电解TiO_2中间相的形成与溢出气体间的关系
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摘要
熔盐电解TiO_2制备金属钛的过程中,钙钛矿是不可避免的中间相。借助间断性实验研究了熔盐电解TiO_2制备金属钛过程中,钙钛矿的形成与TiO_2脱氧及阳极产生气体间的关系。结果表明,CaCl_2熔盐中电解TiO_2制备金属钛的过程,按其脱氧进程可分为3个主要阶段。第1阶段为TiO_2脱氧生成钛的低价氧化物,同时O~(2-)、熔盐Ca~(2+)和未脱氧的TiO_2形成CaTiO_3。第2阶段为CaTiO_3脱氧、脱钙及钛低价氧化物继续脱氧为Ti_2O。第3阶段为Ti_2O进一步脱氧为Ti(2%O)。TiO_2脱氧量、熔盐消耗量及形成CaTiO_3量之间的摩尔比为1:1:1,且钙钛矿形成阶段阳极只有Cl_2放出,钙钛矿形成结束后阳极放出CO_2、CO气体,无Cl_2放出。若以电解TiO_2到含2%氧的Ti[O]所消耗的时间记为100%的话,那么钙钛矿脱氧、脱钙过程约占总时间的38.9%,而钙钛矿形成的时间只占5.6%,其余时间为钛低价氧化物的脱氧过程。因此钙钛矿的形成是该工艺电流效率低的主要原因之一,钛低价氧化物深脱氧速率低是该工艺的主要限制性环节。
CaTiO_3 is an evitable interphase produced during electrolysis of TiO_2 in molten CaCl_2.Here,the relationship between formation of CaTiO_3 and deoxygenation of TiO_2 and emission of gas on the anode was studied by intermittent experiments.The results show that the process of deoxygenation from TiO_2 to Ti can be divided into three stages.The first stage is deoxygenation of TiO_2 and formation of CaTiO_3.The second stage is deoxygenation and decalcification of CaTiO_3 to Ti_2O including deoxygenation of titanium suboxides.The final stage is deoxygenation from Ti_2O to Ti(2%O).The mole ratio of O~(2-)and Ca~(2+)and CaTiO_3 is 1:1:1.It is only Cl_2 that releases from the anode when CaTiO_3 is formed in the cathode.If the whole electrolysis time from TiO_2 to Ti(2%O)is thought 100%,the cost time of stage I,stage II and stage III is 5.6%,38.9%,55.5%,respectively.Formation of CaTiO_3 and deoxygenation of Ti_2O to Ti are both main factors of the low current efficiency.
CaTiO_3 is an evitable interphase produced during electrolysis of TiO_2 in molten CaCl_2.Here,the relationship between formation of CaTiO_3 and deoxygenation of TiO_2 and emission of gas on the anode was studied by intermittent experiments.The results show that the process of deoxygenation from TiO_2 to Ti can be divided into three stages.The first stage is deoxygenation of TiO_2 and formation of CaTiO_3.The second stage is deoxygenation and decalcification of CaTiO_3 to Ti_2O including deoxygenation of titanium suboxides.The final stage is deoxygenation from Ti_2O to Ti(2%O).The mole ratio of O~(2-)and Ca~(2+)and CaTiO_3 is 1:1:1.It is only Cl_2 that releases from the anode when CaTiO_3 is formed in the cathode.If the whole electrolysis time from TiO_2 to Ti(2%O)is thought 100%,the cost time of stage I,stage II and stage III is 5.6%,38.9%,55.5%,respectively.Formation of CaTiO_3 and deoxygenation of Ti_2O to Ti are both main factors of the low current efficiency.
引文
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[2]Mohandas K S,Fray D J.Metallurgical&Materials Transactions B[J],2009,40(5):685
[3]Jiao S,Fray D J.Metallurgical&Materials Transactions B[J],2010,41(1):74
[4]Jiang K,Hu X,Ma M et al.Angewandte Chemie[J],2006,45(3):428
[5]Du Jihong(杜继红),Xi Zhengping(奚正平),Li Qingyu(李晴宇)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2008,37(12):2240
[6]Zou Xingli(邹星礼),Lu Xionggang(鲁雄钢),Li Chonghe(李重和)et al.Electrochimica Acta(电化学学报)[J],2010,55(18):5173
[7]Prabhat K T,Gauthier M,Fray D J.Metallurgical&Materials Transactions B[J],2007,38(6):893
[8]Wang S L,Li Y.Journal of Electroanalytical Chemistry[J],2004,571(1):37
[9]Wang Shulan,Haarberg G M,Kvalheim E.Journal of Iron and Steel Research[J],2008,15(6):48
[10]Dring K,Dashwood R,Inman D.Journal of the Electrochemical Society[J],2005,152(3):104
[11]Chen G Z,Fray D J.Journal of the Electrochemical Society[J],2002,149(11):455
[12]Kobayashi K,Oka Y,Suzuki R O.Materials Transactions[J],2009,50(12):2704
[13]Schwandt C,Fray D J.Electrochimica Acta[J],2005,51(1):66
[14]Bhagat R,Dye D,Raghunathan S L et al.Acta Materialia[J],2010,58(15):5057