摘要
研究了LiF—LaF，体系下，以La—Nj合金和La金属作可溶性阳极，以Ta为阴极，熔盐电解精炼镧过程中不同工艺条件对槽电压、沉积物形貌、产物杂质含量的影响。采用扫描电镜（SEM）对电解精炼所得La沉积物形貌进行观察，采用电感耦合等离子体质谱法（ICP-MS），辉光放电质谱法（GD—MS），高频燃烧-红外法与惰气脉冲-红外热导法进行最终产品金属La的成分分析。结果表明：槽压与电流之间的线性关系受到接触压降、熔盐性质等因素的影响，控制较高电解温度、使用La-Ni合金代替金属La作阳极时槽压较低；沉积物均为枝晶形貌，电流密度增大导致沉积物的形貌由三维多面体转变为二维片状，电解温度升高导致颗粒几何规则性减弱，低电流密度下沉积物生长机制应为阶梯状生长；金属杂质中W，Ta可由50—100μg·g^-1降至2—3μg·g^-1，使用La阳极的实验所得精炼产物金属镧纯度为99．867％（分析77个杂质元素）。
The influence of various technological conditions on the cell voltage, the morphology of lanthanum dendrites, and impuri- ties in the process of molten salt electrorefining of lanthanum was studied in LiF-LaF3 system, with lanthanum-nickel alloy and lantha- num metal as soluble anode and tantalum rod as cathode. The electrodeposited lanthanum metal was analyzed with scanning electron microsopy （SEM）, inductively coupled plasma-mass spectrometry（ ICP-MS）, glow discharge-mass spectrometry（ GD-MS）, high fre- quency combustion-infrared absorption method, the inert gas fusion infrared absorption/thermal conductivity method. The results showed that the linear relationship between voltage and current was affected by other factors, e.g. the contact voltage drop, the proper- ties of fused salt. High temperature and lanthanum-nickel alloy as anode could reduce the cell voltage. With the increase of deposition current density, the morphology of the electrorefining lanthanum metal changed from polyhedron dendrites to feather-like dendrites. With the increase of fused salt temperature, the morphology of dendrites transformed from convex polyhedron into two dimension flakiness. Step growth mechanism was suggested to explaining the growth of lanthanum dendrites using a low current density. The purity of La by electro- refining with lanthanum anode was 99.867% （ the number of analyzing elements were 77 ）. W and Ta impurity content were both 2 - 3μg·g^-1 in deposited lanthanum, while that in lanthanum anode were 50 - 100μg·g^-1
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2013年第5期770-777,共8页
Chinese Journal of Rare Metals
基金
国家科技部高技术研究发展计划项目(863计划)(2011AA03A409)
国家科技部重点基础研究发展计划项目(973计划)(2012CBA01207)资助
关键词
熔盐
电解精炼
镧
电流密度
fused salt
electrorefining
lanthanum
current density
