The role of the silicate groups in the extraction of Mg with the ÅA route method

The principle of the ÅA route method for mineral carbonation is to produce magnesite from Mg cations extracted from silicates, precipitate Mg as Mg(OH)₂ and fuse it with CO₂ to produce magnesite (MgCO₃). Since Mg is situated in distinct parts of the crystal lattice in different silicate groups, it varies from group to group how easily Mg can be extracted. This study focuses on how the lattice structure of various silicate groups influences the mineral carbonation method the ÅA route. Materials on focus include Mg-bearing silicates from neso-, cyclo- and phyllosilicates. The experiments are conducted with the ÅA route, a mineral carbonation method developed at Åbo Akademi University. Based on this study, it can be reinforced that a high Mg content of the raw material does not guarantee success in Mg extraction. Phyllosilicates with high crystalline H₂O provide the highest volumes of Mg. However, other features may diminish the importance of crystalline H₂O. Structural complexity and the location of Mg in the lattice are important factors. Cyclosilicates are excluded from further studies based on unsuccessful results. Despite their low performance in this study, nesosilicates are not yet discarded. Based on the results gained in this study, it can be stated that the lattice characteristics of different silicate groups play a significant role when raw material is selected for mineral carbonation.