铌铁矿固相合成及碳热还原机理研究
摘要
铌是我国比较紧缺的稀有金属之一,我国的铌资源80%储存在包头白云鄂博矿,且主要以铌铁矿、铌铁金红石、易解石等形式存在。铌铁矿(FeNb_2O_6)作为铌精矿的主要矿物,具有很高的经济价值。本文人工合成纯铌铁矿,然后对铌铁矿进行碳热还原,对还原热力学进行了理论分析。采用等温和非等温TG-DSC结合XRD研究了还原反应过程,深入的探讨了铌铁矿还原的动力学机理。
热力学分析表明,铌氧化物的还原顺序为Nb_2O_5到NbO_2,NbO_2到NbO,NbO到NbC,NbC到Nb。
等温热重分析得到了主体还原过程的表观活化能E=515.2KJ/mol,还原反应的速率常数k与温度T的关系为lnk=36-61995/T,反应的动力学方程为[(1-α)-1/3-1]2= kt,为三维扩散Z-L-T方程,表明气体CO在产物层中过的内扩散为整个反应的限制性环节。
对非等温热分析及XRD分析表明,FeNb_2O_6碳热还原分两步进行:在1100-1240℃,FeNb_2O_6首先被还原为金属Fe和NbO_2,该步骤E=264.4KJ/mol,lnk=17.6-31799/T,反应的动力学方程为α+(1-α)ln(1-α)=kt;在1250-1350℃,第一步的还原产物NbO_2被还原为NbC,该步骤E=482.7KJ/mol,lnk=17.6-31799/T,反应的动力学方程为[(1-α)~(-1/3)-1]~2=kt,与等温法得到的结果一致。非等温热分析法能得到整个还原过程的动力学参数。
Niobium is one of rare metal in short on market in China. Niobium resource with 80% through China is deposited in Baiyunebo Ore, and the minerals concerned are niobite, fersmite and ilmenorutile. Niobite (FeNb_2O_6), usually the main phase composition in niobium concentrate, is of high value in economy. In present paper, pure niobite was synthesized in our laboratory, then subjected to carbothermic reduction. The reaction thermodynamics was analyzed, and the kinetics was investigated using isothermal and non-isothermal thermogravimetry and XRD techniques, the underlying mechanism was discussed.
Thermodynamics study indicates that niobium oxide is reduced stage by stage, following the sequence of Nb_2O_5 to NbO_2, then to NbO, and to NbC finally.
According to isothermal thermogravimetry for overall-range reduction reaction, the activation energy E=515.2 KJ/mol, the rate constant of reaction k is correlated with temperature T by the relationship lnk=36-61995/T, and the reaction kinetics follows the ZLT 3-D diffusion equation [(1-α)~(-1/3)-1]~2= kt, whereαdenotes loss-in-weight rate. It indicates that CO gas diffusion cross the reaction product layer is the controlling step in carbothermic reduction of FeNb_2O_6.
The combining of non-isothermal thermogravimetry with XRD techniques shows FeNb_2O_6 reduction consists of two stages: the first is at the temperature range of 1100-1240℃, FeNb_2O_6 is reduced by CO gass to Fe and NbO_2, the kinetics can be characterized by E=264.4KJ/mol, lnk=17.6-31799/T, andα+(1-α)ln(1-α)=kt. The second occurs at T=1250-1350℃, the first-stage product NbO_2 is reduced to NbC, correspondingly, E=482.7KJ/mol, lnk=17.6-31799/T, [(1-α)~(-1/3)-1]~2=kt, in accord with the results obtained by isothermal thermogravimetry.
热力学分析表明,铌氧化物的还原顺序为Nb_2O_5到NbO_2,NbO_2到NbO,NbO到NbC,NbC到Nb。
等温热重分析得到了主体还原过程的表观活化能E=515.2KJ/mol,还原反应的速率常数k与温度T的关系为lnk=36-61995/T,反应的动力学方程为[(1-α)-1/3-1]2= kt,为三维扩散Z-L-T方程,表明气体CO在产物层中过的内扩散为整个反应的限制性环节。
对非等温热分析及XRD分析表明,FeNb_2O_6碳热还原分两步进行:在1100-1240℃,FeNb_2O_6首先被还原为金属Fe和NbO_2,该步骤E=264.4KJ/mol,lnk=17.6-31799/T,反应的动力学方程为α+(1-α)ln(1-α)=kt;在1250-1350℃,第一步的还原产物NbO_2被还原为NbC,该步骤E=482.7KJ/mol,lnk=17.6-31799/T,反应的动力学方程为[(1-α)~(-1/3)-1]~2=kt,与等温法得到的结果一致。非等温热分析法能得到整个还原过程的动力学参数。
Niobium is one of rare metal in short on market in China. Niobium resource with 80% through China is deposited in Baiyunebo Ore, and the minerals concerned are niobite, fersmite and ilmenorutile. Niobite (FeNb_2O_6), usually the main phase composition in niobium concentrate, is of high value in economy. In present paper, pure niobite was synthesized in our laboratory, then subjected to carbothermic reduction. The reaction thermodynamics was analyzed, and the kinetics was investigated using isothermal and non-isothermal thermogravimetry and XRD techniques, the underlying mechanism was discussed.
Thermodynamics study indicates that niobium oxide is reduced stage by stage, following the sequence of Nb_2O_5 to NbO_2, then to NbO, and to NbC finally.
According to isothermal thermogravimetry for overall-range reduction reaction, the activation energy E=515.2 KJ/mol, the rate constant of reaction k is correlated with temperature T by the relationship lnk=36-61995/T, and the reaction kinetics follows the ZLT 3-D diffusion equation [(1-α)~(-1/3)-1]~2= kt, whereαdenotes loss-in-weight rate. It indicates that CO gas diffusion cross the reaction product layer is the controlling step in carbothermic reduction of FeNb_2O_6.
The combining of non-isothermal thermogravimetry with XRD techniques shows FeNb_2O_6 reduction consists of two stages: the first is at the temperature range of 1100-1240℃, FeNb_2O_6 is reduced by CO gass to Fe and NbO_2, the kinetics can be characterized by E=264.4KJ/mol, lnk=17.6-31799/T, andα+(1-α)ln(1-α)=kt. The second occurs at T=1250-1350℃, the first-stage product NbO_2 is reduced to NbC, correspondingly, E=482.7KJ/mol, lnk=17.6-31799/T, [(1-α)~(-1/3)-1]~2=kt, in accord with the results obtained by isothermal thermogravimetry.
引文
[1]王雪峰.矿产资源保护和合理开发利用的对策建议[J].国土资源导刊,2007,4(3): 11-13.
[2]冯启明,周开灿,高德政,等.矿产资源综合利用与可持续发展问题研究[J],矿产综合利用,2000, 1: 33-36.
[3]国家中长期科学与技术发展规划领导小组办公室.国家中长期科学与技术发展规划研究报告(简本),2006.
[4]余永富.白云鄂博矿稀土、铌资源综合利用研究意义重大[J] .稀土信息,2007, 8: 8-9.
[5]任俊,徐光尧,王文梅.铌-铌矿冶工艺及应用[M].南京:南京大学出版社,2001:165-180.
[6]王中兴.铌-钛超导合金[M].北京:冶金工业出版社.1988:12-13.
[7]Е.Ф.吉夫,А.Н.瓦依森别尔格.钽和铌[M].北京:中国工业出版社,1962:32-33.
[8]傅俊岩.铌科学与技术[M].北京:冶金工业出版社.2003 :28-29.
[9]黄金昌.铌的应用和市场[J].世界有色金属,1997,5:25-28.
[10]屈乃琴,陈久录.铌的应用现状与展望[J] .世界有色金属,1998,11:16-19.
[11]布凤山,刘古田,张红,等.微量稀土对超导稳定化基体铜材的性能和组织的影响[J] .中国稀土学报,1996,14(2):178-181.
[12]赵训志,王鉴,张建伟,等.铌氧化物的催化应用[J] .化工时刊,2005,10:42-44.
[13]李尚诣,周渝生,杜华云,等.铌资源开发应用技术[M].北京:冶金工业出版社,1992:56.
[14]张去非.白云鄂博矿床铌资源矿物学基本特征的分析[J].有色金属,2005,57(2):111-113.
[15]林东鲁,李春龙,邬虎林.白云鄂博特殊矿采冶工艺攻关与技术进步[M].北京:冶金工业出版社,2007:27-29.
[16]蓝兰.铌[M] .北京:中国工业出版社,1964:13-14.
[17]李彬.钽铁矿和铌铁矿在酸性氟化物介质中的分解[J].国外稀有金属,1990,3:16-19.
[18]董一诚,孟涛.包头矿选冶新流程的评价[J].包钢科技,1988,3:19-25.
[19]杨永宜,何旭初,董一诚.包头富铌低铁精矿烧结初步试验研究[J].烧结球团,1987,4:18.
[20]何旭初,范鹏,杨天钧.等.提高高炉冶炼含铌铁矿铌回收率的研究[J] .湖南冶金,1990,4:1-4.
[21]何旭初,杨永宜,董一诚.富铌炉料还原冶炼时铌进入铁相过程的研究[J].湖南冶金,1994,5:8-12.
[22]何旭初,杨永宜,董一诚.富铌炉料中锰含量对还原冶炼时铌收率影响的研究[J].湖南冶金,1991,3:16-20.
[23]冶金部长沙矿冶研究院.包头铌资源综合利用新工艺.1992,12.
[24]马伟,钟祥,贺泽全.等.“两步”还原法制备中级铌铁新工艺中铌收率的研究[J].稀有金属,1996,20(4):254-258.
[25]马伟,钟祥,贺泽全.包头铌精矿内配碳球团还原过程中磷行为的研究[J].稀有金属,1996,16(2):51-54.
[26]屈曙光,毛拥军,钟祥.低品味铌精矿二步电炉熔炼Nb-Fe合金[J].矿冶工程,1997,17(2):46-49.
[27]邹廷信,钟祥,黄元琼.等.电弧炉两步法冶炼包头低品位铌精矿能量平衡[J].矿冶工程,2000,20(3):51-54.
[28]曹永仙,高连让.三相交流工频等离子体冶炼铌铁工艺[J] .第五届等离子体科学技术会议论文集,1989,(10):108-110.
[29]杨世山,李治全,曹永仙,等.包头2号矿体选冶经济高效流程的开发[J] .北京科技大学学报,1995,17(3) .218-223.
[30]方觉,张家元,王志荣,等.包头铌铁矿冶炼实验室研究[J] .东北大学学报,1996,17(1):35-40.
[31]张家元,方觉.包头铌铁矿冶炼实验室研究[J].湖南冶金,2004,32(2):7-14.
[32]陈宏,韩其勇,魏寿昆,等.从含铌铁矿中提取铌及制铌铁的新方法[J] .钢铁,1999,34(3):13-19.
[33]范鹏,周渝生,杨天钧.碳饱和铁液中Nb的溶解度[J].金属学报,1991,27(2):143-145.
[34] West A R. Basic Solid State Chemistry[M]. New York:Wiley,1999.212.
[35]伊腾信一.铌钽矿物的合成及其选矿学性质[J].国外稀有金属,1986,2:33-36.
[36]刘韩星,欧阳世翕.无机材料微波固相合成方法与原理[M] .北京:科学出版社,2006,134-136.
[37]中国科学院贵阳地球化学所.矿物X-射线粉晶鉴定手册[M] .北京:科学出版社,1978:89.
[38] E.T.Turkdogan.Physical Chemistry of High Temperature Technology[J]. New York:Academic Press,1980.109.
[39]李余增.热分析[M] .北京:清华大学出版社,1987,32-34.
[40]陈镜泓,李传儒.热分析及应用[M],北京:科学出版社,1985,121-123.
[41] J.H Flynn.Non-isothermal kinetics in solids[J]. Academic Publisher,1997,300:83-92.
[42] N.Koga,et al.Data Treatment In Non-isothermal Kinetics and Diagnostis Limits of phenomenological models[J].Netsu Sokutei,1993,20(4):210.
[43] N. Koga ,H. Tanaka. Accommodation of the actual solid-state process in the kinetic model function[J]. Journal of Thermal Analysis and Calorimetry.1994,(41):455-469.
[44] D.Dollimore,et.al. Correlation between the shape of a TG/DTG curve and the form of the kinetic mechanism which is applying[J].Thermochim.Acta,1992,198(2): 249-257.
[45] Haruhiko Tanaka.Thermal analysis and kinetics of solid state reactions[J]. Netsu Sokutei,1995,267(1):29-44.
[46] A.Ortega. The use of master plots for discriminating the kinetic model of solid state reactions from single constant-rate thermal analysis experiment[J].Thermochim.Acta, 1996.277(1):165-173.
[47] F.L.Cumbrera,F.Sanchez-Bajo. The use of the JMAYK kinetic equation for the analysis of solid-statereactions:critical considerations and recent interpretations[J]. Thermochim.Acta,1995.266(3):315-330.
[48] J.M.Criado, A.Ortega. Comparative study of the kinetics of the thermal decomposition of synthetic and natural siderite samples[J]. Thermochim.Acta,1990.158(2):205-213.
[49] A.Ortega. The incorrectness of the temperature criterion[J].Thermochim.Acta, 1996,276(1):189-198.
[50]于伯领,姜胶东.实用热分析[M] .北京:纺织工业出版社,1988,142-143.
[51]华一新.冶金过程动力学导论[M] .北京:冶金工业出版社,2004,304-305.
[52]林勤,陈宁,叶文,等.铬铁矿直接还原动力学[J] .现代仪器,1998,(5):29-30.
[53] Lin Qing,Chen Ning,Ye Wen.Knetics of Hydrogen Absorption in Hydrogen Storage Alloy[J].Journal Of Univ Of Sci and Tech Beijing.1997,4(2):34-37.
[54]胡荣祖,史启祯.热分析动力学[M] .北京:科学出版社,2001,127-130.
[55]赵沛,郭培民,张殿伟.机械力促进低温快速反应的研究[J] .钢铁钒钛,2007,28(2):1-5.
[56] A.W.Coats, J.P.Redfern.Kinetic parameters from thermogravimetric data[J]. Nature. 1964,201(4914):68-69.
[57] A.W.Coats, J.P.Redfern.Analyst,1963,88(1052):906-924.
[58]刘建华,张家芸,周坪.Co3O4的氢气还原过程动力学研究[J] .金属学报,2008,36(8),837-841.
[59] Madhusudanan,PM.,Krishnan,K.,Ninan,KN. Thermal decomposition kinetics of the Zn(Ⅱ) complex with norfloxacin in static air atmosphere[J].Thermochim.Acta,1986,97:189-201.
[60] Sanchez-ramos,S.domenech-carbo,A.Gimeno-Adelantado,J.V.Thermal decomposition of chromite spinel with chlorite admixture[J]. Thermochim.Acta,2008,476(1):11-19.
[61] B. N.Achar, G. W.Bringly, J. H.Sharp.Kinetics analysis of thermagravimetric data[C]. Anal. Chem, 1969, 41(14): 2060-2062.
[2]冯启明,周开灿,高德政,等.矿产资源综合利用与可持续发展问题研究[J],矿产综合利用,2000, 1: 33-36.
[3]国家中长期科学与技术发展规划领导小组办公室.国家中长期科学与技术发展规划研究报告(简本),2006.
[4]余永富.白云鄂博矿稀土、铌资源综合利用研究意义重大[J] .稀土信息,2007, 8: 8-9.
[5]任俊,徐光尧,王文梅.铌-铌矿冶工艺及应用[M].南京:南京大学出版社,2001:165-180.
[6]王中兴.铌-钛超导合金[M].北京:冶金工业出版社.1988:12-13.
[7]Е.Ф.吉夫,А.Н.瓦依森别尔格.钽和铌[M].北京:中国工业出版社,1962:32-33.
[8]傅俊岩.铌科学与技术[M].北京:冶金工业出版社.2003 :28-29.
[9]黄金昌.铌的应用和市场[J].世界有色金属,1997,5:25-28.
[10]屈乃琴,陈久录.铌的应用现状与展望[J] .世界有色金属,1998,11:16-19.
[11]布凤山,刘古田,张红,等.微量稀土对超导稳定化基体铜材的性能和组织的影响[J] .中国稀土学报,1996,14(2):178-181.
[12]赵训志,王鉴,张建伟,等.铌氧化物的催化应用[J] .化工时刊,2005,10:42-44.
[13]李尚诣,周渝生,杜华云,等.铌资源开发应用技术[M].北京:冶金工业出版社,1992:56.
[14]张去非.白云鄂博矿床铌资源矿物学基本特征的分析[J].有色金属,2005,57(2):111-113.
[15]林东鲁,李春龙,邬虎林.白云鄂博特殊矿采冶工艺攻关与技术进步[M].北京:冶金工业出版社,2007:27-29.
[16]蓝兰.铌[M] .北京:中国工业出版社,1964:13-14.
[17]李彬.钽铁矿和铌铁矿在酸性氟化物介质中的分解[J].国外稀有金属,1990,3:16-19.
[18]董一诚,孟涛.包头矿选冶新流程的评价[J].包钢科技,1988,3:19-25.
[19]杨永宜,何旭初,董一诚.包头富铌低铁精矿烧结初步试验研究[J].烧结球团,1987,4:18.
[20]何旭初,范鹏,杨天钧.等.提高高炉冶炼含铌铁矿铌回收率的研究[J] .湖南冶金,1990,4:1-4.
[21]何旭初,杨永宜,董一诚.富铌炉料还原冶炼时铌进入铁相过程的研究[J].湖南冶金,1994,5:8-12.
[22]何旭初,杨永宜,董一诚.富铌炉料中锰含量对还原冶炼时铌收率影响的研究[J].湖南冶金,1991,3:16-20.
[23]冶金部长沙矿冶研究院.包头铌资源综合利用新工艺.1992,12.
[24]马伟,钟祥,贺泽全.等.“两步”还原法制备中级铌铁新工艺中铌收率的研究[J].稀有金属,1996,20(4):254-258.
[25]马伟,钟祥,贺泽全.包头铌精矿内配碳球团还原过程中磷行为的研究[J].稀有金属,1996,16(2):51-54.
[26]屈曙光,毛拥军,钟祥.低品味铌精矿二步电炉熔炼Nb-Fe合金[J].矿冶工程,1997,17(2):46-49.
[27]邹廷信,钟祥,黄元琼.等.电弧炉两步法冶炼包头低品位铌精矿能量平衡[J].矿冶工程,2000,20(3):51-54.
[28]曹永仙,高连让.三相交流工频等离子体冶炼铌铁工艺[J] .第五届等离子体科学技术会议论文集,1989,(10):108-110.
[29]杨世山,李治全,曹永仙,等.包头2号矿体选冶经济高效流程的开发[J] .北京科技大学学报,1995,17(3) .218-223.
[30]方觉,张家元,王志荣,等.包头铌铁矿冶炼实验室研究[J] .东北大学学报,1996,17(1):35-40.
[31]张家元,方觉.包头铌铁矿冶炼实验室研究[J].湖南冶金,2004,32(2):7-14.
[32]陈宏,韩其勇,魏寿昆,等.从含铌铁矿中提取铌及制铌铁的新方法[J] .钢铁,1999,34(3):13-19.
[33]范鹏,周渝生,杨天钧.碳饱和铁液中Nb的溶解度[J].金属学报,1991,27(2):143-145.
[34] West A R. Basic Solid State Chemistry[M]. New York:Wiley,1999.212.
[35]伊腾信一.铌钽矿物的合成及其选矿学性质[J].国外稀有金属,1986,2:33-36.
[36]刘韩星,欧阳世翕.无机材料微波固相合成方法与原理[M] .北京:科学出版社,2006,134-136.
[37]中国科学院贵阳地球化学所.矿物X-射线粉晶鉴定手册[M] .北京:科学出版社,1978:89.
[38] E.T.Turkdogan.Physical Chemistry of High Temperature Technology[J]. New York:Academic Press,1980.109.
[39]李余增.热分析[M] .北京:清华大学出版社,1987,32-34.
[40]陈镜泓,李传儒.热分析及应用[M],北京:科学出版社,1985,121-123.
[41] J.H Flynn.Non-isothermal kinetics in solids[J]. Academic Publisher,1997,300:83-92.
[42] N.Koga,et al.Data Treatment In Non-isothermal Kinetics and Diagnostis Limits of phenomenological models[J].Netsu Sokutei,1993,20(4):210.
[43] N. Koga ,H. Tanaka. Accommodation of the actual solid-state process in the kinetic model function[J]. Journal of Thermal Analysis and Calorimetry.1994,(41):455-469.
[44] D.Dollimore,et.al. Correlation between the shape of a TG/DTG curve and the form of the kinetic mechanism which is applying[J].Thermochim.Acta,1992,198(2): 249-257.
[45] Haruhiko Tanaka.Thermal analysis and kinetics of solid state reactions[J]. Netsu Sokutei,1995,267(1):29-44.
[46] A.Ortega. The use of master plots for discriminating the kinetic model of solid state reactions from single constant-rate thermal analysis experiment[J].Thermochim.Acta, 1996.277(1):165-173.
[47] F.L.Cumbrera,F.Sanchez-Bajo. The use of the JMAYK kinetic equation for the analysis of solid-statereactions:critical considerations and recent interpretations[J]. Thermochim.Acta,1995.266(3):315-330.
[48] J.M.Criado, A.Ortega. Comparative study of the kinetics of the thermal decomposition of synthetic and natural siderite samples[J]. Thermochim.Acta,1990.158(2):205-213.
[49] A.Ortega. The incorrectness of the temperature criterion[J].Thermochim.Acta, 1996,276(1):189-198.
[50]于伯领,姜胶东.实用热分析[M] .北京:纺织工业出版社,1988,142-143.
[51]华一新.冶金过程动力学导论[M] .北京:冶金工业出版社,2004,304-305.
[52]林勤,陈宁,叶文,等.铬铁矿直接还原动力学[J] .现代仪器,1998,(5):29-30.
[53] Lin Qing,Chen Ning,Ye Wen.Knetics of Hydrogen Absorption in Hydrogen Storage Alloy[J].Journal Of Univ Of Sci and Tech Beijing.1997,4(2):34-37.
[54]胡荣祖,史启祯.热分析动力学[M] .北京:科学出版社,2001,127-130.
[55]赵沛,郭培民,张殿伟.机械力促进低温快速反应的研究[J] .钢铁钒钛,2007,28(2):1-5.
[56] A.W.Coats, J.P.Redfern.Kinetic parameters from thermogravimetric data[J]. Nature. 1964,201(4914):68-69.
[57] A.W.Coats, J.P.Redfern.Analyst,1963,88(1052):906-924.
[58]刘建华,张家芸,周坪.Co3O4的氢气还原过程动力学研究[J] .金属学报,2008,36(8),837-841.
[59] Madhusudanan,PM.,Krishnan,K.,Ninan,KN. Thermal decomposition kinetics of the Zn(Ⅱ) complex with norfloxacin in static air atmosphere[J].Thermochim.Acta,1986,97:189-201.
[60] Sanchez-ramos,S.domenech-carbo,A.Gimeno-Adelantado,J.V.Thermal decomposition of chromite spinel with chlorite admixture[J]. Thermochim.Acta,2008,476(1):11-19.
[61] B. N.Achar, G. W.Bringly, J. H.Sharp.Kinetics analysis of thermagravimetric data[C]. Anal. Chem, 1969, 41(14): 2060-2062.