JOAO COUTINHO FERREIRA
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Resumo IPEN-doc 12608 Recovery of thorium and rare earth elements from sludge with the aid of anionic exchanger2006 - ABRAO, ALCIDIO; FERREIRA, JOAO C.; SALVADOR, VERA L.R.; ZINI, JOSIANE; CARVALHO, FATIMA M.S. deAbstract During operation of a solvent extraction pilot plant for preparation of pure thorium nitrate, a thorium concentrate produced industrially from monazite processing in São Paulo containing the REE as main impurities and some minor elements like iron, titanium, lead, sodium and silica was dissolved with hot nitric acid following by digestion and addition of flocculants was filtered for the separation of some insoluble fraction. Thorium was extracted with TBP-diluent in a pulsed column. Small amount of this thorium nitrate was used for nuclear research and the gross production was supplied to some companies that manufacture thorium gas light mantle in Brazil. The raffinate still containing some thorium and the totality of REE was treated with sodium hydroxide and the hydroxides as sludge are stocked. Nowadays there is a stockpile of circa 25 ton of the mentioned material. In this work it is reported a process for separation of thorium from rare earth elements (REE) and their recovery from this accumulated sludge. It is dissolved with hot nitric acid, filtered to separate any insoluble and an excess of acid is added. The prepared solution is fed into a strong anion ion exchanger previously treated with 1mol L-1 HNO3. Thorium nitrate as an anionic complex is retained while REE and other impurities are passed to the effluent. This effluent is treated to obtain a rare earth concentrate for future work of individual separation of the elements. The resin could retain only very small amounts of cerium and lanthanum, but both are excluded when the column is saturated with thorium. Thorium nitrate is eluted with diluted nitric acid. The process is operationally simple and was developed and successfully performed keeping in mind a future installation for the recovery of thorium and rare earths from the above mentioned sludge.Artigo IPEN-doc 19434 Separation of rare earth by column chromatography using organic resins XAD/DEPHA2013 - ZINI, J.; FERREIRA, J.C.; BERGAMASCHI, V.S.; SANTOS, I.; CARVALHO, F.M.S.Artigo IPEN-doc 11967 Behavior of dialysis for the rare earth elements in cationic membranes2007 - FERREIRA, JOAO C.; CARVALHO, FATIMA M.S. de; ZINI, JOSIANE; SCAPIN, MARCOS A.; ABRAO, ALCIDIOIn this work it is presented a dialysis process as an alternative method for the fractionation of rare earth elements. The used cell was set up with a transparent Pyrex glass cylinder with the membrane set in one extreme and using another glass chamber to collect the dialyzed solute. Cationic Membrane: Nafion® 324 manufactured by Dupont and Ionac® MC-3470XL from Sybron Chemicals were used. A series of exploratory experiments allowed concluding that there was some different behavior as function of the nature of the rare earth solutions, i.e, whether the solutions contained nitrate, sulfate or chloride.