Heterocoagulation　can　occur　between　fine　siderite　and　hematite　particles,　which　would　result　in　the　low　efficiency　of　their　separation　during　the　flotation　process.　To　date,　there　have　been　no　mature　methods　to　increase　their　separation　efficiency.　In　this　paper,　citric　acid　was　used　as　a　regulator　to　enhance　the　slurry　dispersion　efficiency.　Micro-flotation,　scanning　electron　microscopy　(SEM)　analysis,　settling　tests,　particle　size　measurements,　zeta　potential　measurements　and　E-DLVO　theoretical　calculations　were　conducted　in　the　investigations.　A　maximum　recovery　difference　(53.98%)　between　siderite　and　hematite　in　their　mixtures　flotation　was　obtained.　Settling　tests　confirmed　that　citric　acid　contributed　to　improving　the　dispersion　degree　of　the　slurry.　SEM　analysis　indicated　that　citric　acid　could　clean　the　surface　of　particles　and　weaken　the　coagulation　between　siderite　and　hematite,　which　were　in　line　with　the　results　of　particle　size　measurements.　The　zeta　potential　measurements　and　Extended-Derjaguin-Landau-Verwey-Overbeek　(E-DLVO)　theoretical　calculations　indicated　that　the　citric　acid　could　adsorb　on　the　siderite　and　hematite　surfaces　and　decreased　the　surface　charge,　resulting　in　a　visible　increase　of　the　repulsion　energy　between　siderite　and　hematite　particles.　Therefore,　citric　acid　can　be　applied　to　remove　the　easily-ground　carbonate　minerals　first　to　improve　the　flotation　performance　of　hematite　in　the　separation　process　of　carbonate-containing　iron　ores.　©　Wroclaw　University　of　Science　and　Technology.