Journal of Sustainable Metallurgy

, Volume 3, Issue 1, pp 79–89 | Cite as

Hydrometallurgical Processing of Eudialyte Bearing Concentrates to Recover Rare Earth Elements Via Low-Temperature Dry Digestion to Prevent the Silica Gel Formation

  • D. VoßenkaulEmail author
  • A. Birich
  • N. Müller
  • N. Stoltz
  • B. Friedrich
Thematic Section: Green Rare Earth Elements--Innovations in Ore Processing, Hydrometallurgy, and Electrolysis


Eudialyte belongs to the group of cyclosilicate minerals and has a significant content of valuable heavy rare earth elements. In comparison to conventional ores like bastnaesite or monazite, the content of radioactive elements like thorium and uranium is quite low; thus, it is an ideal source for the sustainable extraction of rare earth elements (REE). In this way, a further processing or a disposal, direct or after using phase, of radioactive elements could be minimized. The cyclosilicate structure facilitates the easy decomposition of eudialyte by mineral acids. On one hand, this is a positive effect to lixiviate the REEs but leads to an excess liberation of silicon in the water-based system which involves the risk of silica gel formation. Within this research project, a hydrometallurgical pre-treatment is developed to decompose the eudialyte for the extraction of REEs and to stabilize the silicon in the residue during the following leaching step.


Eudialyte Rare earth element Silica gel Dry digestion Aging Fuming Leaching Hydrometallurgy 



This research is part of the Siemens AG collaborative research center S-FB “Green Mining and Separation” at the Aachen University. We thank the organizers of the 11th International Rare Earths Conference in Singapore for the possibility of an advanced presentation of these research findings.


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Copyright information

© The Minerals, Metals & Materials Society (TMS) 2016

Authors and Affiliations

  1. 1.Institute of Process Metallurgy and Metal Recycling (IME)RWTH Aachen UniversityAachenGermany
  2. 2.Institute of Mineralogy and Economic Geology (IML)RWTH Aachen UniversityAachenGermany

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