Physical modeling of two-phase liquid-gas processes occurring in the refining ladle for Fe-Si alloy refining process.

The article presents the results of research carried out using a water model of a refining ladle for the Fe-Si ferroalloys treatment. These studies were aimed at improving the efficiency of refining and homogenization of liquid Fe-Si ferroalloy in the refining ladle by using a new method of blowing gas through a system of nozzles installed at the bottom of the ladle. The obtained results allowed to determine the proper location of the plug at the bottom of the refining ladle and the possibility of using combined blowing. The tests were carried out for a refining ladle with a capacity of 3 m3 using a physical model on a linear scale of 1:3. The gas flow rate used in the model corresponded proportionally to the value previously used in industrial practice and amounted to 26.8 l/min. Experiments were performed for both combined blowing applications and through a purging plug at the bottom of the ladle. In the case of combined blowing, the volume of the gas stream was divided into two blowing sources (lance and purging plug). As a result of laboratory tests, one of the variants was selected and tested in industrial conditions. These studies confirmed the improvement in the efficiency of refining treatment of the FeSi alloy in terms of reducing the carbon and aluminum content in the alloy.x.

Assessment of refining efficiency during the refining cycle in a foundry degassing unit in industrial conditions.

The article focuses on the issue of improving the efficiency of a Foundry Degassing Unit (FDU) via operational testing of aluminium alloys during casting at MOTOR JIKOV Slévárna a.s.. As part of the research, the efficiency of the refining process in the FDU was assessed. The main emphasis was placed on determining the moment of the greatest decrease in the hydrogen content in the melt and whether it is possible to shorten the refining cycle. The values of the Dichte Index were determined, on the basis of which the degassing curve was plotted and the progress of the melt degassing was assessed. To ensure the required quality of castings, the maximum allowable value of the Dichte Index ranged from 3 to 4%. During the process, the temperature drop during the refining cycle was also determined. The total temperature drop from pouring the melt into the ladle to the end of refining ranged from 26 to 32 °C, which is within the acceptable limits of the foundry. Based on the knowledge resulting from the operational experiments, recommendations were formulated to optimize the refining technology at the FDU for the MOTOR JIKOV Slévárna a.s. foundry.

Model Investigation of Argon Injection into Liquid Steel at Ladle Furnace Station with Using of Innovative Module.

High-quality steels are defined primarily by a small quantity of non-metallic inclusions and a high degree of chemical homogenisation. The ladle furnace (LF) is the most important metallurgical unit in which the quantity of non-metallic inclusions can be significantly reduced while ensuring metal chemical homogenisation. It is achieved largely due to appropriate controlling and the use of increasingly developed inert gas purging techniques. Various types of porous plugs (channel or radial type) are used in the metallurgical ladles. In aggregate units of intermediate-ladle type, various types of channel plugs and/or gas curtains are successfully used. In the research presented herein, a new and innovative module for inert gas injection into liquid steel for deep refining was tested. The presented research relates to the innovative module using to replace the standard porous plug in the steelmaking ladle on the outside-furnace (LF) processing station. Hybrid modelling methods (numerical and physical modelling) were used to carry out research. Module using causes significantly faster alloy additive dispersion in ladle volume compared with the standard solution (the standard porous plug). Furthermore, the obtained flowing structure positively affects liquid steel refining and mixing processes after alloy additive addition. A new technological solution, i.e., gas-injection module-differs from the traditional porous plugs currently used in the steel mills in terms of geometric parameters, external and internal structure, and what is most importantly, terms of the active surface area-shall be understood in as the surface area wherein slots occur.

Numerical and Physical Modeling of Liquid Steel Asymmetric Behavior during Non-Isothermal Conditions in a Two-Strand Slab Tundish-"Butterfly Effect".

This paper presents the results of studies on the occurrence of transient disturbances in the hydrodynamic system of a tundish feeding area and their effect on the casting process. In addition, the effect of changes in the level of superheating of the molten steel fed to the tundish on the evolution of the hydrodynamic system was analyzed. The studies were conducted with the use of a physical model of the tundish and a numerical model, representing the industrial conditions of the process of the continuous casting of steel. When a tundish is fed through a modified ladle shroud that slows down the momentum of the stream, this creates favorable conditions for the emergence of asymmetrical flow within the working tundish volume. The higher the degree of molten steel reheating in the ladle furnace, the stronger the evolution of the hydrodynamic structures in the tundish during the casting process.

Research on the impact of rotor wear on the effectiveness of the aluminium refining process.

Physical modelling is successfully used to understand mechanisms involved in the aluminium refining process by injecting inert gas into the liquid metal through rotors. Two types of industrial impellers, which are extremely different in construction, were tested in the research. The aim of the research was to determine the effectiveness of their operation depending on their degree of wear. This type of research has not been tested on water models so far. During the process, the parameters were changed, such as the gas flow rate from 13 to 19 L/min, the rotor speed from 325 to 400 rpm and the height of the rotor from the bottom of the refining reactor. Tests were carried out for new and worn rotors. Oxygen removal rate curves were prepared on the basis of tests determining changes in oxygen content in the model liquid as a function of time for changing rotor speed values. It was found that the efficiency of hydrogen removal from the model liquid was higher when worn impellers were used in the model. In order to verify results of model tests, a metallographic analysis of samples obtained in industrial conditions and using the analysed process parameters was carried out.

Using Physical Modeling to Optimize the Aluminium Refining Process.

Concern for the environment and rational management of resources requires the development of recoverable methods of obtaining metallic materials. This also applies to the production of aluminium and its alloys. The quality requirements of the market drive aluminium producers to use effective refining methods, and one of the most commonly used is blowing an inert gas into liquid aluminium via a rotating impeller. The efficiency and cost of this treatment depends largely on the application of the correct ratios between the basic parameters of the process, which are the flow rate of the inert gas, the speed of the rotor and the duration of the process. Determining these ratios in production conditions is expensive and difficult. This article presents the results of research aimed at determining the optimal ratio of the inert gas flow rate to the rotary impeller speed, using physical modeling techniques for the rotor as used in industrial conditions. The tests were carried out for rotary impeller speeds from 150 to 550 rpm and gas flow rates of 12, 17 and 22 dm3/min. The research was carried out on a 1:1 scale physical model, and the results, in the form of visualization of the degree of gas-bubble dispersion, were assessed on the basis of the five typical dispersion patterns. The removal of oxygen from water was carried out analogously to the process of removing hydrogen from aluminium. The curves of the rate of oxygen removal from the model liquid were determined, showing the course of oxygen reduction during refining with the same inert gas flows and rotor speeds mentioned above.

Physical and Numerical Modeling of the Impeller Construction Impact on the Aluminum Degassing Process.

This paper presents the results of tests on the suitability of designed heads (impellers) for aluminum refining. The research was carried out on a physical model of the URO-200, followed by numerical simulations in the FLOW 3D program. Four design variants of impellers were used in the study. The degree of dispersion of the gas phase in the model liquid was used as a criterion for evaluating the performance of each solution using different process parameters, i.e., gas flow rate and impeller speed. Afterward, numerical simulations in Flow 3D software were conducted for the best solution. These simulations confirmed the results obtained with the water model and verified them.

Impact of Rotor Material Wear on the Aluminum Refining Process.

The paper presents the results of tests carried out during the refining of the AlSi9Cu3(Fe) alloy in industrial conditions at the FDU stand. In the tests, three different rotors made of classical graphite, fine-grained graphite and classical graphite with SiC spraying were tested for the degree of wear. A series of tests was conducted for five cases-0% to 100% of consumption every 25%-corresponding to the cycles of the refining process. The number of cycles corresponding to 100% wear of each rotor was determined as 1112. The results of the rotor wear profile for all types of graphite after the assumed cycles are presented. Comparison of CAD models of new rotors and 3D scans of rotors in the final stage of operation revealed material losses during operational tests. The study assessed the efficiency of the rotor in terms of its service life as well as work efficiency. It was estimated on the basis of the calculated values of the Dichte Index (DI) and the density of the samples solidified in the vacuum. The structure of samples before and after refining at various stages of rotor wear is also presented, and the results are discussed.

Physical and Numerical Modeling of the Slag Splashing Process.

The influence of technological factors on the process of slag splashing was analyzed in the paper. The problems were solved in several stages using our own and commercial calculation programs and laboratory tests. Based on the performed calculations and simulations, factors affecting the slag splashing were determined. It was observed that the high efficiency of the process can be achieved by optimizing numerous technological parameters, e.g., flow parameters, pressure, and temperature of the nitrogen stream, height and angle of the lance position, as well as slag height into which the gas stream enters and MgO consumption. In addition, the chemical and mineralogical composition of the slag and its physicochemical parameters should be also considered. The obtained results of numerical simulations of slag splashing in the oxygen converter coincide with the results of experiments carried out using the physical model of oxygen converter. This means that the simulations well represent the real course of the slag splashing process for the studied variants.

Evolution of the Numerical Model Describing the Distribution of Non-Metallic Inclusions in the Tundish.

Continuous casting is one of the steel production stages, during which the improvement in the metallurgical purity of steel can be additionally affected by removing nonmetallic inclusions (NMIs). This can be achieved by means of various types of flow controllers, installed in the working space of the tundish. The change in the steel flow structure, caused by those flow controllers, should lead to an intensification of NMIs removal from the liquid metal to the slag. Therefore, it is crucial to understand the behavior of nonmetallic inclusions during the flow of liquid steel through the tundish, and particularly during their distribution. The presented paper reports the results of the modeling studies of NMI distribution in liquid steel, flowing through the tundish. CFD modeling methods-using different models and computation variants-were employed in the study. The obtained CFD results were compared with the results of laboratory tests (using a tundish water model). The results of the performed investigations allow us to compare both methods of modeling; the investigated phenomena were microparticle distribution and mass microparticle concentration in the model fluid. The validation of the CFD results verified the analyzed computation variants. The aim of the research was to determine which numerical model is the best for describing the studied phenomenon. This will be used as the first phase of a larger research program which will provide for a comprehensive study of the distribution of NMIs flowing through tundish steel.