The use of natural gas can reduce the amount of coke needed to produce cast iron. In a common tuyere natural gas is pressed against the surface of the air passage by a stream of hot blow and mixes poorly with it. It leads to incomplete burning of natural gas and its pyrolysis. One way to improve the mixing of natural gas and hot blow is to install the swirler in the air passage. In this case, however, intensification of natural gas burning inside the tuyere can lead to a burnout of the inner cylinder. In Ansys Fluent 18.2, using insulation insert with a swirler made in the form of a collar step at different places along the length of the insert, simulation of gas dynamics and its thermal state is carried out to solve the problem of mixing natural gas and hot blow in the air passage of tuyere. Simpler assumptions were adopted. Among which the simulation area included not only the fluid medium inside the air passage, but also the insulation insert, i.e. the associated problem of heat exchange was solved, and the processes of transfer of heat to water of the cooling system are taken into account in extended boundary conditions. The simplified calculation area scheme was created in the DesignModeler application, and the calculated grid was created in the AnsysMeshing application. The boundary conditions were set for blow (natural gas), as well as for the border of the insert with an air gap separating it from the internal cylinder and the fluid with the tuyere nose. Taking into account the symmetry of the computation region, the calculations were made for the half of tuyere. It has been found that mixing of natural gas and hot blow improves as the swirler moves along the length of the insert to the exit from the air passage. At the same time, in the swirler place the diameter of air passage is not less than downstream of the tuyere. The swirler`s shift toward the exit from air passage reduces the thermal load on the insert, thereby increasing its service life.

Development of advanced materials for the automotive industry allows us to produce a lighter body without losing strength characteristics of the structure. It became possible by the creation and subsequent introduction into the production of such steel grades as IF (Interstitial Free) – steel with no interstitial solute atoms to strain the solid iron lattice and IF-BH (Bake Hardening) – steel with hardening during hot drying. The article provides a brief overview of the history of the emergence of IF steel and the current situation in the production of it in Russia. One of the quality criteria for steels of IF grades is purity of the metal by non-metallic inclusions (NMI), which negatively affect the plastic properties of the material, lead to the formation of surface defects of flat rolled products and reduce the manufacturability due to a decrease in the casting speed of steel, as they cause overgrowing of steel casting nozzles. The article presents investigation results of the content, composition, size and morphology of non-metallic inclusions (NMI) in the metal samples taken at all stages of ladle treatment and casting of IF steel grade production using quantitative metallographic analysis, electrochemical dissolution (ED) followed by X-ray microanalysis of isolated inclusions, Auger electron spectroscopy and fractional gas analysis (FGA). As a result of the analysis of inclusions in the studied samples using a scanning electron microscope, according to morphological features, five characteristic types of inclusions were identified, which reduce the performance properties and strength cha racteristics of the materials produced from them. Results of the analysis of nonmetallic inclusions in metal samples obtained by the ED method are in good agreement with the results of the determination of oxide nonmetallic inclusions by the FGA method. The method of fractional gas analysis shows the dynamics of changes in the content of various types of oxide nonmetallic inclusions during the secondary (ladle) treatment of steel. It is shown that application of the FGA method allows to make analysis of causes of the harmful NMI formation in the metal and to correct operations at ladle treatment.

The authors have analyzed the existing approaches to solve a problem of determining the moment of slag outcome beginning during steel casting from a ladle to a tundish. The solution of this problem is considered in two aspects: the first is the choice of best way to generate a diagnostic signal from the position of the price/quality ratio of its handling, and the second is the development of a method to process this signal in order to obtain useful information. A scheme is proposed to receive a signal of vibration acceleration from a sensor installed on a manipulator of the ladle protective tube. A product sample is developed to arrange that. It provides protection from the influence of industrial disturbances on the sensor. In order to analyze the vibration acceleration signal, the criteria to determine the moment of the slag outcome beginning were determined based on entropy energy calculation. This method and a system developed on its basis are tested under industrial conditions for a real object. The only condition for effective operation of the developed criteria is selection of the subsystem of steel level maintenance at final casting step to the manual mode to eliminate the disturbances from the movement of the slide shutter used to control the flow of liquid steel. According to the results of experiments under real conditions, it was found that the slide shutter control shutdown is to be performed if weight of the ladle content is from 18 to 19 tons approximately. In this mode of operation, the operator has always been able to found such a rate of steel discharge that the level of steel in the tundish is within the technological requirements. As a result, it is possible to ensure the proposed algorithm triggering for each casting earlier than the operator stops the process manually. At the same time, the amount of steel with slag left in ladle does not exceed 3.8 tons comparing to the moment of the slag cut-off made by the operator.

Expensive nickel superalloys are used for manufacture of cast blades of gas turbine engine (GTE). However, for the blades only a small amount of alloy was used and the remainder is used for gating system. Therefore, the most proportion of alloy after casting is a scrap, the use of which as raw material for blades production significantly reduces their cost. However, the use of scrap is associated with some risks: the possibility of alloy contamination by nonmetallic inclusions and loss of alloying elements. So, the investigation of a scrap usage effect on the blades properties is very important. In the first part of article the influence of the scrap amount on the microstructure and phase composition of the ZhS6U-VI nickel-base superalloy were examined. The GTE blades samples, fully produced from the scrap of ZhS6U-VI superalloy by investment casting were investigated. The scrap before using was cleaned from contaminations and ceramic mold remains. Samples were cut from blade dowetail and gating system near dowetail. In addition, cylindrical samples that were casted into the copper mold from the virgin alloy ZhS6U-VI without the scrap and from alloys with 50 % and 100 % of scrap were researched. The alloys microstructures were investigated using scanning electron microscopy and optical microscopy. The phase’s identification was carried out using the energy-dispersive X-ray spectroscopy (EDS) and the calculations of phase composition were made by Thermo-Calc software and literature data about phases in nickel-based superalloys. Content of alloying elements (except carbon) was measured by EDS analysis. The studies were carried out on the samples as-casted and annealed for 4 hours at 1210 °C. It is shown that the use of scrap does not fundamentally change the alloy phase composition at both during vacuum induction melting and vacuum arc melting.

Alloying of corrosion-resistant austenitic steels with nitrogen is widely used in production to stabilize austenite and to improve the strength and other properties of the metal. The possibility of alloying titanium-containing steels with nitrogen by introducing nitrogen into the melt is not possible, as it causes formation of the coarse defects in steel during casting and solidification of the metal (twisting of the peel, large nitride inclusions, accumulations of nitrides, etc.). The method of high-temperature gas nitriding can be alternative to liquid-phase nitriding for alloying austenitic titanium-containing chromium-nickel steels with nitrogen in order to increase their strength properties. In this work, we investigated the possibility of increasing the strength characteristics of thin-sheet austenitic corrosion-resistant Cr – Ni – Ti (Kh18N12T type) steel, containing 1.5 % and 3 % of titanium, through the use of solid-phase high-temperature nitriding. The nitriding was carried out at a temperature of 1000 – 1100 °С in an atmosphere of pure nitrogen for 5 or 8 hours. The average mass fraction of nitrogen in the samples after nitriding for 5 hours was 0.6 % and 0.7 % for the steels with 1.5 and 3 % of titanium, respectively, and after nitriding for 8 hours – 0.8 % and 0.9 %. It was shown that high-temperature nitriding followed by annealing provides a significant (by 2 – 3 times) increase in the metal strength characteristics compared with the state before nitriding, but reduces the ductility. Ductility of the steel is restored during final processing. For Kh18N12Т type steel with 1.5 % of titanium, an increase in the yield strength is obtained – by 3.3 times (from 180 to 600 MPa), strength – by 1.8 times (from 540 to 970 MPa), with a relative elongation of 28 %. An additional increase in strength properties was not found for the steel with 3 % titanium. The obtained results show the possibility of obtaining thin-sheet titanium-containing high-nitrogen steel (or products from it, for example, thin-walled pipes) by applying solid-phase high-temperature nitriding.

Nowadays we can see increase in using of engineering analysis systems in the field of continuous steel casting simulation due to their high accuracy and convergence with industrial experiments results. Such powerful systems as «ANSYS» and «ProCast» allows solving gas-, hydrodynamic and thermal problems, the parallel interaction of which constitutes the essence of most metallurgical processes. Group of authors from the LSTU Chair “Metallurgical technology” have successfully carried out computer experiments in tundish and continuous casting mold processes simulation. The experiments were aimed at first, on studying of further improving in liquid steel flow modifiers (partitions, turbo-stops, thresholds) design, at second, on influence of argon blowing regime on liquid steel flow parameters in the 50-ton tundish workspace, and, at third, on influence of submerged nozzles design on the liquid steel flow in crystallizer, assuming deterministic-dynamic operation mode. The results of calculations are velocity fields of liquid steel flow and flow temperatures fields in tundish and crystallizer, as well as temperature fields in the tundish refractory lining. An equation of primary flow average velocity change on exit from submerged nozzle was also formulated. These preliminary results allow us to assess the velocity changes and direction of the melt flow and formation of volumes with different melt temperatures when using flow modifiers in the ladle, including using of “argon curtain” in the casting chamber. Obtained data on melt flow motion and on location of erosion spots in crystallizing «crust», also on the presence of temperature gradient zones in various regions of crystallizer workspace may be useful to practice engineers engaged in choice of crystallizer submerged nozzle design. Effective control of melt flow in tundish and in crystallizer allows significant improvements in continuous cast slabs and rolled products quality in context of reducing metal products rejection due to defects associated with slag or nonmetallic inclusions presence and due to cracks formed as the result of insufficient thickness of crystallized «crust».

Metallurgical fuel, including various types of mineral fuels: coke, hard coal, brown coal, peat, combustible shales and products of their technological conversion – needs environmental control of their use safety. When burning metallurgical fuel, harmful substances fall into the environment such as chlorine, fluorine, sulfur, arsenic, which worsen the environmental situation. Technical regulations on the safety of coal products contain requirements to limit the content of harmful impurities and their maximum permissible concentrations. Due to the wide spread of fluorine in natural and technological objects and the high toxicity of its compounds, the control of fluorine content is an urgent problem in the industrial use of metallurgical fuel. Physical methods for the determination of fluorine in solid fuel based on excitation of different spectra of the studies allow to identify it without decomposition directly in the source solid material, however, they have several limitations (sensitivity, accuracy of definition, complexity of hardware design). In other methods, mainly in ionchromatography and ionometry, samples are decomposed and fluorine is transferred into the solution. High temperature processes: pyrohydrolysis and combustion melting are usually used for decomposition. The aim of this work was to create a selective method for ionometric determination of fluorine with a fluoride-selective electrode. The study objects were samples of coal: brown, gas, semicoke, coke nut. Effective decomposition of the samples by two-stage high-temperature melting with KNaCO₃ is proposed. Hydrolysis coprecipitation of accompanying interfering cations with chloride iron (II) was carried out for fluorine discharge in the solution in the form of free fluoride. The procedure of decomposition and ionometric determination of fluorine is described. The estimation of trueness and reproducibility of the developed technique by the method of sample variation was carried out. Fluorine content in the studied samples did not exceed the limit- tolerance values for commercial samples of coal products, which indicates the environmental safety of the samples in their subsequent energy application. The developed method is promising for the control of fluorine impurity in metallurgical fuel and is characterized by selectivity and simple carrying out.

A simple theory of thermodynamic properties of liquid nitrogen solutions in Fe – Cr alloys is proposed based on lattice model of the considered solutions. The model assumes a FCC lattice. In the sites of this lattice are the atoms of Fe and Cr. Nitrogen atoms are located in octahedral interstices. The nitrogen atom interacts only with the metal atoms located in the lattice sites neighboring to it. It is assumed that the energy of this interaction depends neither on the composition nor on the temperature. It is supposed that the solution in the Fe – Cr system is perfect. Within the framework of the proposed theory, a relation is obtained that expresses the value of the Sieverts law constant for solubility of N in liquid Cr through the similar constant for the solubility of N in liquid Fe and the Wagner N – Cr interaction coefficient in liquid Fe. A relation is also obtained to express the partial enthalpy of nitrogen dissolution in liquid Cr through the similar quantity for N in liquid Fe and Wagner N – Cr interaction coefficient in liquid Fe. A formula is deduced that establishes a connection between the Wagner N – Fe interaction coefficient in liquid Cr and N-Cr interaction coefficient in liquid Fe. Using the formulas obtained, value of the Sieverts law constant for the solubility of nitrogen in liquid Cr, the enthalpy of dissolution of N in liquid Cr and value of the Wagner N – Fe interaction coefficient in liquid Cr extrapolated to a temperature of 1873 K are calculated. The calculation results are compared with results of the experimental study of nitrogen solubility in liquid Cr carried out by different researchers using different methods. The theory results are in the best agreement with experimental data obtained by the sampling method. Values of the Wagner N – N interaction coefficient in liquid Cr and liquid Fe are discussed.

Thermodynamic analysis was performed for complete reduction of iron oxide during heating the initial system «Fe₃O₄ (e_o mol) – H₂O (b_o mol) – C (excess) » with isothermal exposure. By the nature of ongoing reactions, processes in the system can be divided into four stages. Carbon gasification by water vapor at temperatures below 880 K activates water gas reaction and CO dissociation to form black carbon. Composition of the resulting H₂ – H₂O – CO – CO₂ gas mixture depends only on the temperature. The consumption of carbon at 880 K is ~0,4446 moles on 1 mole of water. Reduction of Fe₃O₄ to wustite FeO_1+x with varying degrees of oxidation occurs in the temperature range 880 – 917 K. Hydrogen reduces oxide at temperatures above 888 K. The percentage part of a whole oxide Fe₃O₄ reduced by hydrogen into this temperature range increases from zero to ~63 %. The total number of Fe₃O₄, reduced to wustite at 917 K is ~123 moles for 1 mole of water. It is possible only with repeated regeneration of reductants CO and H₂ according to the reactions of carbon gasification by water vapor and by dioxide CO₂. The carbon expense is about 78 moles. Wustite FeO_1.092 formed at 917 K can be reduced by monoxide CO only at temperatures of 917 – 955 K to wustite FeO_1.054 with a lower degree of oxidation. Carbon is gasified only by dioxide CO₂, the carbon expense is approximately 18 moles. When isothermal exposure is ~955 K, wustite is reduced to iron. Wustite can be reduced only by carbon monoxide. The carbon expense is approximately 257 mol. For full reduction of 123 mol of Fe₃O₄ in a mixture with an excess of carbon in a closed system at 1 atm, 1 mole of water is sufficient. The total carbon consumption is ~353 moles for obtaining 368 moles of Fe, or ~0.21 kg/kg iron.

A simple theory of thermodynamic properties of liquid nitrogen solutions in Fe-Cr alloys is proposed. The theory based on the lattice model of the considered solutions. The model assumes a FCC lattice. In the lattice sites of this lattice are the atoms of Fe and Cr. Nitrogen atoms are located in octahedral interstices. The nitrogen atom interacts only with the metal atoms located in the lattice sites neighboring to this atom. It is assumed that the energy of this interaction depends neither on the composition nor on the temperature. It issupposed that the solution in the Fe-Cr system is perfect.  Within the framework of the proposed theory a relationship is obtained that expresses the value of the Sieverts law constant for the solubility of N in liquid Cr through the similar constant for the solubility of N in liquid Fe and the Wagner N-Cr interaction coefficient in liquid Fe. A relationship is also obtained  which expresses the partial enthalpy of nitrogen dissolution in liquid Cr through the similar quantity for N in liquid Fe and Wagner N-Cr interaction coefficient in liquid Fe.A formula deduced that establishes a connection between the Wagner N-Fe interaction coefficient in liquid Cr and N-Cr interaction coefficient in liquid Fe. Using the formulas obtained the value of the Sieverts law constant for the solubility of  nitrogen  in liquid Cr, the enthalpy of dissolution of N in liquid Cr and the value of the Wagner N-Fe interaction coefficient in liquid Cr extrapolated to a temperature of 1873 K are calculated. The results of the calculation are compared with the results of the experimental study of the solubility of nitrogen in liquid Cr carried out by different researchers using different methods. The result of the theory are in the best agreement with experimental data obtained by the sampling method (F. Ishii, Ya. Iguchi, Sh. Ban-ya, 1986).The values of the Wagner N-N interaction coefficient in liquid Cr and liquid Fe are discussed.

To date, we can see increase in using of engineering analysis systems in the field of continuous steel casting simulation due to their high accuracy and convergence with industrial experiments results.Such powerful systems as "ANSYS" and "ProCast" allows hydrodynamic and thermal problems solving, the parallel interaction of which constitutes the essence of most metallurgical processes.Group of authors from the LSTU`s Department of metallurgical technologies successfully carried out numbers of computer experiments in intermediate ladle and continuous casting mold processes simulation. This work provided with Russian Foundation for Basic Research financial support, within the framework of the scientific project No. 17-48-480203r_a.Experiments are aimed at first, at studying of further improving in liquid steel flow modifiers (partitions, turbo-stops, thresholds) design, at second, on influence of argon blowdown regime on liquid steel flow parameters in the 50-ton intermediate ladle workspace, and, at third, on influence of submerged nozzles design on the liquid steel flow in crystallizer, assuming deterministic-dynamic operation mode.The result of calculations is: liquid steel flow velocity fields and flow temperatures fields in intermediate ladle and crystallizer, as well as temperature fields in the refractory lining of intermediate ladle . Dependence of primary flow average velocity change on exit from submerged nozzle is formulated.These preliminary results allow us to assess the velocity changes and direction of the melt flow and formation of volumes with different melt temperatures when using flow modifiers in the ladle, including using of "argon curtain" in the casting chamber.Obtained data on melt flow motion and on location of erosion spots in crystallizing «crust», also on the presence of temperature gradient zones in various regions of crystallizer workspace may be useful to practice engineers engaged in choice of crystallizer submerged nozzle design.Effective control of intermediate ladle and crystallizer melt flow allows significant improvements in continuous cast slabs and rolled products quality in context of reducing metal products rejection due to defects associated with slag or nonmetallic inclusions presence and due to cracks formed as the result of insufficient thickness of crystallized «crust»

Abstract: The research is devoted to the development of adaptive   automatic control system of filtration process. processing capacity, quality and cost of the output product of the process depend on the course of this process. Equipments efficiency, quality and cost price of the output product of the process depend on the course of this process.

Currently, disk vacuum filters are used to filter iron ore concentrate. These filters are in most cases  operated by personnel  manually based on the results of laboratory analyses conducted with low frequency and high delay. At the same time, to avoid exceeding the maximum permissible moisture content of sediment, the operator supports it with a certain margin, deliberately reducing the average value of discs rotational frequency. This leads to a decrease vacuum filter efficiency. As a result, taking into account the high costs at energy resources used in the filtration process, the cost price of the concentrate increases and its quality decreases.

The main objective of this study is to increase the disk vacuum filters efficiency. Herewith, the output product moisture must be maintained at the level required by the technology. At the same time, the increase of efficiency should lead to a decrease of specific energy consumption for the filtration process, and the stabilization of moisture should lead to an increase of dehydrated concentrate quality (stability of characteristics).

The ultimate goal of the current research is the development adaptive system control of iron ore concentrate filtration process based on a multiparameter extrem-fuzzy controller. During the study, it was found that  at inputs of this regulator should be fed the total specific resistance of sediment and the filter cloth (integral index determined by concentrate granulometric composition and degree of filter cloth contamination) as well as the degree of approximation to extremum (maximum) of filter efficiency.

It was found that the first input parameter of regulator can be indirectly estimated on the rate module average value of valve position change installed on the vacuum pipe. The average value of this parameter is calculated during of transition process after changing task in control loops of supply pulp density of filter or vacuum in sediment set zone. The second input parameter of the regulator can be indirectly estimated by the difference of present specific efficiency and specific efficiency at the previous step of the extreme regulator work.

paper is to analyze the existing approaches to solve a problem of determining the moment of beginning of slag outcome during steel teeming from a ladle to a tundish. The solution of this problem is considered in two aspects: the first is the choice of the best way to generate a diagnostic signal from the position of the price/quality ratio of its handling, and the second is the development of a method to process this signal in order to obtain useful information. Having made an analytical analysis, in this research a scheme is proposed to receive a signal of vibration acceleration from a sensor installed on a manipulator of a protective tube of a ladle with steel. A sample of a product is developed to arrange that. It provides protection from the influence of industrial disturbances on the sensor. In order to analyze the vibration acceleration signal, the criteria to determine the moment of the beginning of the slag outcome based on entropy energy calculation are developed. This method and a system developed on its basis are tested under industrial conditions for a real object. The only condition for the effective operation of the developed criteria is that from a certain moment the level of steel in the tundish is to be maintained in manual mode to eliminate the disturbances from the movement of the slide shutter used to control the flow of liquid steel. According to the results of experiments under real conditions, it is found that the slide shutter control shutdown is to be performed if the weight of the content of the ladle with steel is from 18 to 19 tons approximately. In this mode of operation, the operator has always been able to found such a rate of steel discharge that the level of steel in the tundish is within the technological requirements. As a result, it is possible to ensure the proposed algorithm triggering for each casting earlier than the operator stops the process manually. At the same time, the amount of steel with slag left in ladle do not exceed 3.8 tons comparing to the moment of the slag cut-off made by the operator.

The present work analyzes the existing mechanism of solid-phase metals reduction from oxides. It was shown that the existed mechanisms of reduction do not explain the diversity of the practical results leading to a generally accepted opinion that there is no single uniform reduction mechanism. This study presents the results of the solid-phase reduction of metals from lump magnetite, siderite, titanomagnetite and chromite types of ore by carbon from various deposits. The obtained results were compared with the results of reduction of chromium, silicon and aluminum by carbon from pure oxides. Change in the electrical characteristics and analysis of the processes of electron- and mass transfer under reducing conditions were performed to clarify the general theoretical concepts of reduction mechanism. It has been concluded that there is general process of transformation of the crystal lattice of oxide into the crystal lattice of metal for reduction of different metals. The positions of electron theory for solid-phase reduction of metals from crystal lattice of oxides were developed using the basic concepts of chemistry, solid state physics about imperfect crystals, quantum mechanics and character of electron distribution and transfer in metals and ionic semiconductors. The theory embraces all the known results of reduction with formation of metal on the surface of high-grade lump ore, nucleation of metal inside of the complex and low-grade types of ore and formation and sublimation of suboxides. Major ideas of the developing theory of electron reduction have been formulated on the basis of metals reduction as a result of the exchange of electrons between the reducing agent and metal cations in oxides by means of the charged anion vacancies formed on the surface and their scattering in the volume. The transformation of the cations’ ionic bond in oxides into metallic bond of the metal phase on the surface (or inside of the oxide lattice) occurs without the displacement of the cations over significant distances and thermodynamic difficulties for the formation of metallic nucleus when the charged anion vacancies merge (skipping the stage of formation of the atoms of metal). There might be no direct contact between the metal and the reducing agent in case of formation of the metal phase inside of the oxide volume. As a result, harmful impurities from the reducing agent, e.g. carbon and sulphur, do not penetrate into iron during reduction of complex and low-grade types of ore. Therefore, for the reduction of iron from such an ore, it is possible to utilize a low-quality reducing agent, e.g. steam coal. The selective solid-phase reduction of iron from lump complex ore makes it possible to obtain a metal-oxide composite material containing pure DRI and valuable oxides which are difficult for reduction, i.e. oxides of magnesium, titanium and vanadium.