熔盐电解法生产钛铁合金的铁-钛氧化物电极材料的制备

Preparation of Fe-Ti Oxide Electrode Material for Production of Ti-Fe Alloy by Molten Salt Electrolysis

熔盐电解法是制备难熔金属及其合金的一种有效方法。以钛铁矿精矿与碳粉混合、模压成型,在氩气保护下,分别于1173,1273和1373 K进行一定时间的碳热还原,制备成含有单质铁微粒的铁-钛氧化物电极作为阴极,在673 K的Li Cl-KCl低温熔盐中进行电解还原获得钛铁合金。在1173,1273和1373 K碳热还原反应3 h所得铁-钛氧化物电极中,单质铁的还原率分别为30.1%,80.1%和82.7%;电极的电导率分别为3.14,8.06和10.87 S·m^-1;开口孔隙率分别为46.1%,50.9%和35.2%。其中在1173 K制备的铁-钛氧化物电极中,单质铁呈粒度较小的圆球状,分布较为均匀,但铁的还原率偏低,且强度较低;在1373 K制备的电极中单质铁发生了明显偏析、富集,汇聚成带状,开口孔隙率显著降低,不利于熔盐电解质向电极内部扩散和浸润;而在1273 K制备的电极中单质铁呈圆球状,粒度为2～6μm,分布较为均匀,且开口孔隙率最大,该电极在673 K的KCl-Li Cl低温熔盐中能够电解还原获得钛铁合金,而且电解时通过电极的电流最大。

Molten salt electrolysis is an effective method to prepare refractory metals and their alloys. Fe-Ti oxide electrode containing iron particles was prepared with compression molding of mixture consisting of ilmenite concentration and carbon powder,by carbon thermal reduction in argon atmosphere at 1173,1273 and 1373 K,respectively,then it was electrochemically reduced to Ti Fe alloy in Li Cl-KCl molten salt at 673 K. When the temperatures of carbon thermal reduction were 1173,1273 and 1373 K,the reduction rates of iron in the electrode were 30. 1%,80. 1% and 82. 7%,respectively. The conductivities of the electrode were 3. 14,8. 06 and10. 87 S·m^- 1,respectively,and the open porosities were 46. 1%,50. 9% and 35. 2%,respectively. The reduced iron in the Fe-Ti oxide electrode prepared at 1173 K uniformly distributed and was of small spherical particle,but the reduction rate of iron was low and the electrode strength was inadequate. In the electrode prepared at 1373 K,enrichment,marked segregation,and converging into strips seemed to occur to the reduced iron. This made the open porosity of the electrode decrease significantly,and the electrode like this was not beneficial for molten salt electrolyte diffusing and infiltrating inside the electrode. The iron in the electrode prepared at1273 K was spherical and had particles size of 2 ~ 6 μm,and the phenomenon of uniform distribution and high open porosity could be observed. Ti-Fe alloy could be obtained by the electrolytic reduction in low temperature molten salt of KCl-Li Cl at 673 K,besides the current was the maximum.