Ensuring the safe and steady operation of a blast furnace hinges on accurate predictions of silicon content. However, these predictions often fall short, proving unreliable and imprecise, particularly in unstable furnace conditions and in the face of substantial data swings. The wide variances and low reliability of silicon concentration predictions make them unsuitable as a reference for daily blast furnace maintenance and adjustments. To counter this engineering challenge, we introduce a novel silicon content prediction technique: the Gated Recurrent Unit Network Quantile Regression (GRUQR). This method amalgamates the Gated Recurrent Unit Network with quantile regression to refine the silicon content prediction model. Our approach first leverages GRUQR to anticipate the silicon content in molten iron across various quantiles. Subsequently, we scrutinize the patterns of silicon content changes and identify the optimal quantile for silicon content under different furnace conditions. We also discuss the reliability of our silicon concentration forecasts and present confidence intervals at various levels. To validate the effectiveness of the proposed GRUQR method, we employ real-world data from a Chinese blast furnace ironmaking process. These prediction results serve as a reliable reference for furnace operators, enabling them to determine the furnace temperature under challenging conditions.

This study aims to investigate the degradation behavior of coke during CO₂ and H₂O gasification reactions. Gasification experiments were conducted in CO₂ and H₂O atmospheres at 1000°C using cokes with different coke reaction indices (CRIs) at 20% reaction ratio. After gasification, the shrinkage ratio in CO₂ gasification was higher than that in H₂O gasification. Moreover, the shrinkage ratio increased with increasing CRI, indicating that the ratio of the surface reaction became larger than that of the internal reaction with increasing CRI at same reaction ratio. The increase value in porosity by gasification reaction decreased with increasing CRI. Owing to the faster diffusion rate of water vapor at 1000°C, water vapor diffuses into the inner part of coke faster, whereas CO₂ gasification reacted from the outer to the inner slowly. Therefore, the increase in porosity of the inner part of coke by H₂O gasification is larger than that by CO₂ gasification. In addition, the degradation behavior in same coke by CO₂ or H₂O gasification did not have obviously difference at same reaction ratio in 1000°C.

High-proportion pellet smelting is the direction of optimization of blast furnace burden structures in the future. In this paper, the effect of SiO₂ content on the softening and dropping properties of magnesia flux pellets was studied. And the influence of SiO₂ content on the mineralogical composition and microstructure of magnesia flux pellets was analyzed, which clarified the reason for the air permeability of the middle and lower columns of magnesia flux pellets becoming poor during smelting. The results show that with increasing SiO₂ content, the T₁₀ (softening start temperature) and T_S (melting start temperature) of the column gradually decrease, and the melting range increases; in particular, T₁₀ and Ts decrease dramatically when the SiO₂ content exceeds 6%. The maximum pressure difference increases from 15.0 kPa to 20.7 kPa, and the characteristic value increases from 644.8 kPa·°C to 1334.8 kPa·°C when the SiO₂ content of magnesia flux pellets increases from 6% to 8%. The mineralogical composition difference between low-silica magnesia flux pellets (SiO₂=3.5%) and high-silica magnesia flux pellets (SiO₂=7.0%) at different temperatures is caused by a large amount of unreacted SiO₂ in high-silica magnesia flux pellets. SiO₂ and silicate produce a large amount of liquid phase at low temperature, which reduces T_S. In addition, the dropping temperature of high-silica magnesia flux pellets is higher than that of low-silica magnesia flux pellets. It’s due to the existence of particulate SiO₂ in the primary slag, which causes the slag to become sticky and makes it difficult to separate the slag from iron.

The effect of Al₂O₃ on the compositional region of silico-ferrite of calcium and aluminum (SFCA) and the liquid phase and the phase equilibria, including SFCA, was investigated in a CaO-SiO₂-Fe₂O₃-5mass%Al₂O₃ system at 1240°C in air. To obtain the desired composition, reagent-grade CaCO₃, SiO₂, Fe₂O₃, and Al₂O₃ powders were weighed, mixed, and equilibrated at 1240°C in air. Each obtained sample was divided into two parts: one was pulverized into a powder and analyzed by XRD, and the other was subjected to microstructural observation and compositional analysis using EPMA. The results revealed that the compositional region of SFCA lies on the CF₃-CA₃-C₄S₃ plane and is C/S = 2.77–7.60 for 5 mass% Al₂O₃. Compared with the SFC composition region for 0 mass% Al₂O₃, the compositional range of SFCA extended in the CF₃-C₄S₃ direction, suggesting that the addition of Al₂O₃ contributes to the stability of SFCA. Furthermore, the liquid-phase region was divided into a ferrite melt with a high Fe₂O₃ concentration and a silicate melt with a high SiO₂ concentration, both of which shifted to the lower Fe₂O₃ side compared to the liquidus isotherm in the CaO–SiO₂–Fe₂O₃ system. Unlike CaO–SiO₂–Fe₂O₃, SFCA-I (SFC-I) was observed in the CaO-SiO₂-Fe₂O₃-5mass%Al₂O₃ system, thus indicating that the addition of Al₂O₃ contributes to the stability of SFCA-I.

The production of industrial metals in pyrometallurgical smelting furnaces is central to modern industry. Tapping of metal and slag from smelting furnaces is a complex and difficult process. Any variations from tap to tap reduce predictability and impact the planning of downstream logistics. Tapping of metal and slag can be generalized as drainage of two immiscible liquids through a particle bed. In the present paper this is studied by both laboratory experiments and numerical modeling of water and oil drainage from a tank. The results show that the numerical model and physical experiment are consistent. This provides confidence that the numerical models can be applied to quantify tapping from metallurgical furnaces.

In order to make better use of sinter return ore and iron oxide scale to achieve effective pre-dephosphorization of molten iron, the effects of final slag morphology, mineral phase structure and polymerization degree on pre-dephosphorization were studied by theoretical analysis, XRD, SEM-EDS, Raman and FTIR spectra. The results show that when the proportion of sinter return ore is less than 20%, the impact on dephosphorization is relatively small. The structural analysis of dephosphorization final slag shows that the increase of sinter return ore will lead to the decrease of phosphorus content in phosphorus-rich phase and the increase of RO phase and iron-rich phase in slag. O²⁻ destroys P–O–P bond more than Si–O–Si bond. When the phosphorus entering the slag decreases, the content of Q⁰(Si) structure decreases, and silicon tends to exist in the form of higher polymerization degree. With the increase of the proportion of sinter return ore, the structure of [FeO₆]⁹⁻ in slag increases, which is not conducive to the migration of phosphorus. When the oxidant is only sinter return ore, the proportion of Q¹(Si) and P–O–Si structure in slag increases obviously, and the evolution of silicate structure is the main reason for the change of polymerization degree of slag. This study can provide theoretical reference and technical basis for the effective utilization of sinter return ore and the reduction of production cost in iron and steel enterprises.

A CFD-PBM coupled mathematical model was proposed to describe the bubble breakup and coalescence behavior in gas-stirred ladle based on the Eulerian-Eulerian approach. The effect of turbulence shear collision, bubble floating velocity difference collision and turbulence random collision on the bubble coalescence behavior were considered; the sensitivity of three typical breakup model including Luo model, Lehr model and Laakkonen model on bubble size distribution were considered. The result showed that the turbulence random collision and bubble floating velocity difference collision were the main mechanism to affect bubble coalescence behavior, while the effect of turbulence shear collision can be ignored. The bubble size distribution predicted by Lehr model was different with other two models and the measured data, because it highly predicted the bubble breakup frequency in current system. The effect of Luo model and Laakkonen model on bubble size distribution were so small that the bubble size distribution is mainly dominated by bubble coalescence behavior. Bubble-induced turbulence would affect the bubble breakup and coalescence behavior, it would promote the bubble coalescence behavior, the volume fraction of large bubbles increased significantly in this work. The size distribution predicted by the present model agree well with the measured data in the water model.

Mold oscillation is a key technology of steel continuous casting. Sinusoidal oscillation and non-sinusoidal oscillation are widely used in actual production. Non-sinusoidal oscillation has many advantages compared with the sinusoidal oscillation, such as it can reduce the depth of oscillation mark, and make slab demoulding easily. But the maximum acceleration of non-sinusoidal oscillation is higher, which will result in the larger inertia force, influence on the service life and running smoothly of the oscillator. The modification ratio of the non-sinusoidal oscillation is bigger, the impact and noise of the oscillator are more serious especially when the mold arrives at the top and bottom position. To control the maximum acceleration of the non-sinusoidal oscillation waveform, a novel waveform function with three sections was proposed. And the displacement, velocity and acceleration curves were continuous and smooth, which had no rigid and flexible impact. Thus, it had good dynamic characteristics and realized the switching between the sinusoidal and the non-sinusoidal oscillation. Then the proposed oscillation waveform function was realized by a mechanical oscillator with double servomotors arranged symmetry. Meanwhile, the angular speed of the servomotor to realize the oscillation waveform was presented and the tested curves were obtained by the experiment. The experiment results show that the oscillation waveform can be realized well, the vertical maximum acceleration of the proposed function is reduced by 13.6%, which is helpful to reduce the inertia force, enhance the motion stability and prolong the service life of the oscillator.

Identifying internal α-alumina (α-Al₂O₃) scales is critical for evaluating the performance of heat-resistant Ni–Al alloys. This study investigated the possibility of using cathodoluminescence (CL) spectra of the alloy surface for nondestructive identification of internal α-Al₂O₃ scales underneath multiple other scales. The presence of internal α-Al₂O₃ scales on a heat-treated Ni-14Al alloy was confirmed by the detection of a CL peak at 695 nm. The scales of this alloy comprised NiO on top followed by NiAl₂O₄ underneath and α-Al₂O₃ at the bottom with thicknesses of 1.1, 0.8, and 0.5 µm, respectively. The intensity of the CL peak at 695 nm was close to the minimum detectable analyte signal intensity. These results demonstrate that surface CL spectra can be used for the nondestructive identification of internal α-Al₂O₃ scales on Ni–Al alloys that are underneath multiple other scales.

In hot strip mills, use of the sizing press and horizontal rolling results in a narrower width at the head and tail portions of slabs in comparison with the middle portion, and these narrow portions, called “width drop,” cause yield loss. Some studies reported that width drop results from the difference in the width spread in horizontal rolling depending on the distribution of the dog bone profile along the slab longitudinal direction. However, the experimental and simulated data in other papers indicated that “width shrinkage” occurs around the head and tail portions after horizontal rolling of slabs with the dog bone profile. Although width drop might actually be influenced by width shrinkage as well as by width spread, few reports have clearly described the mechanism of width shrinkage. Therefore, this paper focuses on an investigation of the influence of width shrinkage during horizontal rolling on width drop. Experiments and FE analyses of horizontal rolling of slabs with the dog bone profile were carried out to investigate the mechanism of width shrinkage. The FE analyses revealed that width shrinkage occurred around the head and tail portions of slabs just after and just before the horizontal rolls, respectively, in horizontal rolling of slabs with a dog bone profile as the cross section. The results also suggested that the distribution of the rolling direction velocity along the width direction around the head and tail portions causes width shrinkage during horizontal rolling.

To investigate mechanism of hydrogen-induced intergranular fractures, low energy positron beams with different energies were applied to hydrogen-induced intergranular fracture surfaces of 80Ni-20Cr alloy, and depth distributions of the lattice defects were evaluated by Doppler broadening spectroscopy and positron annihilation lifetime one. At least at depths between 0.1 µm and 1 µm from the fracture surface, a large number of the lattice defects were homogeneously distributed. Both the dislocation density and monovacancy-equivalent vacancy-type defect one were around ten-times as large as inside the grains. On the other hand, the absolute value of the monovacancy-equivalent vacancy-type defect density was about 9 appm, and obviously not large enough to cause strength reduction and fractures. It was suggested that stress concentration and disordered structures formation at and on the grain boundaries due to hydrogen-enhanced dislocation nucleation, and reduction in the grain boundary cohesive energy due to the trapped hydrogen atoms jointly cause the intergranular fractures.

Zn–Ni alloys were electroplated on a Fe plate with a thickness of 40 µm at 500 A·m⁻² and 293 K in unagitated zincate solutions. The reaction product of epichlorohydrin and imidazole (IME) was added to the solution as a brightener at concentrations of 0–5 mL dm^–3. The corrosion resistance of the obtained Zn–Ni alloy films was investigated from the polarization curve in 3 mass% NaCl solution before and after the corrosion treatment (formation of corrosion products) for 48 hours. Before the corrosion treatment, the corrosion current density of plated films rarely changed, regardless of the addition of IME into the zincate solution, because the reduction reaction of dissolved oxygen rarely changed. However, in films plated from the solution containing IME, the anode reaction was suppressed, and the corrosion potential shifted toward the noble direction. The suppression of the anode reaction with an addition of IME into the plating solution is attributed to the increase in γ-phase in the plated films. After the corrosion treatment, Zn chloride hydroxide of the corrosion product uniformly formed on the surface when increasing the concentration of IME. The reduction reaction of dissolved oxygen was suppressed by increasing the concentration of IME, resulting in a decrease in corrosion current density.

The electrodeposition of an Zn–Zr compound composite is performed under pulsed and double-pulsed current conditions at 313 K in unagitated pH 2 sulfate solutions containing Zn²⁺ and ZrO²⁺ ions and polyethylene glycol. Under constant-current electrolysis at 5000 A·m⁻², coarse granular partial deposits containing Zr compounds are observed. Under pulse electrolysis, such coarse deposits are observed rarely; however, both deposited films containing Zr compounds and exfoliated films are observed. On the contrary, in double-pulse electrolysis at high (5000 A·m⁻²) and low (500 A·m⁻²) current densities, coarse deposits are not observed while fine-particle deposits containing Zr compounds are observed. In double-pulse electrolysis at low current densities, the rate of hydrogen evolution decreases and Zn is deposited without the codeposition of Zr compounds; therefore, the continuous hydrogen evolution is suspended in some areas. That is, the area of hydrogen evolution appears to be random. Although Zr compounds are usually concentrated at the upper regions of the deposited films, regardless of the electrolysis method, it is found to have been codeposited even in the inner regions under double-pulse electrolysis. The corrosion current density in 3 mass% NaCl solution is the smallest for the films produced by double-pulse electrolysis, when comparing with the films obtained by pulse electrolysis and constant-current electrolysis. This can be attributed to the suppression of the reduction reaction of dissolved oxygen.

In this paper, Softening & Melting experiments with different charge ratios are carried out and compared with typical slag phase properties. The relationship between the charge ratio and the softening & melting properties is non-linear correlation. The liquid phase generation process of the slag corresponds to the softening zone and the viscosity change process of the slag phase after the liquid phase is fully generated corresponds to the melting zone. In the softening interval the properties of FeO–CaO–SiO₂ system play a dominant role, while in the melting interval the properties of FeO–CaO–Al₂O₃–SiO₂ system play a dominant role. This provides ideas for the study of the limiting links in the soft fusion zone of complex systems.

Phosphorus is an essential raw material for industry and agriculture, and Japan imports all of it. The phosphorus in steelmaking slag is a promising secondary phosphorus resource comparable to the total amount of phosphorus imported by Japan. Several processes have been proposed to recover phosphorous from steelmaking slags. However, due to the high recovery cost and high environmental load in these processes, phosphorus recovery from steelmaking slag is not yet practiced on an industrial scale. We are developing an electrodialysis process for recovering phosphorus from steelmaking slag extract. Steelmaking slag extract contains not only P anions but also Si anions. This paper has investigated the influence of Si ions on phosphorus separation by electrodialysis. In the case of a solution containing more than 50 ppm of Si content, it was found that Si ions significantly inhibit the transport of phosphorus ions through the membrane.