Study On Process Conditions For Selective Precipitation Of Ce Elements By Mixed Rare Earth Chloride

Cerium is the most abundant element in rare earth elements,and it accounts for about50%of rare earth elements in Baotou rare earth ores.In recent years,with the increasing use of various rare earth elements,the production of cerium as a companion product has been increasing year by year,extraction and separation of Cerium has occupied a large cost in rare earth extraction.The cerium element is oxidized by suitable oxidant,and the trivalent cerium ion is oxidized to tetravalent,and the cerium element is precipitated preferentially in the form of cerium hydroxide by taking advantage of the chemical property difference between the tetravalent cerium and the trivalent rare earth element,the invention can effectively reduce the pressure of the subsequent rare earth extraction and reduce the production cost.In this experiment,the most important process is the oxidation process of cerium.In this study,ozone,hydrogen peroxide and sodium hypochlorite were used as oxidants to oxidize cerium.When ozone is used as the oxidant,orthogonal experimental design is used to determine the best process of ozone cerium oxide.When hydrogen peroxide and sodium hypochlorite are used as the oxidant,the cerium oxidation experiment is carried out under the conditions of different p H,different temperature,and different initial liquid concentration.The optimal conditions of the process are determined,and the oxidation of cerium under different conditions is carried out.Based on kinetic analysis,hydrogen peroxide and sodium hypochlorite are used as the oxidant to follow the first order reaction rate.When using ozone as the oxidant for oxidation,the effect of the reaction conditions on the results was determined through orthogonal experiments,and the experimental conditions were optimized.The reaction temperature was 85?,the reaction time was 4h,the p H of the solution was kept at about 5,and the rare earth concentration of the initial solution was 1.%,when the ozone flux is 1.5L�min^-1,the oxidation rate can reach about 76.29%.When oxidizing cerium with hydrogen peroxide as the raw material,when the reaction temperature is normal temperature and the reaction time is 30 minutes,the p H of the system is about 7,and the initial liquid concentration is 5%,the oxidation rate can reach about 95%.The oxidation reaction is more thorough.When sodium hypochlorite is used as the oxidant,when the reaction temperature is normal temperature and the reaction time is 60min,the p H is 7?8,the initial feed liquid concentration is 2%?5%,the oxidant addition amount is 150%of the theoretical amount,and the oxidation rate can reach 86%about.When pickling the precipitation of cerium hydroxide,when the pickling p H is 2,the liquid-to-solid ratio is2:1ml/g,the stirring speed is 200r/min,and the pickling time is 30min,it has a good pickling effect.Pickling can increase the proportion of cerium in the slag from about 91%to over95%,and the recovery rate of rare earth in the pickling solution is about 4.5%.