Molecular dynamics study on selective flotation of hematite with sodium oleate collector and starch-acrylamide flocculant

Molecular dynamics simulation and experimental verification were employed to investigate the selective flocculation flotation of hematite with sodium oleate (NaOl) and starch-acrylamide (St-AM) as the collector and flocculant, respectively. The simulation results revealed that St-AM selectively formed hydrogen bonds on the hematite surface and that hematite underwent flocculation by the bridging action of the flocculant to satisfy the requirements of the flotation particle size. Interaction between sodium oleate and hematite involves physical adsorption and chemical adsorption, while sodium oleate interacts with quartz via van der Waals forces or electrostatic forces. The interaction energy between sodium oleate and hematite was −164.2042 kcal/mol, much lower than −48.7475 kcal/mol between sodium oleate and quartz, indicating that sodium oleate is more likely to interact with hematite. Molecular dynamics simulation calculations revealed that NaOl and St-AM reacted to form a hydrophobic environment on the hematite surface. On the other hand, quartz surface and water formed a hydration layer conducive to the recovery improvement of hematite flotation. The flotation experiment revealed that under optimal flotation conditions of a pH of 8, a stirring speed of 1900 r/min, and a pulp concentration of 5%, the hematite recovery rate was higher than 90%, considerably higher than that of quartz. Infrared spectroscopy revealed that sodium oleate was mainly adsorbed on the hematite floc surface by chemical and physical adsorption, further verifying the accuracy of molecular simulation.