Recovery of Catapleiite and Eudialyte from Non-Magnetic Fraction of Eudialyte ore Processing of Norra Kärr Deposit

• Published in: Minerals (Basel) Vol. 12; no. 1; p. 19
• Main Authors: Silin, Ivan, Gürsel, Devrim, Büchter, Christian, Weitkämper, Lars, Wotruba, Hermann
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.01.2022
• Subjects: catapleiite; Colour; Energy consumption; Esters; eudialyte; eudialyte ore; Feldspars; Flotation; Impurities; Magnetic separation; Mine tailings; Mineral processing; Mineralogy; Minerals; Nepheline; Norra Kärr; Ores; Phosphoric acid; Rare earth elements; Raw materials; Reagents; REE; Separation; Sustainable development; Tailings; Zirconium; zirconosilicates; United States > US; Sweden; Germany
• ISSN: 2075-163X; 2075-163X
• DOI: 10.3390/min12010019

Eudialyte ores from Norra Kärr (Sweden) and Kringlerne (Greenland) are considered a potential source of rare-earth elements (REE) for the development of a sustainable REE industry outside China. Magnetic separation is successfully applicated to recover eudialyte as a magnetic fraction. In the case of the Norra Kärr deposit, up to 20% of the REE and up to 40% of the Zr are lost during mineral processing in the non-magnetic fraction. Zr and REE are associated with non-magnetic minerals such as catapleiite, low- or non-magnetic eudialyte species, and both their intergrowths. Besides zirconosilicates such as catapleiite and eudialyte, the non-magnetic fraction has valuable and already-liberated minerals such as alkali feldspars and nepheline, which should not be considered as tailings. In this investigation, a possible way to recover REE bearing zirconosilicates from the non-magnetic fraction using flotation is presented. First, a low-grade eudialyte concentrate (1.8% Zr, 0.94% REE) from ground ore was obtained using magnetic separation. The non-magnetic fraction was then treated using froth flotation, and a Zr-REE bearing product (9% Zr, 1.5% REE) was obtained as froth product. For this purpose, phosphoric acid esters were used as selective collectors for zirconosilicates at a pH between 3.5 and 4.5. The reagent regime could be proposed not only to recover Zr- and REE-bearing minerals, but also simultaneously to remove Fe, Ti, and other colored impurities from the nepheline-feldspar product and to minimize the tailings volume.