Study On The Separation Of Iron, Aluminum And Rare Earths From The Acid Leaching Solution Of Waste Rare Earth Phosphor By Naphthenic Acid Extraction

During the separation of waste rare earth fluorescent acid leaching solution by naphthenic acid extraction,the impurities in the liquid are easy to cause emulsification which brings huge economic loss.Among them,iron and aluminum are the main cause of emulsification of naphthenic acid,in addition,during the extraction process,use various extraction agents can cause the"poisoning"of the extraction agent that has a significant impact on the extraction process.In view of the complexity of the current separation process and extraction agents can easily interact with others,this paper used a single naphthenic acid extraction system to remove iron,aluminum and separate rare earth,and research the process conditions.According to the basic data of separation of rare earth by naphthenic acid which we measured,used cascade extraction simulation software to simulate the actual production process,a single extraction agent system was proposed which can complete the removal of aluminum and iron that solved the problem of subsequent extraction and emulsification,and even separated rare earth that avoided the"poisoning"of the extraction agent.In this paper,the extraction rate of naphthenic acid to iron,aluminum and rare earth was determined by chemical analysis method.The extraction order of naphthenic acid to iron,aluminum and rare earth was obtained.The experimental results showed that the extraction sequence was:iron>aluminum>rare earth.With the decrease of initial iron and aluminum ion concentration,and the initial rare earth concentration increases,the extraction rate of iron and aluminum increased rapidly,and the extraction rate of rare earth increased slowly,so selective separation can be achieved.The optimum composition of the liquid was that Fe³⁺concentration was125mg·L^-1,Al³⁺concentration was 1g·L^-1,RE³⁺concentration was 0.7 mol·L^-1,and the extraction rates of iron,aluminum and rare earth were 100%,90.56%,20.19%.The experiment also studied the separation progress of iron,aluminum and rare earth from naphthenic acid system,and obtained the best extraction conditions,the best washing conditions and the best stripping conditions.Under the best conditions,the extraction rates of iron,aluminum and rare earth were 100%,90.56%,and 20.19%,respectively,the elution rates were 28.75%,4.91%,and 2.35%,and the stripping rates were all higher than 99%.The naphthenic acid extraction system can achieve the purpose of removing iron and aluminum,and the naphthenic acid can also be reused in this process.The distribution ratio of optimum extraction conditions of Ce,Eu,Tb and Y was determined by D_Eu>D_Tb>D_Ce>D_Y,and the separation coefficient between the rare earths was determined by single-stage extraction test.The best separation process was selected according to the basic data:hydrogen peroxide oxidation precipitate Ce+Y/Tb/Eu single feed three-outlet process was proposed which has been proved to be highly feasible and economical by the simulation calculation software EDS-DT and has been verified by actual test of the cascade extraction.