A Research Of Purification Of Indium By Oxidation Refining-zone Refining Joint Method

Indium is a kind of scattered metal with national strategic significance,with good mechanical,physical and chemical properties,it is widely used in high-tech industries such as electronic communications,photovoltaic industry,aerospace,and national defense,accordingly,people's requirements for its purity are also increasing.Therefore,the research of indium purification technology is of great significance to increase the added value of indium products and promote the development of related industries.This thesis reviewed the distribution,properties,applications,production technology and status of indium at home and abroad.Using 4N9 refined indium as the raw material,a joint oxidation refining-zone refining method was proposed to purify indium,and the heat-fluid coupling finite element analysis was performed on Solidworks.Based on the theoretical analysis of oxidation refining and zone refining,the advantages of oxidation refining removed impurities whose Gibbs free energy was greater than In₂O₃,then zone refining was used to remove impurities whose equilibrium distribution coefficient deviated from 1,so as to realized oxidation refining-zone refining the combined method efficiently purifies indium.In the oxidation refining experiment of indium,the effects of vacuum degree and crucible material on its purification effect were explored,and suitable process conditions were obtained:heating temperature about 200?240?,vacuum degree about 0.006?0.01 MPa,oxygen was introduced for 1 to 2 min,the content of impurities Al,As,Cd,Cu,Tl,Zn,Fe decreased.In addition,according to the experimental results,the distribution ratio of S,Ni and Ag was calculated.In the zone refining experiment of indium,we mainly explored the influence of the number of zone refining and sampling position on its purification effect,and obtained more suitable process parameters:heating temperature about 220?240?,zone refining speed about 30 mm/h,the refining zone width about 40 mm,and the content of Ag,Cd,Cu,Ni and Pb has decreased.The best zone refining number was 12,and the purity of indium was99.9979%.We conducted a heat-fluid coupling finite element analysis on the oxidation refining-zone refining combined method to purify indium.This model more accurately reflectd the temperature field and flow field distribution law of oxidation refining and zone refining.The coupling analysis result of flow field and temperature field showed that the argon flow rate about 0.10 L/min and the refining temperature about 230?were reasonable refining parameters,which were consistent with the experimental data.