Study On Rare Earth Separation Technology Of P507-non-saponification Buffer Extraction System

Because of its special physical and chemical properties,rare earth is widely used in various fields and become an important strategic resource in China.The main method in rare earth separation is solvent extraction.The pollution of ammonia-nitrogen wastewater during the production is the key problem of the rare earth enterprise.The main reason is using the ammonia or sodium hydroxide in saponification of the extraction process.In view of the above shortcomings,we designed a non-saponification buffer extraction system by using the maleic acid because it has strong buffering capacity to acid.We add the maleic acid in the extraction system and using the non-saponification extraction P507 to separate the rare earth elements,and investigated the of rare earth elements distribution ratio,saturated capacity and separation factor influenced by acidity,maleic acid and rare earth concentrations.And also studied the reaction mechanism.In this paper,the extraction system for P507 buffer were screened,maleic acid found better extraction effect.The buffer theory is when the acidity of the material increases,maleic acid radical combine with hydrogen ions,making modest acidity change of the feed,improving the extraction of rare earth effect.Using the single extraction to study the relationship between the rare earth elements distribution ratio with the rare earth concentrations,acidity and concentrations of maleic acid.Results show that the maximum distribution of rare earth elements is 1.7355 when the concentration of rare earth 0.2mol · L^-1,liquid pH 3.5,maleic acid at a concentration of 0.5 mol · L^-1,Single-grade rare earth extraction volume maximum 0.2285 mol · L^-1.Study the effect of maleic acid concentration on P507 saturation capacity,Results show that the maximum extraction of saturated capacity of Nd?Eu?Tb in the non-saponification buffer extraction system which is 1.44,1.37 and 1.3 times in the P507-oil extraction system.Studied the adjacent rare earth separation coefficient influenced by the rare earth concentrations,acidity and concentrations of maleic acid.The result shows that the adjacent rare earth separation coefficient is increased by liquid PH and decreased by rare earth concentration.Each maximum separation coefficient is?Sm/Nd=12.85,?Eu/Sm=3.32,?Gd/Eu=2.11,?Tb/Gd=7.03,each of them is higher or reach the P507-oil extraction system.The molecular structure of the organic phase was analyzed by infrared spectrum,studied the extraction mechanism of P507 non-saponification buffer extraction system.The P507 nonsaponification buffer extraction system is a cation exchange reaction system.Maleic acid did not enter the organic phase with the rare earth ions.it is just an buffer agent,reduce the acidity of aqueous phase change range by hydrogen ion exchanged during buffer extraction which can improving the extraction efficiency of P507.The P507 non-saponification buffer extraction system use the non-saponification technology can solve the wastewater pollution problem effectively and provides a green and environmentally rare earth extraction and separation method.