Complex Ferroalloys Research Articles

Production of complex Fe-Si-Mn-Cr ferroalloy using high-ash coal: a sustainable metallurgical approach

The article presents the results of comprehensive thermodynamic modeling and laboratory tests conducted for smelting a complex ferroalloy of silicon, manganese, and chromium (Fe-Si-Mn-Cr) from chromium, medium-grade manganese ores, and high-ash coals from Kazakhstan. Thermodynamic analysis was performed using HSC Chemistry software to model the Fe-Si-Mn-Cr smelting process over a temperature range of 900 °C–1800 °C. This analysis involved six actual charge compositions with solid reductant (Csolid) consumption ranging from 5 to 20 kg per 100 kg of Cr and Mn ore mixture. The mechanism of the combined carbothermic reduction of Cr, Mn, Si, and Fe was investigated using the Cr-Si-Al-Ca-Mn-Mg-O-C system. According to thermodynamic data, the optimal consumption of Csolid per 100 kg of ore mixture is 17 kg, and the optimal temperature range for smelting ferroalloys is between 1600 and 1700 °C. Laboratory tests were conducted in a high-temperature Tamman furnace at 1700 °C, resulting in experimental samples of the new complex ferroalloy with an average composition of 14.85% Fe, 14.05% Si, 7.55% Mn, 57.54% Cr, and 6.01% C, with P < 0.03% and S < 0.02%. The phase composition included (Cr, Fe, Mn)3Si and carbides Cr23C6 and (Fe, Mn)3C. The resulting alloy is suitable for alloying high-carbon and tool steels.

Melting time of complex nickel-containing alloys in liquid steel

For development of new ferroalloys and their application, it is necessary to know their physical and chemical characteristics. The most important characteristics of the alloy, on which assimilation and distribution of the main elements of ferroalloys in the iron-carbon melt depend, are their time of melting and dissolution. Using a mathematical model for calculating the melting time, developed by the employees of the Ural Federal University and the Institute of Metallurgy of the Ural Branch of the Russian Academy of Sciences, the authors studied the duration of melting of complex nickel-containing ferroalloys in liquid steel. The program allows one to calculate the temperature of a piece of ferroalloy, thickness of the frozen steel crust, size of the alloy piece and duration of the melting periods depending on physicochemical and thermophysical characteristics of the ferroalloys. The melting mechanism of ferroalloys determines the time of their melting in liquid steel. This work contains mathematical modeling of melting of complex nickel ferroalloys containing %: ~10 Ni; 0.5 – 55.0 Cr; ~0.2 C; ~0.2 Si, in iron-carbon melt. It was found that all the alloys under consideration belong to the group of low-melting ferroalloys and process of their melting proceeds in three periods. With an increase in the initial diameter of ferroalloy piece from 3 to 100 mm, the melting time increases by 250 – 300 times. It is shown that an increase in Cr content up to 37 % in complex alloy leads to a decrease in the melting time, and with a further increase in the Cr content to 55 %, an increase in the melting time occurs. A decrease in temperature of liquid steel bath from 1700 to 1520 °С is accompanied by an increase in the duration of melting of complex ferroalloys by 7 – 8 times. In general, the considered complex nickel ferroalloys are characterized by a much faster melting process in liquid steel compared to standard ferrochrome and ferronickel.

Viscosity of niobium oxide systems for production of complex ferroalloys

The relevance of the development of modern technological solutions for the processing of niobium ore materials used for the production of complex ferroalloys of domestic deposits is shown. The need to develop new technological processes of processing is caused by the fact that when switching to new types of niobium concentrates, the chemical and phase compositions of the starting materials change, and, consequently, this leads to a change in the composition and properties of the melting products (both metallic and oxide). Using an electrovibration viscometer, the temperature dependences of viscosity were studied and the crystallization temperatures of oxide melts of the Nb2O5 – SiO2 – CaO – TiO2 – Al2O3 system were calculated. The compositions of the studied samples correspond to phosphorless niobium slags, which can be obtained by carbothermic method from rough concentrates. The samples were obtained by fusing oxide materials in a high-temperature laboratory electric furnace. On the basis of the obtained data, graphical dependences of viscosity – temperature are constructed. It was experimentally established that oxide melts containing 15 – 26 % Nb2O5 are more “long” (having a wide crystallization range) and unfavorable according to the characteristic viscosity – temperature dependence. An increase in the concentration of niobium pentoxide to 40 % translates slags into the category of “short” (with a high crystallization rate). It is shown that an increase in the concentration of niobium oxide Nb2O5 from 15 to 40 % leads to a decrease in the crystallization temperature of melts by 200 °C and a decrease in the viscosity of melts from 1.32 to 0.24 Pa·s at 1350 °C. The improvement of the physico-chemical characteristics of oxide melts with an increase in the concentration of niobium pentoxide can favorably affect the technical and economic indicators of ferroalloy production.

Potential for obtaining and applying complex niobium ferroalloys

This paper provides information regarding the application of niobium in industry and the scale of its production in the world and the Russian Federation. Most of the niobium deposits in Russia consist of pyrochlore, apatitepyrochlore and columbitepyrochlore types of ores. They contain a significant amount of phosphorus. Therefore, all enrichment schemes for these ores contain a dephosphorization stage which increases the price of the product and reduces the degree of niobium extraction. The paper explores the possibility of improving the end-to-end production scheme: niobium ore – beneficiation – niobium ferroalloy. The bulk of ferroniobium is intended for steel microalloying and can be replaced by complex ferroalloys with a reduced niobium content. The paper considers the issues of obtaining complex niobium ferroalloys from a rough concentrate with a weak content of niobium. It has been established that the addition of 25 – 40 % of silicon or 12 – 30 % of aliminum to the twocomponent metal system Fe – Nb causes the transfer of niobium ferroalloys (15 – 20 % Nb) from the refractory category to lowmelting materials. The crystallization temperatures are less than 1400 °C. The substantiation of using a complex niobium ferroalloy instead of ferroniobium is given. This alloy has reduced niobium content and increased silicon or aluminum content. Higher service characteristics of the complex ferroalloy are noted in comparison with ferroniobium (temperature of the initiation of crystallization and density). They indicate an increased assimilation of niobium when using a complex ferroalloy for steel microalloying. The paper presents data on the possibility of dephosphorization of niobium concentrates in the process of pyrometallurgical production of a complex ferroalloy. An improved scheme for the production of niobiumcontaining ferroalloys is proposed. This consists of the use of niobium concentrate for melting the intermediate ferroalloy containing a reduced concentration of niobium oxides and an increased concentration of silicon (aluminum). This ferroalloy can be used effectively for steel microalloying with niobium.

Non-metallic Inclusions in Different Ferroalloys and Their Effect on the Steel Quality: A Review

Ferroalloys have become increasingly important due to their indispensable role in steelmaking. In addition, the demand for improved steel qualities has increased considerably, which in turn highlights the quality of ferroalloys. This is due to the fact that the impurities in ferroalloys directly and significantly influence the quality of steel products. To gain a better understanding of the main trace elements and inclusions in ferroalloys (such as FeSi, FeMn, SiMn, FeTi, FeCr, FeMo, FeNb, FeV, FeB, some complex ferroalloys) and their behaviours in steel melt after the additions of these ferroalloys, information from a large number of previous results on this topic was extensively reviewed in this work. The applications of different ferroalloys and their production trends were discussed. In addition, the effects of some trace element impurities from ferroalloys on the inclusion characteristics in steel were also discussed. The possible harmful inclusions in different ferroalloys were identified. Overall, the results showed that the inclusions present in ferroalloys had the following influence on the final steel cleanliness: (1) MnO, MnS and MnO–SiO2–MnS inclusions from FeMn and SiMn alloys have a temporary influence on the steel quality; (2) the effect of large size SiO2 inclusions (up to 200 μm) in FeSi and FeMo alloys on the steel cleanliness is not fully understood. The effect of Al, Ca contents should be considered before the addition of FeSi alloys. In addition, Al2O3 inclusions and relatively high Al content are commonly found in FeTi, FeNb and FeV alloys due to their production process. This information should be paid more attention to when these ferroalloys are added to steel; (3) except for the existing inclusions in these alloys, the Ti-rich, Nb-rich, V-rich carbides and nitrides, which have important effects on the steel properties also should be studied further; and (4) specific alloys containing REM oxides, Cr–C–N, Cr–Mn–O, Al2O3, Al–Ti–O, TiS and Ti(C, N) have not been studied enough to enable a judgement on their influence on the steel cleanliness. Finally, some suggestions were given for further studies for the development of ferroalloy productions.

Synthesis of composite of silicon nitride, aluminium nitride, zirconium nitride from complex ferroalloy – ferro-aluminium-silicon-zirconium by nitriding in combustion mode

В работе приведены результаты исследований получения композиционного материала, содержащего нитрид кремния, нитрид циркония и нитрид алюминия, методом самораспространяющегося высокотемпературного синтеза (СВС) азотированием ферросплава ферроалюмосиликоциркония. Представлены результаты исследования влияния давления азота, дисперсности, плотности исходного порошка ферроалюмосиликоциркония и диаметра образцов на количество поглощенного азота, скоростные и температурные характеристики горения в атмосфере азота. Показано, что при увеличении давления количество поглощенного азота, скорость горения и температура горения возрастают. При повышении плотности исходного порошка уменьшается количество поглощенного азота, скорость и температура горения. Увеличение диаметра исходных образцов, состоящих из порошка ферросплава, не приводит к значительному изменению количества поглощенного азота, при этом скорость горения падает и возрастает температура синтеза. Изменение дисперсности исходного ферроалюмосиликоциркония не влияет в значительной степени на изменение количества поглощенного азота, скорости и температуры горения. Выявлено, что распространение фронта волны горения по образцу в атмосфере азота проходит в нестационарном режиме, и полученные композиты имеют макро неоднородную структуру. Установлены оптимальные условия азотирования ферроалюмосиликоциркония: давление азота, диаметр исходного образца, дисперсность и плотность исходного порошка. Выявлены критические параметры азотирования ферроалюмосиликоциркония методом самораспространяющегося высокотемпературного синтеза, при которых удается реализовать формирование и продвижение фронта волны горения в исходном ферросплаве. Приведены вероятные реакции азотирования исходного материала в волне горения. Определен фазовый состав продуктов азотирования ферроалюмосиликоциркония методом рентгеннофазового анализа. Получен композиционный материал, содержащий нитрид кремния, нитрид алюминия и нитрид циркония.

Development of composition and process of obtaining multicomponent ferroalloys

The main product of ferroalloy plants is standard ferroalloys. They often do not have all the necessary service characteristics and are not very suitable for metal processing in a ladle. The developing progressive technology of steelmaking is forced to adapt to the existing range of ferroalloys, the standards for which have not been updated for 50 years or more. In addition, in recent years, the sources and markets of ferroalloy raw materials have changed, and their quality and content of leading elements have decreased. This makes it difficult or excludes the possibility of obtaining ferroalloys according to existing standards. In this regard, the production of more efficient ferroalloys of a new generation is required, suitable for progressive processes in the developing areas of ferrous and non-ferrous metallurgy 795 and smelted from non-traditional types of domestic ore raw materials. These include complex or multicomponent ferroalloys containing, in addition to iron, two or more functional elements. Complex ferroalloys should be created in the most favorable combinations of component. It contributes to the necessary effective impact on the iron-carbon melt with a high degree of assimilation of useful elements in it. The creation of scientific foundations for the formation of new compositions of multicomponent ferroalloys with high consumer properties, and the development of physicochemical processes for obtaining these alloys from unconventional ore raw materials contributes to solving the problems of developing compositions of effective new generation ferroalloys and expanding the ore base of ferroalloy production. When using the developed method of designing the composition of complex ferroalloys using unconventional raw materials, melting technologies were developed; various alloys of the systems were obtained and applied on a laboratory and industrial scale: Fe – Si – Cr, Fe – Si – B, Fe – Si – Ba – Ca, Fe – Si – Al – Nb, Fe – Si – Ca – Mg, Fe – Si – V – Ca – Mn, Fe – Si – Al.

Crystallization temperatures of complex ferroalloys

Thermo-gravimetric method was used to determine the temperature of crystallization onset of alloys of the Fe – Ni – Cr – C – Si system depending on concentration of chromium and nickel. It was shown that complex ferroalloys containing 0.2 – 21.0 % Ni (at Cr = 25 – 28 %); 0.5 – 45.0 % Cr (at Ni = 10 – 11 %); 2.0 % C and 0.3 % Si, iron, and impurities belong to the category of low-melting alloys and have rational values (1320 – 1400 °C) of crystallization temperatures in terms of their use for steel processing in the ladle. An increase of the chromium content to more than 45 % in these alloys is accompanied by an intense increase of their temperatures of the crystallization onset.

Thermodynamic simulation of metal-thermal boron reducing

To improve the quality of steel and cast iron, the micro-alloyed by boron is applied, which is introduced into the melt within a scope of complex ferroalloys. There is information about rather effective application of silicon and aluminum as reducing agents, introduced within a scope of complex ferroalloy with manganese, chrome, tungsten and molybdenum. However, no information was found about application of such a ferroalloy for reducing of boron. Therefore, the purpose of the study was the thermodynamic simulation of boron simultaneous reducing by silicon and aluminum from the CaO-SiO 2 -MgO-B 2 O 3 oxide system. The influence of aluminum content within a complex reducing agent on the boron reducing degree from the oxide system of the following compositions %: 36,7 CaO; 5,6 SiO 2 ; 2,8 MgO; 54,9 В 2 О 3 was studied. For particular study, the alloys of the following composition were taken: %: 60 Si - 5 Al - 35 Fe; 55 Si - 10 Al - 35 Fe; 50 Si - 15 Al - 35 Fe and 65 Si - 35 Fe. The simulation was accomplished within a package of applied programs HSC Chemistry 6.12 with application of Equilibrium Composition module within the temperature range 1400-1600 ° С with a step of 50 ° С . It was determined, that replace of silicon in the alloys by aluminum results in considerable growth of reducing degree, which can reach 99%. Alloys с [Al] orig = 0-52 % have the lowest reducing degree. Presence of с [Al] orig = 5 % in the original alloy enables to increase the reducing degree until 69%. The further growth of the original aluminum content until 10 and 15% enables to reach the reducing degree of 85 and 94%. Based on the study results the conclusion was made about preference to apply aluminum from the Fe-Si-Al complex ferroalloy for boron reducing from the oxide system, since the degree of boron reduction degree is much higher comparing with application only silicon at the same total reducing agent (Si + Al = 65 %) quantity.

Mathematical modelling of the process of melting alloys of the Si-Cr-Ni-Fe system in the iron-carbon melt

The process of melting of the Si-Cr-Ni-Fe ferroalloys in the iron-carbon melt under static conditions was studied using the method of mathematical modelling. It was found that the melting process takes place in three stages. The effect of silicon concentration and the initial size of a piece of alloy on the duration of each stage of alloy melting is revealed. It was shown that an increase in the silicon content from 6 to 40 % in the complex ferroalloy of the 50 mm fraction containing ~ 27 % Cr and ~ 12 % Ni leads to a decrease in the total melting time of the alloys from 67 to 30 seconds at the iron-carbon melt temperature of 1600 ºC.

Manufacturing and Application of Complex Ferroalloys

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The Using Boron-containing Materials in Ferroalloy Industry

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Development of the New Method for Oxidized Nickel Ore Processing

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Development of Smelting Technology of Complex Ferroalloy with the Use of High-ash Coals

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The Thermodynamic Evaluation of the Interphase Distribution of Elements in the Chromium and Nickel-containing System

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ПРОГНОЗИРОВАНИЕ ВРЕМЕНИ ПЛАВЛЕНИЯ КОМПЛЕКСНЫХ ФЕРРОСПЛАВОВ МЕТОДОМ ФИЗИКО ХИМИЧЕСКОГО МОДЕЛИРОВАНИЯ

The purpose of this work is to implement a new approach to the description of the duration of melting (dissolution) of complex new generation ferroalloys during the deoxidation and doping of a metal melt. This approach is aimed at developing a methodology and criteria for the quantification and accounting of the micro-heterogeneity of multicomponent metal melts and their prediction on such important for steelmaking production characteristics as the melting time of ferroalloys, the description of the inter-mine interaction, which allows a deeper understanding of the process. deoxidation and refining of steel. In the work, the approach developed in the Institute of Ferrous Metallurgy of the National Academy of Sciences of Ukraine to solve problems of modeling of non-conformities that relate the composition, structure and properties of melts is used in the work. It is based on the original concept of physicochemical modeling of the processes of interatomic interaction in melts and solutions, developed by E.V. Prihodko. According to it, metal melts are considered as chemically unified systems. Changing their composition affects the complex of physicochemical properties due to changes in the parameters of their electronic structure. The method of calculation of criteria (∆Zy and d), characterizing the degree of difference between the electronic and structural state of the melt, as a chemically unified system, from the mechanical mixture of their initial components and the parameter was used to evaluate and account for the influence of the micron homogeneity of the structure of the metal melts of ferroalloy production. ρl, which takes into account the cluster spin in metal melts. Using these criteria and the available experimental data, analytical dependences were obtained to calculate the melting time of complex (ma-manganese, vanadium, niobium and boromatic) ferroalloys of the new generation. This will allow them to evaluate their effectiveness of application, which is associated with the highest assimilation of the main elements that affect

Deoxidizing and modifying properties of alkaline earth metals within ferroalumosilicocalcium and ferrosilicobarium alloys

Modification of alloys, in particular, by calcium and barium, is one of the promising directions for obtaining alloys with a fine crystalline structure. Complex ferroalloys – ferroalumosilicocalcium and ferrosilicobarium – were developed in the Chemical and Metallurgical Institute after Zh. Abishev. It was shown, that modification of steel by silicon-aluminum complex alloys containing chemically active elements – calcium and barium, should become one of the most effective methods to improve the quality of machine-building metal products.The chemical compositions of the smelted ferroaluminosiliconcalcium and ferrosilicobarium presented. The melting range of the nonmetallic compound formed during the deoxidation of steel by complex alloy containing calcium determined. Results of mechanical tests of the specimens of steel, modified by a complex alloy containing barium considered. A comparison of microstructure of the current production route steel and deoxidized with the complex alloys was carried out.In the course of metallographic studies of experimental steel specimens, a modifying influence on the morphology of nonmetallic inclusions by calcium and barium, supplied in a complex with aluminum and silicon alloys, was established.Metal processing by complex alloys such as ferrosilicoaluminum with calcium (FASC) and ferrosilicobarium (FSAB) indicates the possibility of achieving a higher degree of refining from oxide nonmetallic inclusions and a more even distribution of them in the ingot.The results of the industrial heats also indicated a possibility of improving of quality of casting through the decreasing of hot thermal cracks and gas-shrinkage defects, cleaner grain boundaries, a significant reduction in the number and size of carbide inclusions.

Thermodynamic model of the influence of temperature and carbon on the production of ferroalloy and calcium carbide from the basalt of Dubersay deposit

The article covers the results of researches on thermodynamic modeling of ferroalloy and calcium carbide obtaining from basalts of deposit Dubersay. The software package HSC-5.1, based on the principle of Gibbs energy minimum uses in the study. The influence of temperature (from 500 to 2500 °C) and the amount of carbon (from 40 to 60 % of the basalt mass) in the basalt–Fe–nC system was determined. It has been established that iron silicides are formed at T ≥ 1300 °C, Si at T ≥ 1400 °C, CaSi and Al at T&gt; 1700 °C and CaC2 – at T ≥ 1800 °C. An increase of the amount of carbon from 40 to 60 % allows rise the degree of distribution of Si in the alloy up to 94 %, calcium in CaCl2 – up to 62.3 %, aluminum – to alloy up to 93.9 %. An increase of the amount of carbon allows increase the silicon concentration in alloy up to 55 % (at 1800 °C), aluminum – up to 17 % (at 2000 °C) and calcium carbide capacity – up to 350 dm3/kg. The method of rototable planning of the second order allows find equations of regressions of the influence of temperature and amount of carbon on the equilibrium distribution of silicon, aluminum, and calcium between the ferroalloy and calcium carbide. On the basis of this equations were determined, that within the temperature range 1956-1996 °C from the Dubersay deposit basalt, the ferroalloy with a content of ΣSi and Al 60.8-65.4 % (including 12- 15 % Si) and calcium carbide with a capacity of 250-300 dm3/kg are formed. Wherein degree of recovery into the alloy for silicon is 91-91.4 % and for aluminum is 63-75.1 % and calcium – into CaC2 is 60-60.7 %. The resulting ferroalloy by the content of silicon and aluminum can be attributed to the complex ferroalloy – ferrosilicoaluminium, calcium carbide – to the industrial product of grade from 3 and up to the highest.

SHS Technology for Composite Ferroalloys. 1. Metallurgical SHS: Nitrides of Ferrovanadium and Ferrochromium

The development of specialized self-propagating high-temperature synthesis (SHS) for complex ferroalloys used in steel smelting and in blast-furnace technology is discussed. To that end, a new approach to the SHS process has been conceived: the metallurgical SHS process, in which the basic raw material consists of various metallurgical alloys including dusty waste from ferroalloy production. In that case, synthesis involves exchange exothermal reactions. The product is a composite based on the initial inorganic compounds; the binder is iron or an iron alloy. Depending on the state of the initial reagents, the metallurgical SHS processes may be gas-free, gas-absorbing, or gas-liberating. For each case, the combustion conditions will be very different. Thermal matching may be used in organizing the metallurgical SHS process in systems that are not strongly exothermal. The self-propagating high-temperature synthesis of nitrided ferrovanadium and ferrochrome is investigated. It is shown that the phase composition of the initial alloy strongly affects the combustion of ferrovanadium in nitrogen. In the nitriding of σ ferrovanadium, transformation of the intermetallide to an α solid solution is activated on reaching the phase-transition temperature (~1200°C). The composite structure of the nitriding products of ferrovanadium is formed under the influence of solid–liquid droplets consisting of molten iron and solid vanadium nitride. Solid-phase reaction of ferrochrome with nitrogen facilitates high degrees of nitriding. The combustion rate of ferrochrome on nitriding during coflow filtration, as in chromium, increases with increase in the nitrogen flow rate. The degree of nitriding of the ferrochrome in forced filtration (4.7–7.5% N) is much less than that in natural filtration (8.8–14.2% N).

Physicochemical characteristics, production and application of boron-bearing complex ferroalloys

The expediency of producing and using complex ferroalloys in steelmaking is analyzed in terms the manufacturing technology, the raw materials employed, and the interactions of the ferroalloys with the molten steel. The need to produce complex ferroalloys with boron is established. The fundamental principles for determining the best composition of such alloys are presented. The basic compositions of complex ferroalloys with boron (ferrosilicomanganese with boron, ferrosilicon with boron, ferrosilicomanganese with boron and chromium) are established by studying the physicochemical properties of alloys and their interactions with the steel melt. If the characteristics (melting point, density, melting time of the ferroalloy in liquid steel, etc.) of complex ferroalloys with boron are compared with those of ferroboron, which is widely used, the complex alloys have clear benefits. The composition of the complex ferroalloys with boron includes active elements (Si, Al, Ti) facilitating the binding of oxygen and nitrogen from the steel melt in strong compounds and hence preventing their reaction with boron. The recommended boron content in the ferroalloy is 0.7–2%. That permits increase in the quantity of complex ferroalloys with boron in the steel and hence increase in the reliability and stability of boron assimilation. At elevated temperatures (1430–1570°C), the oxidation of ferrosilicoboron is 4–7 times less than that of ferroboron. Data are presented regarding the industrial production and use of ferrosilicoboron in the steel-smelting shop. The boron assimilation from complex alloys in microalloying of the steel is studied. The use of ferrosilicoboron does not require significant changes in the existing system for reduction by ferrosilicon; the boron assimilation is 77.8–96.3% (mean 86.6%). With a boron concentration of 0.0021–0.0027% in the steel during ladle treatment, its content in the cast metal will be no less than 0.0020%. If boron is introduced in steel by means of ferrosilicomanganese with boron, the boron assimilation is increased by a factor of 1.6 (from 48 to 77%, on average) in comparison with the use of ferroboron.