| dc.description.abstract | This thesis aims to investigate the mechanisms of formation of hydroxylbastnäsite, a significant source of rare earth elements, in order to uncover the fundamental principles governing its crystallisation. The precise knowledge gap is described in Chapter 1.
In Chapter 2, we investigated the interaction of calcite (CaCO3) and single REE-bearing (La, Nd, Dy) aqueous solutions at low hydrothermal conditions (21-220 ¿C). The role of the calcite surface structure and reactivity, as well as the role of temperature and ionic radius of the REE in question, were discussed.
In Chapter 3, the main objective was to reveal whether the solubility of the host carbonate minerals has an impact on mineralisation processes. Such a question piqued our curiosity as carbonatite deposits frequently contain different Ca-Mg carbonate minerals; thus, we have explored the interaction of single REE-bearing (La, Pr, Nd and Dy) aqueous solutions with aragonite (CaCO3) and dolomite (CaMg(CO3)2) at low hydrothermal conditions (21-220 ¿C).
In Chapter 4, in similar settings to Chapter 2 and 3, Ce was studied. Ce has the oxidation states 3+ and 4+, unlike the rest of the REEs (except Eu). Such results in unique properties, thus the role of Ce in the formation of bastnäsite was studied via mineral replacement and through crystallisation from solution experiments at low hydrothermal conditions. By combining two experimental settings, a more in-depth picture was gained on the behaviour
of Ce in REE-carbonate deposits, revealing the relationship between Ce-carbonates and Ce- oxides.
In Chapter 5, a summary of the findings, their applications, and potential future work are discussed. | en |
