Preparation Of Nd-Si Alloy By Direct Electroreduction Of Solid Oxides In Molten LiCl

Presently as a kind of important strategic resources,rare earth has very important value for many fields related to people's livelihood and military.In particular,rare earth have certain irreplaceability in metallurgy,military industry,petrochemical and other fields due to their special photoelectric and magnetic properties.This irreplaceability coupled with the scarcity of rare earth resources has also made rare earth resources a strategic resource of international significance.As a rare earth power country,China has the advantages of the richest rare earth resource reserves,the most uniform varieties,and the largest output,etc.,and has a very important position in the world's rare earth industrial chain.However,with the discovery of new rare earth resources in other countries and the tightening of China's policies on rare earth mining and export,the pattern of the world's rare earth industry is constantly changing.In order to cope with this change,it is very meaningful to use and produce rare earth resources flexibly and efficiently.The proposed FFC process provides a new idea for the conversion of rare earth oxides to rare earths.SiO₂,as one of the most abundant substances on the earth,has the characteristics of being cheap and readily available.Silicon also has a wealth of applications and is of great significance to today's electronic information society.In the early experiments proposed by the FFC process,this method was applied to the reduction of SiO₂.Subsequent research on co-reduction of SiO₂ with other metal oxides has also been conducted.It provides some theoretical basis and support for this article.However,it is the first time that SiO₂ and rare earth oxides have been prepared by molten salt electrolytic co-reduction.In this paper,SiO₂ and rare earth oxides are selected for co-reduction in molten lithium chloride by molten salt electrolysis,and their alloys are obtained.Prove the feasibility of this method.Some representative Nd₂O₃ and SiO₂ co-reductions were selected and their reduction in LiCl molten salt was discussed.Therefore,this article will be divided into the following three aspects:1.The thermodynamic theoretical calculations of the raw materials SiO₂,Nd₂O₃ and SiO₂-Nd₂O₃ mixed systems were performed.Cyclic voltammetry was performed using the hole electrode method.The feasibility of the reduction was verified by theoretical calculation and analysis of the test results of cyclic voltammetry.2.Constant-voltage electrolysis was performed in LiCl molten salt at973K.For the mixed system of SiO₂-Nd₂O₃,the effect of different voltages on its reduction was studied,and the co-reduction process of the mixed system of SiO₂-Nd₂O₃ was investigated based on the reduction at different times under the optimal potential.A control group of the Si-Nd₂O₃ system was set up,and the reduction conditions at different voltages and at different times were also studied to compare the co-reduction process of the two oxides.3.XRD,SEM-EDS and other testing methods were used to characterize the reduction products and verify the reduction results.And according to the reduction results and conditions of the SiO₂-Nd₂O₃ system,constant voltage electrolysis was performed on the SiO₂-Gd₂O₃ system to determine the applicability of the method to heavy rare earth elements.