Abstract: In recent years, the content of carbonate minerals in Donganshan iron ore has been increasing, leading to deteriorated reverse flotation performances or even “unclear separation between concentrate and tailing”. Based on single mineral flotation tests, SEM and EDS analysis means were used to study the case. The result shows that the adsorptive cover of siderite that is weakly depressible by starch on the hematite and quartz is the main cause for difficult reverse flotation of Donganshan iron ore containing carbonate minerals. Therefore, the key in realizing an efficient separation between the iron minerals and the quartz is to separate the siderite prior to the reverse flotation or to find a flotation agent capable of effectively activating or depressing siderite.

Key words: Siderite, Hematite, Quartz, Reverse flotation