Systematic investigation on bastnaesite flotation in the presence of dissolved calcium ions using organic acids as chelating agents

This study systematically investigated the potential of organic acids as Ca²⁺ ions chelating agents in bastnaesite flotation. Naturally, bastnaesite is associated with calcium-bearing gangue minerals, such as calcite (CaCO₃) and fluorite (CaF₂). The flotation beneficiation of bastnaesite in the presence of calcium-bearing minerals (e.g., calcite) is exceptionally complex due to the release of Ca²⁺ ions into the flotation pulp which changes the solution chemistry and bastnaesite surface properties. This study seeks to address the challenge of dissolved Ca²⁺ ions on bastnaesite flotation using organic acids, namely lactic, succinic, and citric acids. Systematic micro-flotation experiments were followed by electro-kinetic tests, solution chemistry studies, and XPS characterization. The results of this study showed that the elevated concentration of Ca²⁺ ions dramatically decreased bastnaesite flotation recovery values. However, organic acids formed soluble chelates with Ca²⁺ ions, effectively eliminating the detrimental impact of dissolved Ca²⁺ ions on bastnaesite flotation.