Study On Extraction And Enrichment Of Low Concentration Rare Earth And Separation Of Impurity Aluminum By Non-equilibrium With P507

Ion-adsorption rare earth ore,rich in mid-heavy rare earth elements(REEs),is an important strategic resource in China.REEs in ion-adsorption rare earth ore are adsorbed on clay minerals like kaolinite in ionic states to form ion-adsorption rare earth ore with extremely low grade of REO,and they cannot be concentrated through conventional physical beneficiation methods.Conventional ammonium sulfate leaching-ammonium bicarbonate precipitation and enrichment processes have many problems,such as low utilization rate of rare earth,ammonia nitrogen generation and radioactive waste residue pollution.The leaching-extraction integration technology developed by Huang X W can directly enrich and recover rare earth from the leaching solution with low concentration of rare earth,and the high-concentration rare earth chloride can be directly used as raw material for the separation and purification of single rare earth.The yield of rare earth is greatly improved,and the ammonia nitrogen and radioactive waste residue pollution can be solved from the source.The content of REO in the leach solution after in-situ leaching is extremely low,while that of Al is relatively high,and the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore are still unclear,and relevant studies are urgently needed to provide support for the efficient separation of impurity Al in the extraction and enrichment process of low-concentration rare earth.In this paper,the extraction mechanism of the binary extraction system of rare earth and Al was firstly studied.Then,the extraction kinetics of rare earth and Al in the coexistence of rare earth and Al was studied.Finally,the separation behavior of low-concentration rare earth and Al in simulated rare earth leaching solution was studied.The main developments are as follows:(1)The extraction mechanism of the binary extraction system of rare earth and A1 was studied.The results show that the extraction of rare earth ions and Al3+ follows the cation exchange mechanism in the binary extraction system of rare earth and Al.In the unary extraction system,the extraction capacity of P507 for La3+,Nd3+,Y3+and Al3+is ranked as La3+<Al3+<Nd3+<Y3+.When the equilibrium pH of aqueous phase is in the range of 1.38～2.40,with the increase of the equilibrium pH,βRE/Al of binary extraction system of rare earth and Al increases,but it is always greater than that of the single rare earth and Al system.(2)The extraction kinetics of rare earth and Al in the coexistence system of rare earth and Al was studied.The results show that the βRE/Al decreases gradually with the increase of extraction reaction time and the higher the equilibrium pH of aqueous phase,the greater theβRE/Al.The extraction of RE3+is much faster than that of Al3+,but the stability of Al3+-loaded organic phase is greater than that of RE3+-loaded organic phase,thus prolonging the mixing time is conducive to the replacement of rare earth ions in the extraction complex by Al3+ in the aqueous phase.(3)The separation behavior of low-concentration rare earth and Al in simulated rare earth leaching solution was studied.The results show that:with the increase of extraction reaction time,the extraction rates of rare earth and A1 and βRE/Al increase gradually,indicating that prolonging the extraction reaction time appropriately is conducive to the separation of rare earth and Al.With the increase of aqueous phase equilibrium pH,βRE/Al increase gradually in both centrifugal extraction and separation funnel extraction processes,and and βND/Al are always higher than 10 during centrifugal extraction,which is more conducive to the separation of light rare earth and Al.With the increase of the concentration of impurity Al3+,the extraction rates of both RE and Al decrease gradually,but βRE/Al increases gradually,indicating that the centrifugal extraction is beneficial to the separation of rare earth and Al when impurity Al accumulates.With the increase of the concentration of REO,βRE/Al has little change(about 12),and βND/Al,βGd/Al,βY/Al increase gradually(always higher than 40),indicating that improving the separation factor of light rare earth and Al is of great importance for the effective separation of low concentration rare earth and Al.