DIDYMIUM SEPARATION FROM LANTHANUM BY SOLVENT EXTRACTION USING 2-ETHYLHEXYLPHOSPHONIC ACID MONO-2-ETHYLHEXYL ESTER AND LACTIC ACID
SEPARAÇÃO DE DIDIMIO E LANTÂNIO A PARTIR DA EXTRAÇÃO POR SOLVENTES USANDO ÉSTER MONO-2-ETIL-HEXÍLICO DO ÁCIDO 2-ETIL-HEXIL FOSFÔNICO E ÁCIDO LÁCTICO
Scal, Maíra Labanca Waineraich; Seruff, Luciana Amaral; Vera, Ysrael Marrero
http://dx.doi.org/10.4322/2176-1523.1131
Tecnol. Metal. Mater. Min., vol.13, n4, p.373-380, 2016
Abstract
This article reports the separation of didymium from lanthanum by solvent extraction using 2-ethylhexyl phosphonic acid mono–2–ethyl hexyl ester (HEH(EHP)) as extracting reagent. The aim of the study was to evaluate the effect of lactic acid addition as well as the feed solution pH variation on the didymium separation from lanthanum. We carried out batch and continuous extraction experiments. In batch experiments, we observed that the extractions of REEs increased along with the increase of lactic acid concentration and feed solution pH. The best conditions for Pr/La separation were obtained at pH 3.5 and lactic concentrations varying between 1.1 and 2.6 times the total REE molar concentration. In the continuous extraction experiments, when no lactic acid was added in the feed solution and with A/O 1:1, the extractions of La, Pr and Nd were 2.0%, 22.3% and 29.5%, respectively. When lactic acid was added in the feed solution, the extractions of La, Pr and Nd were 7.0%, 57.8% and 73.7%, respectively. The addition of lactic acid in the feed solution increased the REE total concentration in the loaded organic phase, the Pr/La separation factor and the total REE mass flow rate, by 2.6, 2.8 and 2.7 times, respectively.
Keywords
Solvent extraction, Rare earth elements, Lactic acid, HEH(EHP).
Resumo
Neste trabalho estudamos a separação de dídimo e lantânio utilizando a técnica de extração por solventes e com o extratante éster mono-2-etil-hexílico do ácido 2-etil-hexil fosfônico (HEH(EHP)). O objetivo deste trabalho foi avaliar o efeito que sobre a separação de didímio e lantânio tem a adição de ácido lático e a variação do pH da alimentação aquosa. Realizamos ensaios em batelada e em regime contínuo. Nos testes em batelada, observamos que o aumento da concentração do ácido láctico e do pH aumentaram a extração dos ETRs. As melhores condições de separação de Pr/La foram obtidas em pH 3,5 e ácido láctico em concentração de 1,1 a 2,6 vezes a concentração de ETRs. Em regime contínuo, para uma razão de fases A/O 1:1 e quando o licor não foi condicionado com ácido lático, as extrações de La, Pr e Nd foram: 2,0%, 22,3% e 29,5%, respectivamente. Quando o licor foi condicionado com ácido lático as extrações de La, Pr e Nd foram: 7,0%, 57,8% e 73,7%, respectivamente. A adição de ácido lático na alimentação aumentou a concentração total de ETRs na fase orgânica carregada, o fator de separação Pr/La e a vazão mássica total de ETRs em 2,6, 2,8 e 2,7 vezes, respectivamente, quando se compara com o teste sem a presença do ácido lático na alimentação.
Palavras-chave
Extração por solventes, Elementos de terras raras, Ácido lático, HEH(EHP).
Referências
1 Gupta CK, Krishnamurthy N. Extractive metallurgy of rare earth. Boca Raton: CRC Press; 2005.
2 Ceccaroli B, Alstad J. Trends in separation factors for the Lanthanum series as obtained in solvent extraction from an aqueous thiocyanate solution. Journal of Inorganic and Nuclear Chemistry. 1981;43:1881-1886.
3 Bhattacharyya SN, Ganguly KM. The effect of complexing agent on the extraction of lanthanides by di(2-ethyl hexyl) phosphoric acid. I. Glycine. Radiochimica Acta. 1986a;39:199-203.
4 Bhattacharyya SN, Ganguly KM. The effect of complexing agent on the extraction of lanthanides by di(2-ethyl hexyl) phosphoric acid. II. 3 – Mercapto propionic acid. Radiochimica Acta. 1986b;40:17-20.
5 Bhattacharyya SN, Ganguly KM. The effect of complexing agent on the extraction of lanthanides by di(2-ethyl hexyl) phosphoric acid. Hydrometallurgy. 1993;32:201-208.
6 Xiaobo S, Yige W, Deqian L. Selective separation of yttrium by CA-100 in the presence of a complexing agent. Journal of Alloys and Compounds. 2006;408-412:999-1002.
7 Yin S, Wu W, Bian X, Zhang F. Solvent extraction of La(III) from chloride medium in the presence of two water soluble complexing agents with di-(2-ethylhexyl) phosphoric acid. Industrial & Engineering Chemistry Research. 2013;52:8558-8564.
8 Chang H, Li M, Liu Z, Hu Y, Zhang F. Study on separation of rare earth elements in complex system. Journal of Rare Earths. 2010;28:116-119.
9 Nair SGK, Smutz M. Recovery of lanthanum from didymium chloride with Di(2-ethylhexyl)-phosphoric acid as solvent. Journal of Inorganic and Nuclear Chemistry. 1967;29(7):1787-1797.
10 Narayanan P, Nair VR, Moharana LN. Commercial production of high purity neodymium oxide from mixed rare earths chloride by solvent extraction using PC-88a as extractant. In: Proceedings of the International Symposium on Solvent Extraction (ISSE); 2002 September 26-27; Bhubaneswar, India. New Delhi: Allied Publishers Pvt. Ltd; 2002. p. 227-234.
11 Morais CA, Ciminelli VST. Process development for the recovery of high-grade lanthanum by solvent extraction. Hydrometallurgy. 2004;73:237-244.
2 Ceccaroli B, Alstad J. Trends in separation factors for the Lanthanum series as obtained in solvent extraction from an aqueous thiocyanate solution. Journal of Inorganic and Nuclear Chemistry. 1981;43:1881-1886.
3 Bhattacharyya SN, Ganguly KM. The effect of complexing agent on the extraction of lanthanides by di(2-ethyl hexyl) phosphoric acid. I. Glycine. Radiochimica Acta. 1986a;39:199-203.
4 Bhattacharyya SN, Ganguly KM. The effect of complexing agent on the extraction of lanthanides by di(2-ethyl hexyl) phosphoric acid. II. 3 – Mercapto propionic acid. Radiochimica Acta. 1986b;40:17-20.
5 Bhattacharyya SN, Ganguly KM. The effect of complexing agent on the extraction of lanthanides by di(2-ethyl hexyl) phosphoric acid. Hydrometallurgy. 1993;32:201-208.
6 Xiaobo S, Yige W, Deqian L. Selective separation of yttrium by CA-100 in the presence of a complexing agent. Journal of Alloys and Compounds. 2006;408-412:999-1002.
7 Yin S, Wu W, Bian X, Zhang F. Solvent extraction of La(III) from chloride medium in the presence of two water soluble complexing agents with di-(2-ethylhexyl) phosphoric acid. Industrial & Engineering Chemistry Research. 2013;52:8558-8564.
8 Chang H, Li M, Liu Z, Hu Y, Zhang F. Study on separation of rare earth elements in complex system. Journal of Rare Earths. 2010;28:116-119.
9 Nair SGK, Smutz M. Recovery of lanthanum from didymium chloride with Di(2-ethylhexyl)-phosphoric acid as solvent. Journal of Inorganic and Nuclear Chemistry. 1967;29(7):1787-1797.
10 Narayanan P, Nair VR, Moharana LN. Commercial production of high purity neodymium oxide from mixed rare earths chloride by solvent extraction using PC-88a as extractant. In: Proceedings of the International Symposium on Solvent Extraction (ISSE); 2002 September 26-27; Bhubaneswar, India. New Delhi: Allied Publishers Pvt. Ltd; 2002. p. 227-234.
11 Morais CA, Ciminelli VST. Process development for the recovery of high-grade lanthanum by solvent extraction. Hydrometallurgy. 2004;73:237-244.
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