CARLOS ALBERTO DA SILVA QUEIROZ

CARLOS ALBERTO DA SILVA QUEIROZ

Página do item completo

Resultados de Busca

Agora exibindo 1 - 5 de 5

Trace amounts of rare earth elements in high purity samarium oxide by sector field inductively coupled plasma mass spectrometry after separation by HPLC
2006 - PEDREIRA, W.R.; QUEIROZ, C.A.; ABRAO, ALCIDIO; ROCHA, SORAYA M.; VASCONCELLOS, MARI E. de; BOAVENTURA, G.R.; PIMENTEL, M.M.
Pure cerium dioxide preparation for use as spectrochemical standard and analysed by inductively coupled plasma mass spectrometry (SF ICP-MS)
2005 - QUEIROZ, C.A.S.; PEDREIRA, W.R.; ABRAO, A.; ROCHA, S.M.R.; VASCONCELLOS, M.E.; SENEDA, J.A.; FORBICINI, C.A.L.G.O.; BOAVENTURA, G.R.; PIMENTEL, M.M.
Thermoanalytical characterization of neodymium peroxicarbonate
2002 - QUEIROZ, C.A.S.; MATOS, J.R.; VASCONCELLOS, M.E.; ABRAO, A.
Enrichment of yttrium from rare earth concentrate by ammonium carbonate leaching and peroxide precipitation
2006 - VASCONCELLOS, MARI E. de; ROCHA, SORAYA M.R. da; PEDREIRA FILHO, WALTER dos R.; QUEIROZ, CARLOS A. da S.; ABRAO, ALCIDIO
The rare earth elements (REE) solubility with ammonium carbonate vary progressively from element to element, the heavy rare earth elements (HRE) being more soluble than the light rare earth elements (LRE). Their solubility is function of the carbonate concentration and the kind of carbonate as sodium, potassium and ammonium. In this work, it is explored this ability of the carbonate for the dissolution of the REE and an easy separation of yttrium was achieved using the precipitation of the peroxide from complex yttrium carbonate. For this work is used a REE concentrate containing (%) Y2O3 2.4, Dy2O3 0.6, Gd2O3 2.7, CeO2 2.5, Nd2O3 33.2, La2O3 40.3, Sm2O3 4.1 and Pr6O11 7.5. The mentioned concentrate was produced industrially from the chemical treatment of monazite sand by NUCLEMON in Sao Paulo. The yttrium concentrate was ˜ treated with 200 g L−1 ammonium carbonate during 10 and 30 min at room temperature. The experiments indicated that a single leaching operation was sufficient to get a rich yttrium solution with about 60.3% Y2O3. In a second step, this yttrium solution was treated with an excess of hydrogen peroxide (130 volumes), cerium, praseodymium and neodymium peroxides being completely precipitated and separated from yttrium. Yttrium was recovered from the carbonate solution as the oxalate and finally as oxide. The final product is an 81% Y2O3. This separation envisages an industrial application. The work discussed the solubility of the REE using ammonium carbonate and the subsequent precipitation of the correspondent peroxides.
Study on radiogenic lead recovery from residues in thorium facilities using ion exchange and electrochemical process
2010 - SENEDA, J.A.; FORBICINI, C.A.L.G. de O.; QUEIROZ, C.A. da S.; VASCONCELLOS, M.E. de; FORBICINI, S.; RIZZO, S.M. da R.; SALVADOR, VERA L.R.; ABRÃO, A.
Brazil has one of the biggest mineral thorium reserves, enabling the use of this material in its nuclear reactors. Consequently, this cycle of the fuel would need an initial purification stage of the natural thorium, generating residues from chemical treatment. This work provides operational parameters for the recovery of existing values in these residues, especially the radiogenic lead, that is a radioisotope of thorium decay chain, using ionic exchange technique associated to the electrochemical one. The treatment by ionic exchange in anionic resin and hydrochloric acid medium, provides about 33.4% of radiogenic lead. At the electrochemical process, lead was reduced to a metal in nitric acid medium, presenting a recovery of 98%. The electrochemical process presents an increase in the cost, nevertheless the technological importance of the radiogenic lead in the production of new elements, besides being a strategic material, justifies its use.