Metallurgist最新文献

The ladle refining of iron-carbon melts is an essential component of the modern technology used in the production of iron and steel, ensuring the high quality of metal products. However, in the context of mini- and micro-factories using technological units of a limited volume, it is often unfeasible to implement modern, highly efficient refining, deoxidation-alloying, and heating schemes that are commonly used by ladle furnaces and degassers. In addition, the issue of the widespread use of various production wastes for the production of cast iron and steel in order to recycle them and reduce the consumption of conventional charge materials is relevant. Therefore, a new method of submerged arc reduction of elements useful for metallurgy from industrial waste and secondary materials directly into an iron-carbon melt for its deoxidation-alloying (refining), homogenization, and heating by a submerged electric arc is proposed. This technology eliminates the use of expensive reagents, ferroalloys, and alloying elements. Based on the conducted research, a scheme of the processes of submerged arc reduction of elements was established, the design of submerged arc furnace assemblies and their composition were proposed, and the high efficiency of the new method of ladle refining in comparison with conventional analogs was demonstrated.

The paper describes the existing technologies and challenges associated with galvanized metal production at the Novolipetsk Steel (NLMK) plant. Possible ways to improve the process using machine-learning tools are proposed.

The production of direct reduced iron production is accompanied by the generation of by-products, specifically gas purification sludge and metallized fines with a high iron content. Processing this iron poses certain technical and technological challenges. Studies were conducted at the Lebedinsky ore mining and processing plant to analyze the chemical composition, phase distribution, and particle size distribution of iron ore sludge. Pilot smelting of iron-containing hot briquetted iron sludge was carried out in a 100-kW electric arc furnace, resulting in the production of foundry cast iron. The sludge and coke screenings were layered in a ratio of 15 g of coke screenings per 100 g of sludge. Complete melting of the entire charge volume was achieved at 1340 °C. This developed technology is protected by a patent from the Russian Federation.

New dependencies and relationships were identified for the first time after the implementation of abrasion-resistant surfacing technology on heat-strengthened steel 65G. This technology revealed the nature of the Vickers hardness distribution in the vertical and horizontal directions of the surfacing area and demonstrated their identity. It has been established that the thermal effects from the welding arc reduce the hardness of the base metal located directly in the lower part of the surfacing area. Compared with the planar direction, the thermal influences on metal hardness, size of the thermal influence zone, and the heat-affected zone are more pronounced in the depth of the surfacing area. This study clarifies the changes in HV hardness in various zones is provided based on recent studies in materials science and metallurgy.

The article describes modern methods for controlling and optimizing the energy mode of melting in electric arc furnaces and units for out-of-furnace steel processing using optical emission spectroscopy systems. These systems enable the determination of melt and slag temperatures, plasma temperatures in the arc combustion area, and slag composition, as well as the analysis of emission intensity from the melt and slag surfaces. The analysis revealed that depending on the range of steel to be smelted and the peculiarities of smelting technology at a particular electric arc steel-making furnace, control systems for smelting monitoring can be developed according to the obtained indicators of one or a combination of the abovementioned parameters.

The effect of thermal, thermomechanical, and aeroacoustic treatment on the structure formation and mechanical properties of BrB2 alloy (rods drawn after quenching) was studied. According to the results of studying the alloy properties after these types of treatment under the optimized conditions, performing pre-aging aerothermoacoustic treatment provides higher yield strength without a decrease in ductility, and improves heat resistance of BrB2 alloy. The resulting yield strength exceeds that of BrB2.5 alloy.

A method and results of model studies of the operation of a proposed new system for mechanized feeding of filler sand to the ladle nozzle are presented. The design solutions incorporated into the system and the relationships obtained to justify its energy-force parameters are validated.

The global trend of ore quality degradation, which is occurring in parallel with increased production volumes of primary metals, has led to the necessity of comprehensive processing of raw materials. This involves the concentration and recycling of metallurgical technogenic wastes, which were previously considered unprofitable. In particular, this means the introduction of dump tailings and sludges from holding ponds to concentration, as well as the feeding of matured concentrates, dump, and recycled slags, and in-house low-grade reverts to metallurgical processing. The feed and the product of its concentration demonstrate an increased content of the refractory spinel phase, which has a variable composition. A share of the technogenic feed in charge of head smelting units exceeds 20%. The majority of main smelting units employ autogenous processes, such as flash smelting, liquid bath smelting, and oxygen-flash smelting. The processing of technogenic low-heat feed in autogenous smelting units results in thermal imbalance, loss of melt homogeneity, and, consequently, disrupts the discharge of smelting products, potentially leading to complete shutdown of the unit. Such behavior is typical for both types of autogenous units operated in the Nornickel Polar Division, namely the Vanukov furnace and the flash smelting furnace. The issue of melt heterogeneity and the formation of refractory accretion at problem areas of the flash smelting furnace is widely known and sufficiently investigated in foreign literature as well as by the authors of this paper. However, further investigation is required for the Vanukov furnace, with a particular focus on the formation mechanism of the intermediate layer phase in the melt. This investigation should aim to develop effective mitigation strategies to address the adverse impact of this phase formation.

The process of blast furnace production relies heavily on the quality and composition of its charge materials, among which iron ore sinter plays a crucial role. The consistency in the fractional composition is intrinsically linked to the method employed for their fragmentation. This fragmentation, or crushing, is influenced by the type of load applied and is inherently dependent on the design and functionality of the crushing machinery utilized. Based on the mechanics of the crushing process, a mathematical model has been developed to describe the interaction between the sprocket teeth and the material being crushed. This model aids in determining the optimal conditions that facilitate the material entry into the active crushing zone of a toothed rotary crusher. Through this analysis, it becomes evident that rotors outfitted with chevron and spiral-configured sprocket teeth significantly outperform those with a linear arrangement. Experimental investigations into the agglomerate crushing process have shed light on the outcomes of different deformation methods. When subjected to compression deformation, it was observed that the resulting material contained 17.2% of fines smaller than 5 mm and a -10 mm fraction amount to 31.1%. Conversely, a more controlled process emerges during stretching in bending, which remarkably reduces the −10 mm fraction to only 1.6%. Building upon these insights, a modernized toothed rotary crusher featuring a nonlinear rotor was developed and implemented in the sintering production of Branch No. 1 AISW of SMMC. The introduction of this advanced crusher led to notable improvements in the screening process of hot sinter. After employing this upgraded machinery, there was a 2–4% increase in the amount of return material alongside a significant 6–7% reduction in screenings during the classification stage on the conveyor path for supplying blast furnace No. 1 with charge materials. Moreover, this optimization ensured the elimination of oversized pieces, specifically those exceeding 80 mm.

The processing of fine dust from copper smelters in Kazakhstan is an urgent task. The currently used technology of hydrometallurgical dust processing, which involves leaching with sulfuric acid to produce lead cake and a solution containing copper and zinc, fails meet modern requirements. The significant content of arsenic in the dust (up to 15%) hinders the production of high-quality products. In this study, fine dust from a copper smelter in Kazakhstan, obtained following conversion of copper mattes from autogenous smelting in Vanyukov furnaces, was used. Comprehensive analytical studies of the elemental and phase composition of dust were carried out using a Bruker D 8 ADVANCE X‑ray diffractometer and a scanning electron microscope with a JED-2300 energy dispersive X‑ray spectrometer (JEOL). This ensured the reliability of the data on the elemental composition of the initial dust, which were subsequently used to examine the behavior of arsenic and other non-ferrous metals under conditions of reduction roasting with natural gas.

In order to gain a deeper understanding of the mechanism of the reduction roasting, a detailed thermodynamic analysis was carried out to examine the interactions between dust components and natural gas within the temperature range of 500–1000 K. Thermodynamic calculations were carried out using Outotec HSC Chemistry 8.1.5 software. It was established that favorable conditions are created for the reduction of zinc and copper ferrites, as well as arsenic oxide (As⁵⁺) when roasting dust with natural gas. It was demonstrated that the preliminary roasting of dust with natural gas ensures the most effective reduction of arsenic oxide (As⁵⁺) and the production of arsenic-free calcine with the subsequent high selective separation of Pb, Cu, and Zn from it into commercial products.

The use of this method will significantly improve the technological performance of leaching fine dust with sulfuric acid due to the preliminary maximum removal of arsenic from the general technological scheme and the destruction of copper and zinc ferrites, which are relatively insoluble in acid, to their readily soluble oxides, with their subsequent dissolution.