Metallurgical and Materials Transactions B

, Volume 49, Issue 1, pp 460–465 | Cite as

The Influence of Lactic Acid Concentration on the Separation of Light Rare Earth Elements by Continuous Liquid–Liquid Extraction with 2-Ethylhexyl Phosphonic Acid Mono-2-ethylhexyl Ester

  • Rafael de Carvalho Gomes
  • Luciana Amaral Seruff
  • Maira Labanca Waineraich Scal
  • Ysrael Marrero Vera


The separation of rare earth elements (REEs) using solvent extraction adding complexing agents appears to be an alternative to saponification of the extractant. We evaluated the effect of lactic acid concentration on didymium (praseodymium and neodymium) and lanthanum extraction with 2-ethylhexyl phosphonic acid mono-2-ethyl hexyl ester [HEH(EHP)] as extractant. First, we investigated in batch experiments the separation of lanthanum (La) and didymium (Pr and Nd) using McCabe–Thiele diagrams to estimate the number of extraction stages when the feed solution was or was not conditioned with lactic acid. Additionally, we conducted continuous liquid–liquid extraction experiments and evaluated the influence of lactic acid concentration on the REE extraction and separation. The tests showed that the extraction percentage of REEs and the separation factor Pr/La increased when the lactic acid concentration increased, but the didymium purity decreased. Lanthanum, praseodymium, and neodymium extraction rate were 23.0, 89.7, and 99.2 pct, respectively, with 1:1 aqueous/organic volume flow rate and feed solution doped with 0.52 mol L−1 lactic acid. The highest didymium purity reached was 92.0 pct with 0.26 mol L−1 lactic acid concentration.



We acknowledge the Brazilian National Council for Scientific and Technological Development (CNPq).


  1. 1.
    C.K. Gupta and N. Krishnamurthy: Extractive Metallurgy of Rare Earth. CRC Press., Boca Raton, Florida, 2005, pp. 172-75.Google Scholar
  2. 2.
    Carlos A. Morais and Virginia S.T Ciminelli. Hydrometallurgy, 2004, vol. 73, pp. 237-244.CrossRefGoogle Scholar
  3. 3.
    G.M. Ritcey: Solvent Extraction. Principles and Applications to Process Metallurgy. G. M. Ritcey & Associates Incorporated, Ottawa, Canada, 2006, pp.Google Scholar
  4. 4.
    W. Wang, H.L. Yang, H.M. Cui, D.L Zhang, Y. Liu and J. Chen, Ind. Eng. Chem. Res., 2011, vol. 50, pp. 7534–7541.CrossRefGoogle Scholar
  5. 5.
    S.H. Yin, S.W. Li, F. Xie, J.H. Peng and L.B. Zhang, RSC Adv, 2015, vol. 5, pp. 64550–64556.CrossRefGoogle Scholar
  6. 6.
    S.H Yin, W. Wu, X. Bian, Y. Luo and F. Zhang, Ind. Eng. Chem. Res., 2013, vol. 52, pp. 8558–8564.CrossRefGoogle Scholar
  7. 7.
    H. Chang, M. Li, Z. Liu, Y. Hu and F. Zhang, J. Rare Earths, 2010, vol. 28, pp. 116.CrossRefGoogle Scholar
  8. 8.
    M.L.W. Scal, L.A. Seruff, Y.M. Vera, Technol. Metal. Mater. Miner., São Paulo, 2016, vol. 13, pp. 373-380.Google Scholar
  9. 9.
    S.H. Yin, S.W. Li, W.Y. Wu, X. Bian, J.H. Peng and L.B. Zhang, RSC Adv., 2014, vol. 4, pp. 59997-600001.CrossRefGoogle Scholar
  10. 10.
    A.B. da Luz and F.F. Lins: Rochas & Minerais Industriais. Usos e Especificações, CETEM/MCT, Rio de Janeiro, RJ, 2005, pp. 629-654.Google Scholar
  11. 11.
    M.L.W. Scal, L.A. Seruff, and Y.M. Vera. 2015. Comparação entre a saponificação do extratante e a adição de ácido lático usados na separação de didímio de lantânio a partir da técnica de extração por solvente. XXVI Encontro Nacional de Tratamento de Minérios e Metalurgia Extrativa.Google Scholar

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2017

Authors and Affiliations

  • Rafael de Carvalho Gomes
    • 1
  • Luciana Amaral Seruff
    • 1
  • Maira Labanca Waineraich Scal
    • 1
  • Ysrael Marrero Vera
    • 1
  1. 1.Center for Mineral Technology (CETEM)Rio de Janeiro-RJBrazil

Personalised recommendations