Seznam abstraktů 2025: POSTEROVÁ SEKCE A

Assessing and quantifying the impact of various factors on nitrogen content in metal is vital for optimizing technological and operational strategies to minimize or prevent nitridation in the final steel product. Recognizing how individual factors affect nitrogen levels is crucial for predicting nitrogen quantities during both production and processing stages within a closed production cycle. This study investigates the factors influencing nitrogen content in crude steel before tapping, using Cohen's distribution table and graphical analysis. Although the impact of after-blows on nitrogen content is well established, the paper also explores other factors contributing to nitridation before tapping from the basic oxygen furnace.

This study focuses on the numerical analysis of molten steel flow in the CC mold of a continuous casting device for two steel grades - ferritic low-carbon stainless steel 409L and normalized structural steel S275N, according to EN 10025-3. The objective was to investigate the influence of the physical and metallurgical properties of these steels on their flow behavior and thermal conditions in the solidification zone. Computational Fluid Dynamics (CFD) simulations were performed at two different casting speeds.
Velocity profiles and temperature gradients were analyzed along two reference lines: one positioned at the steel surface and the other along the vertical sidewall of the mold. Based on the temperature gradient profiles, the position of the initial solidification point in the strand was determined for each steel grade and process configuration. The results showed significant differences in the hydrodynamic behavior and heat transfer characteristics between the two steels, which were manifested in variations in the length of the liquid zone and the formation of the primary solid shell. The ferritic stainless steel 409L exhibited higher fluidity and faster solidification, while S275N exhibited slower heat dissipation and lower turbulent kinetic energy.
The results provide a basis for optimizing the technological parameters of continuous casting processes with respect to the specific behavior of different steel grades.

Hydrodynamic conditions in the tundish play a crucial role in ensuring the quality of liquid steel and the effectiveness of refining processes during continuous casting. The present study focuses on the numerical comparison of flow characteristics in a four-strand tundish under various geometric configurations of impact pads and positional deviations of the ladle shroud. The calculations were performed using Computational Fluid Dynamics (CFD) in Ansys Fluent, employing the realizable k-ε turbulence model and particle tracking methods to determine residence time distributions. Simulated setups included impact pads of the Spherical K4 type and a standard impact pad, with modifications to their geometry and positional deviations of the ladle shroud from the reference axis. The analysis demonstrated that the standard impact pad results in longer residence times, enhancing the homogenization of liquid steel, however, this benefit is counterbalanced by the development of more dominant piston-type flow and a higher tendency toward red eye formation under misaligned shroud conditions. In contrast, configurations incorporating the Spherical K4 pad demonstrated a more uniform velocity field and higher flow stability under varying ladle shroud positions. These findings highlight the importance of impact pad design in maintaining stable flow behavior, particularly under non-ideal ladle shroud alignment, minimizing uneven refractory wear, mainly in the slag line region near the ladle shroud, and reducing dead flow zones.

Natural gas-fired walking-tray furnaces are an innovative solution for heat treatment of metals, providing increased energy efficiency and reducing environmental impact. The article analyzes the prospects for introducing this technology into the metallurgical industry of Kazakhstan. Particular attention is paid to comparison with traditional heating methods, identifying key benefits such as reduced emissions of carbon dioxide, nitrogen oxides and particulate matter, as well as the cost-effectiveness of switching to natural gas. The scientific novelty of the study lies in the comprehensive assessment of the design features of continuous furnaces with a walking pallet and the development of innovative approaches to automated control of temperature conditions. The article presents new data on the possibilities of optimizing the processes of heating blanks using intelligent control systems, which allows minimizing production losses and improving product quality. The practical significance of the study lies in the development of recommendations for adapting this technology to the conditions of Kazakhstan's metallurgy, including the modernization of existing production facilities. The introduction of continuous furnaces with a walking pallet on natural gas will allow enterprises to significantly reduce operating costs, reduce their carbon footprint and increase competitiveness in the global market. In addition, the importance of developing gas transportation infrastructure for the successful integration of this technology in regions with limited access to natural gas is emphasized. The proposed solution opens up new opportunities for the modernization of metallurgical enterprises in Kazakhstan, ensuring a balance between production efficiency, environmental safety and economic benefits.

The steel industry is currently investing globally in various technologies enabling the reduction of carbon footprint. To help in the transition, VTT developed 3 “hybrid” concepts that combines gasification and syngas processing technologies together producing biosyngas and biohydrogen which can replace fossil fuels.

Methods
Biomass gasification route to syngas is a well-established technology to utilize biogenic carbon efficiently. However, it has rarely been introduced in the iron and steel industry which commonly utilizes technologies based on fossil carbon, for instance, MIDREXNG natural gas reforming-based gas direct reduction of iron ore. The biomass-syngas route typically compromises of a gasifier, dryer, hot gas filter, reformer and gas cleaning steps. The feasibility studies were simulated as mass and energy balances and based on the balances, technoeconomic calculations were made. The focus of the research was to find suitable biogenic carbon-based gas to be used as a reductant in a conventional DRI shaft furnace. The importance of the gas quality was noticed during the study as well as the importance of gas recirculation for process overall efficiency.

Conclusions
Biosyngas route can potentially be more cost effective than using pure hydrogen. The carbon permit cost is higher than the carbon capture cost for MEA based solvents in the steel industry, therefore it is more beneficial to capture biogenic carbon from the process.

The smelting units, which are used for melting metal waste, are equipped with lances for blowing gaseous media. In case of refining lances, this is oxygen. These gaseous media enable, in particular, the melting of scrap and the intensive homogenisation of the resulting melt. In this connection, blowing systems have been developed both for blowing the gaseous media onto the melt surface or into the melt itself and also for blowing the gaseous mixture with powdery substances. In the design of the blowing systems and the individual lance heads and nozzles, it is necessary to respect certain recommendations, the derivation of which is based on long experience and knowledge gained in this field. The present paper summarises these recommendations for the design and construction of the refining lance heads. Furthermore, the paper describes lance heads made of cast and forged components including the method of their cooling by circulating water. The paper deals with only a part of the whole rather complex issue, but the design recommendations and description of the design of selected refining lance heads should help designers and engineers to navigate this issue as well as the process of designing systems that meet high quality, efficiency and operational reliability requirements.

In light of the European Union’s energy transition strategy aimed at minimizing dependence on fossil fuels, hydrogen has emerged as a key non-carbonaceous reducing agent, offering significant potential for application in metallurgical processes. This study focuses on the material characterization of selected high-grade manganese ores and evaluates their suitability for hydrogen-based reduction. The investigated samples originated from Burkina Faso, Gabon, Ghana, and South Africa—regions known for some of the highest-quality manganese deposits globally.
Material testing included chemical, mineralogical, physical, and thermal property analyses, with an emphasis on reducibility. The effectiveness of hydrogen reduction largely depends on the oxidation state of manganese in the ores. Ores rich in MnO₂, such as those from Gabon, demonstrated the highest suitability due to the favorable reduction path to MnO. Gabonese ore, dominated by porous pyrolusite and with low SiO₂ content, showed promising characteristics for low-temperature hydrogen reduction (below 500 °C).
In contrast, ores from South Africa and Ghana, which contain manganese primarily in carbonate form (rhodochrosite), exhibited lower potential for hydrogen-based processing. These ores are more suitable for carbothermal reduction, as the dissociation of MnCO₃ to MnO does not align with hydrogen reduction pathways. Overall, the study confirms that mineralogical composition—specifically the presence of higher manganese oxides—plays a critical role in determining the feasibility of hydrogen utilization in manganese ore reduction. The findings support the selection of specific ore types for further thermodynamic simulations and experimental work in the development of low-emission metallurgical technologies.

The presented research focuses on identifying differences in the lengths of transition areas during the continuous casting of steel in a three-strand "T"-type tundish, considering various numbers of active strands. The study compares results from three types of measurements: in the first measurement, casting was simulated with three active strands (full capacity); in the second measurement, the simulation was realised with the middle strand disabled; and in the third measurement, the continuous casting process was simulated with one of the outer strands disabled. The measurement results indicate which mode, involving one inactive strand, is more suitable when one strand needs to be disabled in real-world operations during continuous steel casting. The research was realised in the SimConT laboratory located at the Technical University of Košice, at the IMTECH Institute. The SimConT laboratory specializes in the physical modeling of continuous steel casting processes. For the measurements, a three-strand "T"-type tundish model was used, scaled at 1:3 relative to the actual tundish used in continuous steel casting operations at Železiarne Podbrezová a.s.

Hydrogen carriers were mixed into syngas reduction gas mixture and fed into a DRI reactor to study whether it is feasible to reduce hematite pellets into iron with at least 96% reduction rate. Carbon based hydrogen carriers are tested to determine if there is carbon formation to the pellets or the reactor outlet, inorganic hydrogen carriers such as ammonia are tested as well, and their endothermic reformation effect is assessed to determine the trade off between energy consumption and hydrogen production for the DRI reaction. The reactor can be loaded with over 100 grams of hematite and the test rig supports a variety of gas and liquid feeds that can be experimented with. Inlet and outlet gas compositions were analyzed with ABB gas analyzers. The pellet compositions were analyzed with SEM-EDS and the reduction degree of the pellets were calculated from mass change.
It was determined that Passing grade (>96% reduction degree) DR iron can be made by feeding hydrogen carriers directly into the reactor. Carbon based hydrogen carriers tend to form elemental carbon. Especially the cooling outlet gas will be problematic and would require scrubbing and filtering in larger scale. The endothermic reforming reactions sometimes cool the reactor significantly, especially with ammonia. Due to the endothermic nature of hydrogen carrier decomposition, the hydrogen production for the DRI reaction is a trade-off of energy.

Carbon footprint has, for decades, become a centre of research regarding environmental threats that the world still faces. The impact of pyrometallurgical processes on the environment has played and still plays a role in the climate changes. This is observed through different events that affect nature and the universe. Reduction processes have largely contributed to carbon emissions; hence, researchers have embarked on researching new reductants. Biomass has recently been the centre of numerous tests. Many biochars have shown potential to replace the generic coke used for centuries. It is therefore of great importance to categorise biomass that might be used for reduction, for adsorption or for energy generation. This paper develops a critical comparison of different biomass for pyrometallurgical use and essentially for reduction. Amongst the prospective biochars compared in this paper are palm kernel shells biochar, coconut biochar, sugarcane biochar, macadamia biochar and malt waste biochar. All biochars were produced through pyrolysis in an alumina tube furnace under argon. Ultimate and proximate analyses were used to characterise the raw biomass and the generated biochars. Results have shown that although all biochars show high fixed carbon content, some may require reconditioning to be usable in furnaces through agglomeration.

Computed tomography (CT) was used to evaluate the internal quality of the zinc alloy castings. The castings are produced by high pressure die casting process from ZP0430 zinc alloy, which contains aluminium and copper. High pressure die casting process is very complicated and sensitive to casting parameters such as filling rate, solidification time, die tempering and others. A certain percentage of porosity is always present in the castings. As part of the research into the die casting process, the internal porosity of Langmutter castings produced in an eight-cavity die was investigated. Castings produced using normal casting parameters and modified casting parameters based on numerical simulation of the casting process were evaluated. Computed tomography was used to determine the distribution of cavities in the casting, their quantity and subsequently their volume and porosity. In the castings produced using the normal casting parameters, the average number of cavities was 679 and the porosity was 0.108 %. When the modified casting parameters were implemented, the average number of cavities in the castings decreased to 454 and the porosity to 0.077 %. It has been shown that the modified casting parameters are more suitable for the high pressure die casting process in terms of porosity formation.

Decarbonization is essential - and it must begin immediately. As one of the leading global producers of CO₂, the metallurgical industry must contribute its share to mitigating the climate crisis. However, alongside the development and implementation of low- and zero-carbon technologies, we must ask a fundamental question: will the “green label” not merely create an illusion of sustainability? There is a real risk that under the banner of technological efficiency, total resource consumption will increase and industrial activity will shift toward a more sophisticated form of planetary destruction. This paper highlights the dangers of rebound effects, the neglect of planetary boundaries, and the emergence of “green” industry as a form of moral alibi. It also considers a broader context: the historical responsibility of industrialized nations, the imperative of climate justice, the geopolitical consequences of carbon policies, and the need for a systemic transformation. In conclusion, the paper calls on the academic community to actively engage in these debates, to ask uncomfortable questions, and to seek responsible answers.