Haifeng Li

This study employs a numerical simulation approach to investigate argon bubble flow behavior within a steel continuous casting mold, with a focus on the impact of bubble swarm correction models. Three scenarios are compared: one without any correction and two incorporating drag coefficient corrections, specifically designed for bubble swarm effects. The results demonstrate that incorporating these correction models significantly improves the predictive accuracy of simulations. In particular, the inclusion of a bubble swarm correction model reduces the error in predicted bubble trajectories by 51.7% and 23.0%, respectively, when measured by Hausdorff distances against experimental trajectory data, compared to the scenario without corrections. These findings underline the importance of selecting an appropriate drag correction model for accurate simulations of bubble dynamics and their interaction with the liquid steel in continuous casting molds. This study highlights that drag correction models tailored to the specific conditions of the continuous casting process are essential for achieving realistic predictions.

The injection of pulverized coal into blast furnaces has alleviated the demand for metallurgical coke, and co-injection technology combining natural gas and pulverized coal with high oxygen enrichment has the potential to further reduce coke use and hence CO2 emissions. This work presents a steady-state operational model for the co-injection of natural gas and pulverized coal into blast furnaces developed based on mass and energy balance. With the support of industrial data from the commercial blast furnace, the matching relationship between natural gas rate, pulverized coal injection rate, and oxygen enrichment is quantitatively examined under the constraints of raceway adiabatic flame temperature and top gas temperature. The effect of natural gas rate on coke rate and CO2 emission reduction is investigated. The results show that increasing natural gas injection rate, lower pulverized coal rate and higher oxygen enrichment maintains a constant raceway adiabatic flame temperature and coke rate. Under the optimal operating conditions, the pulverized coal, coke rate, and CO2 emissions are reduced by 30.2%, 7.3% and 6.2%, respectively. The model and its results are expected to be helpful for a better understanding co-injection of natural gas and pulverized coal into blast furnaces, as well as contribute to reducing coke rate, pulverized coal rate, and CO2 emissions.

Due to rapid developments in computer technologies over the last two decades, computer-based process modeling has become an important tool for the improvement of existing process technologies and the development of innovative ones

Under the global dual-carbon background, heightened public awareness of climate change and strengthened carbon taxation policies are increasing pressure on the steel industry to transition. Given the urgent need for carbon reduction, the exploration of low-carbon pathways in a blast furnace (BF) metallurgy emerges as crucial. Evaluating both asset retention and technological maturity, the development of low-carbon technologies for BFs represents the most direct and effective technical approach. This article introduces global advancements in low-carbon metallurgical technologies for BFs, showcasing international progress encompassing hydrogen enrichment, oxygen enrichment, carbon cycling technologies, biomass utilization, and carbon capture, utilization, and storage (CCUS) technologies. Hydrogen enrichment is identified as the primary technological upgrade currently, although its carbon emission reduction potential is limited to 10% to 30%, insufficient to fundamentally address high carbon emissions from BFs. Therefore, this article innovatively proposes a comprehensive low-carbon metallurgical process concept with the substitution of carbon-neutral biomass fuels at the source stage—intensification of hydrogen enrichment in the process stage—fixation of CCUS at the end stage (SS-IP-FE). This process integrates the cleanliness of biomass, the high-efficiency of hydrogen enrichment, and the thoroughness of carbon fixation through CCUS, synergistically enhancing overall effectiveness. This integrated strategy holds promise for achieving a 50% reduction in carbon emissions from BFs in the long processes. Critical elements of these core technologies are analyzed, assessing their cost-effectiveness and emission reduction potential, underscoring comprehensive low-carbon metallurgy as a pivotal direction for future steel industry development with high technological feasibility and emission reduction efficacy. The article also proposes a series of targeted recommendations, suggesting short-term focus on technological optimization, the medium-term enhancement of technology research and application, and the long-term establishment of a comprehensive low-carbon metallurgical system.

At present, blast furnace (BF) ironmaking is still the main process for producing hot metal in China and around the world. Under the constraint of the global goal of “double carbon”, it is urgent to carry out hydrogen metallurgical innovation for the existing BF ironmaking process with higher carbon emissions. In recent years, BF technology with hydrogen enrichment and pure oxygen has made some progress, effectively reducing carbon emissions of hot metal per tons, but it is still unable to break through the technical bottleneck of emission reduction of more than 30%. In view of this, the authors put forward an ironmaking technology of a reduction smelting furnace (RSF) that is hydrogen-rich and utilizes pure oxygen and carbon recycle (Hy-O-CR), which breaks through the technical defect of traditional BF emission reduction of less than 30% by reshaping the furnace. Firstly, the construction process of the mass and energy balance model for two main unit modules in the new process (RSF with Hy-O-CR and top gas cycle) is introduced, and then the parameter optimization under specific scenario conditions is analyzed, and the influence mechanism of several key variables on the parameters in the furnace is obtained. Finally, the emission of CO₂ in the whole process is explored in the case of two typical operating parameters. The results show that after using CCUS technology, the minimum value of direct CO₂ emission is 215.93 kg/tHM, which is as high as 84.58% compared with the traditional BF process. Even if the removed CO₂ is counted in carbon emissions, the minimum value of direct or indirect carbon emissions is 729.85 kg/tHM, and the proportion of emission reduction can reach 47.87%. The research results show that the reconstruction of Hy-O-CR technology can change the ratio of direct reduction and indirect reduction, which greatly breaks through the emission limit of the traditional BF and provides a new reference for hydrogen metallurgy technology and a basis for further study of the optimization of RSF size.

Theoretically, the vertical sinter sensible heat recovery process can significantly improve the recovery rate of sinter sensible heat. However, the segregated distribution of the sinter and uneven gas–solid flow in vertical cooling furnaces result in insufficient contact and heat exchange between the high-temperature sinter and the cooling gas, thereby limiting the improvement in the sinter sensible heat recovery rate. A Venturi vertical cooling furnace can improve the contact heat transfer between gases and solids and the uniformity of the sinter and the cooling gas temperature. However, this leads to a significant increase in the gas pressure drop and affects the integrity of the downward movement of the sinter. To control the increase in the gas pressure drop while increasing the sensible heat recovery and maintaining the integral flow of the sinter, this study takes a Meishan Steel vertical cooling furnace as the research object and uses the DEM-CFD coupling model to optimize the structural parameters of the Venturi-type vertical cooling furnace. Firstly, a scaling method was designed to reduce the computational cost. Secondly, based on the on-site conditions, the selection range of structural parameters for the Venturi furnace was determined. Finally, an orthogonal experiment was designed. Taking the sensible heat recovery of the sinter and the pressure drop of the cooling gas as the main index, the integrity of the sinter flow was taken as the secondary index to study the Venturi structure parameters suitable for the Meishan Steel vertical cooling furnace, including the width of the vertical part w, the length of the vertical part l, the contraction angle of the contraction part β, and the expansion angle of the expansion part α. The results showed that the order of structural parameters affecting the sensible heat recovery was w, β, α, and l, and the order of parameters affecting the gas pressure drop was w, β, l, and α. The appropriate structural parameters of the Venturi furnace type, obtained by considering the sensible heat recovery and gas pressure drop, were w = 1.1 m, β = 16°, α = 13°, and l = 0.5 m. In addition, in order to improve the integrity of the sinter flow, it was also necessary to increase the wall friction of the particles in the central area of the vertical section by adding steel plates. The results can provide theoretical guidance for improvements to the Meishan Steel vertical cooling furnace. The operation parameters corresponding to the Venturi furnace type can be studied later.

The blast furnace and basic oxygen furnace (BF-BOF) is still the main process used for the production of iron and steel in China. With the approach of the “dual carbon” target, the iron and steel industry needs to transform and upgrade to “green” and “low-carbon” practices. At present, the low-carbon hydrogen metallurgy technology route based on hydrogen instead of carbon is mainly adopted at home and abroad, and the domestic route is mainly based on oxygen-rich BFs and hydrogen-based shaft furnaces (SFs). It promotes the transformation of the traditional BF to hydrogen-rich, oxygen-rich, and carbon-recycled (Hy-O-CR) technology. A new ironmaking system and method for a reduction smelting furnace (RSF) with Hy-O-CR is presented in this paper. The ironmaking system includes nine sets of equipment, such as an RSF, gas dust collector, dryer, CO₂ separator, electrolytic water device, blower, heat exchanger, storage tank of reduction gas, and chimney. From top to bottom, the RSF includes an indirect reduction zone, a soft melting dripping zone, and a coke combustion zone. The ironmaking methods include coke and ore mixed charging, injection of the mixed reduction gas composed of electrolytic green hydrogen and circulating gas from the furnace gas into the indirect reduction zone, injection of oxygen into the coke combustion zone, CO₂ recovery of the furnace top gas, and slag and iron treatment. By redesigning the size of the furnace type and optimizing the parameters, the metallization rate of the indirect reduction zone can be as high as 85–95%, and the carbon consumption per ton of hot metal can be greatly reduced. By using oxygen to recycle the reduction gas produced by its reactor, the process achieves the goal of reducing CO₂ emissions by more than 50%, thus realizing green and low-carbon metallurgy.

Sinter sensible heat recovery via a vertical cooling furnace is a new type of waste heat recovery process proposed based on coke dry quenching. However, the segregation of the burden in a vertical cooling furnace is serious, resulting in a large amount of cooling gas escaping from the short-circuit channel of the vertical cooling furnace, which seriously affects the uniform gas–solid heat transfer in the furnace. To improve the burden distribution and gas flow in such a furnace, this paper proposes a Venturi-type vertical cooling furnace. Based on the single silo of a vertical cooling furnace in Meishan Steel, a slot model was established, and the improvement effect of the Venturi furnace structure on the burden distribution and gas flow was studied using the DEM–CFD coupling method. The results show that compared with the existing furnace type, the inclined wall of the Venturi furnace changed the direction of the high D_nv (average diameter) channel from vertical to inclined-vertical and reduced the D_nv from >0.033 m to 0.028~0.03 m in the vertical part of the variable-diameter section, thus reducing the influence area of the high D_nv channel. The minimum and average values of the voidage in the contraction part of the variable-diameter section increased from 0.28 and 0.315 to 0.31 and 0.33, respectively, which caused the voidage distribution to change from U-shaped to W-shaped along the longitudinal direction while simultaneously reducing the longitudinal fluctuation range of the voidage from 0.28~0.39 to 0.298~0.37. The gas flow direction changed from vertical-upward to vertical-inclined-upward, which increased the gas–solid contact. The gas velocity increased significantly. In the vertical section, the average gas velocity was 2.34 m/s, which was 30.73% higher than the velocity of 1.79 m/s of the existing furnace type. In the variable-diameter section, the average gas velocity was 3.52 m/s, which was 72.55% higher than the velocity of 2.04 m/s of the existing furnace type. The high-speed gas channel basically only existed in the sidewall area and the center area of the vertical section, and the length was reduced from 3.11 m to 2.52 m, which reduced the influence area. In the variable-diameter section, the high-speed gas channel disappeared, and the uniformity of the gas velocity distribution was greatly improved. The gas pressure drop increased from 4140 Pa to 6410 Pa, with an increase of 54.83%. Therefore, when designing the Venturi furnace type, it was necessary to take into consideration the improvement in the gas velocity distribution and the increase in the pressure drop. The research results of this paper can provide guidance for the structure optimization of the sinter vertical cooling furnace.

The present work aimed to develop a predictive model for the end temperature of liquid steel in advance to support the smooth functioning of a vacuum tank degasser (VTD). An ensemble model that combines extreme learning machine (ELM) with a self-adaptive AdaBoost.RT algorithm was established for the regression problem. Based on analyzing the energy equilibrium of the VTD system, the factors were determined for predicting the end temperature of liquid steel. To establish a hybrid ensemble prediction model, an ELM algorithm was selected as the ensemble predictor due to its strong performance and robustness, and a modification of the AdaBoost.RT algorithm is proposed to overcome the drawback of the original AdaBoost.RT by embedding statistical theory to dynamically self-adjust the threshold value. For efficient VTD operations, an ensemble model that combines ELM with the self-adaptive AdaBoost.RT algorithm was established to model the end temperature of liquid steel. The proposed approach was analyzed and validated on actual production data derived from a steelmaking workshop in Baosteel. The experimental results reveal that the proposed model can improve the generalization performance, and the accuracy of the model is feasible for the secondary steel refining process. In addition, a polynomial equation is obtained from the ensemble predictive model for calculating the value of the end temperature. The predicted results are in good agreement with the actual data with <1.7% error.