Effect of Humic Acid Binder on Oxidation Roasting of Vanadium–Titanium Magnetite Pellets via Straight-Grate Process

The oxidation roasting of vanadium–titanium magnetite (VTM) pellets with a new composite binder was investigated using a pilot-scale straight-grate. The evolution of the chemical and phase composition, the compressive strength, and the metallurgical properties of the fired VTM pellets were investigated. Under a preheating temperature of 950 ∘C, a preheating time of 18 min, a firing temperature of 1300 ∘C, and a firing time of 10 min, the compressive strength of the fired pellets was as high as 2344 N per pellet. The fired pellets mainly consisted of hematite, pseudobrookite, spinel and olivine. The total iron content of the fired pellets was 0.97% higher using 0.75 wt% humic acid (HA) binder instead of 1.5 wt% bentonite binder. These properties are beneficial for the production efficiency and energy efficiency of their subsequent use in blast furnaces. Moreover, both the softening interval and the softening melting interval of the HA binder pellets were narrower than those of the bentonite binder pellets, conducive to the smooth and successful smelting of the VTM pellets in a blast furnace.

A mathematical model of metallization of titanium-magnetite ores of Kachkanar deposit in Midrex shaft furnace

Development of a technology for obtaining direct reduction iron from titanium-magnetite ores, which will be the main ore base of the Ural ferrous metallurgy in the future, is one of the urgent tasks of metallurgical science. The world and domestic experience of the development of direct iron reduction processes, which are the most environmentally friendly of all existing methods of obtaining iron from ore considered. It was shown that the technology of metallization of iron ore materials in the Midrex shaft furnace has received the most widespread application. It is noted that the accumulated experience of using Midrex technology in Russian Federation will allow increasing the production of metallurgical raw materials with a reduced carbon footprint. An algorithm and a block diagram for calculating technical and economic indicators of the metallization process for the Midrex process shaft furnace are described. A methodology for calculating material and thermal balance of the Midrex process has been developed, taking into account the use of iron ore raw materials containing vanadium and titanium in the charge. On its basis, an algorithm was developed and a mathematical model of the metallization process was implemented, calculations of the metallization process of titanium-magnetite pellets obtained from the ores of the Kachkanar deposit in the Midrex mine furnace were performed. A comparison of the indicators of the metallization process of titanomagnetite pellets carried out in the shaft furnace of JSC “OEMK named after A.A. Ugarov” and obtained using the created software product showed satisfactory convergence of the results.

Effect of the reaction of ammonia gas on the swelling of metallic iron and its oxides during nitriding processes

In order to study the relationship and effect of nitrogen gas in the reducing gases used in the reducibility tests of iron oxides, under isothermal conditions, a test scheme was executed using ammonia gas, such that its decomposition of the gas in the reactor produced a mixture of H2 and N2 gases. Furthermore, the addition of 6% NH3 in a 28% H2 and 68% N2 gas stream was planned to obtain a gas composition of 70% N2 and 30% H2. This would allow comparing the reducibility curves between both conditions, assuming that the possible difference between both conditions to compare the volume changes of the reduced samples. The difference to be studied will be based on the estimation and comparison of the rate of formation of metallic iron in the stages of reduction of Hematite / Magnetite / Wustite (FeO), as well as the effects of nitrogen absorbed by the fresh metallic iron produced, or present. in iron catalysts to produce ammonia, from the reducing gas mixture, on the volume change of the samples. Likewise, the catastrophic volume changes caused by nitrogen are compared by comparing sources of this gas in solid carbonaceous reducers. Keywords: Gaseous Reduction, Direct Reduced Iron, isothermal tests. References [1]O. Dam G. “The Influence of Nitrogen on the Swelling Mechanism of Iron Oxides During Reduction”. Univ. of London. PhD Thesis 1983. [2]J. Bogde. “Thermoelectric Power Measurements in Wustite. Univ. of Michigan”. 1976. [3]O. Dam G. y J. Jeffes. “Model for the Assessment of Chemical Composition of reduced iron ores from single measurements. Ironmaking and Steelmaking”. Vol. 14, N`5. 1987. [4]M. Yang. “Nitriding-Fundamentals, modelling and process optimization”. Tesis PhD. Worcester Polytech Institute. 2012. [5]EL Kasabgy. T and W-K. LU. “The Influence of Calcia and Magnesia in Wustite on the Kinetics of Metallization and Iron Whisker Formation”. Metallurgical 1980 American Society for Metals and the Metallurgical Society of AIME Volume 11b, pp. 410-414. 1980. [6]“Srikar Potnuru Studies nn the Physical Properties and Reduction Swelling Behavior of Fired Haematite Iton ore Pellets”. MSc Thesis. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2012. [7]R. Agarwal, S. Hembram. “To Study the Reduction and Swelling Behavior Iron Ore Pellets”. BSc. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2013. [8]C. Seaton., J. Foster. and J. Velasco. “Structural Changes Occurring during Reduction of Hematite and Magnetite Pellets Containing Coal Char”. Transactions ISIJ, Vol. 23, 1983, pp. [10]C. Bozco. “Interaction of Nitrogen with Iron Surfaces”. Journal of Catalysis 49. pp16-41. 1977. [11]L. Darken y R. Gurry. “Physical Chemistry of Metals”. Mc Graw hIll . 1953. [12]H. Weirdt and Z. Zwell, Trans. AIME. 229. 142. 1969. [13]J. Schulten. Trans. Soc. Faraday. 53, 1363, 1957. [14]E. Barret y C. Wood. Bureau of Mines R-I 3229. 1934

Preparation, Sintering Behavior and Consolidation Mechanism of Vanadium-Titanium Magnetite Pellets

High-quality oxidized pellets are the basis to achieve high-efficiency utilization of vanadium–titanium magnetite (VTM) ores. Bentonite was used as a binder of VTM. The main phase composition of VTM is titanomagnetite and ilmenite. When the amount of bentonite is 1%, the compressive strength and dropping strength of VTM pellets can meet the requirements. To improve metallurgical properties, the pellets need to be roasted. The best conditions for roasting are as follows: calcination temperature of 1523 K and a calcination time of 20 min. The consolidation mechanism, phase transformation, and crystal structure transformation of VTM in the process of oxidation roasting are also explained.

Effect of Incremental Utilization of Unground Sea Sand Ore on the Consolidation and Reduction Behavior of Vanadia–Titania Magnetite Pellets

In the iron and steel industry, improving the usage amount of New Zealand sea sand ore as a raw material for ironmaking can reduce the production costs of iron and steel enterprises to a certain extent. In this paper, New Zealand sea sand ore without any grinding pretreatment was used as a raw material, oxidized pellets were prepared by using a disc pelletizer, and the effect of sea sand ore on the performance of green pellets and the metallurgical properties of oxidized pellets was investigated. The effects of sea sand ore on the compressive strength, falling strength, compressive strength of oxidized pellets, and reduction performance were mainly investigated. X-Ray Diffraction (XRD) patterns and Scanning Electron Microscope (SEM) analysis methods were used to discuss the influence of sea sand ore on the microstructure of the pellets’ oxidation and reduction process. As the amount of sea sand ore used increased, the compressive strength of green pellets was gradually decreased, and the falling strength of green pellets and the compressive strength of oxidized pellets were gradually increased. When the amount of sea sand ore used was 40%, the reduction swelling index of pellets was 16.31%. The increase of sea sand ore used made the reduction of pellets suppressed and the reduction rate decreased. When the amount of sea sand ore used increased to 40%, the reduction degree of sea sand ore pellets was only 60.06%. The experimental results in this paper provide specific experimental data for the large-scale application of New Zealand sea sand ore in the blast furnace ironmaking process.

Efecto de la descomposición de gas de amoniaco (NH3) sobre el hinchamiento de óxidos de hierro durante reducción

Con el objeto de estudiar la relación y efecto del gas nitrógeno en los gases reductores utilizados en los ensayos de reducibilidad de óxidos de hierro, en condiciones isotérmicas, se ejecutó un esquema de ensayos utilizando gas amoniaco, tal que la descomposición del gas en el reactor produjera un gas de H2 y N2. Además, se planifico la adición de 6% de NH3 en una corriente de gas 28% H2 y 68% N2 para obtener una composición de gas de 70% N2 y 30% H2. Esto permitiría la reinterpretación de los datos de laboratorio para comparar las curvas d reducibilidad entre ambas condiciones, asumiendo que la posible diferencia entre ambas condiciones a comparar los cambios de volumen de las muestras reducidas. La diferencia a estudiar se basará en la estimación y comparación de la velocidad de formación de hierro metálico en las etapas de reducción de hematita/magnetita/wustita (FeO), así como los efectos del nitrógeno absorbido por el hierro metálico fresco producido, partir de la mezcla de gas reductor, sobre el cambio de volumen de las muestras. Así mismo se comparan empíricamente los cambios catastróficos de volumen causados por el nitrógeno comparando fuentes de este gas en reductores carbonosos sólidos. Palabras clave: reducción gaseosa, hierro de reducción directa (HRD), catálisis, catalizador de hierro, amoniaco, hinchamiento, absorción, nitruración. ensayos isotérmicos, nitrógeno en carbón. Referencias [1]O.G. Dam . The Influence of Nitrogen on the Swelling Mechanism of Iron Oxides During Reduction. Univ. of London. PhD Thesis 1983. [2]J.D Bogde.- Thermoelectric Power Measurements in Wustite. Univ. of Michigan. 1976. [3]O.G. Dam y J. Jeffes. Model for the Assessment of Chemical Composition of reduced iron ores from single measurements. Ironmaking and Steelmaking. 1987. Vol. 14, N`5. [4]M. Yang. Nitriding-Fundamentals, modelling and process optimization. Tesis PhD. Worcester PolytechInstitute. 2012. [5]T. EL Kasabgy y W-K. LU. (1980). The Influence of Calcia and Magnesia in Wustite on the Kinetics of Metallization and Iron Whisker Formation. Metallurgical 1980 American Society for Metals and the Metallurgical Society of AIME Volume 11b, September 1980, pp. 410-414. [6]Srikar Potnuru Studies nn the Physical Properties and Reduction Swelling Behavior of Fired Haematite Iton ore Pellets. MSc Thesis. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2012. [7]R.S Agarwal y S.S. Hembram. To Study the Reduction and Swelling Behavior Iron Ore Pellets. BSc. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2013. [8]C.E. Seaton y J.S. Foster. and Velasco. Structural Changes Occurring during Reduction of Hematite and Magnetite Pellets Containing Coal Char. Transactions ISIJ, Vol. 23, 1983, pp. [10]C. Bozco. et.al. Interaction of Nitrogen with Iron Surfaces. Journal of Catalysis 49. 1977. [11]L.S. Darken y R.W. Gurry, Physical Chemistry of Metals. Mc Graw hIll . 1953. [12]H. A. Weirdt, y Z .Zwell. Trans. AIME. 229. 142. 1969. [13]J.J.S.Schulten. et al. Trans. Soc. Faraday. 53, 1363, 1957. [14]E.G.Barret y C.F. Wood. Bureau of Mines R-I 3229. 1934.