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This study simulated the corrosion reaction of S-carbon bricks in a hearth at different carbon contents, flow velocities and temperatures, and their macroscopic and microscopic morphologies were observed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results showed that the dissolution of elemental carbon from carbon bricks into molten iron was a rate-controlled reaction. Increasing the temperature to around 1500 °C and decreasing the carbon content to around 4.5% reduced the saturated solubility of carbon in molten iron, and the erosion degree and dissolution rate of the carbon bricks increased correspondingly. For the flow velocity, its increase promoted mechanical flushing and led to an increase in the convective heat transfer coefficient of molten iron, which would increase the hot-side temperature of the hearth sidewall, promoting carbon unsaturation in hot metal and the dissolution reaction. [ABSTRACT FROM AUTHOR]

A new tuyere small sleeve coating structure that balances the high thermal conductivity of the copper substrate with the high wear resistance of the protective layer was developed in this paper. This structure can achieve a low-carbon blast furnace by reducing the heat loss from the tuyere. The 3D model was established via Solidworks for modeling and Ansys for numerical simulation, the temperature field of the annular wear-resistant layer structure tuyere small sleeve with different widths of the wear-resistant layer was analyzed and compared with the temperature and stress field of traditional tuyere small sleeve. The results show that the design of the annular wear-resistant layer structure of the tuyere small sleeve is more effective. The new annular wear-resistant layer structure for the tuyere small sleeve results in a decrease of 24 K in the average temperature of the wear-resistant coating. The comparison of this structure with tuyere sleeves without wear-resistant coatings shows a 16.7% reduction in heat loss, improves the wear resistance of the tuyere, providing new technological ideas for low-carbon blast furnace production. Compared with the tuyere sleeve completely covered with a wear-resistant coating, the maximum thermal stress of this structure decreased from 624.98 Mpa to 427.99 Mpa, resulting in a reduction of 31.5%, which is beneficial for the service life of the tuyere sleeve. The copper surface temperature of the new tuyere small sleeve is in a safe range when the temperature is below 2273 K. [ABSTRACT FROM AUTHOR]

The sulfur content of hot metal in a blast furnace is an important index that reflects the production effects and quality of the hot metal. Establishing an accurate prediction model for hot metal sulfur content can guide the production process. In the present study, the blast furnace production data were collected and then preprocessed using box plotting. Cross-validation was used in the training process of the model to improve the generalization performance and robustness of the model. Two models for predicting the sulfur content in hot metal were established based on extreme gradient boosting (XGBoost) and multilayer perceptron (MLP) algorithms. The results show that coal consumption (CC), coal ratio (CLR), and sinter consumption (SC) are all positively correlated with hot metal sulfur content. The oxygen enrichment rate (OER) was negatively related to hot metal sulfur content. Both the extreme gradient boosting (XGBoost) and multilayer perceptron (MLP) models predicted hot metal sulfur content effectively; however, the extreme gradient boosting (XGBoost) model had a higher hit rate, accuracy, and stability, with the hit rate achieving 95.07%. [ABSTRACT FROM AUTHOR]

HIsmelt is well suited for smelting vanadium–titanium magnetite due to its flexibility in feedstock selection and tolerance to high viscosity slag, compared with the blast furnace. In this work, the effect of smelting time on the distribution behavior and recovery rates of vanadium and titanium in HIsmelt smelting of vanadium–titanium magnetite was investigated by experiment for the first time. The relationship between slag viscosity and temperature at different smelting times was further revealed by thermodynamic calculations. The experimental results show that extending the smelting time increases the FeO content in the slag, the LV rose from 0.66 to 5.02, the LTi declined from 206.90 to 114.86, the shorter smelting time is favorable for increasing the recovery ratio of vanadium and titanium in metal and slag. In addition, slag viscosity decreases with increasing smelting time. The precipitation of high melting point titania spinel and CaTiO3 phases is responsible for the significant increase in slag viscosity at 1300 °C. [ABSTRACT FROM AUTHOR]

High-alumina fly ash microbeads and steel slag were used as main raw materials to synthesize feldspar porous ceramics via high-temperature solid phase sintering by adding pulverized coal as a pore-forming agent. The effects of the steel slag and pore-forming agent on the apparent porosity and flexural strength of porous ceramics were investigated. The phase composition and microstructure of porous ceramics were characterized using X-ray diffraction and scanning electron microscopy, and the results indicated that the added amount of steel slag was only related to the amount of liquid phase formed in porous ceramics. The higher the amount of steel slag added, the more the liquid phase formed. At the same sintering temperature, the higher the pore former content, the higher the porosity of the porous ceramics and the lower the bending strength. When porous ceramics were sintered at 1160 °C steel slag melted and fly ash microsphere structures were formed. When the porous ceramics were sintered at 1190 °C, the fly ash microsphere structure disappeared. After the internal liquid phase of the ceramic was formed, the lower the sintering temperature, the larger the porous ceramic structure factor, the more sensitive the flexural strength to changes in porosity and the higher the theoretical strength of ceramic densification. Moreover, as the sintering temperature decreased, the network structure formed during the reaction of fly ash microbeads with CaO greatly increased the flexural strength of fly ash ceramics. When the sintering temperature, sintering time and pore former content were 1170 °C, 120 min, and 10%, respectively, the obtained porous ceramics presented superior apparent porosity and flexural strength (49.21% and 12.88 MPa, respectively), and the main crystalline phase of porous ceramics was anorthite featuring pore size ranging from 5 to 50 μm. [ABSTRACT FROM AUTHOR]

Steel slag, clay, quartz, feldspar, and talc were mixed to prepare steel slag ceramics. Crystalline phase transitions, microstructures, and the main physical-mechanical properties (water absorption, linear shrinkage, and flexural strength) of steel slag ceramics for various MgO/Al2O3 ratios were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical testing. The results indicated the significant effect of the MgO/Al2O3 ratio on these properties. A decrease in the MgO/Al2O3 ratio resulted in a major crystalline phase transformation from quartz and pyroxene phases to quartz and anorthite phases. High MgO content facilitated production of pyroxene phases. High Al2O3 content favored production of anorthite phases. The water absorption of all the samples (below 0.5%) met the Chinese national standard requirements. Samples with an MgO/Al2O3 ratio of 0.6 exhibited excellent flexural strength, reaching 62.20 MPa. FactSage software was used to predict batch viscosity, which increased with decreasing MgO/Al2O3 ratios. [ABSTRACT FROM AUTHOR]

In this study, SiO2–Al2O3–CaO–MgO steel slag ceramics containing 5 wt % MgO were used for the preparation of ceramic bodies, with the replacement of 5–20 wt % quartz and feldspar by fly ash. The effect of the addition of fly ash on the sintering shrinkage, water absorption, sintering range, and flexural strength of the steel slag ceramic was studied. Furthermore, the crystalline phase transitions and microstructures of the sintered samples were investigated by XRD, Fourier transform infrared (FTIR), and SEM. The results showed that the addition of fly ash affected the crystalline phases of the sintered ceramic samples. The main crystal phases of the base steel slag ceramic sample without fly ash were quartz, diopside, and augite. With increasing fly ash content, the quartz diffraction peak decreased gradually, while the diffraction peak intensity of anorthite became stronger. The mechanical properties of the samples decreased with the increasing amount of fly ash. The addition of fly ash (0–20 wt %) affected the optimum sintering temperature (1130–1160 °C) and widened the sintering range. The maximum addition amount of fly ash should be 15 wt %, for which the optimum sintering temperature was 1145 °C, water absorption was 0.03%, and flexural strength was 43.37 MPa higher than the Chinese national standard GBT 4100-2015 requirements. [ABSTRACT FROM AUTHOR]