高炉炉缸含钛保护层物相及TiC_(0.3)N_(0.7)形成机理
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摘要
基于高炉破损调查取样分析,借助X射线荧光分析、X射线衍射分析、电子探针分析、扫描电子显微镜结合能谱分析等手段分析了高炉炉缸、炉底不同部位形成的含钛保护层化学成分、物相组成和微观形貌,并建立正规溶液热力学模型对Ti(C,N)形成的热力学条件进行分析,然后针对高炉的实际工况,明晰高炉炉缸TiC_(0.3)N_(0.7)形成的条件.结果表明,高炉炉缸侧壁最薄处炭砖残余厚度仅为200 mm;炉缸炉底炭砖表面普遍存在含钛保护层,保护层平均厚度在300～600 mm左右,高炉炉缸不同部位形成的保护层中Ti(C,N)主要以TiC_(0.3)N_(0.7)形式存在,并与Fe相聚集在一起. Ti(C,N)固溶体实际混合摩尔生成吉布斯自由能显著低于标准混合摩尔生成吉布斯自由能和理想混合摩尔生成吉布斯自由能.在不同温度条件下,TiC和TiN在固溶体中存在的比例不同,高温时以析出TiC为主,低温时以析出TiN为主. Ti(C,N)固溶体的形成与高炉热力学状态条件直接相关,TiC_(0.3)N_(0.7)在该高炉炉缸中的形成温度为1423℃.
In theory and practice,TiO_2-bearing iron ores are the preferred raw materials for prolonging blast furnace times due to their protection of the refractory lining of the hearth. Currently,however,a lack of detailed understanding of the mineralogical composition,formation mechanism,and ratio of C to N in the Ti( C,N) solid solution leaves the blast furnace operator unable to employ a scientific and effective measure to deal with abnormal hearth erosion. As a result,frequent hearth breakouts might occur,causing great financial loss to steel companies. In the present work,in an attempt to clarify the essence of longevity blast furnaces,investigations were conducted into blast furnace hearth damage together with dissection analyses,to derive the mineralogical composition and microstructure of titanium-bearing protective layers. The results show that the exact chemical composition of the TiC_xN_(1-x)which formed in the blast furnace is TiC_(0.3)N_(0.7). Based on thermodynamic analysis,the standard Gibbs free energy of the formation of Ti( C,N) decreases at first,then increases with increasing TiC content. At different temperatures,the proportion of TiC and TiN in the solid solution is different,i. e.,more Ti C at higher temperatures but more TiN at lower temperatures. At 1423 ℃,the TiC_(0.3)N_(0.7) is formed in the hot-side of the investigated blast furnace hearth,and the thickness of the titanium-bearing protective layer varies with smelting intensity,temperature,and circulation strength of hot metal. This paper classifies the protective layer into various types based on formation mechanism.Finally,a comprehensive regulatory scheme is presented to act as a basis for extending the lifespan of the blast furnace hearth.
In theory and practice,TiO_2-bearing iron ores are the preferred raw materials for prolonging blast furnace times due to their protection of the refractory lining of the hearth. Currently,however,a lack of detailed understanding of the mineralogical composition,formation mechanism,and ratio of C to N in the Ti( C,N) solid solution leaves the blast furnace operator unable to employ a scientific and effective measure to deal with abnormal hearth erosion. As a result,frequent hearth breakouts might occur,causing great financial loss to steel companies. In the present work,in an attempt to clarify the essence of longevity blast furnaces,investigations were conducted into blast furnace hearth damage together with dissection analyses,to derive the mineralogical composition and microstructure of titanium-bearing protective layers. The results show that the exact chemical composition of the TiC_xN_(1-x)which formed in the blast furnace is TiC_(0.3)N_(0.7). Based on thermodynamic analysis,the standard Gibbs free energy of the formation of Ti( C,N) decreases at first,then increases with increasing TiC content. At different temperatures,the proportion of TiC and TiN in the solid solution is different,i. e.,more Ti C at higher temperatures but more TiN at lower temperatures. At 1423 ℃,the TiC_(0.3)N_(0.7) is formed in the hot-side of the investigated blast furnace hearth,and the thickness of the titanium-bearing protective layer varies with smelting intensity,temperature,and circulation strength of hot metal. This paper classifies the protective layer into various types based on formation mechanism.Finally,a comprehensive regulatory scheme is presented to act as a basis for extending the lifespan of the blast furnace hearth.
引文
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[21] Jonsson S. Assessment of the Fe-Ti--C system calculation of the Fe-Ti--C system and prediction of the solubility limit of Ti(C,N)in liquid Fe. Metall Mater Trans B,1998,29(2):371
[22] Morizane Y,Ozturk B,Fruehan R J. Thermodynamics of Ti Oxin blast furnace type slags. Metall Mater Trans B,1999,30(1):29
[23] Jung I J,Kang S,Jhi S H,et al. A study of the formation of Ti(CN)solid solutions. Acta Mater,1999,47(11):3241
[24] Jung I J,Kang S. A study of the characteristics of Ti(CN)solid solutions. J Mater Sci,2000,35(1):87
[25] Zhang J Y. Physical Chemistry of Metallurgy. Beijing:Metallurgical Industry Press,2004(张家芸.冶金物理化学.北京:冶金工业出版社,2004)
[26] Guo H J. Physical Chemistry of Metallurgy. 2nd Ed. Beijing:Metallurgical Industry Press,2006(郭汉杰.冶金物理化学教程. 2版.北京:冶金工业出版社,2006)
[27] Kang S. Stability of nitrogen in titanium carbonitride solid solutions. Met Powder Rep,1998,53(5):37
[28] Du H G. Blast Furnace Smelting Principle of Vanadium Titanium Magnetite. Beijing:Science Press,1996(杜鹤桂.高炉冶炼钒钛磁铁矿原理.北京:科学出版社,1996)
[29] Jiao K X,Zhang J L,Zuo H B,et al. Composition and formation mechanism of viscous layers in blast furnace hearth. J Northeast Univ Nat Sci,2014,35(7):987(焦克新,张建良,左海滨,等.高炉炉缸黏滞层物相及形成机理.东北大学学报(自然科学版),2014,35(7):987)
[30] Jiao K X,Zhang J L,Hou Q F,et al. Analysis of the relationship between productivity and hearth wall temperature of a commercial blast furnace and model prediction. Steel Res Int,2017,88(9):1600475-1
[2] Liu Z J,Zhang J L,Yang T J. Low carbon operation of superlarge blast furnaces in China. ISIJ Int,2015,55(6):1146
[3] Jiao K X,Zhang J L,Liu Z J,et al. Properties and application of carbon composite brick for blast furnace hearth. J Min Metall Sect B-Metall,2015,51(2):143
[4] Jiao K X,Zhang J L,Liu Z J,et al. Dissection investigation of Ti(C,N)behavior in blast furnace hearth during vanadium titanomagnetite smelting. ISIJ Int,2017,57(1):48
[5] Inada T,Kasai A,Nakano K,et al. Dissection investigation of blast furnace hearth-Kokura No. 2 blast furnace(2nd campaign).ISIJ Int,2009,49(4):470
[6] Shinotake A,Nakamura H,Yadoumaru N,et al. Investigation of blast furnace hearth sidewall erosion by core sample analysis and consideration of campaign operation. ISIJ Int,2003,43(3):321
[7] Takatani K,Inada T,Takata K. Mathematical model for transient erosion process of blast furnace hearth. ISIJ Int,2001,41(10):1139
[8] Jiao K X,Zhang J L,Liu Z J,et al. Analysis of the phase of the solid iron layer in blast furnace hearth. Chin J Eng,2017,39(6):838(焦克新,张建良,刘征建,等.高炉炉缸凝铁层物相分析.工程科学学报,2017,39(6):838)
[9] Zhang J L,Jiao K X,Liu Z J,et al. Comprehensive regulation technology for hearth protective layer of blast furnace longevity.Iron Steel,2017,52(12):1(张建良,焦克新,刘征建,等.长寿高炉炉缸保护层综合调控技术.钢铁,2017,52(12):1)
[10] Li Y,Li Y Q,Fruehan R J. Formation of titanium carbonitride from hot metal. ISIJ Int,2001,41(12):1417
[11] Li Y,Fruehan R J. Thermodynamics of Ti CN and Ti C in Fe-C sat melts. Metall Mater Trans B,2001,32(6):1203
[12] Bai C G,Pei H N,Zhao S J,et al. An investigation of the relationship between the particle size of titanium carbonitride and the viscosity of blast furnace slag bearing high titania. Iron Steel Van Tit,1995,16(3):6(白晨光,裴鹤年,赵诗金,等.碳氮化钛粒度与熔渣粘度关系的研究.钢铁钒钛,1995,16(3):6)
[13] Zhen Y L,Zhang G H,Chou K C. Viscosity of CaO-Mg O--Al2O3-SiO2-Ti O2melts containing Ti C particles. Metall Mater Trans B,2015,46(1):155
[14] Zhen Y L,Zhang G H,Chou K C,et al. Influence of Ti N on viscosity of CaO-Mg O--Al2O3--SiO2--(Ti N)suspension system.Can Metall Q,2015,54(3):340
[15] Liu Y X,Zhang J L,Zhang G H,et al. Influence of Ti(C0. 3N0. 7)on viscosity of blast furnace slags. Ironmak Steelmak,2017,44(8):609
[16] Wang X Q. Blast Furnace Smelting Vanadium Titanium Magnetite. 1st. Beijing:Metallurgical Industry Press,1994(王喜庆.钒钛磁铁矿高炉冶炼. 1版.北京:冶金工业出版社,1994)
[17] Song J C. Titanium Material Protection Technology. Beijing:Metallurgical Industry Press,1994(宋建成.高炉含钛物料护炉技术.北京:冶金工业出版社,1994)
[18] Wada H,Pehlke R D. Nitrogen solubility and nitride formation in austenitic Fe-Ti alloys. Metall Trans B,1985,16(4):815
[19] Ozturk B,Fruehan R J. Thermodynamics of inclusion formation in Fe-Ti-C--N alloys. Metall Trans B,1990,21(5):879
[20] Sumito M,Tsuchiya N,Okabe K,et al. Solubility of titanium and carbon in molten Fe--Ti alloys saturated with carbon. Trans Iron Steel Inst Jpn,1981,21(6):414
[21] Jonsson S. Assessment of the Fe-Ti--C system calculation of the Fe-Ti--C system and prediction of the solubility limit of Ti(C,N)in liquid Fe. Metall Mater Trans B,1998,29(2):371
[22] Morizane Y,Ozturk B,Fruehan R J. Thermodynamics of Ti Oxin blast furnace type slags. Metall Mater Trans B,1999,30(1):29
[23] Jung I J,Kang S,Jhi S H,et al. A study of the formation of Ti(CN)solid solutions. Acta Mater,1999,47(11):3241
[24] Jung I J,Kang S. A study of the characteristics of Ti(CN)solid solutions. J Mater Sci,2000,35(1):87
[25] Zhang J Y. Physical Chemistry of Metallurgy. Beijing:Metallurgical Industry Press,2004(张家芸.冶金物理化学.北京:冶金工业出版社,2004)
[26] Guo H J. Physical Chemistry of Metallurgy. 2nd Ed. Beijing:Metallurgical Industry Press,2006(郭汉杰.冶金物理化学教程. 2版.北京:冶金工业出版社,2006)
[27] Kang S. Stability of nitrogen in titanium carbonitride solid solutions. Met Powder Rep,1998,53(5):37
[28] Du H G. Blast Furnace Smelting Principle of Vanadium Titanium Magnetite. Beijing:Science Press,1996(杜鹤桂.高炉冶炼钒钛磁铁矿原理.北京:科学出版社,1996)
[29] Jiao K X,Zhang J L,Zuo H B,et al. Composition and formation mechanism of viscous layers in blast furnace hearth. J Northeast Univ Nat Sci,2014,35(7):987(焦克新,张建良,左海滨,等.高炉炉缸黏滞层物相及形成机理.东北大学学报(自然科学版),2014,35(7):987)
[30] Jiao K X,Zhang J L,Hou Q F,et al. Analysis of the relationship between productivity and hearth wall temperature of a commercial blast furnace and model prediction. Steel Res Int,2017,88(9):1600475-1