To　address　the　challenges　associated　with　the　agglomeration　and　encapsulation　of　chalcopyrite　by　molybdenite　in　flotation　slurries,　which　hinder　the　effective　separation　of　copper　and　molybdenum,　this　study　investigated　the　effects　of　various　dispersants　on　the　dispersion　behavior　of　chalcopyrite　and　molybdenite,　along　with　the　underlying　mechanisms.　Optical　microscopy,　focused　beam　reflectance　measurements　(FBRM),　infrared　spectroscopy,　zeta　potential　analysis,　and　other　analytical　techniques　were　employed.　The　results　revealed　that　the　dispersion　behaviors　of　chalcopyrite　and　molybdenite　align　with　the　EDLVO　theoretical　model.　At　a　slurry　pH　of　12,　the　dispersant　effectively　dispersed　molybdenite　and　minimized　its　agglomeration　around　chalcopyrite.　The　dispersive　capabilities　of　the　tested　dispersants　followed　the　order:　sodium　carbonate　(Na2CO3)　＞　sodium　hexametaphosphate　(SHMP,　(NaPO3)6)　＞　sodium　silicate　(Na2O·nSiO2)　＞　ammonium　bicarbonate　(NH4HCO3).　Specifically,　carbonate　ions　produced　by　the　hydrolysis　of　Na2CO3　were　chemically　adsorbed　onto　the　molybdenite　surface,　while　hexametaphosphate　primarily　adhered　through　physical　adsorption.　This　adsorption　enhanced　the　dispersion　of　molybdenite　particles　by　increasing　electrostatic　repulsion　between　them.　Mixed　ore　flotation　experiments　demonstrated　that　both　Na2CO3　and　SHMP　significantly　reduced　the　copper　grade　in　the　molybdenum　concentrate,　from　3.95%　to　2.69%　and　2.67%,　respectively.　©　The　Minerals,　Metals　&　Materials　Society　2025.