Interaction behavior between coarse-particle pyrite and fine-particle pyrite in flotation.

Pyrite is commonly associated with gold deposits and serves as a gold-bearing mineral. The flotation recovery of gold-bearing pyrite generally determines the overall gold recovery. In this study, pyrite from a gold ore in southwestern Guizhou Province was selected to investigate the interaction behavior between coarse-particle pyrite (CPy) and fine-particle pyrite (FPy) during flotation. Flotation tests were conducted in combination with laser particle size analysis, optical microscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and a self-assembled "Particle Attachment Dynamic Observation System." The results showed that the recovery of FPy (P80 = 26.75 µm) was lower than that of CPy (P80 = 147.89 µm) under the same collector concentration (butyl xanthate). However, the flotation recovery of the CPy-FPy mixture was consistently higher than that of either CPy or FPy alone, particularly at low collector concentrations. Further investigation confirmed that CPy acted as a carrier for FPy, enhancing its recovery into the froth during mixed flotation. Calculations based on the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) model demonstrated that butyl xanthate increases hydrophobic forces between pyrite particles, promoting agglomeration. This finding explains why the flotation recovery of the CPy-FPy mixture in a butyl xanthate suspension exceeds that of CPy or FPy alone.