Waste from corundum production in the form of porous alumina sludge is a promising material for providing ferrous metallurgy with cheap alumina-containing slag-formers. However, the direct feeding of the pulverized materials to the steelmaking furnace generally results in a significant carryover of such materials with waste gases. This paper considers the possibility of making briquettes from porous sludge of corundum production by cold briquetting using various common binders (molasses, cement, powder based on polyacrylamide, emulsion based on polyvinyl acetate). A comparison of the features of cold briquetting of powdered porous materials (slimes from the production of electrocorundum) and dispersed crystalline materials (fines of chrome ore) was made. Experiments were carried out to determine the impact strength of briquettes on different binder (“cold” strength) and tests to determine the “hot” strength (by the “thermal shock” test method). The authors have determined the consumption of the binder required to obtain satisfactory characteristics of briquettes from corundum slimes and from chrome ore fines. A technique has been developed and a mechanism for the binding of particles of loose and crystalline materials has been determined during briquetting using polyacrylamide powder. The destruction of a briquette of loose materials occurs mainly along the grains of the most porous material, and briquettes of crystalline materials are destroyed along the boundaries of the grains glued with a binder. For porous materials, the binder consumption increases more than twice as compared to briquetting on the same binder crystalline bodies of a fine fraction, and the binder must necessarily impregnate the entire volume of the porous material.

Cold-drawn metal has a number of undeniable advantages over the hot-rolled one. Increased hardness, high surface quality, stability of the diametrical dimension along the length of the workpiece are the basis for choosing calibrated metal as effective workpieces for the manufacture of long parts such as shafts, axles, and rods. In some cases, such workpieces require a small amount of machining, for example, threading or making necks at the ends of a bar. The wider use of the calibrated metal is hindered by residual stresses that are formed during its manufacture. In the first part of this article, it was proposed to use small plastic deformations to control residual stresses. By the example of a new process of surface plastic deformation, which is called orbital burnishing, the working and residual stresses in cylindrical workpieces are determined. In the second part of the article, the process of enveloping surface plastic deformation is considered, which, at high productivity, makes it possible to reduce the residual tensile stresses in the calibrated metal or form the surface layers of the workpiece compressive stress. A technique for the experimental determination of residual stresses in the volume of a body is based on layer-by-layer removal of the inner and outer layers of cylindrical samples. Influence of the main parameters of the enveloping deformation process on the components of the residual stress tensor is established. A range of relative compressions (0.1 – 1.0 %) is revealed, at which residual compressive stresses are formed in the surface layers of the workpiece. It was found that at a relative compression of 0.5 %, the maximum residual compression stresses are created. Enveloping surface deformation has a positive effect on the residual stress state and on colddrawn metal – the residual tensile stresses can be reduced, removed or converted into compressive ones.

The work is devoted to development of a method for accounting residual technological stresses in wheel disks, which will provide both the versatility of the approach and the accuracy of calculations. The analysis of stresses in the wheel disk from the action of assembly (interference between the hub and the axle) and operational loads is carried out on basis of the results of finite element modeling. Verification of adequacy of the used model was made by comparing the calculated information with the experimental data of JSC “VNIIZHT”. The analysis of calculated and experimental values of radial stresses was carried out for the most loaded (critical) zones of the disk during operation – the zones of its interface with the rim and the hub. It was found that by setting the interference fit value to be greater than the actual one, it is possible to obtain the formation of additional stresses in the wheel, which, with a sufficient degree of accuracy, reflect the effect of residual technological stresses on its stress-strain state. On the example of calculating a wheel with a flat-conical disk (GOST 10791 – 2011), it is shown that an increase in the interference fit value by 60 % (from 0.25 mm to 0.4 mm per diameter) makes it possible to adequately predict the magnitude of stresses in the most critical disk elements. The maximum relative deviations of the calculated values of radial stresses from the experimental ones, both along the outer and inner sides of the wheel, do not exceed 14 %. Despite the simplicity of implementation, the proposed method provides an increase in the accuracy of predicting the strength characteristics of wheels, as well as the possibility of using it for various standard wheel sizes.

The purpose of the work was to examine the reasons for formation of non-deformable non-metallic inclusions in rail steel and ways to reduce the rejection of finished rails due to the defects revealed during ultrasonic testing. The study was conducted at the steelmaking plant of JSC “Ural Steel”. In the central laboratory of the combine, a chemical analysis of non-metallic inclusions was carried out in the samples of finished rails produced from blanks manufactured by JSC “Ural Steel” and rejected at the ultrasonic test unit during the rail production at the “Aktobe Rail and Section Works” LLP. Non-metallic inclusions by their composition are represented by aluminium oxides. The most probable reasons for their formation have been determined as following: the use of aluminium containing ferroalloys and interaction of the melt components with refractory materials and casting powder. The authors made analysis of the ferroalloys used in production of rail steel. Industrial trials of the manufacturing process of continuously cast blanks from rail steel were carried out, where FS65 ferrosilicon, which contains aluminium, was replaced with silicon carbide. An increasing degree of silicon and carbon recovery in trial heats was noted. Evaluation of contamination with non-metallic inclusions and mechanical properties of the rail steel manufactured using the experimental technology showed that the service characteristics of the rail steel meet requirements of the state standard GOST R 51685 – 2013. The full-scale experiment has confirmed that the technology of alloying E76F rail steel with silicon carbide at JSC “Ural Steel” is technically feasible. The yield of 100-meter rails was increased by 17 % on a trial batch produced from JSC “Ural Steel” continuously cast blanks.

To predict the conditions for metals reduction from an oxide melt by gas in bubbling processes, a thermodynamic modeling technique has been developed that provides an approximation to real systems. The main difference between the accepted method and the well-known one is in conducting successive calculation cycles with withdrawal of the generated gases and the metal phase from the working medium. This paper presents the results of thermodynamic modeling of nickel and iron reduction processes from B₂O₃ – CaO– Fe₂O₃ – NiO melts by mixtures of CO– CO₂ and H₂ – H₂O containing 0 – 60 % CO₂ (H₂O) in the temperature range of 1273 – 1673 K. The calculations evaluated the content of nickel and iron oxides in the melt and the degree of their reduction. It is shown that, regardless of the gas composition, this process proceeds in several stages. At the first stage, Fe₂O₃ is reduced to Fe₃O₄ and FeO. С_Fe2O3 values decrease to almost zero, while С_Fe3O4 and C_FeO increase simultaneously. By the end of the phase, С_FeO reaches its maximum value. At the second stage, the Fe₃O₄ → FeO transition occurs, when С_Fe3O4 values reach maximum, nickel and iron begin to reduce to metal. At reduction by CO– CO₂ mixture, an increase in temperature reduces the metallization of both nickel and iron. Similarly, an increase in the CO₂ content of the introduced gas affects. During interaction of the oxide melt with a gas containing 60 % CO₂ , the third stage is absent. At reduction by H₂ – H₂O mixture, an increase in temperature reduces the metallization of nickel, but increases metallization of iron. With increasing water vapor content in the introduced gas, the degree of metallization of both nickel and iron decreases. The obtained data are useful for creating technologies for selective reduction of metals and formation of ferronickel of the required composition.

A computer simulation of the chemical process of direct iron reduction in aggregates was performed with the use of MIDREX technology. The analysis of four variants of this technology, which differ in the type of raw material and temperature of the working process, was carried out. It was determined that when the process temperature increased, the required consumption of natural gas decreased, and methane in the waste gas was completely eliminated. It was also noted that at a constant process temperature, the concentrations of all components of the system were linearly dependent on flow rate of the reducing gas. This circumstance allowed us to write a single balance equation for all variants of the studied chemical process.

The report describes a simple theory of thermodynamic properties of nitrogen solutions in liquid Ni– Co alloys. This theory is completely analogous to the theory for liquid nitrogen solutions in alloys of the Fe– Cr system proposed previously by the authors in 2019. The theory is based on lattice model of the Ni– Co solutions. The model assumes FCC lattice. In the sites of this lattice are the atoms of Ni and Co. Nitrogen atoms are located in octahedral interstices. The nitrogen atom interacts only with the metal atoms located in the lattice sites neighbouring to it. This interaction is pairwise. The initial values for the calculation are the Sieverts law constants for nitrogen solubility of in liquid nickel and in liquid cobalt. The result of the calculation is the value of the Wagner interaction coefficient in liquid nickel-based alloys at 1873 K = –1,35. This value is in good agreement with the experimental data (Kowanda and Speidel, 2003).

The constant increase in the consumption of ferrous, non-ferrous, precious and rare metals in the national economy requires an increase in the efficiency of minerals mining and processing. One of the main methods of enrichment used in the technological process of processing various ores is foam flotation. The authors provide a brief description of this process and analysis of various designs of flotation machines. The article is devoted to the modernization of the aeration unit of flotation machines with “RIF” design. It is noted that the design of such machines effectively uses the modular principle of assembly aggregates, which allows you to upgrade individual unit, increasing the efficiency of the machine as a whole. The main part of this unit is an impeller – the most complex and fast – wearing part. The paper analyzes various designs of impellers and their manufacturing technologies. It is noted that in the existing designs of flotation machines, the impellers are made of steel. It is proposed to replace this material with polyurethane, which has become widely used as a structural material due to the emergence of additive technologies in the production of various parts. This material has a relatively low cost and has an increased resistance to wear. The article formulates the main requirements for the most important operations of the technological process of impeller manufacturing. For this purpose, a 3D model of the upgraded impeller design was developed in the SolidWorks 3D computer-aided design system. The authors propose an additive technology for layer-by-layer production of an impeller on a 3D printer using the Ultimaker Cura slicer program. For the manufacture of the proposed design of the impeller made of polyurethane, the production technology was developed by the method of layer-by-layer deposition method of Fused Deposition Modeling (FDM).

The article provides a method of mathematical modeling to improve temperature operating modes of heating furnaces for hot strip mills. The object of the research is the thermal operation of a continuous walking beam furnace for heating slabs before rolling. The subject of the research is statistical modeling of metal heating in furnaces of this type. The creation of a statistical model consists of factors selection, construction of regression model, correlation analysis and assessment of the variables significance, adjustment of factors and obtaining regression equations. The main part of the research refers to a statistical model based on a comprehensive analysis. This model is based on the results of 15 automated industrial experiments on Russian heating furnaces of hot strip mills and describes the heating process in walking-beam furnace with acceptable accuracy. The adaptation of the statistical model and error calculation has been carried out. The article contains graphs comparing real temperatures and temperatures calculated on the basis of mathematical and statistical models for one of the experiments. The main conclusions are formulated based on the results of the research done. For the first time in metallurgical practice, a statistical model has been developed that describes the process of metal heating in a five-zone continuous furnace with eight heating subzones. Since the regression function is defined, interpreted and justified, and the assessment of the accuracy of the regression analysis meets the requirements, it can be assumed that the model and predicted values have sufficient reliability.

Two-coordinate welding machine is used to obtain welds on various elements of high quality metal structures. The main disadvantage of the existing equipment is that the work on this machine is currently performed manually. This operation is quite dangerous and monotonous. In addition, hydraulic drive is used as the main drive of the system. Replacement of the hydraulic drive of a two-coordinate welding machine with an electric drive is substantiated in order to increase the efficiency of the entire system. The authors have developed an automated system for a two-coordinate machine for welding embeds, controlled on the basis of a programmable logic controller. A functional diagram of an automated electric drive for such machine was proposed. The design of the object’s electric drive was carried out. The necessary elements of the developed automation system were selected. On the basis of the technological process, an algorithm has been developed that allows automating the process of embeds welding. The developed algorithm provides the necessary security measures, carrying out self-diagnostics at the stage of system startup. In order to check the performance of the developed algorithm, an automated electric drive was simulated using the MATLAB Simulink software. The developed system contains two internal and three external circuits that control the required parameters: speed, current, torque, flux linkage and force. The dynamic characteristics of the presented parameters are obtained, confirming the operability of the developed automated electric drive system. An economic calculation of the automation system proposed for implementation has been carried out. The total costs for the modernization will amount about 55 thousand rubles with a payback period of about one year.