Flotation reagents can change the surface properties of minerals, leading to differences in the interaction between mineral particles and affecting the mutual aggregation or dispersion of particles. In this work, we studied the role of activator copper sulfate, collector butyl xanthate and frother terpineol in adjusting the potential energy of pyrite particles from the perspective of the interfacial interaction. We evaluated the surface characteristics using contact angle analysis and zeta potential measurements under different reagents. A microscope was used to observe aggregation state of particles. The hydrophobic agglomeration kinetics of pyrite was studied through the turbidity meter measurement, and the interaction energy between pyrite particles was calculated using the extended-Derjaguin-Landau-Verwey-Overbeek (extended-DLVO) theory. The results showed that the repulsive potential energy is dominant among pyrite particles in aqueous suspensions and that the particles are easy to disperse. Flotation reagents can effectively reduce the repulsive energy between pyrite particles and increase the attraction energy between particles, which is conducive to the hydrophobic agglomeration of fine pyrite. Reagent molecules can greatly reduce the electrostatic repulsion potential energy of the pyrite particles’ interface, increase the hydrophobic attraction potential energy between the particle interfaces, and its size is 2 orders of magnitude larger than the van der Waals attraction potential energy, which is the main reason for induced the agglomeration of fine pyrite and is conducive to the flotation recovery of fine pyrite. Generally, the order in which the reduction of pyrite agglomeration was affected by the additions of flotation reagents was butyl xanthate > terpineol > copper sulfate.

In this paper, the influence of sodium hexametaphosphate (SHMP) in coal slime flotation was studied, and the interaction between SHMP and coal slime flotation particles was revealed through XRD test, contact angle measurement, zeta potential test, scanning electron microscopy analysis, XPS analysis, and DLVO theoretical calculation. The experimental results show that when the dosage of SHMP is 1500 g/t, the recovery rate of clean coal combustibles increases by 9.61 %. SHMP reduces the hydrophobicity of clay minerals (kaolinite) in coal slime flotation and also enhances the dispersibility of coal slime particle. Scanning electron microscopy and energy dispersive analysis showed that SHMP reduced the number of clay particles (kaolinite) on the coal surface, thereby reducing the ash content of the clean coal. In this paper, SHMP is mainly used to modify the surface of kaolinite so as to reduce the hydrophobicity of the mineral, that is, to improve the recovery rate of clean coal combustibles in coal slime flotation.