Fundamental Study On Separation Of Light Rare Earth Elements In P507-HCL-Tartaric Acid System

Since the rare earth(RE) products have particular physical and chemical properties,they are widely used in metallurgy, petrochemical industry, various functional materials and glass ceramic field etc. In order to obtain individual rare earth element or mixed several rare earth elements from mixed rare earth feed, P204 or P507 as extractant saponified by ammonia liquor 0r ammonium acid carbonate are used to separate rare earth elements, but this method Produces drain water contained high concentration NH4+,which heavily give environment pollution.In this thesis, the coordination agent tartaric acid is added to rare earth and the unsaponified P507 is used as extractant in order to improve the process of separating light rare earth. The distribution ratio of rare earth elements in rare earth chloride solution and P507 extractant,separation coefficient, saturated extraction capacity and acidity, citric, acid concentration rare earth concentration were studied. The mechanics and the kinetics of the light rare earth extraction were studied.Under the conditions of different rare earth feed,acidity and tartaric acid concentration,the distribution ratio of the light rare earths and extraction saturated capacity in P507—HCI—Tartaric Acid system were studied by single stage extraction experiments. The ternary linear regression equation of feed acidity,tartaric acid concentration and rare earth concentration was obtained,and the effect of them on the distribution ratio and separation coefficient were analyzed. The results show that,when feed acidity PH is 1.0,tartaric acid concentration 0.25mol/L and rare earth concentration 0.25mol/L, the max distribution ratio(D) comes up to DLa=0.1966?DCe=0.7781?DPr=1.6215 and DNd=2.4899 respectively,the max separation coefficient(?) are ?Ce/La=4.08 ? ?Pr/ce=1.98 and ?Nd/Pr=1.62. Moreover, the capacity of unsoaponified P507 extracting rare earth increases with tartaric acid concentration,its maxium is 29.7g/L, which increases nearly 50% compare to soaponified P507.Simulation experiments of countercurrent extraction indicated that the optimum processing conditions. Best concentration of HCl was 5mol/L, The phase ratio was 2:1(O/A). Back-extraction efficiencies can reached over 98% after 5-stage of stripping. At this point, the aqueous phase was high in rare earth concentrations, but low in acidity. The consistence of residual acid in mixed organic was about 0.8mol/L.The P507—HCl—Tartaric Acid system, which can extracts rare earth directly without saponification, shorten the process line. The new system, which has a good effect in extraction and high separation coefficient, also easy in stripping. In addition, the organic phase has a stable chemical structure and could be recycled. It was a feasible technology proved by experiment. Owing to extraction without saponification, the new process can significantly lowering ammonia nitrogen waste water and reduces the production cost. The new system is a green metallurgical technology.