Researcher: M.Sc. Rita Kallio

Supervisors: Professors Timo Fabritius (metallurgy), Saija Luukkanen (mineral processing) and Ulla Lassi (hydrometallurgy)

Description of the project:

Scandium provides technological advantages particularly in solid oxide fuels cells and aluminum alloys in respect of transportation applications due to its capacity to increase strength and weld-ability. The focus of this project is to develop a material and a cost-efficient process to extract scandium from recently discovered Kiviniemi mafic intrusion, which is a primary scandium occurrence with estimated 13.4 Mt @ 163 ppm Sc. Based on the geochemical characteristics of scandium, its enrichment to ore grades by geological processes is scarce. Consequently, the estimated global Sc production is currently only 15 t/a. With such a limited current global scandium production, the Kiviniemi deposit provides a potential new source for expectedly increasing demand of this unique rare earth metal, classified as critical raw material for European Union. There are no other Kiviniemi-type scandium deposits known in Europe. In the Kiviniemi deposit, scandium occurs in pyroxene and amphibole, which respond well to magnetic preconcentration (Figure 1). In addition to the conventional preconcentration methods, the proposed processing scheme investigated in this research includes high-temperature upgrading of the concentrate to produce Sc-containing amorphous phase along with crude iron. Sc-containing amorphous phase is further treated with hydrometallurgical processes to produce the desired Sc2O3-product. The purpose of this research is to investigate the main features and boundary conditions related to each proposed step, the results of which will be published in appropriate journals. This project promotes the beneficiation of Kiviniemi scandium deposit through interdisciplinary research, extending from mineral processing to the pyrometallurgical treatment and hydrometallurgical aspects of scandium extraction.

Figure 1. Stereomicroscope images of dry magnetic separated fractions from the Kiviniemi sample. The dark particles (black and green) represent scandium-containing pyroxene and amphibole, together with ilmenite, iron oxides and sulphides. The red grains are garnet (almandine) and the colourless or slightly yellow/orange grains are mainly plagioclase and potassium feldspar. A-D): 250-500 µm size fraction separated with A) hand magnet, B) Frantz 0.4 A, C) Frantz 0.8 A and D) Nmags; E-H): 125-250 µm size fraction; I-L): 63-125 µm size fraction; and M-P): 32-63 µm size fraction, separated in respective order.