|
|
|
|
|
|
Growth Mechanism of Magnesioferrite Spinel in Solid Phase Modification of CaO-SiO2-FeO-MgO System |
JIANG Liang, LI Jiaxin, WU Ting, YANG Che, YIN Weijie, HAN Fenglan, CHEN Yuhong
|
School of Material Science and Engineering, North Minzu University, Yinchuan 750021 |
|
|
Abstract teel slag is a by-product of the steelmaking process, and its yield are about 15% of steel production. The recycling of steel slag is one of the key issues that steel companies need to solve. With its composition characteristics, a small amount of steel slag has been used in metallurgy, engineering backfilling, road construction, sewage treatment and preparation of glass-ceramics. Besides, the incorporation of steel slag into cement to prepare steel slag cement is an effective and efficient way to use. However, the existence of wustite phase, which is difficult to separate in steel slag, limits its application in the field of building materials. The oxidative modification can transform the wustite in the steel slag to the ferromagnetic magnetite, and there is no greenhouse gas emission during the upgrading process. The oxidative upgrading process of CaO-SiO2-FeO system steel slag has been studied in the past, but the CaO-SiO2-FeO-MgO system which is closer to the actual steel slag composition has relatively less research. In addition, the nucleation and growth mechanism of the magnesioferrite spinel in the oxidation process still needs further exploration. This work refers to the actual composition of the converter steel slag of a steel plant, and the solidification of the steel slag is carried out by calcination under an oxidizing atmosphere (Synthetic air). X-ray diffraction (XRD) analysis, backscattered scanning electron microscopy (BEI-SEM) and X-ray energy dispersive spectroscopy (EDS) were used to analyze the mineral phase products of CaO-SiO2-FeO-MgO system synthesis slag, combined with thermodynamics. The calculation software (FactSage 7.0) was used to study the thermodynamic trends of the main product phase formation. In addition, simultaneous thermal analyzer (TG-DSC) was carried out to study the kinetic mechanism of the formation of magnesioferrite spinel, and the corresponding kinetic model was also established. The results show that with the solid phase reforming temperature rising from 1 000 ℃ to 1 150 ℃, the yield of magnesioferrite spinel increases first and then decreases, and reaches a maximum value when the upgrading temperature is 1 100 ℃. The magnesioferrite spinel changes in the (311) crystal plane corresponding to the diffraction angle as follows: 2θ=35.44° (1 000 ℃)→2θ=35.49° (1 050 ℃)→2θ=35.49° (1 100 ℃)→2θ=35.43°(1 150 ℃). With the oxidation temperature increa-sing from 1 000 ℃ to 1 150 ℃, the weight gain of the 600 s oxidation system increases from 351.273×10-3 mg to 499.077×10-3 mg, and the weight gain of the 1 800 s oxidation system increases from 364.390×10-3 mg to 535.341×10-3 mg. According to the kinetic mechanism, the solid phase modification process of CaO-SiO2-FeO-MgO quaternary system can be divided into three stages: initial stage, chemical reaction phase and diffusion phase. The theoretically calculated kinetic model is well consistent with the thermogravimetric change trend of the TG experimental results. The kine-tic model can accurately describe the nucleation and growth process of the magnesium iron spinel during the solid phase reforming of steel slag.
|
Published: 02 July 2019
|
|
Fund:This work was financially supported by the Ningxia Higher Education Scientific Research Project (NGY2018-142), the Ningxia Science and Technology Support Project (2017EZ08) and the Project of “State Key Laboratory of Powder Materials & Advanced Ceramics” (1804). |
|
|
[1] |
Han F L, Wu L E. Industrial solid waste recycling in west of China, Science Press, China,2017(inChinese).韩凤兰,吴澜尔.工业固废循环利用,科学出版社,2017.
|
[2] |
China Iron and Steel Application Association Metallurgical Slag Development and Utilization Working Committee. China Scrap Steel,2017(1),47(in Chinese).中国废钢铁应用协会冶金渣开发利用工作委员会.中国废钢铁,2017(1),47.
|
[3] |
Zhang L N, Zhang L, Wang M Y, et al. Transactions of Nonferrous Metals Society of China,2005,15(4),938.
|
[4] |
Semykina A, Shatokha V, Seetharaman S. Ironmaking & steelmaking,2013,37(7),536.
|
[5] |
Semykina A, Shatokha V, Iwase M, et al. Metallurgical and Materials Transactions B,2010,41(6),1230.
|
[6] |
Semykina A, Nakano J, Sridhar S, et al. Metallurgical and Materials Transactions B,2010,41(5),940.
|
[7] |
Semykina A. Metallurgical and Materials Transactions B,2012,43(1),56.
|
[8] |
Hou X K, He N, Yuan J S. Journal of the Chinese Ceramic Society,2013,41(8),1142(in Chinese).侯新凯,贺宁,袁静舒.硅酸盐学报,2013,41(8),1142.
|
[9] |
Xue P, He D F, Xu A J, et al. Ironmaking & Steelmaking,2017,52(7),104(in Chinese).薛鹏,贺东风,徐安军,等.钢铁,2017,52(7),104.
|
[10] |
Jiang L, Bao Y W, Yang Q X, et al. Steel Research International,2017,88(11),257.
|
[11] |
Jiang L, Bao Y W, Chen Y H, et al. Materials Review B: Research Papers,2018,32(2),650.
|
[12] |
Bale C, Bélisle E, Chartrand P, et al. Calphad,2009,33(2),295.
|
[13] |
Engstr?m F, Adolfsson D, Yang Q, et al. Steel Research International,2010,81(5),362.
|
[14] |
O’neill H S C, Annersten H, Virgo D. American Mineralogist,1992,77(7),725.
|
[15] |
Antao S M, Hassan I, Parise J B. American Mineralogist,2005,90(1),219.
|
[16] |
Dieckmann R, Schmalzried H. Berichte der Bunsengesellschaft für physikalische Chemie,1977,81(3),344.
|
[17] |
Faller J G, Birchenall C E. Journal of Applied Crystallography,1970,3(6),496.
|
[18] |
Goel R, Kellogg H, Rrain J. Metallurgical and Materials Transactions B,1980,11(1),107.
|
[19] |
Keller H, Schwerdtfeger K, Petri H, et al. Metallurgical and Materials Transactions B,1982,13(2),237.
|
[20] |
Ren H J. Nonferrous metals bath smelting, Metallurgical Industry Press, China,2001(in Chinese).任鸿九.有色金属熔池熔炼,冶金工业出版社,2001.
|
[21] |
Zhang L N. Study on selective precipitation valuable constituent in copper smelting slags. Ph.D. Thesis, Northeastern University, China,2005(in Chinese).张林楠.铜渣中有价组分的选择性析出研究.博士学位论文,东北大学,2005.
|
[22] |
Turkin A, Drebushchak V, Kovalevskaya Y, et al. Journal of Thermal Analysis and Calorimetry,2008,92(3),717.
|
[23] |
Blackman L. Journal of the American Ceramic Society,1959,42(3),143.
|
[24] |
Phillips B, Muan A. Journal of the American Ceramic Society,1958,41(11),445.
|
[25] |
Yadav U, Pandey B, Das B, et al. Ironmaking & Steelmaking,2013,29(2),91.
|
[26] |
Paladino A. Journal of the American Ceramic Society,1960,43(4),183.
|
[27] |
Zhang L N, Zhang L, Wang M Y, et al. Acta Physico-Chimica Sinica,2008,24(9),1540(in Chinese).张林楠,张力,王明玉,等.物理化学学报,2008,24(9),1540.
|
[28] |
Semykina A, Nakano J, Sridhar S, et al. Metallurgical and Materials Transactions B,2011,42(6),471.
|
[29] |
Avrami M. The Journal of Chemical Physics,1939,7(12),1103.
|
[30] |
Li J, Xu A, He D, et al. International Journal of Minerals Metallurgy and Materials,2013,20(3),253.
|
|
|
|