This paper focuses on the study of current knowledge regarding the use of hydrogen as a reducing agent in the metallurgical processes of iron and steel production. This focus is driven by the need to introduce environmentally suitable energy sources and reducing agents in this sector. This theoretical study primarily examines laboratory research on the reduction of Fe-based, metal-bearing materials. The article presents a critical analysis of the reduction in iron oxides using hydrogen, highlighting the advantages and disadvantages of this method. Most experimental facilities worldwide employ their unique original methodologies, with techniques based on Thermogravimetric analysis (TGA) devices, fluidized beds, and reduction retorts being the most common. The analysis indicates that the mineralogical composition of the Fe ores used plays a crucial role in hydrogen reduction. Temperatures during hydrogen reduction typically range from 500 to 900 °C. The reaction rate and degree of reduction increase with higher temperatures, with the transformation of wüstite to iron being the slowest step. Furthermore, the analysis demonstrates that reduction of iron ore with hydrogen occurs more intensively and quickly than with carbon monoxide (CO) or a hydrogen/carbon monoxide (H₂/CO) mixture in the temperature range of 500 °C to 900 °C. The study establishes that hydrogen is a superior reducing agent for iron oxides, offering rapid reduction kinetics and a higher degree of reduction compared to traditional carbon-based methods across a broad temperature range. These findings underscore hydrogen’s potential to significantly reduce greenhouse gas emissions in the steel production industry, supporting a shift towards more sustainable manufacturing practices. However, the implementation of hydrogen as a primary reducing agent in industrial settings is constrained by current technological limitations and the need for substantial infrastructural developments to support large-scale hydrogen production and utilization.

The article presents the results of the investigation of changes in the chemical and mineralogical composition of slag during steel production in a blown oxygen converter. This process was monitored using the slag samples that were collected during the period when oxygen blowing into an oxygen converter was interrupted. The slag samples were collected after 150 s (2.5 min), then after 5, 8, 11, and 24 min of oxygen blowing, and in minute 27 when oxygen blowing was terminated. The sampling was carried out within five consecutive melting processes. The article presents and documents the changes in the contents of CaO, CaO (free), Fe (total), FeO, SiO₂, and in the basicity of the slag during oxygen blowing. It also provides the characteristics of individual structural components formed during oxygen blowing and a detailed description of the lime assimilation process, including the formation of the final structure of the slag, consisting of dicalcium silicate (2CaO·SiO₂), tricalcium silicate (3CaO·SiO₂), RO-phase, and calcium ferrites (2CaO·Fe₂O₃). The results of the investigation of the changes in the chemical composition of the slag during oxygen blowing in an oxygen converter were compared with the changes in the structural composition of the slag.

This article deals with material research of selected types of quartz and quartzites in order to determine the priority of their use in the production of ferrosilicon and pure silicon, respectively. The highest quality quartzes and quartzites are commonly used in metallurgy, but not all types of these silicon raw materials are suitable for the production of ferrosilicon and pure silicon, despite their similar chemical composition. Behavior differences can be observed in the process conditions of heating and carbothermic production of ferrosilicon and silicon. These differences depend, in particular, on the nature and content of impurities, and the granularity (lumpiness) and microstructure of individual grains. The research focused primarily on determining the physicochemical and metallurgical properties of silicon raw materials. An integral part of the research was also the creation of a new methodology for determining the reducibility of quartzes (or quartzites), which could be used for real industrial processes and should be very reliable. The results of the laboratory experiments and evaluation of the physicochemical and metallurgical properties of the individual quartzes (or quartzites) are presented in the discussion. Based on comparison of the tested samples’ properties, their priority of use was determined. This research revealed the highest quality in quartzite from Sweden (Dalbo deposit) and Ukraine (Ovruč deposit) and quartz from Slovakia (Švedlár deposit). The use of these raw materials in industrial conditions is expected to result in the achievement of better production parameters, such as higher yield and product quality and lower electricity consumption.

The automotive industry is one of the most important customers for the foundry industry. In particular, casting of engine parts for combustion engines is one of the most demanding areas of casting technology. New generation of engine blocks and cylinder heads are getting geometrically more complicated in order to maintain or even increase performance. With the increased complexity, the strain for the casting molds is growing and the widely used technology of core making with standard silica sands is, for several applications, no longer reaching the demanded results. Furthermore, in last decade, there has been an effort in using inorganic binders in core making process, which brings along some additional technological challenges. In order to cope with these challenges, in this paper, silica and non-silica sands with round and angular grains as well as with fine and coarse grains are examined using an inorganic binder for strength, permeability, and thermal stability. The results shall provide useful information about the possibilities of application and combining different types of foundry sands, both silica and non-silica. With their impact on the selected sand core properties, they can help in solving problems in the core making process as well as reaching a high quality of the final product-casting.

Modern steel plants produce today a large portfolio of various steel grades, many for end-uses demanding high quality. In order to utilize the maximum productivity of the continuous-casting machine, it is sometimes necessary to cast steel grades with different chemical compositions in one sequence. It is important, therefore, to know the possibilities of a specific continuous-casting machine to make the Intermix connections as short as possible. Any interference with established procedures may, however, have a negative impact on the cleanliness of the cast steel. Using physical and numerical simulation tools, it was found that reducing the steel level in the tundish during the exchange of ladles makes it possible to shorten the transition zone. However, when the steel level is reduced, the flow of steel is impaired, which can have a negative effect on the cleanliness of the cast steel and, in extreme cases, may even lead to entrapment of slag in the mold. The cleanliness of cast steel was evaluated using one of the most advanced tools for automatic steel cleanliness evaluation, AZtecFeature (Oxford Instruments, Abingdon, UK), which enables determination of the type, size, distribution, and shape, as well as the chemical composition, of individual types of non-metal inclusions.

In connection with the increasing requirements for cleanliness in conticast steel, it is necessary to develop original solutions. The tundish, as the last refractory-lined reactor, gives enough space to remove inclusions by optimizing the flow of steel. The basic component of the tundish is the impact pad, the shape of which creates a suitable flow of steel, thus making it part of the tundish metallurgy. The optimal steel flow in the tundish must avoid creating dead zone areas, or the slag “eye” phenomenon in the slag layer around the ladle shroud, and is intended to create conditions for the release of inclusions by promoting reactions at the steel-slag phase interface. The flow also has to prevent excessive erosion of the tundish refractory lining. This paper compares the standard impact pad with the “Spheric” spherical impact pad using computional fluid dynamiscs (CFD) tools and physical modelling. The evaluation criteria are residence time and flow in the tundish at three different casting speeds.