When steel is smelted in electric arc furnaces, and during its subsequent treatment in ladle-furnace units, a significant amount of power is required. This power is supplied through the use of graphitized electrodes, which are pivotal for achieving the required temperatures. However, these electrodes are costly, significantly affecting the overall production costs. Therefore, efforts to reduce the cost of steel by minimizing the consumption of graphitized electrodes are crucial for metallurgists. The primary factor influencing the consumption rate of these electrodes is their surface oxidation by oxygen present in the furnace atmosphere. Recent studies have shown that a magnesium hydroxide-based coating can significantly mitigate this issue. When applied to the surface of graphitized electrodes, this coating was shown to reduce their weight loss by 30–40

Russia has an impressive titanium mineral resource while the contribution into the global production of titanium concentrates is quite insignificant. The current annual demand of Russian enterprises for titanium raw materials is 40 times higher than its production. To improve and launch the processing of domestic titanium raw materials characterized by low quality and complex polymineral composition, new process solutions are required. These solutions should aim at the full extraction of TiO2 and related valuable components from the ore deposits whose development is planned or already started (for example, Afrikanda – perovskite-titanomagnetite deposit located on the Kola Peninsula). This report presents the results of studying the chemical and mineral compositions of perovskite and ilmenite concentrates with the purpose to assess the possibility of their joint processing using carbothermic reduction melting. Emission spectrometry, X-ray diffraction, electron microscopy, and X-ray spectral microanalysis were applied in these studies. It was found that the basis of the ilmenite gravity concentrate sample is modified ilmenite represented by leucoxenization products – pseudorutile and rutile, with their total content in the concentrate to be about 80 wt. %. Composition of other minerals (alumochromite, chromite, magnetite) includes titanium in the form of impurities – 2 – 3 wt. %. In the perovskite flotation concentrate sample titanium is contained in perovskite and titanite making up the bulk of the ore minerals of the concentrate. As for rare and rare-earth elements contained in the ilmenite sample – monazite having up to 33 wt. % Ce, and zircon were found. Perovskite sample contains rare-earth elements (REE concentration in wt. %) in loparite-(Ce) (22.8), aluminocerite-(Ce) (46.2), anсylite-(Ce) (51.3), torite (22.3), as well as in the main mineral – perovskite (2.8). With the exception of perovskite and loparite-(Ce), other REE-containing minerals are rare, and their share in total does not exceed 1 wt. %

При выплавке стали в дуговых электропечах и ее внепечной обработке в агрегатах ковш-печь подвод электроэнергии для создания необходимой температуры осуществляется с помощью графитированных электродов, стоимость которых достаточно высока и оказывает заметное влияние на себестоимость продукта. Поэтому работа, направленная на снижение себестоимости стали путем снижения расхода графитированных электродов, для металлургов является актуальной. Расход графитированных электродов в значительной степени зависит от окисления их поверхности кислородом атмосферы печи. Результаты испытания показали, что покрытие на основе Mg(OН)2, нанесенное на поверхность образцов из графитированных электродов при температурах испытания в окислительной атмосфере, снижает на 30–40% убыль их массы. Защитные свойства испытуемого покрытия объясняются тем, что при попадании на поверхность графитированного электрода материал покрытия глубоко проникает в поры, закупоривает их и обволакивает поверхность. Под воздействием температуры вода испаряется, а покрытие, имеющее высокую адгезию, остается на поверхности. При температуре 350 °С Mg(OН)2 разлагается с образованием MgO с температурой плавления 2850 °С. Высокая плотность покрытия препятствует проникновению кислорода атмосферы к графиту электрода и снижает скорость его окисления. When steel is smelted in electric arc furnaces and its out-of-furnace treatment in ladle-furnace units, power supply to create the required temperature is carried out by graphite electrodes, the cost of which is quite high and has a noticeable impact on the cost of production. Therefore, work aimed at reducing cost of steel by reducing the consumption of graphite electrodes is relevant for metallurgists. Consumption of graphitized electrodes depends to a large extent on oxidation of their surface by oxygen in the furnace atmosphere. The test results showed that the magnesium hydroxide-based coating applied to the graphite electrode surface reduced the weight loss by 30–40% at the test temperature in an oxidising atmosphere. With increasing temperature, the effect of mass loss increases. The protective properties of the tested coating are explained by the fact that it penetrates deep into the pores and envelopes the graphite electrode surface. Under the influence of temperature the water evaporates and the coating, which has high adhesion, remains on the surface. At 350 °C Mg(OH)2 decomposes to form MgO with a melting point of 2850 °C. The high coating density prevents atmospheric oxygen from penetrating the graphite electrode and reduces the oxidation rate.

To assess the possibility of joint processing of ilmenite (FeTiO3) and perovskite (CaTiO3) concentrates using a duplex process involving solid-phase reduction of iron (metallization) and subsequent separating melting into pig iron and titanium slag, the properties of slag melts were studied. The crystallization beginning point (liquidus temperature) and the corresponding viscosity of titanium slag depend on its chemical composition. The increase in titanium oxides content results in increase of these properties, while the presence of iron and calcium oxides leads to their decrease. During the joint processing of ilmenite (IC) and perovskite (PC) concentrates, the CaO content in the slag can be adjusted by changing their PC/IC ratio, and the FeO fraction is determined by the degree of iron metallization during the preliminary reduction roasting of a concentrate mixture with a carbon reducing agent. To select the optimal PC/IC ratio the temperature dependences of the viscosity of model oxide melts of the TiO2–FeO–CaO–Al2O3–MgO system, similar in composition to the slags formed as a result of melting mixtures of perovskite and ilmenite concentrates within the range of PC/IC ratios equaling to 0.6÷1.4, and the metallization degree from 75 to 95% were determined. According to the results obtained, within the entire range of studied compositions and temperatures, the viscosity of slag melts does not exceed 0.8 Pa·s. That is to say, such slags will be sufficiently fluid at the tapping point if the melt temperature is higher than liquidus temperature — the crystallization beginning point. Increasing the PC/IC ratios when decreasing the metallization from 95 to 75%, results in a monotonous decrease in liquidus temperature and its corresponding viscosity from 1490 оC and 0.79 Pa·s up to 1270 оC and 0.17 Pa·s, respectively. It is recommended to use a charge containing equal mass fractions of concentrates (PC/IC equal to 1) at the consumption of carbon reducing agent based on metallization of 85% iron. In this case, slags with a relatively low iron oxide content (3.1%) will be fluid (0.38 Pa·s), and have liquidus temperature of 1400 оC which will allow carrying out top and bottom melt at operating temperatures of 1500–1550 оC.

Технологический процесс выплавки стали в АО «АрселорМиттал Темиртау состоит из трех этапов: выплавка полупродукта в конвертере, внепечная обработка на установке ковш-печь и получения сляба на машине непрерывной разливки заготовки. По существующей технологии создание нужной жидкоподвижности рафинирующего шлака на установке ковш-печь осуществляется присадками в качестве разжижителя плавикового шпата. При применении плавикового шпата токсичные выделения фтора создают на рабочей площадке напряженную экологическую обстановку. Присутствие фтористых соединений в шлаке отрицательно влияет на стойкость футеровки ковша. Использование твердых шлаковых смесей на основе оксида алюминия на установке ковш-печь позволяет, не меняя технологического процесса и расхода шлакообразующих (извести), устранить: выделения фтора в атмосферу цеха, отрицательное влияние на стойкость шлакового пояса футеровки ковша, снизить себестоимость стали из-за отказа от применения плавикового шпата и снижения расхода алюминия, используемого для раскисления шлака. The technological process of steel smelting at ArcelorMittal Temirtau JSC consists of three stages: intermediate melting in a converter, outoffurnace treatment at a ladle-furnace unit and slab production at a continuous casting plant. According to the existing technology, the creation of the necessary fluidity of the refining slag at the ladle-furnace unit is carried out by adding fluorspar as a diluent. When fluorspar is used, toxic fluoride emissions create a stressful environment in the workplace. The presence of fluoride compounds in the slag adversely affects the durability of the ladle lining. The use of solid slag mixtures based on alumina on the ladle-furnace unit makes it possible, without changing the technological process and the consumption of slag-forming (lime), to exclude: fluorine emission into the atmosphere of the shop, negative influence on the durability of the ladle lining slag belt, reducing the cost of steel due to the abandonment of fluorspar and reducing the consumption of aluminum used for slag deoxidation.

The Bakal siderites belong to poor, hard-to-enrich carbonate iron ores. The low content of phosphorus and non-ferrous metals makes siderites a valuable raw material for obtaining highly metallized concentrate suitable for use in steelmaking processes. Reduction of siderites in a rotating furnace at 1300 – 1350 °C followed by magnetic separation of waste rock allows to obtain a concentrate with metallization degree over 90 % and a content of waste rock of about 5 % suitable for steelmaking as raw materials. The purpose of this work is to evaluate the efficiency of the process aimed at obtaining metal from siderite ore including obtaining of highly metallized siderite concentrate in a recovery furnace, as well as its hot loading into ore-thermal furnace and melting process itself. To do this, the electric melting was calculated in the electric ore melting furnace providing for determination of a large number of parameters including the electricity consumption required for melting. As raw materials we used a highly metallized siderite concentrate (φ met = 92.3 %) containing 35 % of waste rock and, for comparison, a briquetted metallized siderite concentrate obtained from a lump concentrate in which a significant amount of waste rock was removed by wet magnetic separation. The results analysis shows that increase in concentrate temperatures from 25 to 1000 °C decreases specific energy consumption and at the same time increases the furnace productivity to values comparable to the parameters of melting briquetted concentrate. This confirms the efficiency of the developed process. To reduce the melting point of high-magnesium slag, it is proposed to use colemanite as flux.

Abstract—The fuming of copper smelting slag in a Vanyukov furnace by the products of methane conversion by oxygen, water vapor, and carbon dioxide in the temperature range 1473–1773 K is thermodynamically modeled. For this purpose, a technique is developed to describe the changes in the phase compositions in the systems under study during their bubbling as functions of the amount of an introduced reducing gas; this technique is characterized by cyclic calculations and the removal of the formed gases and metal phase from the working medium composition. The calculation results demonstrate that the interaction of the gas with melt oxides proceeds in two stages regardless of the melt composition. At the first stage, Fe3O4 is reduced to FeO and ZnO, to Zn. Therefore, the content of Fe3O4 and ZnO in the melt decreases and that of FeO increases. At the second stage, metallic iron appears and the content of iron and zinc oxides decreases. A significant influence of temperature on fuming is shown. When the temperature increases from 1473 to 1773 K, the fuming process is significantly intensified, which is accompanied by a fourfold decrease in the amount of the reducing gas required to achieve close degrees of zinc recovery. The gas composition weakly affects the process. The most effective reducing agent is shown to be the gas formed by the steam conversion of methane, which is due to the minimal costs of its production. The results obtained make it possible to predict the indicators of the process of fuming by methane conversion products and will be useful for creating new technologies.

The Bakal deposit located in the Southern Urals near the city of Bakal, Chelyabinsk region, is one of the largest deposits of carbonate iron ores (siderites). The total deposit of siderites is about 1 billion tons. They are not in demand among metallurgists because of their low iron content and high magnesium content. At the same time, the Urals metallurgical enterprises are suffering from shortage of iron ore raw materials including steelmaking ore raw materials. The high purity of siderites in terms of phosphorus and non-ferrous metals makes it possible to use methods of coke-free metallurgy for their processing. Pyrometallurgical processing of siderites including their reduction roasting in a rotary furnace followed by grinding and magnetic separation allows obtaining a concentrate to be used as a steelmaking raw material having metallization degree above 90 % and a waste rock content under 3 – 7 %. Calculations showed that the costs of electricity used for melting scrap metal and metallized siderite concentrate containing 30 % of waste rock and loaded into the furnace at temperatures above 1000 °C are close. We propose a siderite processing method including reduction of the initial ore in a rotary furnace, and melting of resulting metallized concentrate hot loaded (at temperatures above 1000 °C) into a furnace. The empty rock of metallized siderite concentrate contains a large percentage of magnesium oxide that makes it refractory. To obtain liquid slag, it is proposed to add boric anhydride in the form of colemanite. To assess the B2O3 effect on melting of the metallized siderite oxide phase in the process of electric melting, studies on the viscosity correlation of the magnesian steelmaking slag containing B2O3 with temperature and its composition were carried out. It was found that at the discharge temperature (1600 °C) the resulting magnesia slag with the ratio of MgO/SiO2 in the initial siderite equaling to 0.75 – 1.25 has a low viscosity (less than 3.65 P).

Metallurgical companies in the Urals account for 50 – 60 % of local raw materials. Its deficit is compensated by the use of materials imported from Central Russia, the Kola Peninsula and Kazakhstan. Replacing them with the local raw materials would increase the competitiveness of metal produced in the Urals, so the question of assessing the possibility of replacing imported raw materials with local ones is very relevant. Such raw materials could be siderite ores from the Bakal deposit. They are not in demand by metallurgists because of their low iron content and high magnesium content. With growth of siderites in a charge the magnesium oxide content in slag increases that influences its viscosity and makes it difficult or impossible to smelt using more than 20 % of siderites. The use of boron oxide has been suggested to liquefy the slag. The synthetic slag containing 26.8 % CaO, 38.1 % SiO2 , 11.8 % Al2O3 , 23.6 % MgO, simulating composition of slag from MMK blast-furnace smelting with the addition of 30 % of burnt siderites is short and unstable. The temperature corresponding to the slag viscosity at the blast furnace outlet (0.5 Pa·s) is 1390 °C and the temperature corresponding to the melting point (viscosity 2.5 Pa·s) is 1367 °C. If boric anhydride is added to such a slag, it becomes long and stable. In the melts, when the proportion of B2O3 is increased from 0 to 12 %, the temperature at which the slag viscosity is 0.5 Pa·s and 2.5 Pa·s decreases to 1260 °C, and 1100 °C, respectively. This makes it possible to significantly increase the siderite content in blast furnace charge.

The technological process of steel smelting at “ArcelorMittal Temirtau” JSC includes three stages: converter smelting of semi-finished products, ladle treatment, and continuous casting of slabs. According to the current technology, a desired flowability of the refining slag is created in the ladle-furnace unit by thinner additives, such as fluorspar. When using fluorspar, toxic fluorine emissions aggravate the environmental situation at the worksite. In addition, the presence of fluoride compounds in the slag adversely affects the durability of the ladle lining. Without modifying the technological process and the consumption of slag-forming agents (lime), solid slag mixtures, based on aluminum oxide, can be used in the ladle-furnace unit to eliminate fluorine emissions into the workshop atmosphere, neutralize the negative effect on the resistance of the ladle lining slag belt, as well as reduce the cost of steel due to the refusal of fluorspar and reduced consumption of aluminum for slag deoxidization.

High quality steels have a low sulfur content. Steel is purified from sulfur by treating it with highly basic slags. Scarce fluorspar is used to provide slags with the required fluidity, which decomposes during smelting with the liberation of toxic fluorine into a workshop atmosphere. Alumina is also a thinner for highly basic slags, which is present in sufficient concentrations in aluminothermic production slags that are sent to landfill and create pressure on the environment. Slag dumps are "technogenic deposits" that can be a raw material base. In particular, industrial ferroalloy slags with a high alumina content may be used to prepare a thinning slag-forming mixture that can be used in steelmaking instead of scarce fluorspar. Preparation of a slag-forming mixture from waste slag will reduce the environmental pressure on slag dumps and their use as a slag thinner during steel refining in the working area of a steelmaking workshop by eliminating toxic fluorine emissions released during fluorspar decomposition. Replacement of scarce fluorspar with a slag-forming mixture in steelmaking will reduce steel cost by lowering aluminum consumption for slag deoxidation.

Metallurgical plants in the Urals are experiencing a shortage of iron ore raw materials, which is compensated by the use of materials imported from Central Russia, the Kola Peninsula and Kazakhstan. Replacing them with the local raw materials would increase the competitiveness of metal produced in the Urals, so the question of assessing the possibility of replacing imported raw materials with local ones is very relevant. Such raw materials could be siderite ores from the Bakal deposit. They are not in demand among metallurgists because of their low iron content and high magnesium content. Calculations of blast furnace smelting made by means of balance logical-statistical model showed that additions of annealed and metallized concentrates improve performance. However, with increasing siderites in the charge, content of magnesium oxide in the slag increases, which affects its viscosity and makes it difficult or impossible to smelt using more than 20 % of siderites. It was proposed to use boron oxide to liquefy the slag. Thermodynamic modeling was used to assess the effect of adding 1 – 3 % B2O3 to the charge on chemical composition of the slag and distribution of boron between the metal and oxide phases. It was shown that in the melting process, boron is recovered from the slag phase and partially transferred to the metal. This leads to a decrease in B2O3 content in the final slag. Comparative analysis of the calculated and experimental data shows a close content of boron in the metal, determined theoretically and experimentally. It should be taken into account when calculating the charge. According to the calculations, the main reducing agent of boron is silicon, and the experimental data shows that it is carbon.

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. СFe2O3 values decrease to almost zero, while СFe3O4 and CFeO increase simultaneously. By the end of the phase, СFeO reaches its maximum value. At the second stage, the Fe3O4 → FeO transition occurs, when СFe3O4 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.

The devitrification, “cold” crystallization, and glass transition temperatures and melting point of samples in the B2O3–CaO–Al2O3–PbO system have been determined by differential thermal analysis. The viscosity of aluminum calcium borate melts containing up to 6.9% PbO has been measured in the temperature range 1153–1573 K. The results demonstrate that lead oxide additions reduce melt viscosity and that the density and surface tension of the melts increase with increasing lead oxide content and decrease with increasing temperature. High- and low-temperature regions have been identified where the melts have properties of Newtonian fluids. Cooling leads to polymerization and vitrification of the melts.

Thermodynamic modeling method have been used to describe the process of Iron and Nickel joint reduction from oxide melt of the B2O3-CaO-FeO-NiO system by Carbon monoxide and Hydrogen. Fractional inducing of reducing agent and periodic removal of metal gases from working body composition are applied in the method. The equilibrium states are determined for each unit portion of gas, and oxide component composition of the working body in each calculation cycle is taken from the previous data. Such approach is originality of the method. The approach gives possibility to bring the simulated processes closer to real technologies as well as to estimate reactions completeness in pyrometallurgical aggregates. The calculations were carried out accounting disproportionation of FeO into Fe and Fe3O4. It was shown that as a result of FeO disproportionation under neutral conditions (Ar), the resulting metallic Iron interacts with Nickel oxide to form ferronickel. As a result, the initial composition of the B2O3-CaO-FeO-NiO system variation, take place. Additionally, Fe3O4 appears in the working body. The relationship of Iron and Nickel oxides contents in oxide melt, degrees of its reducing and composition of ferronickel formed depending on temperature and induced reducing agent are revealed. The Hydrogen quantity consumed for metal reducing, at which the same degree of Nickel metallization is achieved, is much less comparing to CO. However, the resulting ferroalloy has less Nickel content, which is associated with increase of reduced Iron content. The obtained information is useful for prognoses of thermal extraction processes acting during useful components extraction from oxide melts, for example, nonferrous metallurgy slag.