Inclusion Removal Research Articles

Dual composite architectonics: Behavior of ZrB2–SiC–TaB2 composites under abrasive conditions

The influence of abrasive impact on ZrB2–SiC–TaB2 ceramic composites with homogeneous distribution of components in ZrB2 matrix and with «dual composite » structure (ZrB2–SiC)-(TaB2–SiC) has been studied. It was shown that at the same content of components the abrasive wear of the ceramic with the «dual composite » structure is significantly less than that of the composite with homogeneous distribution of single-phase components in a single-phase matrix. On the surface of the studied composites there were no furrows and grooves typical for the abrasive action on the material. At abrasive impact on ceramic composite with homogeneous distribution of components there was a formation of subsurface cracks with the subsequent tearing off of material segments with the size exceeding the size of inclusions in the matrix. Abrasive wear of ceramics with the «dual composite » structure at a high content of composite inclusions occurs by "erosion" of the matrix at the interface with composite inclusions with subsequent removal of inclusions. Composites with «dual composite » structure had higher residual strength compared to ceramic with homogeneous distribution of components. It was found that the difference in the character of abrasive wear of composites is largely in relation to the distribution of residual stresses formed due to the difference in the thermal linear expansion coefficients of the components.

Simulation of Inclusion Removal in Bottom-blowing Ladle with Tracking the Collision of Inclusions and Bubbles in Transient Time Steps

Simulation of Inclusion Removal in Bottom-blowing Ladle with Tracking the Collision of Inclusions and Bubbles in Transient Time Steps

A novel experimental set-up for generating microbubbles for the removal of inclusions from water and liquid metals

ABSTRACT To enhance steel cleanliness, extensive research has been conducted on bubble flotation techniques for inclusion removal. However, effective removal of nonmetallic inclusions smaller than 50 μm remains a challenge during standard liquid metal processing operations. These tiny inclusions have insufficient rising speeds to enable them to float out to the slag layer on their own. Several studies have demonstrated that the use of 500-μm bubbles would be necessary to facilitate the flotation of sub-50-μm inclusion particles from liquid steel within a tundish. Our approach to generating microbubbles in liquid metals uses liquid shearing flows. This method splits forming bubbles into smaller sizes by applying intense shear stresses. As a result, significantly larger surface areas are created, enhancing the interaction between the microbubbles and the inclusions. To test the effectiveness of this approach, a novel setup comprising submerged nozzles within a liquid metal was designed, manufactured, and operated. This setup allowed for experimentation with different rotational speeds and effluent gas flow rates, thereby determining the bubble sizes produced. Microbubbles within the desired size range (400–600 µm) were successfully generated in a Cerrolow 136 eutectic alloy.

Digital Twin Design of a Turbulence Inhibitor in a Tundish Based on the Production Cluster Mining Algorithm

The lack of a direct and linear relation between inclusion removal from tundishes and the design of their turbulence inhibitors is a difficult challenge. In contrast to the traditional method of optimizing flow control devices based on the residence time distribution curve, this study used the inclusion/flow field database production clustering mining algorithm to conduct step-by-step data mining on the tundish flow field; to produce relevant facts of the flow field characteristics in the inclusion aggregation zone; and to extract the data mining results from the fact database to screen a digital twin algorithm that forecasts the inclusion aggregation area in a tundish to optimize the flow control device. The results showed that the inclusion aggregation area in the tundish impact zone is above the turbulence inhibitor and that the inclusion aggregation area outside the tundish impact zone is at the vortex center of the flow field. According to the mining results, a pseudo-code for screening the inclusion aggregation area was developed, and the turbulence inhibitor was optimized with the help of the digital convergence of the digital and physical models. Finally, in a tundish, the inclusion removal rate in molten steel was increased by 14.4%. The turbulence inhibitor designed by the digital twin method is currently being used in a Chinese steel mill.

Effect of Al2O3 on Inclusion Removal in H13 Steels Using High-Basicity LF (Ladle Furnace) Refining Slags

In this experiment, a quaternary fluorine-free refining slag system of CaO-SiO2-Al2O3-MgO was selected, with basicity ratios of 2, 4, and 6 and calcium-aluminum ratios of 1.5, 2.1, and 3. High-temperature “slag-steel equilibrium” experiments were conducted to investigate the influence of different basicity ratios and calcium–aluminum ratios on the morphologies, compositions, sizes, and quantities of the inclusions in H13 steel, aiming to improve the cleanliness of H13 steel to meet practical industrial requirements. The experimental results showed that with the increase in the basicity ratio and the calcium–aluminum ratio, the morphologies of the inclusions changed from elliptical to regular circular, with more regular edges. As the basicity ratio increased from 2 to 6, the densities of the inclusions showed a decreasing trend, with values of 40, 35, 30, 25, 32, and 30 inclusions/mm2. When the basicity ratio remained the same, the average size of the inclusions in the steel decreased first and then increased with the increases in the calcium–aluminum ratios, with sizes of 1.59 μm, 1.23 μm, and 1.38 μm, respectively. Among these, when the basicity ratio was 6 and the calcium–aluminum ratio was 2.1, the control effect on the densities and sizes of the inclusions was the best, yielding an inclusion density of 25 inclusions/mm2 and a size of 1.15 μm. Additionally, reducing the Al2O3 content in the slag could reduce the Al2O3 contents in the inclusions, which also promoted improvements in the elastic deformation capacities of the inclusions. With increases in the calcium–aluminum ratios in the slag system, the masses of the inclusions decreased due to the reduced Al contents in the steel. The Al contents in the steel also had an impact on the compositions of the inclusions.

Influence of refining slag on transformation and separation of nonmetallic inclusions in 316L stainless steel

To determine the effects of C/A ratio (CaO/Al2O3) and the basicity B (CaO/SiO2) of Al2O3–CaO–SiO2–MgO(–CaF2) refining slags on the characteristics of inclusions and sulfur (S) content in 316L stainless steels, equilibrium experiments between the slag and steel were carried out at 1873 K under laboratory conditions. Thermodynamic investigations were performed to understand how the chemical compositions of the inclusions changed and to evaluate the desulfurization capabilities of the refining slags. Additionally, a mathematical model was established for predicting the separation of nonmetallic inclusions during refining and characterizing the movements of the inclusions at the “slag–steel” interface. First, the findings showed that increasing the slag basicity B in the range of 1.0–7.0 led to a reduction in the dissolved [O] mass fraction from 0.0033% to 0.0021% and the total oxygen (T.O.) from 0.0050% to 0.0031% while also slightly improving the cleanliness of the steel by increasing the C/A ratio within the range 1.0–2.2. Then, the average compositions of the inclusions in the steel were approximately (mol pct SiO2)/(mol pct MnO) = 0.57 (±0.08), and the Al2O3 content grew from 6.55% to 18.36% (mol pct), while increasing the slag basicity B resulted in an increase in the Al2O3 content of the inclusions. Once the B exceeded 5.0, further increases in the slag basicity did not continuously increase the desulfurization capability. Finally, all calculations of refining slag with the model yielded separation rates were higher than 80% for inclusions with diameters of 5 μm. For inclusion removal after slag refining, the results of the experiments exhibited consistent agreement with the predictions from the mathematical model.

Study on Multiphase Flow Characteristics During RH Refining Process Affected by Nonradial Arrangement of Gas‐Blowing Nozzle

Bath stirring, degassing, and decarburization in steel refining are strongly related to flow behaviors. The bubble plume produced in Ruhrstahl–Heraeus (RH) up‐snorkel plays an important role during refining, since it not only acts as a bubble pump, but also provides the reaction interface. Herein, it is aimed to form a new flow pattern in the up‐snorkel by using a nonradially arranged gas‐injection nozzle to enhance the 260 ton RH refining process. The results show that an upward spiral steel flow is produced, when nonradial gas‐injection nozzles are used in the up‐snorkel. Meanwhile, some bubbles moved toward the center region of the up‐snorkel, which may be caused by the centripetal effect in a rotational steel flow. This leads to a more uniform bubble distribution on the cross section of the snorkel, compared to that of the conventional case. Specifically, the circulation flow rate is increased by about 18.0%, and the mixing time are shortened by about 26.2% (criteria of ±5%), compared to that of the conventional case. In addition, the inclusion removal rate is increased by 0.5%, 4.8%, and 11.3% for the inclusion size of 20, 50, and 100 μm, respectively, compared to the conventional radial nozzle case.

Thermodynamic investigations of steel deoxidation process with calcium and barium

The use of alloys with alkaline earth metals (AEM) it possible to optimize the processes of deoxidation and refining of steel from non-metallic inclusions. The technologies of ladle treatment of the melt with the use of AEM complexes to obtain high-quality metal products even if it is impossible to use expensive equipment (vacuumers, tribe apparatus, etc.), which is often typical for small steel foundries. At the same time, a number of issues related to the mechanisms implemented during the refining of liquid steel with calcium and barium require further study. In the course of this work, the authors constructed state diagrams of double (CaO–BaO) and ternary (FeO–CaO–BaO) oxide systems and carried out thermodynamic modeling of equilibria in the Fe–Ca–Ba–C–O system. It is noted that in this system there is an extensive equilibrium region of the oxide melt with solid solutions of CaO-based oxides. The solubility surfaces of components for the temperatures of steel ladle treatment (1550–1600 °С) and for different carbon contents (0; 0,1; 0,4 % С) are constructed for the studied system. A comparative analysis of the constructed diagrams suggests that a change in the carbon content within the indicated limits does not significantly affect the type of the diagrams. It follows that the revealed patterns will be maintained in the production of a wide range of economically alloyed low-carbon steels. It is shown that during the deoxidation of steel without aluminum, and with a calcium content typical for real production processes (about 30 ppm), the expected active oxygen content is about 30 ppm (log[O] = –2.5), which does not meet modern requirements for purity become. At the same time, a change of the barium content has practically no effect on the degree of deoxidation of the metal. Thus, it is shown that the main role of calcium and, especially, barium in the processing of liquid steel is modification and removal of non-metallic inclusions from the melt

The Removal of Inclusions with Different Diameters in Tundish by Channel Induction Heating: A Numerical Simulation Study.

The quality of the bloom will be impacted by the non-metallic impurities in the molten steel in the tundish, which will reduce the plasticity and fatigue life of the steel. In this research, a mathematical model of a six-flow double-channel T-shaped induction heating tundish was established, the effects of induction heating conditions on the removal of inclusions in the tundish were investigated, and the impact of various inclusion particle sizes on the removal effect of inclusions under induction heating was explored. The results show that the Residence Time Distribution (RTD) curve produced through numerical simulation and physical simulation is in good agreement. The reduction of inclusion particles in the channel is made affordable by the dual-channel induction heating technique. As the diameter of inclusion particles increases from 10 μm to 50 μm, the probability of inclusion particles being removed from the channel gradually decreases from 70.9% to 56.1%.

Transient Analysis of Fluid Flow, Solidification, and Inclusion Behavior in Electromagnetically Stirred Bloom Caster Mold Using Bifurcated Submerged Entry Nozzle

Herein, the effect of bifurcated submerged entry nozzle (SEN) port angles on transient flow, solidification, and inclusion behavior in a bloom caster mold with electromagnetic stirring (EMS) is investigated. A 3D numerical model is developed to simulate the process, including time‐varying electromagnetic field and Lagrangian inclusion tracking approach, by varying inclusion density and size. The inclusion is modeled to be entrapped in the solidified shell when primary dendrite arm spacing (PDAS) is greater than inclusion size. As compared to the case without use of EMS, the percentage of shell thickness at the strand outlet is seen to increase by 22.18%, 9.45%, 8.03%, 9.31%, and 13.40% for different port angle values of 0°, 15°, 20°, 25°, and 30°, respectively, with EMS. The results show that EMS significantly influences the flow behavior by generating the swirl flow pattern that hinders the movement of inclusion downward in the domain. The bifurcated SEN with 30° port angle (without EMS) is seen to reduce inclusion entrapment and hence enhance inclusion removal. The outcome of present research may provide useful insights for optimizing the parameters of bloom caster mold to improve product quality, reduce production costs, and increase overall efficiency.

Study of Dispersed Micro-bubbles and Improved Inclusion Removal in Ruhrstahl–Heraeus (RH) Refining With Argon Injection Through Down Leg

Study of Dispersed Micro-bubbles and Improved Inclusion Removal in Ruhrstahl–Heraeus (RH) Refining With Argon Injection Through Down Leg

Artificial Hsp104-mediated systems for re-localizing protein aggregates

Spatial Protein Quality Control (sPQC) sequesters misfolded proteins into specific, organelle-associated inclusions within the cell to control their toxicity. To approach the role of sPQC in cellular fitness, neurodegenerative diseases and aging, we report on the construction of Hsp100-based systems in budding yeast cells, which can artificially target protein aggregates to non-canonical locations. We demonstrate that aggregates of mutant huntingtin (mHtt), the disease-causing agent of Huntington’s disease can be artificially targeted to daughter cells as well as to eisosomes and endosomes with this approach. We find that the artificial removal of mHtt inclusions from mother cells protects them from cell death suggesting that even large mHtt inclusions may be cytotoxic, a trait that has been widely debated. In contrast, removing inclusions of endogenous age-associated misfolded proteins does not significantly affect the lifespan of mother cells. We demonstrate also that this approach is able to manipulate mHtt inclusion formation in human cells and has the potential to be useful as an alternative, complementary approach to study the role of sPQC, for example in aging and neurodegenerative disease.

Investigation of gas purging configuration in an industrial ladle by computational fluid dynamics

A three-dimensional model was developed to investigate the effects of gas nozzle configuration in an industrial gas-stirred ladle on flow pattern, mixing time, heat transfer, inclusion removal, and shear stress on the wall. Population balance model coupled with computational fluid dynamics was chosen to evaluate the inclusion removal. The properties of phases and the size distribution of inclusion were in agreement with literature data. Gas nozzle locations were investigated in terms of radius and angle. It was found that an increase in angle and decrease in radius of gas nozzle location decreased shear stress on the wall. Also, as gas nozzle locations got closer to each other, bubble plumes overlapped, and turbulent kinetics was affected. This in turn affected temperature, mixing time, and inclusion removal. Therefore, by changing angle and radius, these parameters did not have similar trends. From the performed investigations, it was found that the best gas injection location was angle of 140° and radius of 0.65R. Shear stress, mixing time and inclusion removal at ladle with the plug radius of 0.65R were improved by 38.7%, 1.3%, and 0.87%, respectively. In addition, at ladle with the plug angle of 140°, shear stress, mixing time, and inclusion removal were increased by 6%, −6.57%, and 8%, respectively. By choosing this gas injection location, ladle performance was optimum in all parameters.

Research Status of Numerical Simulation of Nonmetallic Inclusions Interfacial Removal

The removal of inclusions in liquid steel has always been the focus of research, and the removal of inclusions is mainly through the process of the inclusion through the slag–steel interface. The inclusion removal process can be subdivided into inclusions in molten steel grew up rise, in steel–slag interface through separation, adsorb dissolved in molten slag 3 steps. Based on the microscopic process of three steps, this article summarizes and discusses the mathematical model, fluid mechanics model, and experimental verification method of inclusion removal process, analyzes limiting and influencing factors of inclusion removal process, and comprehensively describes the numerical simulation research progress of inclusion removal process. With the development of numerical simulation techniques and experimental equipment, some progress has been made in the study of interfacial removal of inclusions. The inclusion interface removal behavior can be analyzed semiquantitatively based on dynamic force model. The computational fluid dynamics model has advantages in studying the phenomena of the inclusion interface, and the phase‐field method is often used to simulate the removal process of the inclusion interface. The combination of water model and numerical simulation, high‐temperature laser confocal method, and other methods is of great help to explore the interface behavior of inclusions.

Effect of low basicity refining slag on evolution and removal of oxide inclusions in 55SiCrA spring steel

Effect of low basicity refining slag on evolution and removal of oxide inclusions in 55SiCrA spring steel

Numerical investigation of solidification behavior and inclusion transport with M-EMS in continuous casting mold

The present study deals with the development of a multiphase numerical model of the continuous casting process of steel bloom. Two SEN configurations that differ in port angles are considered for the study of flow pattern, temperature distribution, solidification thickness, interface fluctuation and inclusion behavior during the process. The influence of mold electromagnetic stirring (M-EMS) on the various output parameters is examined. The results show that the upper circulation loop formed in the 15° port angle case is responsible for higher inclusion removal, high interface level, and low solidification thickness in the meniscus region compared to that of the 30° case. The presence of M-EMS completely changes the flow pattern below SEN. Strong rotational flow coupled with oppositely directed swirl flow provides high tangential velocity near the solidification front and high axial velocity in the core region. It results in fluctuation in shell thickness along the casting direction and decreasing the superheated steam penetration. However, flow patterns remain unaffected above the SEN as upwards swirl flow is not able to reach this region. On applying the M-EMS, inclusion entrapment in solidifying shell increases for both 15° and 30° cases. In contrast, inclusion removal at the interface decreases for 15° case and increases for 30° case.

Study on the Effect of Calcium Alloy on Arsenic Removal from Scrap-Based Steel Production.

Scrap steel is a kind of resource that can be recycled indefinitely. However, the enrichment of arsenic in the recycling process will seriously affect the performance of the product, making the recycling process unsustainable. In this study, the removal of arsenic from molten steel using calcium alloys was investigated experimentally, and the underlying mechanism was explored based on thermodynamic principles. The results show that the addition of calcium alloy is an effective means of reducing the arsenic content in molten steel, with the highest removal percentage of 56.36% observed with calcium aluminum alloy. A thermodynamic analysis revealed that the critical calcium content required for arsenic removal reaction is 0.0037%. Moreover, ultra-low levels of oxygen and sulfur were found to be crucial in achieving a good arsenic removal effect. When the arsenic removal reaction occurs in molten steel, the oxygen and sulfur concentrations in equilibrium with calcium were wO=0.0012% and wS=0.00548%, respectively. After successful arsenic removal, the arsenic removal product of the calcium alloy is Ca3As2, which usually does not appear alone. Instead, it is prone to combining with alumina, calcium oxide, and other inclusions to form composite inclusions, which is beneficial for the floating removal of inclusions and the purification of scrap steel in molten steel.

In English

Oil and oil products enters surface waters as a result of man-made disasters, caused, in particular, by military operations. In order to prevent ecological catastrophe, it is necessary to remove hydrocarbons from water surface. The paper is devoted to the development of materials for the extraction of non-polar liquids from aqueous media. Magnetic sorbents based on non-carbonized biopolymers (both plant cellulose and keratin) are proposed. Biopolymer matrices of different morphology on the level of fiber bundles were used for the composite preparation. Dependent on origin, the matrices are characterized by different morphologies at the level of fiber bundles: they are straight (cellulose obtained from wood and corn cobs), helical (cellulose of tea leaves or scaly (keratin from animal wool). Magnetite particles were inserted into biopolymer matrices after the removal of non-cellulose and non-keratin inclusions from them. The samples were investigated with SEM and FTIR techniques, magnetite was identified with XRD analysis. The most homogeneous distribution of magnetic particles, a size of which is less than 1 mm, was found for the matrix obtained from corn cobs. This composite contained the least amount of iron (0.24 mass. %), namely this sample demonstrates the best flotation. The sorbent based on cellulose from tea leaves contained 71% of iron: the particles sink almost completely. The capacity towards non-polar liquids was estimated as follows (g g–1): 1.6–8.6 (vegetable oil), 10.5–16.4 (crude oil), 9.8–14.5 (kerosene). After the removal of crude oil from water surface, no film of this liquid was visually observed. The value of chemical oxygen demand was » 0.2 mgO2 dm–3, this is less than the demand for drinking water. Moreover, the sorbent can be easy removed from water surface with magnet. As found, the sorbents can be used for removal of toxic metal ions from water. As found, magnetic particles improves sorption of Pb2+ ions but decrease Cd2+ sorption. Thus, the sorbents with small content of inorganic modifier can be used for the removal of oil and oil products from water surface. The sorbents, which demonstrate bad flotation, can be used for the recovery of inorganic ions. The advantages of biopolymer-based sorbents over known material is a simple preparation procedure that involves cheap and available feedstock. Moreover, the sorbents can be easy separated from aqueous phase with magnet.

Inclusions Removal in Industrial Silicon by SiO2-CaO-Al2O3 Based Slag System

Inclusions Removal in Industrial Silicon by SiO2-CaO-Al2O3 Based Slag System

Characteristics of Bubble Behavior and Inclusion Removal in Liquid Steel Based on Industrial Trials of Argon Injection into Ladle Shroud

A series of industrial trials of argon injection into ladle shroud (AIILS) with different argon-blowing rates were conducted in this study. Firstly, bubbles in actual liquid steel of the tundish were captured by the method of “cold steel plate dipping” and characterized by microscope examination. A detailed investigation on the three-dimension morphology of bubbles was carried out by using industrial computerized tomography (ICT). Then, the two-phase flow of liquid steel and argon gas in the tundish was numerically simulated to further investigate the motion behaviors of bubbles in liquid steel of the tundish. The simulated results showed that bubbles in the size range of this investigation had a large enough filtration rate to demonstrate a good performance on inclusion removal. Finally, the effect of AIILS on inclusion removal was analyzed by detecting the variations of inclusions as well as total oxygen content in steels taken from the ladle, tundish, and casting billet. The method of AIILS was more effective at improving the removal of inclusions in the range of 5 to 10 μm and obviously increased the removal rate of total oxygen content.