自蔓延法铝热还原氧化锆的研究

Self-Propagating Aluminum Thermal Reduction of Zirconium Oxide

研究采用以ZrO2-Al-Mg-Fe2O3-SiO2为反应原料直接还原ZrO2。该方法以铝热还原ZrO2为基础,并结合了自蔓延反应的特点。研究涉及了该体系的热效应、渣金分离、渣和金属物相构成、金属微观形貌和组成等。绝热温度计算表明, ZrO2-Al-Mg-Fe2O3-SiO2体系能满足自蔓延反应的内部温度要求。单位质量热效应的计算表明,体系中加入Fe2O3能有效地提高反应体系的放热量。差热分析(DTA)显示:与ZrO2-Al体系相比, ZrO2-Al-Fe2O3体系在631℃下存在明显放热峰,表明Al与Fe2O3反应放出高热量为ZrO2直接还原及渣金分离提供热能和温度条件。ZrO2-Al-Mg-Fe2O3-SiO2体系直接还原ZrO2得到了以Zr为主要成分的金属,实现了渣金分离。扫描电镜/能谱分析(SEM/EDS)显示:金属球中各部分分层存在,各层间的Zr和Fe的含量存在明显差异,其中富锆相以树枝状结晶析出。惰气熔融红外吸收法分析表明,金属产物氧含量仅为0.024%(质量分数)。该研究为直接还原ZrO2制备锆合金和制备高纯金属锆方法提供了支撑。

The direct reduction of ZrO2 based on the aluminum thermal reduction was studied,which combined the advantages of the self-propagating reaction.ZrO2,Al,Mg,Fe2O3 and SiO2 were used as raw materials.The thermal effect of the system,separation and composition of slag and metal phase,metal microstructure and oxygen content of the metal were involved.The thermal calculation result showed that the addition of Fe2O3 could improve the heat release and ensure the self-propagating reaction in ZrO2-Al-Mg-Fe2O3-SiO2 system.The differential thermal analysis(DTA)results showed that the ZrO2-Al-Fe2O3 system exhibited a significant exothermic peak compared with ZrO2-Al systemat 631℃,due to the reaction of Al and Fe2O3,and the conditions of direct reduction of ZrO2 and the separation of slag and metal were ensured by heat release.The metal with Zr as the main component had been produced in the ZrO2-Al-Mg-Fe2O3-SiO2 system,and the separation of slag and metal were also achieved.The scanning electron microscope/energy dispersive spectroscope(SEM/EDS)results showed that there were some layers in the metal sphere,and the contents of Zr and Fe showed a significant difference between different layers,which was due to that the zirconium-rich phase in the metal product was preferentially precipitated as dendritic crystals.And the oxygen content of the metal reached 0.024%(mass fraction).This study showed the possibility on the preparation of zirconium alloy or high purity zirconium by direct reduction of ZrO2.