Utilization of crown ether as selective collector for the flotation separation of pollucite from feldspar and quartz

Quartz and feldspar are the primary impurities in the mineral processing of pollucite. Due to the highly similar surface properties of these three minerals in terms of physicochemical characteristics, achieving efficient flotation enrichment of pollucite has been a challenging problem. To address this issue, the development of flotation collectors with high selectivity towards pollucite is crucial. In this study, different-sized crown ethers acted as selective collectors for the direct flotation to detach pollucite from feldspar and quartz were investigated, leveraging the selective bonding of crown ethers to alkali metal active site on the surface of pollucite. The properties of 21-crown-7 ether (21C7), benzo-21-crown-7 (B21C7) and dibenzo-21-crown-7 (DB21C7) (with three different cavity sizes) were investigated as collectors for pollucite flotation. The experimental results indicated that DB21C7 exhibited the best collecting performance. The mechanism was studied through various experimental measurements and computational simulations, and the results revealed that the selective adsorption mechanism of crown ethers onto the surface of pollucite was achieved through a combination of chelation interaction involving “spatial effect” and hydrogen bonding interaction. This work has disclosed that crown ether compounds may hold significant potential as collectors for flotation of pollucite.