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Apatite for extraction - Leaching of kiirunavaara apatite for simultaneous production of fertilizers and REE
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
R&D Mineral Processing, LKAB, Kiruna, Sweden.
2012 (English)In: XXVI International Mineral Processing Congress: IMPC 2012, New Delhi, India, September 24-28, 2012 : conference proceedings, New Dehli: The Indian Institute of Metals , 2012, p. 4707-4714Conference paper, Published paper (Refereed)
Abstract [en]

Loussavaara-KiirunavaaraAB's (LKAB) iron ore mine, Kiirunavaara, is of magnetite type and associated with apatite, a calcium phosphate mineral. Rare earth elements (REE) have been found in connection with the apatite but also in other minerals. An apatite concentrate was produced by flotation, in order to investigate the possibilities to extract REE from the apatite by hydrometallurgical means. The content of rare earth elements calculated as oxides (REO) was 0.44% in the concentrate. Initially, leaching was done with large excess of sulfuric acid, hydrochloric acid, and nitric acid to study the REE solubility with different acids. In sulfuric acid, the leaching recoveries of the different REE varied between 35% and 69%. The reasons for the relative low recoveries, were that the rare earth elements precipitated together with huge amounts of gypsum, that was formed during leaching. However, both hydrochloric- and nitric acid gave almost complete extraction of the REE into solution. Analysis of the small leaching residue obtained, revealed, that mainly the light REE remained in the residue indicating that a small part of the light REE were present in the concentrate, in some acid, insoluble mineral other than apatite. With the aim to separate the REE from the phosphoric acid, the solutions from hydrochloric- and nitric acid leaching were neutralized to a pH of approximately 2 with ammonia. During neutralization, REE were precipitated as phosphates with good recoveries and a concentrate of 10.5% REO suitable for further upgrading was obtained, while the remaining solution can be used for fertilizer production. In further solvent extraction studies, it was shown, that after re-dissolution the REE could be effectively extracted by Cyanex 923, thus allowing for purification from calcium and phosphate ions. The REE were finally stripped from the organic phase and a REE nitrate solution was produced.

Place, publisher, year, edition, pages
New Dehli: The Indian Institute of Metals , 2012. p. 4707-4714
Keywords [en]
Apatite, Cyanex 923, Leaching, Rare earth elements, REE, Solvent extraction
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
URN: urn:nbn:se:ltu:diva-27455Scopus ID: 2-s2.0-84879993302Local ID: 0e8dcda5-2c2d-497c-b35d-b64bf3fa6266ISBN: 9788190171434 (print)OAI: oai:DiVA.org:ltu-27455DiVA, id: diva2:1000639
Conference
International Mineral Processing Congress : 24/09/2012 - 28/09/2012
Note

Godkänd; 2012; 20130813 (andbra)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2023-11-11Bibliographically approved

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Sandström, Åke

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