Apatite concentrate originating from iron ore beneficiation at LKAB in Kiruna, Sweden, contains ~3500 mg/kg of Rare Earth Elements (REEs) distributed between three main phases: fluorapatite, allanite and monazite. For the recovery of REEs from apatite to be economically feasible, it is important to identify the composition and distribution of the REEs within the melted and re-solidified concentrate, i.e. within the slag. This will allow further upgrading of the product using an additional mineral-processing step prior to hydrometallurgical treatment and recovery by electrometallurgy.
To reach the present goals, the apatite concentrate was doped with Nd2O3 allowing, through different analytical techniques (SEM-EDS, EPMA, XRD and ICP-MS), the determination of the distribution of REEs to different phases after melting and solidification. The effect of other compounds, such as CaO, SiO2 and Al2O3, on the composition and distribution of the REEs was also studied, and the implications of the pyrometallurgical treatment discussed.