Influence of the Gangue Compositions on the Reduction Swelling Index of Hematite Briquettes

The metallurgical properties of oxidized pellets are of great importance to achieve high efficiency and smooth running of blast furnace and gas-based direct reduction shaft furnace. In this study, the new method of adding B-Mg compound additive has been put forth to improve metallurgical properties of pellets. The effects of adding B-Mg additive on the strength of green balls, cold compressive strength, reduction swelling, and the strength after reduction and cooling of oxidized pellets are investigated through the experiments and microstructure analysis. The results revealed that, the B-Mg additive has not-so-remarkable effects on the properties of green balls. The rational addition amount of B-Mg additive is 0.6 %, and B-Mg additive make it feasible to reduce roasting temperature of the pellets. High temperature properties show remarkable improvement with the increase of B-Mg additive amount, the RSI decrease from 14.7% to 7.17%, and the strength of pellets after reduction and cooling increase from 162.5 N to 650.8 N when the addition amount increases from 0 to 0.6%.

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Fundamental Study on Application of Gas-Based Shaft Furnace Direct Reduction Process to High Efficiency and Clean Utilization of Paigeite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.753 ◽

2011 ◽

Vol 233-235 ◽

pp. 753-758

Author(s):

Zhao Cai Wang ◽

Man Sheng Chu ◽

Zhuang Nian Li ◽

Jue Tang ◽

Qing Jie Zhao ◽

...

Keyword(s):

Electric Furnace ◽

Shaft Furnace ◽

Direct Reduction ◽

Reduction Process ◽

Technical Problems ◽

Direct Reduction Process ◽

Comprehensive Utilization ◽

Iron Concentrate ◽

New Process ◽

Reduction Swelling

The paigeite resources are abundant in China, but most of them are difficult to be utilized efficiently because of the current technical problems on industrial practice. It is necessary to perfected and innovated for comprehensive utilization of paigeite. The new process of gas-based shaft furnace direct reduction-electric furnace smelting separation provides a new way to efficient and clean comprehensive utilization of paigeite resources. In this paper, the pellets are prepared from boron-bearing iron concentrate. The mechanisms of roasting, the rules of reduction, and the properties of reduction swelling are also investigated. And then the pellets after reduction are smelted and separated in electric furnace to study the properties of products and analyze the feasibility and superiority of new technique. The results showed that boron-bearing iron concentrate is a kind of good raw material for pelletizing process. The properties of boron-bearing pellets after roasting for 20 min at 1200°C could meet to the requirements of gas-based shaft furnace direct reduction process, which exhibited fast reaction rate, good reduction swelling properties and high compressive strength both before and after reduction. With the new process, the efficient separation of boron and iron can be realized. The high boron grade and high activity of boron-rich slag obtained from new process can be used directly in boric acid manufacture. The new process shows excellent tech-economy feasibility to achieve efficiency and clean comprehensive utilization of paigeite resources.

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Influences of hydrogen-enriched atmosphere under coke oven gas injection on reduction swelling behaviors of oxidized pellet

Journal of Central South University ◽

10.1007/s11771-016-3244-4 ◽

2016 ◽

Vol 23 (8) ◽

pp. 1890-1898 ◽

Cited By ~ 1

Author(s):

Hong-ming Long ◽

Hong-tao Wang ◽

Zhan-xia Di ◽

Tie-jun Chun ◽

Zheng-gen Liu

Keyword(s):

Gas Injection ◽

Coke Oven ◽

Coke Oven Gas ◽

Oxidized Pellet ◽

Reduction Swelling ◽

Swelling Behaviors

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Reduction-swelling behaviour of pellets bearing iron ore and charcoal

Canadian Metallurgical Quarterly ◽

10.1016/s0008-4433(98)00021-4 ◽

1998 ◽

Vol 37 (5) ◽

pp. 441-448 ◽

Cited By ~ 15

Author(s):

R Nascimento

Keyword(s):

Iron Ore ◽

Swelling Behaviour ◽

Reduction Swelling

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Effect of Finely Ground Limestone and Dolomite on Compression Strength and Reduction Swelling of Vanadium-Titanium Pellets

Materials ◽

10.3390/ma14164433 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4433

Author(s):

Hao Liu ◽

Shihong Peng ◽

Ke Zhang ◽

Yuelin Qin ◽

Fei Meng ◽

...

Keyword(s):

Compression Strength ◽

Raw Material ◽

Scarce Resources ◽

Green Pellet ◽

Metallurgical Properties ◽

Cold Compression ◽

Reduction Swelling ◽

Vanadium Titanium ◽

Reduction Index ◽

Ground Limestone

Vanadium−titanium magnetite (VTM) is an important raw material for ironmaking under the situation of increasingly demanding scarce resources. To further improve the metallurgical properties of pellets, and to satisfy the requirements of blast furnace slag basicity, finely ground dolomite and limestone have been added to the pellet. In this study, the effect of finely ground dolomite and limestone on the metallurgical properties (green pellet drop strength, cold compression strength, reduction swelling index, and microscopic mineral structure) of VTM pellets were investigated. With the addition of finely ground dolomite and limestone, the drop strength of the green pellet was improved. The effect of adding finely ground limestone was greater than adding finely ground dolomite. Adding more finely ground dolomite and limestone compared to pellets without limestone and dolomite, the cold compression strength was decreased, which was attributed to the decomposition of limestone and dolomite during the induration of pellets. With the addition of dolomite, the reduction swelling index (RSI) increased firstly and then decreased. When the basicity of the pellet was 0.54 to 0.94, the slag phase with the lowest melting point was formed, corresponding to the maximum of the reduction swelling index. For the pellets with added limestone, the reduction swelling of the pellets deteriorated. The reduction index of the pellets increased and reached the maximum (26.6%) at a basicity of 1.54, which belongs to abnormal swelling.

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

Athenea ◽

10.47460/athenea.v1i2.6 ◽

2020 ◽

Vol 1 (2) ◽

pp. 5-11

Author(s):

Oscar Dam

Keyword(s):

Structural Changes ◽

Metallurgical Society ◽

Swelling Behavior ◽

Ore Pellets ◽

Materials Engineering ◽

Swelling Mechanism ◽

Magnetite Pellets ◽

Reduction Swelling ◽

Institute Of Technology ◽

American Society

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.

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