HCl, HF, and H3BO3) were added simultaneously. Concentrations were measured using inductively coupled plasma–optical emission spectrometry. Analytical performance was evaluated using spiking recovery tests (NG) and certified reference (slag) material (CRM). Spiking recoveries for Al, Ca, Fe, K, Mg, Na, and Si were between 5% and 116% (method 1) and 94%–116% (methods 2 and 3). CRM recoveries for Al, Ca, Fe, Mg, Mn, P, Si, Ti, and V were between 2% and 102% (method 1) and 92%–103% (methods 2 and 3). The unsuitability of method 1 was evident due to the low recoveries. Methods 2 and 3 digested Ca- and Si-containing BOF slag completely without visible residue. The sufficient recoveries verified the adequacy of the methods. The suitability of method 3 probably depended on the phases of samples, as quartz was not completely digested from the NG. Method 2 completely digested the inorganic material of NG, and the spiking test showed no loss of volatile silicon compounds. These methods have not been published for NG or NG ash and validated for slag before. [ABSTRACT FROM AUTHOR]

Harnessing basic oxygen furnace gas (BOFG) from steel mills as an alternative carbon source is a promising option to reduce greenhouse gas (GHG) emissions. This study explores two process concepts to purify CO from BOFG for subsequent phosgene synthesis: (i) vacuum pressure swing adsorption (VPSA) yielding pure CO, and (ii) CO2 separation via monoethanolamine (MEA) absorption producing CO‐enriched gas. By combining process optimization with life cycle assessment (LCA), process parameters are identified that minimize GHG emissions. The MEA concept can reduce emissions by up to 60 %, whereas the VPSA concept achieves a reduction of 47 %. Utilizing renewable energy enables further reductions, indicating additional environmental benefits in the future. Overall, both processes effectively produce low‐carbon CO for phosgene synthesis, with increasing environmental benefits in future energy systems. [ABSTRACT FROM AUTHOR]

Construction industry intends to promote effective utilization of waste materials obtained from various sources to develop an eco‐friendly building material for high performance, life cycle sustainability, and reduction of carbon footprints globally. The current study focusses to produce concrete mix by using industrial wastes such as ground granulated blast furnace slag (BOF) and glass powder (GP). Samples are prepared by utilizing industrial wastes partially for M35 grade concrete. The ground granulated BOF and GP are used with 10%–40% and 0.1%–0.4%, respectively, as the partial replacement of cement. Under different curing periods, the specimens were characterized for their physical and mechanical properties. Test results were analyzed to check the workability, compressive strength, flexural strength, and water absorption of the sample mixes prepared. The highest compressive and flexural strength of the samples are found to be 46.23 MPa and 5.13 MPa, at the optimal replacement of BOF and GP in the proportion of 30% and 0.2%, respectively. [ABSTRACT FROM AUTHOR]

Furnace temperature and oxygen content are important parameters reflecting the combustion inside a circulating fluidized bed (CFB) boiler. Accurately predicting boiler output is a complex task due to the high noise and nonsmoothness of actual boiler input and output data. In this paper, a new hybrid convolutional neural network (CNN), bidirectional long short-term memory (biLSTM) network, and squeezing and excitation (SE) network prediction model is proposed to significantly improve the prediction accuracy of oxygen content and furnace temperature by combining the advantages of multiple deep learning networks. This network can extract spatiotemporal characteristics of input parameters such as coal feed to effectively predict boiler furnace temperature and oxygen content. CNNs can extract complex features such as dynamic and static nonlinearities between multiple variables affecting the furnace temperature and oxygen content, as well as high noise. The biLSTM network layer can efficiently handle the temporal information of irregular trends in modeling time series components; SE can extract the important information between channels through the feature relationships between channels for better overfeature extraction. The CNN-biLSTM-SE model can effectively solve the problem of nonlinear mapping complexity between inputs and outputs. Experiments show that the proposed CNN-biLSTM-SE model outperforms existing methods. The experimental results showed that the average MAPE errors for oxygen content prediction were CNN-biLSTM-SE (0.038), CNN-biLSTM with attention mechanism (AM) (0.043), CNN-biLSTM (0.051), CNN-LSTM (0.051), biLSTM (0.051), RNN (0.051), LSTM(0.0052), and CNN(0.0054). Extensive experiments in CFB boilers with oxygen content and furnace temperature show that the proposed CNN-biLSTM-SE model achieves better results in terms of goodness-of-fit, generalization ability and accuracy. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) landfills are a significant source of methane (CH4) emissions in the United States, contributing to global warming. Current landfill gas (LFG) management methods, like the landfill cover system and LFG collection system, do not entirely prevent LFG release. Biocovers have the potential to reduce CH4 emissions through microbial oxidation. However, LFG also contains carbon dioxide (CO2) and trace hydrogen sulfide (H2S) depending on waste composition, temperature, moisture content, and age of waste. An innovative biogeochemical cover (BGCC) was developed to tackle these concerns. This cover comprises a biochar-based biocover layer overlaid with a basic oxygen furnace (BOF) steel slag layer. The biochar-based biocover layer oxidizes CH4 emissions, while the BOF slag layer reduces CO2 and H2S through carbonation and sulfidation reaction mechanisms. The BGCC system's field performance remains unexamined. Therefore, a large-scale tank setup simulating near-field conditions was developed to evaluate the BGCC system's ability to mitigate CH4, CO2, and H2S from LFG simultaneously. Synthetic LFG was passed through the BGCC in five distinct phases, each designed to simulate the varying gas compositions and flux rates typical of MSW landfill. Gas profiles along the depth were monitored during each phase, and gas removal efficiency was measured. After testing, biocover and BOF slag samples were extracted to analyze physico-chemical properties. Batch tests were also conducted on samples extracted from the biocover and BOF slag layers to determine potential CH4 oxidation rates and residual CO2 sequestration capacity. The results showed that the BGCC system's CH4 removal efficiency decreased with higher CH4 flux rates, achieving its highest removal (74.7–79.7%) at moderate influx rates (23.9–25.5 g CH4/m2-day) and reducing to its lowest removal (27.4%) at the highest influx rate (57.5 g CH4/m2-day). Complete H2S removal occurred during Phase 3 in the biocover layer of BGCC system. CH4 oxidation rates were highest near the upper (277.9 µg CH4/g-day) and lowest in the deeper region of the biocover layer. In the tank experiment, CO2 breakthrough occurred after 156 days due to drying of the BOF slag layer, with an average residual carbonation capacity of 46 gCO2/kg slag after moisture adjustment. Overall, the BGCC system effectively mitigated LFG emissions, including CH4, CO2, and H2S, at moderate flux rates, showing promise as a comprehensive solution for LFG management. [ABSTRACT FROM AUTHOR]

A demonstration-scale outdoor constructed wetland (CW) wastewater treatment system was evaluated for about two years for its effectiveness in treating septic system effluents. The system included three treatment cells: an anaerobic cell, an aerated cell, and a basic oxygen furnace slag (BOFS)-based phosphorus (P) treatment cell. High removal efficiencies were achieved, with reductions of >99% for PO4-P, >83% for NH3-N, >99% for cBOD5, and >76% for COD, with influent concentrations averaging 6, 48, 63, and 143 mg L−1, respectively. Additionally, pathogens removal were high, with an over 99% decrease in E. coli and total coliform levels. The BOFS cell was critical, elevating effluent pH to 10.9 ± 1.5, which effectively inactivated pathogens. Environmental safety before discharge was ensured by CO2(g) sparging to adjust the pH and a zero-valent iron layer in the BOFS cell to control dissolved metal concentrations. Analytical techniques (FESEM-EDX, FTIR, and XANES) confirmed the formation of Ca carbonate and Ca phosphate on spent BOFS, highlighting their role in the treatment process. This study highlights the potential of integrating complementary technologies in constructed wetlands for sustainable and efficient wastewater management. [ABSTRACT FROM AUTHOR]

When steel is smelted in electric arc furnaces, and during its subsequent treatment in ladle-furnace units, a significant amount of power is required. This power is supplied through the use of graphitized electrodes, which are pivotal for achieving the required temperatures. However, these electrodes are costly, significantly affecting the overall production costs. Therefore, efforts to reduce the cost of steel by minimizing the consumption of graphitized electrodes are crucial for metallurgists. The primary factor influencing the consumption rate of these electrodes is their surface oxidation by oxygen present in the furnace atmosphere. Recent studies have shown that a magnesium hydroxide-based coating can significantly mitigate this issue. When applied to the surface of graphitized electrodes, this coating was shown to reduce their weight loss by 30–40% at the test temperature in an oxidizing atmosphere. Notably, as the temperature increases, so does the benefit of this weight loss reduction. The efficacy of the tested can be attributed to its unique properties. Upon application to a graphitized electrode's surface, the coating material penetrates deeply into the pores, effectively sealing them and forming a protecting layer over the surface. As the temperature rises, water within the coating evaporates, leaving behind a highly adhesive residue. At 350 °C, the Mg(OH)2 in the coating decomposes to form MgO, which has a melting point of 2850 °C. This results in a high-density coating that acts as a barrier against atmospheric oxygen, thereby significantly slowing down the rate of graphite oxidation in the electrodes. [ABSTRACT FROM AUTHOR]

The objective of basic oxygen furnace (BOF) steelmaking is to achieve molten steel with final carbon content, temperature, and phosphorus content meeting the requirements. Accurate prediction of the above properties is crucial for end-point control in BOF steelmaking. Traditional prediction models typically use multi-variable input and single-variable output approaches, neglecting the coupling relationships between different property indicators, making it difficult to predict multiple outputs simultaneously. Consequently, a multi-output prediction model based on the fusion of deep convolution and attention mechanism networks (FDCAN) is proposed. The model inputs include scalar data, such as the properties of raw materials and target molten steel, and time series data, such as lance height, oxygen supply intensity, and bottom air supply intensity during the blowing process. The FDCAN model utilizes a fully connected module to extract nonlinear features from scalar data and a deep convolution module to process time series data, capturing high-dimensional feature representations. The attention mechanism then assigns greater weight to significant features. Finally, multiple multi-layer perceptron modules predict the outputs—final carbon content, temperature, and phosphorus content. This structure allows FDCAN to learn complex relationships within the input data and between input and output variables. The effectiveness of the FDCAN model is validated using actual BOF steelmaking data, achieving hit rates of 95.14% for final carbon content within ±0.015 wt%, 84.72% for final temperature within ±15 °C, and 88.89% for final phosphorus content within ±0.005 wt%. [ABSTRACT FROM AUTHOR]

Basic oxygen furnace (BOF) slag is an industrial waste produced from steel-making. It can be utilized as building material, but its high content of free CaO (f-CaO) causes volume expansion of materials and limits its utilization. However, carbonation of BOF slag can decrease the f-CaO content, improve stability, and reduce carbon emissions. This study investigated the influence of temperature, pressure, liquid to solid, reaction time, and stirring pattern on f-CaO consumption and CO2 sequestration, which reached a maximum f-CaO consumption and CO2 sequestration of 99.58% and 5.12% (51.2 g CO2/Kg BOF slag), respectively, under optimum conditions. According to the results of the XRD patterns of carbonated slag, no peaks of CaO were detected, the peaks of Ca2Fe2O5 and Ca2SiO4 were slightly reduced, and new peaks of CaCO3 were detected. The reaction process has been described by a shrinking core model revealing that the diffusion of reactants through the product layer was the rate-limiting step for carbonation. The kinetic equation for CO2 sequestration was derived as: InK = − 2132.83·T−1–9.1543. This approach presents a green, cost-effective, and rapid method for enhancing steel slag utilization while capturing and storing CO2. The method proposed in this paper holds significant potential for wider adoption. [ABSTRACT FROM AUTHOR]

Global crude steel production is expected to continue to increase in the coming decades to meet the demands of the growing world population. Currently, the dominant steelmaking technology worldwide is the conventional highly CO2 -intensive blast furnace–basic oxygen furnace production route (also known as the Linz–Donawitz process), which uses iron ore as raw material and coke as a reducing agent. As a result, large quantities of special gases that are rich in carbon monoxide (CO) are by-products of the various stages of the steelmaking process. Given the challenges associated with satellite-based estimates of carbon dioxide (CO2) emissions at the scale of emitting installations due to significant background levels, co-emitted CO may serve as a valuable indicator of the carbon footprint of steel plants. We show that regional CO release from steel production sites can be monitored from space using 5 years of measurements (2018–2022) from the TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel-5 Precursor satellite, benefiting from its relatively high spatial resolution and daily global coverage. We analyse all German steel plants with blast furnaces and basic oxygen furnaces and obtain associated CO emissions in the range of 50–400 kt yr -1 per site. A comparison with the respective CO2 emissions on the level of emitting installations available from emissions trading data of the European Union Emissions Trading System yields a linear relationship with a sector-specific CO/CO2 emission ratio for the analysed steelworks of 3.24 % [2.73–3.89; 1 σ ], suggesting the feasibility of using CO as a proxy for CO2 emissions from comparable steel production sites. An evaluation at other steel production sites indicates that the derived CO/CO2 emission ratio is also representative of other highly optimised state-of-the-art Linz–Donawitz steelworks outside Germany and that the emission ratio is potentially valuable for estimating sector-specific CO2 emissions from remotely sensed CO emissions, provided that the underlying CO emission estimate is not affected by other sources. [ABSTRACT FROM AUTHOR]

Reducing CO 2 emissions of the iron and steel industry, a typical heavy CO 2 -emitting sector, is the only way that must be passed to achieve the 'dual-carbon' goal, especially in China. In previous studies, however, it is still unknown what is the difference between blast furnace-basic oxygen furnace (BF-BOF), scrap-electric furnace (scrap-EF) and hydrogen metallurgy process. The quantitative research on the key factors affecting CO 2 emissions is insufficient. There is also a lack of research on the prediction of CO 2 emissions by adjusting industrial structure. Based on material flow analysis, this study establishes carbon flow diagrams of three processes, and then analyze the key factors affecting CO 2 emissions. CO 2 emissions of the iron and steel industry in the future is predicted by adjusting industrial structure. The results show that: (1) The CO 2 emissions of BF-BOF, scrap-EF and hydrogen metallurgy process in a site are 1417.26, 542.93 and 1166.52 kg, respectively. (2) By increasing pellet ratio in blast furnace, scrap ratio in electric furnace, etc., can effectively reduce CO 2 emissions. (3) Reducing the crude steel output is the most effective CO 2 reduction measure. There is still 5.15 × 108-6.17 × 108 tons of CO 2 that needs to be reduced by additional measures. [ABSTRACT FROM AUTHOR]

The study of alkali-activated materials as a replacement for portland cement has been growing in recent years due to the sustainable nature of these materials. Nevertheless, ternary alkali-activated pastes using waste glass as a precursor have been insufficiently studied concerning their rheological, mechanical, and microstructural properties. In addition, there is a lack of research studying alkali-activated mixtures using basic oxygen furnace (BOF) slag and glass waste as precursors. Therefore, this paper aims to study the effect of glass powder (GP) content as a precursor, the effect of the activator ratio in alkali-activated ternary pastes of BOF slag, metakaolin (MK), and GP, and the influence of the Na2SiO3/NaOH ratio on its mixtures. The activator solutions of NaOH and Na2SiO3/NaOH were used in the production of the pastes. The liquid/solid ratio was kept fixed at 0.6 and the molarity of the NaOH solution was fixed at 12 M, seeking to analyze the impact of the Na2SiO3/NaOH ratio, with adopted values of 0.75, 1.5, and 2.5. We also aimed to study the impact of the glass content in the mixture for the values of 10%, 20%, and 25%, replacing the BOF slag. The workability by the minislump test, rheology, compressive strength for 1 and 28 days, and microstructural parameters were analyzed. ANOVA was performed to determine the significance of variables in the workability and compressive strength parameters. Pastes with the highest activator ratio (Na2SiO3/NaOH=2.5) produced better compressive strength (34.74 to 36.11 MPa) and lower minislump spreads (90 to 98 mm) compared with the mixtures with Na2SiO3/NaOH=1.5 and 0.75, besides indicating a denser microstructure, linked to higher production of aluminosilicate gels. Higher GP contents generated pastes with lower mechanical performance (16.7 MPa for Na2SiO3/NaOH=0.75) and microstructural qualities, albeit with better workability (124-mm minislump spread). [ABSTRACT FROM AUTHOR]

Steel slag is a significant environmental liability generated by pyrometallurgical processes. Residue generation, such as granulated blast furnace slag and basic oxygen slag (BOF), is intrinsic in steel production. Blast furnace slag, generated in the carbothermal reduction of iron ore, is almost entirely used as a supplementary cement material in Portland cement. BOF slag, produced in the conversion of pig iron into steel in a basic oxygen converter, is still not consolidated or valued for reuse. This research proposes the reuse and valorization of BOF slag combined with blast furnace slag in clinker-free cement production. Cement formulations were produced with different slag and gypsum contents, ranging from 80 to 90% blast furnace slag, 10 to 20% gypsum, and 10 to 15% BOF slag. All formulations were evaluated for compressive strength at ages of 3, 7, 14, 28, 91, and 180 days of curing. At the initial ages, the cement formulations exhibited high resistance. On the 3rd day, the cement formulations reached up to 10 MPa, and on the 7th day, 40 MPa. At late ages, the best-performing formulation, ECO2, showed, after 28 days of hydration, a compressive strength greater than 50 MPa, and at 180 days, a compressive strength greater than 80 MPa. It was possible to understand that BOF slag acts in cement alkaline activation with pH increase, more or less actively due to the presence of lime, portlandite, and calcite. [ABSTRACT FROM AUTHOR]

During the top blowing process of the basic oxygen furnace, the oxygen jet may react with CO before it reaches the surface of the molten bath. This combustion reaction affects the dynamic characteristics of the jet, which, in turn, affects its interaction with the bath. In this study, a numerical model is developed to investigate the transient and steady combustion characteristics of the supersonic jet emitted from the top lance. The transient combustion simulation shows that the CO ratio gradually decreases while the CO2 mole fraction increases at the interaction boundary region between jet and ambient due to the chemical reactions. In addition, the jet profile is changed when the postcombustion is introduced. Due to the flame formation and turbulence change at the jet combustion interface, the axial velocity at height of 2 m (x = 73 re) is 89% higher than that of the noncombustion reaction jet flow. In the results, it is demonstrated that the combustion interface is favorable to reduce the jet decay, resulting a higher dynamic pressure before the jet reaches the bath surface. Furthermore, a higher core temperature and lower density are obtained for the combustion jet compared to that of without combustion reaction. [ABSTRACT FROM AUTHOR]

Carbonation of BOF slag offers a promising solution to reduce f-CaO content and simultaneously capture CO2. This study investigated the influence of particle size on f-CaO consumption and CO2 sequestration of BOF slag while exploring the kinetics of the carbonation process. Under optimum conditions, the finest particle size achieved f-CaO consumption and CO2 sequestration values reaching 99.72% and 5.57%, respectively; whereas the largest particle size exhibited values of 97.89% and 3.4%, respectively. The shrinking core model accurately described the carbonation process with internal diffusion identified as the rate-limiting step for the whole process. The transition point between two rate-limiting steps was determined along with an established equation between particle size, CO2 sequestration and time. The XRD patterns and SEM images illustrated morphological changes in slag before and after carbonation. These findings can provide crucial insights for optimizing the carbonation process and facilitating its utilization as cementitious materials. [ABSTRACT FROM AUTHOR]

To realize efficient P removal and resource utilization of steelmaking slag, a synthetic slag with appropriate basicity was produced by co-processing the practical dephosphorization slag and basic oxygen furnace slag. The selective leaching behavior and dissolution kinetics of P were investigated. The results indicated that the P dissolution efficiency and reaction rate were significantly influenced by the variety in stirring rate and pH. However, the decreasing solid/liquid ratio and particle size can significantly enhance the reaction rate, while exerting a slight impact on the P dissolution efficiency. The leaching temperature had less influence on both P dissolution efficiency and reaction rate. Under the optimal leaching conditions, the leaching reaction of the P-condensed phase primarily occurred within the initial 3 min, and, finally, the P dissolution efficiency reached 87.5%, with an extremely low dissolved amount of Fe. After leaching, the Fe-rich residue consisted of massive Fe2O3, MgO, and MnO, with only 0.32% P2O5. This residue can be used as a raw material or flux in steel plants. Furthermore, it was found that the selective leaching of P was controlled by diffusion through the product layer, with the apparent activation energy of 5.80 kJ/mol. The empirical equation has been established. [ABSTRACT FROM AUTHOR]

This study investigated the effects of lithium slag and iron tailings on the hydration mechanism of Basic Oxygen Furnace (BOF) slag cement paste with the addition of 0.06% diethanol-isopropanolamine (DEIPA). This study examined the fluidity, compressive strength, pore solution pH, and hydration products of BOF slag-based composite cementitious materials. The results showed that DEIPA facilitated the conversion from ettringite (AFt) to monosulphate (AFm) and improved the early compressive strength of the BOF slag–cement mortar. Incorporating lithium slag into the DEIPA-containing BOF slag–cement system promoted AFt formation, increased calcium-silicate-hydrate production, and enhanced the microstructure. BOF slag, lithium slag, and iron tailings exhibit synergistic effects in cement pastes. BOF slag and lithium slag provided the reactive components SiO2 and Al2O3. In the early hydration stages, the iron tailings primarily served as fillers, accelerating the system's reactions. [ABSTRACT FROM AUTHOR]

In the steelmaking process, inaccurate composition of raw materials, experimental process parameter control, and other factors bring about large statistical uncertainty to the phosphorus content prediction of molten steel. Meanwhile, lots of models mainly predict the end‐point phosphorus content, but the composition change during the whole production process is still in the gray box condition, where the exact refining state is unknown. These two problems increase the difficulty in process parameter optimization and control. In order to improve the phosphorus content control in the steelmaking process, this work proposes the functional relevance vector machine (FRVM) method. This method smooths the time series of process parameters to continuous functions by functional data analysis to predict the phosphorus content change during the whole production process, and estimates the probabilistic distributions of regression weights based on the Bayesian framework to directly output the probabilistic confidence interval of the phosphorus content. The real‐world steelmaking dataset validates that the mean relative prediction error of phosphorus content by the FRVM method is less than 18.04% during the whole production process and the end‐point hit rate is 86.46% when the prediction error is within ±0.005 wt%. [ABSTRACT FROM AUTHOR]

Engineered geopolymer composites (EGC) have emerged as a more environmentally friendly alternative to conventional engineered cementitious composites (ECC). These composites offer high mechanical and durability features. However, there is a lack of research on EGC, particularly with basic oxygen furnace (BOF) slag as a precursor and iron ore tailings (IOT) as a partial replacement to fine aggregate. Despite their effectiveness as industrial waste products in conventional concrete, this study aimed to determine the optimal compositions of fly ash (FA), steel fibres (SF), and IOT by varying their percentages. Overall, 150 mix combinations were tested, including six binder combinations, five combinations of fine aggregates, and five percentage variations in SF. Finally, one optimum mix was selected for each binder combination, based on the ultimate compressive strength values corresponding to the six optimal mixes. The compressive strengths of all the mixes were evaluated at both 7 and 28 days of curing, involving three replicate samples after oven curing (initial 24 h) followed by subsequent ambient curing until their respective ages. The highest observed compressive strength after 28 days was 41.77 MPa for 50 mm cubes. This strength was achieved with a composition of 60% FA, 1.5% SF, and 45% IOT. An increase in IOT percentage led to a nearly linear increase in strength, while the strength peaked at 1.5% for steel fibres. The addition of BOF slag significantly enhanced the compressive strength compared to mixes with full FA. A 40% fly ash replacement with BOF slag resulted in an average strength that was 39% higher than the combination with 100% fly ash. However, the strength growth decreased after a 10% replacement. Analysis of variance was conducted using the design of experiments methodology to determine the significance of the parameters and their interactions. All three independent parameters were found to be statistically significant, while their interactions were not. Utilizing Taguchi's analysis method with the L25 orthogonal array, it was concluded that IOT percentage was the most influential parameter. [ABSTRACT FROM AUTHOR]

Droplet splashing behavior caused by the top blowing supersonic jets impacting the liquid metal surface significantly affects the decarburization efficiency and refractory erosion during the basic oxygen furnace (BOF) steelmaking process. However, simulating the mass and size of splashing droplets is challenging because the droplet size differs by multiple orders of magnitude from the molten bath. Herein, a hybrid model (VOF-to-DPM) coupling the volume of fluid model (VOF) and discrete phase model (DPM) was combined with the adaptive mesh refinement (AMR) technique to successfully achieve high-resolution and quantitative capture of splashing droplets. The simulation results are in good agreement with the droplet splashing rate calculated by the theoretical formula based on the Blowing number (NB) within the allowable error range. The generation mechanisms of splashing droplets caused by single-hole and multiple-hole jets impacting the liquid surface were clarified. Furthermore, the effects of oxygen lance height and top blowing flow rate on the total droplet mass, mass and percentage of droplets sprayed on the furnace wall, and the droplet size were also investigated. It was revealed that with the decrease of the oxygen lance height, the total droplet mass increases and then decreases, and the droplet size increases. As the top blowing flow rate increases, the total mass and size of droplets both tend to increase. The proportion of droplets sprayed on the furnace wall increases sequentially when the impact cavities are in the penetrating mode, splashing mode, and quasi-dimpling mode. Moreover, the relationship between the cavity morphology and the droplet splashing was quantitatively characterized. As the modified cavity shape index (Icm) increases, the droplet splashing mass increases then decreases and finally increases. The change in cavity mode is the main factor affecting the droplet splashing behavior. [ABSTRACT FROM AUTHOR]

The global steel industry is integral to the development of modern infrastructure, yet it stands as one of the most significant contributors to greenhouse gas (GHG) emissions worldwide. This dichotomy brings forth the imperative for an in-depth analysis of GHG inventory practices and the pursuit of sustainable production methods. This mini-review paper addresses the current methodologies for GHG accounting within the steel sector, emphasizing the critical role of accurate and transparent emissions data as the basis for effective climate change mitigation strategies. Evaluating the prevalent carbon-intensive blast furnace-basic oxygen furnace (BF-BOF) production route, this paper contrasts traditional practices with innovative reduction initiatives, particularly those aligned with the emergence of green steel. We delve into the advancements in electric arc furnace (EAF) technology, direct reduced iron (DRI) processes utilizing green hydrogen, and the potential of carbon capture, utilization, and storage (CCUS) systems. The analysis extends to a critical examination of the challenges and opportunities these technologies face, including economic viability, scalability, and the readiness of energy infrastructure to support such a transition. Further, this review highlights the significance of verification and validation in reinforcing the credibility of GHG inventories. We scrutinize the materiality of reported emissions in the context of evolving regulatory frameworks and stakeholder expectations, stressing the need for standardized and rigorous assurance practices. Highlights: • The global steel industry is a major contributor to greenhouse gas emissions, and there is a need for accurate emissions data to address climate change. • Transitioning to green steel production, using technologies like electric arc furnace (EAF) and direct reduced iron (DRI) with green hydrogen, can significantly reduce emissions. • Verification and validation of greenhouse gas inventories are crucial for credibility in the context of evolving regulatory frameworks. [ABSTRACT FROM AUTHOR]

Severe greenhouse gas emissions have made global warming one of humanity's most critical and intricate environmental challenges. As the world's largest producer and exporter of steel, China's steel industry contributes substantially to carbon emissions. The government formulated the policies and pathways to achieve carbon neutrality, and enterprises have proactively pursued low‐carbon technologies. In this review, the decarbonization process in the Chinese steel industry is classified into three stages according to the decarbonization amount and technological maturity: the improvements of the blast furnace‐basic oxygen furnace, the attempt of the nonblast furnace, and the preparatory electricity‐hydrogen coupling metallurgy. This article reviewed the industrial‐scale low‐carbon metallurgical technologies represented by the Baowu HyCORF process, bottom‐blowing O2‐CO2‐pulverized lime converter process, gas‐based direct reduction shaft furnace process, Molong HIsmelt process, and Ouye furnace process, as well as pointed out the development limitations of those processes. Additionally, the study presented prospects for zero‐carbon emission technologies coupling green energy generation and hydrogen metallurgy. These findings will offer substantial support for advancing research and development of low‐carbon metallurgical technologies and formulating relevant policies in the future. [ABSTRACT FROM AUTHOR]

To realize the high‐efficiency utilization of iron‐rich coal, it is necessary to conduct in‐depth research on the ash fusion characteristics and regulation mechanism. In this paper, the ash fusion temperature test of iron‐rich coal in Xinjiang (ZC) under different atmospheres was first carried out. Then, red mud (HJ) from Huajin Aluminum Industry and black water pipe scale (GDG) were selected as the additives. After the same ashing procedure, the two additives were mixed with iron‐rich coal ash in different proportions to realize the regulation of the chemical composition of the coal ash to improve the ash fusion characteristic. The ash fusion temperature (AFT) experiment was carried out in the automatic ash melting point analyzer, and high‐temperature ash melting slags at different temperatures were prepared. The mineral phases of coal ash and slag were characterized by XRD and compared with the Factsage simulation calculation results to reveal the influence mechanism of coal ash fusion temperature. The result shows that the fusion temperature of ZC iron‐rich coal ash is significantly different between oxidizing atmosphere and weak reducing atmosphere. Compared with the oxidizing atmosphere, the four characteristic temperatures of ZC iron‐rich coal ash are significantly lower under weak reducing conditions, and the difference is about 150°C. The addition of red mud and pipeline scale increased the fusion temperature of ZC coal ash to varying degrees. The addition of HJ ash has little effect on the deformation temperature of ZC coal ash, while the addition of different proportions of HJ ash significantly increases the flow temperature of ZC coal ash. When the addition ratio of HJ ash is 40%, the flow temperature FT of ZC coal ash increases most obviously, which is about 50°C. The addition of HJ ash and GDG ash will lead to an increase in the content of iron‐containing spinel, thereby increasing the ash flow temperature. [ABSTRACT FROM AUTHOR]

The rotation speed of the basic oxygen furnace (BOF) and the shape of the tapping hole have an important influence on the amount of slag carryover during the tapping process. The CFD fluid simulation software Fluent is used to analyze the flow field of the 210 t BOF rotation tapping process. The results revealed that the amount of slag carryover in the early stage is the largest when the tapping hole inclination angle is 0° and the rotation speed is 1.0 r/min. The flow field analysis shows that this is caused by the fluctuation of molten steel and slag, which makes the slag flow into the tapping hole again. The case of a rotation speed of 1.2 r/min shows the least amount of slag carryover. By comparing the three kinds of tapping holes, it can be known that a reduction in the tapping hole diameter brought a decrease in yield loss and a decrease in amount of slag carryover. As the height of molten steel decreases, the shear stress on the tapping hole decreases. The increase in the diameter of the tapping hole increases the shear stress, which in turn increases the wear of the refractory material. [ABSTRACT FROM AUTHOR]

The steel industry in China, the world's largest, contributes to about 15% of the nation's total carbon emissions. Instead of direct combustion, the technology of converting off-gas from the steel industry into liquid fuels not only enhances the added value of this byproduct but also helps alleviate carbon emissions. This study, for the first time, integrates the specific circumstances of China to evaluate the carbon emissions of Ethanol to Jet (ETJ) and Fischer–Tropsch to Jet (FTJ) fuel technologies utilizing Basic Oxygen Furnace Gas (BOFG) and Coke Oven Gas (COG) as feedstocks. Six cases were examined using Aspen Plus (V11) for mass and energy balance: Case 1: BOFG/ETJ, Case 2: BOFG/FTJ, Case 3: COG/ETJ, Case 4: COG/FTJ, Case 5: (COG + BOFG)/ETJ, and Case 6: (COG + BOFG)/FTJ. The analysis underscores that the FTJ pathway exhibits superior carbon reduction efficiency relative to ETJ. Compared to traditional petroleum-based aviation fuels (86.65 g CO2eq/MJ), the FTJ pathways utilizing COG or COG + BOFG as feedstocks exhibit significant advantages in greenhouse gas (GHG) emission reductions, with carbon emissions of 23.60 g CO2eq/MJ and 41.48 g CO2eq/MJ, respectively, representing reductions of 72.76% and 52.13%. Furthermore, employing uncertainty analysis based on the Monte Carlo method establishes the credibility of the findings. Finally, sensitivity analysis for parameter optimization and process improvements demonstrates the significant impact of the life cycle assessment (LCA) allocation method on computational results for exhaust gas feedstocks. Given the limited coverage of lifecycle assessments for Ethanol to Jet and Fischer–Tropsch to Jet pathways in China, this study could assist policymakers in determining the development trajectory of sustainable aviation fuel (SAF) in China. [ABSTRACT FROM AUTHOR]

Global crude steel production is expected to continue to increase in the coming decades to meet the demands of the growing world population. Currently, the dominant steelmaking technology worldwide is the conventional highly CO2-intensive Blast Furnace – Basic Oxygen Furnace production route (also known as the Linz-Donawitz process) using iron ore as raw material and coke as a reducing agent. As a result, large quantities of special gases that are rich in carbon monoxide (CO) are by-products of the various stages of the steelmaking process. Given the challenges associated with satellite-based estimates of carbon dioxide (CO2) emissions at the scale of emitting installations due to significant background levels, co-emitted CO may serve as a valuable indicator of the carbon footprint of steel plants. We show that regional CO release from steel production sites can be monitored from space using 5 years of measurements (2018–2022) from the TROPOspheric monitoring instrument (TROPOMI) on board the Sentinel-5 Precursor satellite benefiting from its relatively high spatial resolution and daily global coverage. We analyse all German steel plants with blast furnaces and basic oxygen furnaces and obtain associated CO emissions in the range of 50–400 kt yr-1 per site. A comparison with the respective CO2 emissions on the level of emitting installations available from emissions trading data of the European Union Emissions Trading System yields a linear relationship with a sector-specific CO/CO2 emission ratio for the analysed steelworks of 3.24 % [2.73–3.89; 1 σ ] suggesting the feasibility of using CO as a proxy for CO2 emissions from comparable steel production sites. [ABSTRACT FROM AUTHOR]

Fused cement clinker can be produced from molten basic oxygen furnace slag (BOFS) by way of a reductive thermochemical treatment. During the thermochemical treatment, oxidic iron is reduced to metallic iron and separated. The resulting low-iron slag has a chemical and mineralogical composition similar to ordinary Portland cement (OPC) clinker. In this study, the hydraulic reactivity of the fused clinker from BOFS with and without gypsum was investigated using isothermal calorimetry, differential scanning calorimetry, in situ X-ray diffraction and powder X-ray diffraction. Furthermore, a synthetic fused clinker without foreign ions and fused clinker produced by a mixture of both materials was studied. The hydraulic reaction of the fused clinker from BOFS was considerably slower than that of OPC. However, the reaction can be accelerated by adding gypsum as a sulfate carrier. Furthermore, the results showed an increased reaction rate with decreasing content of foreign ions such as Fe, P or Mn. [ABSTRACT FROM AUTHOR]

The replacement of the blast furnace—basic oxygen furnace (BF-BOF) steelmaking route with the direct reduced iron—electric arc furnace (DRI-EAF) route reduces the direct CO2 emissions from steelmaking by up to 68%; however, the DRI shaft furnace is one of the largest remaining point source emitters in steelmaking. The capital and operating expenses of two potential nearly carbon-neutral DRI process configurations were investigated as a modification to a standard Midrex DRI facility. First, amine-based post-combustion capture with a 95% capture rate was considered as the benchmark, as it is currently commercially available. A second, novel configuration integrated the Midrex process with pressurized chemical looping—direct reduced iron (PCL-DRI) production. The capital expenditures were 71% and 28% higher than the standard Midrex process for a Midrex + amine capture plant, and a PCL-DRI plant, respectively. There was an incremental variable operating cost of USD 103 and USD 44 per tonne of CO2 for DRI production using amine capture and PCL-DRI, respectively. The amine capture configuration is most sensitive to the cost of steam generation, while PCL-DRI is more sensitive to the cost of electricity and the makeup oxygen carrier. An iron-based natural ore is recommended for PCL-DRI due to the low cost and availability. Based on the lower costs compared to amine-based post-combustion capture, PCL-DRI is an attractive means of eliminating CO2 emissions from DRI production. [ABSTRACT FROM AUTHOR]

The oxygen blast furnace (OBF) process with top gas recycling is recognized as a promising ironmaking process, due to its high productivity and low CO2 emissions. The solid flow plays a crucial role in this process. Therefore, the solid flow in OBF was investigated using a cold experimental OBF model in this paper. The results indicate that the plug flow is the primary solid flow pattern in the upper and middle zones of the OBF. A slight convergence flow and a smaller deadman zone were observed at the bosh. The influence of recycled gas on solid flow was found to be quite limited. Additionally, the raceway size affects the burden structure and deadman zone, but the production rate had little impact. Both the raceway size and production rate have different effects on the repose angle of the deadman zone, and it varies by 14–18°. The findings of this study may have important implications for understanding the structure of solid flow in OBF. The results can be used to optimize the process parameters and equipment design to improve the efficiency of iron production while reducing environmental impact. [ABSTRACT FROM AUTHOR]

In this study, a portable spectral analysis instrument based on spontaneous emission spectroscopy (SES) was developed for the in situ, non-intrusive, and quantitative measurement of gaseous Na inside ZD coal-fired boilers, which is mainly applied for predicting slagging in furnaces. This technology is needed urgently because the problem of fouling and slagging caused by high alkali metals in ZD coal restricts the rational utilization of this coal. The relative extended uncertainty for the measurement of gaseous Na concentration is Urel = 10%, k = 2, which indicates that measurement data are reliable under working conditions. It was found that there is a clear linear relationship between the concentration of gaseous Na and fouling in high-alkali coal boilers. Therefore, a fast and efficient method for predicting the slagging and fouling of high-alkali coal boilers can be established by using this in situ online real-time optical measurement. [ABSTRACT FROM AUTHOR]

It has been proposed that antidiabetic drugs, such as metformin and imatinib, at least in part, promote improved glucose tolerance in type 2 diabetic patients via increased production of the inflammatory cytokine GDF15. This is supported by studies, performed in rodent cell lines and mouse models, in which the addition or production of GDF15 improved beta-cell function and survival. The aim of the present study was to determine whether human beta cells produce GDF15 in response to antidiabetic drugs and, if so, to further elucidate the mechanisms by which GDF15 modulates the function and survival of such cells. The effects and expression of GDF15 were analyzed in human insulin-producing EndoC-betaH1 cells and human islets. We observed that alpha and beta cells exhibit considerable heterogeneity in GDF15 immuno-positivity. The predominant form of GDF15 present in islet and EndoC-betaH1 cells was pro-GDF15. Imatinib, but not metformin, increased pro-GDF15 levels in EndoC-betaH1 cells. Under basal conditions, exogenous GDF15 increased human islet oxygen consumption rates. In EndoC-betaH1 cells and human islets, exogenous GDF15 partially ameliorated cytokine- or palmitate + high-glucose-induced loss of function and viability. GDF15-induced cell survival was paralleled by increased inosine levels, suggesting a more efficient disposal of intracellular adenosine. Knockdown of adenosine deaminase, the enzyme that converts adenosine to inosine, resulted in lowered inosine levels and loss of protection against cytokine- or palmitate + high-glucose-induced cell death. It is concluded that imatinib-induced GDF15 production may protect human beta cells partially against inflammatory and metabolic stress. Furthermore, it is possible that the GDF15-mediated activation of adenosine deaminase and the increased disposal of intracellular adenosine participate in protection against beta-cell death. [ABSTRACT FROM AUTHOR]

In the present context of global decarbonization, the steelmaking sector plays a key role. It is indeed one of the so-called hard-to-abate sectors. The high emissions from steelmaking depend on the use of the Blast Furnace-Basic Oxygen Furnace (BF-BOF) route, which generates 1.8 tCO2eq per ton of Liquid Steel (LS). The production of direct reduced iron (DRI) to power an electric arc furnace is currently the most adopted solution to achieve the decarbonization goals. This alternative, based on the use of natural gas, offers a decarbonization potential of about 34% compared to the BF-BOF route. The most promising alternative, however, consists of using electrolysis-based hydrogen (H2) to produce DRI. This solution would drastically reduce direct and indirect process emissions but requires a radical energy transition. In the current transition phase, waste-based H2 production routes could be attractive, but their potential need to be evaluated with respect to the steelmaking process. To this concern, the objective of the present work is to assess the decarbonization potential of three waste-based H2 production routes (i.e., gasification, incineration and anaerobic digestion-based) with respect to the electrolysis-based steelmaking route. An environmental analytical model was therefore developed to evaluate the total (i.e., direct, indirect, and avoided) greenhouse gases emissions associated with the production of 1 ton of LS by employing the different routes. A sensitivity analysis was also carried out to understand the benefit provided by each waste-based H2 alternative in the current energy transition phase. The results obtained confirmed the need for radical emission reductions from electricity generation to make electrolysis-based H2 production environmentally favorable and revealed a high decarbonization potential for waste-based routes in the current energy transition phase. [ABSTRACT FROM AUTHOR]

For the soil in an area which has been repeatedly chosen as one of the 10 most polluted places in the world, stabilization of Pb and Zn was assessed in batch, incubation, and column experiments. Single and combined amendment of scrap-recycling slag (Slag-R), charcoal, coal ash, hydrated lime, and basic oxygen furnace (BOF) slag were applied for the stabilization. Notably, the combined amendment of Slag-R and hydrated lime exhibited superior stabilization efficiencies than the individual use of all stabilizing agents and combined use of charcoal and hydrated lime. The combined amendment of Slag-R and hydrated lime decreased Pb levels by 92–99% and Zn levels by 63–88% in the incubation experiments and by 75% and 89–93%, respectively, in the column experiments. In particular, the combined amendment showed a synergistic effect for Pb stabilization because a higher pH enhanced sorption onto the slag and because sorption onto Fe (hydr)oxides of the sorbent possibly helped to remove Pb. Zinc had a relatively lower sorption tendency, so it was mainly controlled by the pH increase from hydrated lime. Although the addition of hydrated lime was very effective in stabilizing high concentrations of Pb and Zn, the dosage should be controlled carefully because excessively high pH redissolves Pb and Zn as anions. [ABSTRACT FROM AUTHOR]

Slag, a by-product of the iron and steelmaking industry, has been identified as an alternative construction material; however, there are currently limited engineering reuse applications for some slags. Steel slag coarse aggregates (>6 mm) has been successfully used in the asphalt mix for the surface course in pavement constructions; nonetheless, the construction applications of finer slag particles (<6 mm) are limited due to their expansive properties when hydrated. Therefore, this research aims to investigate the potential of using granulated blast furnace slag (GBFS) in controlling the swelling of fine particles of fresh basic oxygen furnace slag (BOFS). A series of laboratory tests were conducted to evaluate the engineering properties, swelling, and shear behavior of BOFS-GBFS mixtures to identify controlling factors and governing mechanisms of swelling, followed by acceptable mix proportions for potential use in pavement applications. Both accelerated swell tests and long-term swell consolidation tests demonstrated an exponential reduction in the hydration-induced expansion of BOFS with the addition of GBFS. For example, up to 77% of the swelling reduction was observed by replacing 30% of BOFS particles with GBFS. In contrast, the peak deviatoric stress of BOFS was reduced linearly with an increase in GBFS content, causing a 15% reduction of friction angle with a 30% addition of GBFS content. Optical microscopy and micro-computed tomography (CT) analysis revealed the bond formed between BOFS-GBFS particles due to the chemical reaction between the free lime in BOFS with silica and alumina in GBFS in the presence of water. The overall laboratory results were summarized by developing a design chart in which the optimal mix of GBFS to BOFS lies between 25% and 30%, volumetric swelling is less than 1%, and the peak friction angle is about 43°. [ABSTRACT FROM AUTHOR]

Ludwigite is a multi-element coexisting iron ore. Through the sinter pot experiment, the effect of ludwigite on the metallurgical properties of the sinter is studied, and its action mechanism is revealed combined with X-ray diffraction (XRD) analysis. The appropriate amount of ludwigite is obtained on the evaluation mechanism of softening and melting properties of the sinter, which provides theoretical guidance for practical production. The results show that with the increase of the amount of ludwigite, the yield, vertical sintering speed, and drum index in the metallurgical properties of the sinter show a gradual downward trend, and the low-temperature reduction pulverization index RDI+3.15 shows a gradual upward trend. The addition of ludwigite is conducive to the formation of calcium ferrite and promotes the activity of MgO. The addition of excessive ludwigite will lead to the formation of Mg2B2O5 and Ca3B2O6, Slag phase is formed. With the increase of the proportion of ludwigite, the melting range of the sinter is slightly widened, and the permeability is improved first and then reduced. Under this ore blending condition, ludwigite resources can be added and used in sintering batching, and the proportion shall not exceed 6%. [ABSTRACT FROM AUTHOR]

This document is a discussion of a research paper titled "Probing the Stochastic Unconfined Compressive Strength of Lime–RHA Mix Treated Clayey Soil." The paper explores the use of lime and rice husk ash as binders to stabilize clayey soil. The authors conducted tests to measure the unconfined compressive strength of soil-binder specimens with varying amounts of rice husk ash and lime. They used artificial neural networks and Gaussian process regression to analyze and predict the data. The discussers raise questions about the influence of suction on the strength of the blends and the effect of dry density, suggesting further evaluation of these factors. [Extracted from the article]

Due to the presence of free lime (FL) in slag and its lack of reaction with concrete components, concrete containing slag reduces strength. Pozzolanic Portland cement (PPC) in the presence of moisture and normal heat during chemical reactions with lime (calcium hydroxide) generates stable calcium silicates that have adhesion properties. By using PPC instead of Portland cement type I in roller compacted concrete (RCC) containing basic oxygen furnace slag (BOFS), it is possible to determine the mechanical properties of RCC due to the reaction between the FL in BOFS and PPC. Therefore, this study aims to investigate the effect of PPC on the mechanical properties of RCC containing BOFS. For this purpose, specimens are made with various cement content values (225-400 kg/m3), various BOFS content values (0-50%) and with the optimum moisture. The properties examined in this paper are compressive strength, indirect tensile strength, and static modulus of elasticity tests. The results show that the use of PPC is effective in compensating the negative impact of using BOFS and providing the minimum specified mechanical properties. Also, the proportion of consumption of PPC with BOFS value is determined for the possibility of maximum reaction between FL and pozzolan in cement. [ABSTRACT FROM AUTHOR]

As the largest carbon emitter in China's manufacturing sector, the low-carbon transition of the steel industry is urgent. CO2 capture, utilization, and storage (CCUS) technology is one of the effective measures to reduce carbon emissions in steel industry. In this paper, a comprehensive assessment model of source–sink matching-levelized cost in China's steel industry is constructed to evaluate the potential, economy, and spatial distribution of CCUS retrofits of blast furnaces in the BF-BOF steel industry. The results show that, if no extra incentive policy is included, the levelized cost of carbon dioxide (LCOCD) of 111 steel plants with a 420.07 Mt/a CO2 abatement potential ranges from −134.87 to 142.95 USD/t. The levelized cost of crude steel (LCOS) range of steel plants after the CCUS retrofits of blast furnaces is 341.81 to 541.41 USD/t. The incentives such as carbon market and government subsidies will all contribute to the early deployment of CCUS projects. The CCUS technology could be prioritized for deployment in North China, Northwest China, and East China's Shandong Province, but more powerful incentives are still needed for current large-scale deployment. The research results can provide references for the early deployment and policy formulation of CCUS in China's steel industry. [ABSTRACT FROM AUTHOR]

The study presented in the paper evaluated the properties of pavement quality concrete (PQC) containing coarse aggregates made from aged and unaged basic oxygen furnace (BOF) slag. Workability, air content, strength, drying shrinkage, expansion, abrasion resistance and expansive potential of PQC were evaluated. Air content and workability of fresh slag concrete increased marginally. Compressive and flexural strength of the concrete containing aggregates of aged and unaged slag was observed to be less than the strength of normal concrete. The reduction in strength of concrete containing aged slag aggregates was more as compared to the concrete containing unaged slag aggregates due to the presence of a dusty coating around the aged aggregates. The drying shrinkage of the concrete increased with the content of steel slag aggregates. The abrasion resistance of the slag concrete was found to be better than the abrasion resistance of conventional concrete. Deterioration of slag concrete was not observed due to normal water curing up to 90 days. However, accelerated aging of concrete in water at 70°C resulted in the localised cracking and eruptions due to expansion. The study showed that, aged as well as unaged slag aggregates may be used for the preparation of concrete mixtures of required properties for road construction. [ABSTRACT FROM AUTHOR]

An industrial by‐product of the steel industry called basic oxygen furnace (BOF) slag has recently undergone extensive research for high‐end applications outside of road load and landfill. In contrast to the Bogue methodology used with regular Portland cement, BOF slag lacks a quick and straightforward quantitative phase analysis procedure that would allow it to be employed as a high‐end raw material. The main phases of BOF slag (C2S, C2(A,F), Ff, RO‐Phase, and f‐C) can be calculated using the method presented in this paper based on chemical composition. [ABSTRACT FROM AUTHOR]

The steel industry produces the most widely used metal on earth. The main challenge of the industry for the next decade is the steel production transformation process. The CO2 intensive blast furnace/basic oxygen furnace (BOF) route will be substituted by a combination of a Direct Reduced Iron plant (based on natural gas, at later stage on "green" hydrogen) with an Electric Arc Furnace (EAF) or a Submerged Arc Furnace (SAF), heated with renewable energy. Thus, the well‐known latent hydraulic granulated blast furnace slag (GBS) being successfully used in cement and concrete for more than 140 years will vanish step by step. GBS is used as a supplementary cementitious material (SCM) not only, but in particular, due to its clinker reduction and from there its CO2 reduction potential for the cement and concrete production. Whereas the DRI process itself does not generate any slag, EAF and SAF will do. These slags will be very different. Moreover, the new EAF slags will be also different compared to today's scrap based EAF slag. However, specific slag/metal ratios, resulting slag volumes, chemical and mineralogical compositions and physical properties of the new slags are yet unknown. Thus, also their cementitious and environmental properties are still unknown. Different running projects aim mainly to create slags being similar to GBS. The main objective is to provide the cement and concrete industry furthermore with a (latent) hydraulic SCM. [ABSTRACT FROM AUTHOR]

A basic oxygen furnace (BOF) is the main unit process for refining carbon steel. The aim of this work was to study the use of vibration and audio signal measurements to monitor, predict, and control the BOF process. Vibration and audio data from nearly 300 blows were collected and analyzed together with process variables. We could confirm high correlations between some of the process variables and vibration and audio measurements. Median filtered low-frequency (3–20 Hz) audio as well as X- and Z-direction acceleration root mean square (RMS) time series correlate with the off-gas temperature, although this is much more significant for the audio data. For Y-direction measurements (the upward direction) the correlation is negligible. The low-frequency audio and vibration data are likely related to the rate of decarburization. Median filtered mid-frequency (100–1000 Hz) audio as well as X-, Y-, and Z-direction acceleration RMS time series correlate with the lance height measurement during the interval 20–600 seconds from the beginning of oxygen blow. For the audio data, the correlation was high even without median filtering. We suggest that audio and vibration activity in this frequency range is possibly related to the formation of the metal–slag–gas foam and maybe even to slopping. [ABSTRACT FROM AUTHOR]

Civil engineering faces a substantial challenge when dealing with soft and compressible clayey soils. Conventional soil stabilization techniques involving ordinary Portland cement (OPC) result in notable CO2 emissions. This study explores the utilization of basic oxygen furnace (BOF) slag, a by-product of steel production, for strengthening kaolin clay. This research investigates the influence of BOF slag particle size, BOF slag content, and the use of activators such as lime and ground granulated blast-furnace slag (GGBFS) on the stabilization of kaolin clay. The strength development is assessed through unconfined compressive strength (UCS) test, bender element (BE) test, and scanning electron microscopy (SEM). The findings reveal that higher BOF content and extended curing periods enhance soil strength, and lime and GGBFS effectively augment the stabilizing properties of BOF slag. Stabilizing kaolin clay with a 30% BOF/GGBFS mixture in a 50/50 ratio with 1% lime and curing for 7 days yielded a compressive strength of 753 kPa, meeting the Federal Highway Administration's requirement for lime-treated soil. These combined measures contribute to developing a more robust and stable material with enhanced geotechnical properties. [ABSTRACT FROM AUTHOR]

Identification of the factors influencing refractory lining wear and its residual thickness in the basic oxygen furnace (BOF) is a prerequisite for optimizing the steelmaking process. In this study, the factors that contribute significantly to the wear of the refractory lining in the most stressed areas of the banded lining (i.e., the trunnion ring area and slag line area) are identified. Knowledge of the rate at which a given factor acts on refractory wear is closely related to the development of technological procedures aimed at limiting its influence. This research evaluates the technological causes and describes the lining wear mechanism and the thermodynamic parameters of the reactions between the MgO–C metal, slag, and gunning material phases. In researching the topic, real operational data were processed using statistical methods and data analysis, which were supported by thermodynamic modeling of chemical reactions. The results show that the combination of technological factors, mechanical action of the raw materials, blowing and free oxygen in the metal, silicon from the pig iron, and slag viscosity have the greatest influence on the residual thickness of the MgO–C refractory lining in BOFs. Refractory gunning material consumption, its effect on campaign length, and the cost-effectiveness of repair work were also analyzed. [ABSTRACT FROM AUTHOR]

Steel-making production is a dynamic process that has the characteristics of high temperature and heat, and a complex reaction mechanism that causes the mechanism model possibly to be unavailable and the system to be a black box. In this article, a dynamic operation optimization (DOO) problem is refined from the basic oxygen furnace (BOF) steel-making process, and the system model is formulated by a data analytics method. This prevents to solve the optimization problem with derivative-based optimization methods. To circumvent these difficulties, a surrogate-model-based derivative-free optimization algorithm is proposed for solving the DOO problem. In order to establish the surrogate model with the least number of function evaluations, a subset selection strategy is designed to find a sparse structure for the optimization problem, based on which a set of simple bases is determined to establish the surrogate model. Moreover, this also reduces the scale of the parameter optimization problem. Numerical experiments on actual production data verify the applicability and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Due to decarbonization commitment made by steelmaking companies, the steel industry is tackling a technological transition from blast furnace (BF)–basic oxygen furnace (BOF) route to direct reduction iron (DRI)–electric arc furnace (EAF) route. Under this scenario, ferrous scrap becomes a critical factor for reaching CO2 reduction challenge. However, ferrous scrap can be considered one of the most complex industrial raw materials. In addition, scrap presents a huge heterogeneity in both physical and chemical characteristics. However, for producing high‐quality steel products, certainty on scrap specifics is required. Herein, an artificial intelligent model based on spectral information for the segmentation of different materials contained in the ferrous scrap is proposed. Developed solution offers a processing pipeline through a 2D–3D convolutional neural network algorithm based on a dataset with more than 428 million of pixels through hyperspectral cameras in the 400–1700 nm range. By this model, the detection of ferric fraction, stainless steel, aluminum, zinc, copper, sterile, and rubber and plastic materials are assessed. This work aims at increasing the reliability of the steelmaking process by lowering the number of steel quality noncompliance rejection due to lack of knowledge and uncertainties of these raw material compositions. [ABSTRACT FROM AUTHOR]

The cooling paths and kinetics in the system Cu-Fe-O are investigated by the empirical micro- and nanoscale analysis of slags from the flash furnace smelter at Olympic Dam, South Australia. We aim to constrain the exsolution mechanism of delafossite (Cu1+Fe3+O2) from a spinel solid solution (magnetite, Fe3O4) and understand why cuprospinel (CuFe2O4) is never observed, even though, as a species isostructural with magnetite, it might be expected to form. Flash furnace slags produced in the direct-to-blister copper smelter at Olympic Dam contain four Cu-bearing phases: Cu-bearing magnetite, delafossite, metallic copper, and cuprite. Delafossite coexists with magnetite as rims and lamellar exsolutions, as well as bladed aggregates, associated with cuprite within Si-rich glass. The empirical compositions of magnetite and rim delafossite are (Fe2+6.89Cu2+0.86Co0.13Mg0.15Si0.02)8.05 (Fe3+15.52Al0.41Ti0.01Cr0.01)15.95O32, and (Cu1+0.993Co0.002Mg0.002)0.997(Fe3+0.957Al0.027Ti0.005Si0.004)0.993O2, respectively. The measured Cu content of magnetite represents a combination of a solid solution (~6 mol.% cuprospinel endmember) and exsolved delafossite lamellae. Atomic-resolution high-angle annular dark field scanning transmission electron microscope (HAADF STEM) imaging shows epitaxial relationships between delafossite lamellae and host magnetite. Defects promoting the formation of copper nanoparticles towards the lamellae margins suggest rapid kinetics. Dynamic crystallization under locally induced stress in a supercooled system (glass) is recognized from misorientation lamellae in delafossite formed outside magnetite grains. The observations are concordant with crystallization during the cooling of molten slag from 1300 °C to <1080 °C. Melt separation through an immiscibility gap below the solvus in the system Cu-Fe-O is invoked to form the two distinct delafossite associations: (i) melt-1 from which magnetite + delafossite form; and (ii) melt-2 from which delafossite + cuprite form. Such a path also corroborates the published data explaining the lack of cuprospinel as a discrete phase in the slag. Delafossite rims form on magnetite at a peritectic temperature of ~1150 °C via a reaction between the magnetite and copper incorporated in the oxide/Si-rich melt. The confirmation of such a reaction is supported by the observed misfit orientation (~10°) between the rim delafossite and magnetite. HAADF STEM imaging represents a hitherto underutilized tool for understanding pyrometallurgical processes, and offers a direct visualization of phase relationships at the smallest scale that can complement both experimental approaches and theoretical studies based on thermodynamic modelling. [ABSTRACT FROM AUTHOR]

An organic field-effect transistor (OFET) based on poly 3-hexyl thiophene (P3HT) as an active layer has been developed to detect ammonia vapor. Silicon dioxide (SiO2) as the dielectric layer on this FET is grown on the surface of the p-type silicon substrate by heating in an oxygen atmosphere in the furnace at 1000 C for 3 hours, oxygen gas (O2) is flowed into the furnace during the heating process. The results of the energy-dispersive X-ray spectroscopy (EDS) characterization showed that the silicon substrate which had been oxidized contained about 35 % O2. P3HT as the active layer was grown on the surface of the SiO2 layer using the spin coating method. The I-V characteristics of FET show that the drain-source current (IDS) is affected by changes in the gate voltage (VG). The greater the VG, the higher the Id-s produced. The effect of ammonia vapor shows that IDS on the I-V curve decreases with increasing concentration of ammonia vapor. The dynamic response of the FET to ammonia vapor shows that the greater the VG, the higher the sensitivity of the device. For VG = 0 volt, the sensitivity of FET in ammonia sensing is 0.236 volt/%, meanwhile for VG = – 8 volt, the sensitivity of FET in ammonia sensing is 0.264 volt/%. [ABSTRACT FROM AUTHOR]