铝热法直接还原氧化锆制备金属锆的研究  

Perpetration of Zr from ZrO_(2) by Aluminothermic Reduction

作　　者：黄景存 刘海 马朝辉 闫国庆 王力军 Huang Jingcun;Liu Hai;Ma Zhaohui;Yan Guoqing;Wang Lijun(Division of Rare Metals Metallurgy and Materials,GRIMAT Engineering Institute Co.,Ltd.,Beijing 100088,China)

机构地区：[1]有研工程技术研究院有限公司稀有金属冶金材料研究所,北京100088

出　　处：《稀有金属》2021年第9期1103-1110,共8页Chinese Journal of Rare Metals

基　　金：国家重点研发计划重点专项(2017YFB0305400);国家自然科学基金项目(51674035)资助。

摘　　要：研究改进了金属热还原法制备核级金属锆的工艺,首先采用铝热法直接还原氧化锆制备Al-Zr中间合金,再通过真空电子束熔炼炉真空脱铝精炼得到金属锆。利用差热分析(DSC)确定了铝热还原制备Al-Zr中间合金的理论可行性,发现反应约在945℃发生。通过添加KClO_(3)为发热剂,控制体系热效应为3000 kJ·kg_(-1),加入34.00%(质量分数)的CaO和8.00%的CaF_(2)辅助造渣,产物渣金分离效果显著,Al-Zr中间合金收率可达到73.40%。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、化学成分分析对Al-Zr中间合金进行表征,结果表明:铝热还原法可以成功制备Al-Zr中间合金;其内部微观结构呈层片状,由富Al相和富Zr的Al_(3)Zr相组成,最优氧含量为0.044%。利用Al,Zr饱和蒸汽压差异,通过电子束熔炼炉对中间合金进行真空脱铝精炼。XRD和元素分析表明,电子束炉精炼产物主要为金属锆,其中Zr含量为97.44%,主要杂质气体元素O含量为0.23%,N含量为0.14%。Zirconium had good mechanical properties and processing properties,excellent corrosion resistance in high temperature and high pressure water at 300~400 ℃,low thermal neutron absorption cross section(0.18×10^(-28) m^(2)).Due to the good compatibility with uranium fuel,it was often used as a reactor fuel cladding material.In addition,zirconium hydride was the most ideal neutron moderator material.Therefore,zirconium was an indispensable strategic metal material in the nuclear industry.The main method for preparing metallic zirconium was the Kroll method.The process was mainly divided into two steps:zirconium oxide was coked and chlorinated with chlorine and petroleum coke in a high-temperature furnace to prepare zirconium tetrachloride,and then zirconium tetrachloride was replaced and reduced by magnesium to obtain zirconium sponge.The method had high equipment maintenance cost,used dangerous gas chlorine,could not realize the cycle of magnesium chloride,had poor economy,and the quality of the mass-produced zirconium sponge could not meet the nuclear-level requirements.The metal thermal method for direct reduction of zirconia had simple process,low cost,was clean and efficient,and had high product quality.Therefore,it was of great significance to study and improve the metal thermal reduction method to directly reduce ZrO_(2) to produce nuclear-grade metal zirconium.At present,the reduction of zirconia by the metal thermal reduction method needs to solve two core problems:one is to provide sufficient heat to reach a higher reaction temperature,and the other is to realize the separation of product slag and gold.The research idea in this paper was to add KClO_(3) to the raw material to make a strong exothermic reaction with Al during the preparation of Al-Zr master alloy by thermite reduction of zirconia to provide sufficient heat source for the system;at the same time,CaO and CaF_(2) were also added to assist Al_(2)O_(3) production.Slaging to improve the separation effeciency of slag-gold;then through the electro

关 键 词：铝热还原法 Al-Zr中间合金 渣金分离 脱铝精炼 锆 

分 类 号：TF841.4[冶金工程—有色金属冶金]