熔盐电解精炼铪的研究  

Electro-Refining of Hafnium in KCl-NaCl-K_2HfF_6 Molten Salt

作　　者：叶章根[1] 陈松[1] 李文良[1] 吴延科[1] 王力军[1] 

机构地区：[1]北京有色金属研究总院矿物资源与冶金材料研究所,北京100088

出　　处：《稀有金属》2012年第5期791-798,共8页Chinese Journal of Rare Metals

基　　金：总装备部国家重大产业技术开发专项

摘　　要：研究了NaCl-KCl-K2HfF6体系下,以海绵铪和还原铪粉作可溶性阳极,不锈钢为阴极,熔盐电解精炼铪的工艺条件。采用X射线衍射物相分析(XRD)对不同方法制备的铪氟酸钾进行了分析,采用示差扫描量热法(DSC)测量了NaCl-KCl-K2HfF6熔盐体系的熔点,采用扫描电镜(SEM)对该熔盐体系下电解精炼得到的铪粉进行了观察,并采用激光衍射散射式粒度分布测定仪测定了铪粉的粒度分布。结果表明氟硅酸钾烧结法制备的铪氟酸钾纯度高,无有害杂质。最佳工艺条件为:熔盐组成为K2HfF620%(质量分数),NaCl∶KCl为1∶1(摩尔比);电解温度750℃;阳极料为海绵铪和还原铪粉时,电流密度分别为1.2和0.5 A·cm-2。在此条件下得到的铪粉精炼效果良好,产品主要杂质总含量降低至0.07%以下。阴极电流密度较低时,电解得到的铪粉形貌是粗大的块状颗粒,粒度分布在80～150μm之间。增大电流密度,铪粉粒度减小,并出现类似树枝状形貌。进一步增大电流,出现细小的不规则颗粒,粒度分布在40～90μm。增加电解时间可以提高杂质元素与铪之间的分离效果。Process of molten salt electrorefining of hafnium was studied in NaCl-KCl-K2HfF6 system,with hafnium sponge and reducing hafnium powder as solubility anode and stainless-steel rod as cathode.Various analysis methods were used including XRD to K2HfF6 prepared by different methods,DSC to melting point of NaCl-KCl-K2HfF6 molten salt system,SEM to hafnium powder produced by electrorefining in the molten salt system and laser diffraction scattering type size distribution determination to particle size distribution of hafnium.Results showed that the purity of K2HfF6 prepared by K2SiF6 sintering method was high without harmful impurities.Investigation showed that the main impurity contents in hafnium powder decreased to 0.07% under the condition that the K2HfF6 weight ratio of 20%,the NaCl∶ KCl molar ratio of 1∶ 1,temperature of 750 ℃,cathode current density of 1.2 and 0.5 A · cm-2 when anode material was hafnium sponge and reducing hafnium powder.The morphology of hafnium in low current density was thick and massive with the particle size distribution of 80～150 μm,while hafnium powder size decreased and became dendrite in higher current density.Furthermore,hafnium particles became fine and irregular with the particle size distribution of 40～90 μm when it sostenuto increased.Investigation found that prolonging electrolysis time was beneficial to improve the separation of impurity elements from hafnium powder.

关 键 词：熔盐电解 精炼 K2HfF6 铪粉 

分 类 号：TF111.522[冶金工程—冶金物理化学]