Study On Electrolytic Refining Of Gallium

Gallium is one of the important materials in high-tech industry.There is an increasing demand of gallium.with the rapid development of smartphones and electronic devices.The study onpurification tecnology of gallium is becoming more and more important.Electrolytic refining is a common method for purifying gallium.But the hydrogen evolution reaction will happen at cathode in electrolytic refining process of Gallium,which may influence the electrolytic refining process and reduce the current efficiency.To control the hydrogen evolution reaction and increase the current efficiency,this thesisis work to optimize the electrolytic process conditions and design the dynamic electrolytic tank,improve electrolyte circulation systerm and employ dynamic electrolysis.This thesis mainly studies three parts:pre-electrolysis,electrolytic refining and recycling of waste electrolyte.Based on the study of experimental factors such as pre-electrolytic time,current density and concentration of NaOH,the rule of the concentration of Ga,the concentration of NaOH,conductivity and current efficiency were determined,and then the pre-electrolytic endpoint was determined.Based on the study of experimental factors such as current density,the concentration of NaOH,the concentration of Ga,electrolytic time,and electrolytic temperature,the rules of the concentration of Ga,the concentration of NaOH,conductivity and current efficiency in static electrolysis were determined,and then the electrolytic parameters were determined,which make the current efficiency achieve a preferredvalue.On the basis of the preferred experimental conditions,do dynamic electrolysis,and then determine whether this method is continuous,study on the influences of the flow rate of electrolyte.The waste electrolyte should be disposed and utilized circularly,study on the influences of current density and electrolytic time,and then the parameters were determined.The experimental results showthat the conditions of pre-electrolysis are as follows:electrolytic time 7 h,current density 22 A/dm2,the concentration of NaOH 150 g/L,pre-electrolytic endpointare determined as of 35 g/L Ga,140 g/L NaOH,current efficiency 71.67%.The conditions of static electrolysis are as ollows:room temperature,current density 2 A/dm2,initial concentration of NaOH 130 g/L,initial concentration of Ga 30g/L,electrolytic time 15 h.The current efficiency is kept at more than 94%generally.The conditions of dynamic electrolysis are as follows:roomtemperature,current density 2 A/dm2,initial concentration of NaOH 130 g/L,initial concentration of Ga 30 g/L,the flow rate of electrolyte 1080 mL/h.Compared with static electrolysis thedynamic electrolysis can effectively reduce the hydrogen evolution reaction,increase the current efficiency,and the current efficiency is kept at more than 96%generally.The product purity is 99.999869%.The conditions of recycling of waste electrolyte are electrolytic time 48h and current density 14 A/dm2,and end of lower concentration of impurities,can be utilized circularly.