Extraction And Separation Of Hydrazine From The Enrichment Solution Of Hydrazine

Heavy rare earth elements(HREEs)were recognized as “super monosodium glutamate” for manufacture,and yttrium(Y)is widely used in rare earth aluminum alloy,rare earth ceramics,laser crystal and other rare earth functional materials.China is abundant in ionabsorbed rare earth deposits,specifically the concentrated yttrium and middle yttriumconcentrated europium ores.But it is an industrial challenge to separate Y and HREEs,beaceuse of Y3+ and HREEs3+ have similar properties.Now,in order to separate Y3+ and HREEs3+,we have to saponificate extracters with NH4+,Na+,Ca2+ or Mg2+ every times before extract and separate Y3+.The process brings up a number of problems,such as consumed a large number of acid and base,generate a lot of waste water,besides that,the poor efficiency of Y3+ and HREEs3+ separation and a high saponification extent will result in the emulsification and third phase during extraction.With the development of China's rare earth industry,sustainable processing for REEs separation is urgently needed.To overcome the pollution from saponification wastewaters,some clean technologies for REEs separation have been developed.The ionic liquid type saponification strategy involves breaking the dimers in acidic extractants by neutralizing the organic phosphinic acid or organic carboxylic acid using quaternary ammonium hydroxide or quaternary phosphonium hydroxide.tri-n-octylmethylammonium bis-secoctylphenoxyl acetate([N1888][CA12])prepared by ionic liquid type saponification for Y3+ and HREEs3+ separation.Furthermore,Tri-n-butyl phosphate(TBP)was used as the phase modifier to accelerate phase separation and improve the stability of organic phase and the quantitative stripping of yttrium and other HREEs3+ from loaded organic phase was achieved with water and NaOH rather than hydrochloric acid.Put forward a technology for separating and purifying Y3+ that ues [N1888][CA12] to separate Y3+ and HREEs3+,quantitative stripping by water,extracters regeneration by NaOH.In this paper,the extraction mechanism and stripping property of bifunctional ionic liquid [N1888][CA12] for yttrium separation were investigated.The extraction mechanism of rare earth elements(REEs)could be deduced as neutral mech-anism combined with ion association via slope analysis and mass balance methods.The extraction order of HREEs in [N1888][CA12] system followed a positive sequence,which is in contrast to that in the CA12 system.The quantitative stripping of yttrium and other HREEs from loaded organic phase was achieved with water rather than hydrochloric acid.Furthermore,a novel sustainable process for the eparation of yttrium from rare earth enrichments using [N1888][CA12] as extractant was developed.Yttrium-enriched rare earth solution containing 0.16 mol/L yttrium and 0.20 mol/L total REEs was adopted as practical feed.Yttrium product with a purity of 99.1 mol.% was obtained via 13 stages of extraction section,8 stages of scrubbing section and 5 stages of stripping section by using separating funnel array.The organic phase consisting of [N1888][CA12] was stable after regeneration.Neither acid nor base was consumed during the extraction,scrubbing and stripping steps.The addition of TBP contributes to shorten phase separation time,increase extraction capacity of REE and decrease viscosity of organic phase.The slope analysis method and infrared spectroscopy were conducted to investigate the ion-association extraction mechanisms.Extraction and stripping performances of the different systems were also compared.The article shows that the extrac-tion performance of [N1888][CA12] and TBP is superior to that of [N1888][CA12] for heavy rare earth elements.In order to recycling extracters fastly,10 stages of stripping section were used to stripping loaded extracters by mixed-settler extractor.After extracters stripped,extracters regenerated by Na OH or Na2C2O4,and removed RE(OH)3 or RE2(C2O4)mechanically by filtration and centrifugation.The concentration of rare earth in recycled eatracters below 10-6 mg/L,it meet the requirements of the recycling extracters.