Green Mining | REPRO – Assessment of Rare Earth Metal Recovery Processes
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29 kesä REPRO – Assessment of Rare Earth Metal Recovery Processes

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Name: Assessment of rare earth metal recovery processes

Acronym: REPRO

Duration: 1.1.2012 – 28.2.2014.

Total costs (€)/Tekes support 399 973 € / 239 000 €

Leading research organization partner: Teknologian Tutkimuskeskus Oy  VTT

Contact persons: Lea Räsänen ,VTT, lea.rasanen(at)vtt.fi

www: www.vtt.fi

Research organization partners: Geologian Tutkimuskeskus (GTK), Oulun Yliopisto

Company partners: Yara Suomi Oy, Outotec Oyj

Number of reviewed publications, incl. submitted manuscripts: 2

Number of other publications and reports: 5

Number of thesis: Master 1

Number of patents: 1

Need and motivation of the project:
Rare-earth elements (REE) are naturally occurring non-toxic materials whose extraordinary functional properties have created increasing demand for their uses in emerging technologies that contribute to environmental, energy efficiency and health solutions.

Finland with its apatite and carbonatite mineral deposits is one of the few countries within European Union where REE (rare earth elements) can be found. In the past, as a byproduct of phosphate fertilizer process, a REE concentrate was also semi-commercially manufactured for some years in Finland.

In REPRO project, the past Finnish rare earth concentrate production in connection with the apatite processing were reviewed and possibilities for updating the recovery technologies was surveyed.

 

Key results

The historical production and possible future technologies in the REE recovery from apatite in nitrophosphate ferlizer process, and in the so called wet process phosphoric acid process, are summarized. Kemira process for the recovery of rare earth metals in 1965-1972 in Oulu was the key production process and interviews of former Kemira scientists were performed.

It was concluded that the traditional recovery systems do no offer an economical solution for the REE recovery from apatite mineral containing < 1 wt-% REO and with a high fluoride content. Instead, improved flotation technologies for better recovery of rare earths from the apatite minerals could be developed and alternative extraction techniques for their recovery from either the fertilizer manufacturing streams or from its side product phosphogypsum should be developed.

Improved recovery of REE to apatite concentrate is possible when supported by mineral characterisation and choice of flotation chemicals.  Conventional leaching of REE form the apatite concentrate can be complemented with e.g. liquid-liquid extraction by using generic hydrophobic ionic liquids, bis(2-ethylhexyl)phosphoric acid (DEHPA), and kerosene. Alternatively, ion exchange technology to separate the rare earths from leachates is possible.

Solvent extraction of ion exchange can be used to recover rare earths from phosphogypsum. As an alternative, new sulphate reducing biological (SRB) treatment can be used.  Based on the SRB-approach a new patented method was developed for the recovery of rare earth concentrate from phosphogypsum.

 

Commercialization measures and/or potential

The PCT-period of Koukkari & al.  “Method for recovering rare earth metals from waste sulphates” (FI20136167) will come to end  22.5.2016 and the application will be forwarded to national stages.

 

List of publications

Salminen, J., Virolainen, S., Kinnunen, P., Salmi,O. Sustainable Mining, Metals processing, and Recovery in Chemical Process Technology for a Sustainable Future, T. Letcher, Ed., The Royal Society of Chemistry, RSC, Cambridge, UK, 2015.

Takaluoma, Esther M., Oilunkaniemi, Raija, Lehmann, Christian W., and Laitinen, Risto S. Crystal structure of tris(phenylselenolato-κSe)tris(tetrahydro-furan-κO )thulium(III), Acta Cryst. 2014, E70, m389.

Salminen J., Recovery Of Rare Earth And By-Product Metals From Streams, Minerals in Circular Economy, Mince, Espoo, Finland, 26-27.11.2014.

Salminen, J., Mäkinen, J., Räsänen,L., Koukkari, P., Yang,J., Heino, N., Laitinen,R., Lajunen, M.:REPRO – Assesment of Rare Earth Metal Recovery Processes, TEKES Green Mining Seminar, 26.11. 2014 (poster)

Salminen J., Mäkinen J., Räsänen L., Koukkari P., Rare Earth Metals Recovery From Igneous Sources, The 4th International Conference ’’Mining Industry – View to the Future’’, Kirovsk, Murmansk Region, Russia, 20-21.11.2014.

Salminen, J., Räsänen, L., Mäkinen, J., Kaunisto, J., Koukkari, P., Rare Earth Metals Leaching And Recovery From Igneous Sources, ISSP2014, Karlsruhe, Germany, 21-25.7.2014.

Koukkari, P., Mäkinen,J., Bomberg, M., Lehtonen, A. & Arnold, M. 2013. Method for recovering rare earth metals from waste sulphates. FI 125550 B, 30.11.2015.

Kouri, K., Harvinaisten maametallien kompleksointi ja erottaminen, Kirjallisuuskatsaus, Oulun yliopisto, 2012.