电解TiO2中间相的形成与溢出气体间的关系

Relationship between interphases formed and gases released during electrolysis of TiO2

摘要:

熔盐电解TiO₂制备金属钛的过程中,钙钛矿是不可避免的中间相,这已得到国内外研究者的公认。本研究借助间断性实验,主要研究了熔盐电解TiO₂制备金属钛过程中,钙钛矿的形成与TiO₂脱氧及阳极产生气体间的关系。研究结果表明,CaCl₂熔盐中电解TiO₂制备金属钛的过程,按其脱氧进程可分为三个主要阶段。第一阶段为 TiO₂脱氧生成钛的低价氧化物,同时O_2-、熔盐Ca₂₊和未脱氧的TiO₂形成CaTiO₃。第二阶段为CaTiO₃脱氧、脱钙及钛低价氧化物继续脱氧为Ti₂O。第三阶段为Ti₂O进一步脱氧为Ti(2% O)。TiO₂脱氧量、熔盐消耗量及形成CaTiO₃量之间的摩尔比为1:1:1, 且钙钛矿形成阶段阳极只有Cl₂放出,钙钛矿形成结束后阳极放出CO₂、CO气体,无Cl₂放出。若以电解TiO₂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。

Abstract:

it is well know that CaTiO₃ is the evitable interphase produced during electrolysis of TiO₂ in molten CaCl₂. Here, the relationship between formation of CaTiO₃ and deoxygenation of TiO₂ and emition of gas on the anode is studied by the intermittent experiments. The results show that the process of deoxygenation from TiO₂ to Ti can be dividied three stages. The first stage is deoxygenantion of TiO₂ and formation of CaTiO₃. The second is deoxyenation and decalcification of CaTiO₃ to Ti₂O including deoxygenation of titanium suboxides. The final stage is deoxygenation from Ti₂O to Ti (2% O). the mole ratio of O_2- and Ca₂₊ and CaTiO₃ is 1:1:1. Cl₂ releases from the anode when CaTiO₃ is formed in the cathode. If the whole electrolysis time from TiO₂ 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 CaTiO₃ and deoxygenation of Ti₂O to Ti are both main factors of the low current effeciency.