Study On The Thermal Reduction Of Zirconium Oxide Based On Self-propagation

According the present situation and existing problems of the preparation process of zirconium or hafnium at this stage,the preparation method of self-propagating metal thermal reduction based on self-propagation is proposed in this paper.The the advantages short reaction time and high energy of self-propagating had been combined with the metal thermal reduction which has the advantages of the simple control and short process.And one pure metal or alloy with high purity,large particle size and low oxygen content is expected to be produced.Thermodynamic calculation had been studied to judge whether the self-propagating reaction could be occurred,and the ratio of the experimental raw materials and the experimental conditions also could be guided.The reduction process and the separation of slag and metal phase had been studied.The structure,morphology and composition of the slag phase and metal phase had been studied by XRD,SEM,EDS,ICP-MS and inert gas pulse infrared thermal conductivity.The following conclusions has been given next.(1)The thermal equilibrium calculations showed that the products Al2O3 and Zr-Al-Fe solid solution would be produced by the reduction ofZrO2-Fe2O3-Al system.(2)The results of experiment of system HfO2-Ca-CaCl2-ZnCl2showed the possibility of the reduction of HfO2,but the main product is CaHfO3.The process needs to be further studied.(3)The DTA analysis showed that the system ZrO2-Fe2O3-Al had a high heat release at 63? C due the the addition of Fe2O3,compared to the ZrO2-Al.(4)Thereaction system of ZrO2-Fe2O3-SiO2-Al-Mgwith the molar ratio ofl:1:5:0.5:0.25 had achieved the effective separation of gold and slag.The analysis showed that the slag phase is composed of Al2O3 and MgAl2O4,which indicated that Al2O3 and MgO were slagging,but SiO2did not play the role of slagging.The metal phase is composed of Al3Zr,[Al,Si,Zr]and Fe,and the main component of the metal phase is Al3Zr.(5)Low oxygen content alloy had been effectively prepared by Al-Mg reduction system and the oxygen content is as low as 0.024%,which isl/5 of nuclear grade zirconiumstandard.It provided a feasible new method for the preparation of high purity zirconium or its alloy.