The content of carbonate minerals in Dong Anshan iron ore was increasing in recent years, which deteriorated reverse flotation indices or even resulted in unclear separation between concentrate and tailing. In dodecylamine and sodium oleate systems, reverse flotation tests were undertaken with artificial mixed minerals of martite, quartz and siderite. Based on mineral flotation tests, the effect mechanism of siderite on reverse flotation were investigated in terms of SEM and EDS. Results showed that siderite was weakly depressed by starch, and the adsorption of siderite on hematite and quartz was the main cause for reverse flotation difficulties. In reverse flotation in dodecylamine system, the adverse effect of siderite on reverse flotation could be reduced when the amount of starch increased, and iron minerals and quartz were separated effectively. Therefore, the reverse flotation in dodecylamine system could be considered to realize separating effectively iron minerals and quartz of Donganshan iron ore containing carbonates, but which had high requirements on pH. Other methods were siderite being separated prior to reverse flotation or inventing flotation agents capable of effectively activating or depressing siderite.
