Depression mechanism of novel organic phosphoryl depressants on calcite: DFT and coordination studies

Calcite, a commonly encountered gangue mineral, is often found associated with precious metal minerals. The separation of calcite from metallic minerals is typically achieved through flotation, necessitating the development of efficient and targeted calcite depressants. This study focuses on investigating the depressant effects of three novel calcite depressants containing phosphoryl groups, namely aminotrimethylene phosphonic acid (ATMP), tetrasodium (HEDP), and diethylenetriaminepentakis (DTPMPA), through micro-flotation experiments. The obtained flotation results demonstrated the successful depression of calcite by all three reagents, with DTPMPA exhibiting the most pronounced depressing effect. Moreover, density functional theory (DFT) analysis revealed that DTPMPA possessed superior depressant capabilities on the calcite surface compared to the other two novel depressants. Coordination studies further elucidated that phosphoryl groups can form stable 6-coordination structures with calcium atoms on the calcite surface, with the coordination ability being influenced by the molecular properties of the reagents. These findings hold significant implications for achieving an efficient separation of calcite from metallic minerals, emphasizing the importance of developing high-efficiency and targeted calcite depressants.