前人研究表明,二次赤铁矿是导致烧结矿低温还原粉化的主要因素,它的生成与烧结原料中MgO含量有关,但其影响机理尚不明确。通过热重法测定不同MgO和Fe2O3比例试样在升温恒温降温过程中质量变化,定量地了解MgO对Fe2O3向Fe3O4转变的影响。同时结合XRD分析和光学显微镜观察,揭示了矿物和相结构变化,研究了烧结过程中MgO对二次赤铁矿生成的抑制机理。结果表明,加入MgO后,它与Fe2O3反应形成了铁酸镁和含镁磁铁矿,前者促进了升温过程含镁磁铁矿生成, 而后者低温下比磁铁矿更稳定,抑制了降温过程磁铁矿氧化, 减少了二次赤铁矿的生成。因此,明确了加入少量MgO改善烧结矿低温还原粉化性能的主要原因。
Abstract
Previous researches show that the secondary hematite is a main factor to result in low temperature reduction degradation of sinter, and its formation relates with MgO content in raw materials of sinter, but the mechanism has been not very clear until now.The mass changes of samples with different proportions of MgO and Fe2O3 during heatingup, constant temperature sintering and cooling process were measured to understand quantitatively the effect of MgO content on transformation between Fe2O3 and Fe3O4 by a thermogravimetric method, simultaneously the Xray diffraction (XRD) and the optical microscopy (OM) were used to follow the changes of mineral phase and microstructures in samples for investigation of the mechanism of MgO depressing the secondary hematite formation in sintering process of iron ores. The results show that after addition of MgO which reacts with Fe2O3 to form magnesium ferrite and magnesioferrite, the former promotes the formation of the magnesioferrite during the heatingup process and the latter is more stable than the magnetite in low temperature to depress the oxidation of magnetite in the cooling process, so resulting in decreasing of the secondary hematite in sinter. Therefore, it make clear the reason to improve the low temperature reduction degradation of sinter after addition of MgO in the raw materials.
关键词
MgO /
氧化铁 /
稳定性 /
二次赤铁矿
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Key words
MgO /
iron oxide /
stability /
secondary hematite
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中图分类号:
TF046.4
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参考文献
[1] Shigaki I, Sawada M, Gennai N. Increase in low-temperature reduction degradation of iron ore sinter due to hematite-alumina solid solution and columnar calcium ferrite [J]. Trans. ISIJ., 1986, 26 (6):503-511.
[2] Dwarapudi S, Ghosh T K, Shankar A, Tathavadkar V, Bhattacharjee D, Venugopal R. Effect of pyroxenite flux on the quality and microstructure of hematite pellets [J]. Int. J. Miner. Process, 2010, 96 (1):45–53.
[3] Sugahara K, Sato K. Degradation of sintered ore during reduction [J]. Tetsu-to-Hagane., 1969, 55 (13):1107-1118.
[4] Bradshaw A V, Matyas A G. Structural changes and kinetics in the gaseous reduction of hematite [J]. Metall. Trans. B, 1976, 7 (1):81-87.
[5] Hayes P C, Grieveson P. Microstructural changes on the reduction of hematite to magnetite [J]. Metall. Trans. B, 1981, 12 (3):579-587.
[6] Unal A, Bradshaw A V. Rate processes and structural changes in gaseous reduction of hematite particles to magnetite [J]. Metall. Trans. B, 1983, 14 (3):743-751. ,
[7] Panigrahy S C, Verstraeten P. Dilewijns. J. Influence of MgO addition on mineralogy of iron ore sinter [J]. Metall. Trans. B, 1984, 15 (1):23-32.
[8] Pimenta H P, Seshadri V. Influence of Al2O3 and TiO2 on reduction degradation behaviour of sinter and hematite at low temperatures [J]. Ironmak. Steelmak., 2002, 29 (3):175-179.
[9] Dwarapudi S, Devi T U, Rao S M, Ranjan M. Influence of pellet size on quality and microstructure of iron ore pellets [J]. ISIJ Int., 2008, 48 (6):768-776.
[10] 武轶,刘自民,李小静,宋灿阳.烧结矿中适宜MgO含量的研究 [J].钢铁研究,2016,44(3):6-8.
[11] Friel J J, Erickson Jr E S. Chemistry, microstructure and reduction characteristics of dolomite fluxed magnetite pellets [J]. Metall. Trans. B, 1980, 11 (2):233–243.
[12] Panigrahy S C, Verstraeten P, Dilewijns J. Effect of MgO addition on strength characteristics of iron ore sinter [J]. Ironmak. Steelmak., 1984, 11 (1):17-22.
[13] 周国凡,杨福.添加MgO对球团矿成球性能及强度的影响[J].钢铁研究,2009, 37(2):10-12.
[14] Panigrahy S C, Jena B C, Rigaud M. Characterization of bonding and crystalline phases influxed pellets using peat moss and bentonite as binders [J]. Metall. Trans. B, 1990, 21 (3):463–474.
[15] Yadav U S, Pandey B D, Das B K, Jana D N. Influence of magnesia on sintering characteristics of iron ore [J]. Ironmak. Steelmak., 2002, 29 (1):91-95.
[16] 吕庆,李福民,王文山,胡宾生. w(MgO)对含钒、钛烧结矿强度和烧结过程的影响[J].钢铁研究, 2007, 35(1):5-8.
[17] Dwarapudi S, Ghosh T K, Shankar A, Tathavadkar V, Bhattacharjee D, Venugopal R. Effect of pellet basicity and MgO content on the quality and microstructure of hematite pellets [J]. Int. J. Miner. Process, 2011, 99 (1):43-53.
[18] 司金凤,贾彦忠,李凤臣.配加高镁球团矿高炉炉料结构的研究[J].钢铁研究,2016,44(3):1-5.
[19] 刘清才,张洋宾,兰苑培,陈黔湘,敖万忠,张东升.轻烧白云石对烧结矿性能的影响[J].钢铁,2013,48(3):15-18.
[20] Dwarapudi S, Ghosh T K, Tathavadkar V, Denys M B. Effect of MgO in the form of magnesite on the quality and microstructure of hematite pellets [J]. Int. J. Miner. Process, 2012, 112-113 (1): 55-62.
[21] Dwarapudi S, Banerjee P K, Chaudhary P, Sinha S, Chakraborty U, Sekhar C, Venugopalan, T, Venugopal R. Effect of fluxing agents on the swelling behavior of hematite pellets [J]. Int. J. Miner. Process, 2014, 126 (1):76-89.
[22] Zhu D Q, Chun T J, Pan J, Zhang J L. Influence of basicity and MgO content on metallurgical performances of Brazilian specularite pellets [J]. Int. J. Miner. Process, 2013, 125 (1):51-60.
[23] 刘洪波, 郭兴敏.氧分压对烧结过程中二次赤铁矿生成的影响[J].钢铁研究,2015,27(2):7-13.
[24] 边秒莲,吴胜利,张丽华,朱娟,王清峰,龙芳仪.低FeO烧结条件下的适宜配碳量和碱度[J].钢铁, 2012, 47(3):6-10.
[25] Blesa M C, Amador U, Moran E, Menendez N, Tornero J D, Carvajal R. Synthesis and characterization of nickel and magnesium ferrites obtained from, alpha-NaFeO3 [J]. J. Solid State Ionics, 1993, 63 (5): 429-436.
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脚注
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基金
利用XRD-XRF进行铁矿石矿物定量与表征方法的基础研究;氧化钐直接高温电解制备Sm2Fe17合金方法的研究
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