Abstract: With the increase of siderite content in raw iron ore,the iron grade and recovery of the reverse flotation concentrate derived from Donganshan mixed magnetic concentrate was decreased.In order to well develop the high siderite iron ore resources,and improve the reverse flotation concentrate index,a new modification fatty acids collector DTX-1 synthesized by Northeastern University was used in stepped flotation of the mixed magnetic concentrate,Donganshan Dressing Plant,at room temperature.The results showed that mixed magnetic concentrate of Donganshan Dressing Plant,were treated by the closed-circuit process of siderite concentration by one direct flotation,and desilication by reverse flotation of one roughing,one cleaning,two scavenging and middles back to the flow-sheet,iron concentrate with iron grade of 65.87% and recovery of 67.92% was achieved.Comparing with the concentrate index of on-site reverse flotation process of one roughing,one cleaning and three scavenging,iron grade and recovery of concentrate was increased by 2.47 and 2.82 percentage points respectively,iron concentrate index is improved remarkably with relative complex mineral processing operation.

Key words: Mixed magnetic concentrate, Siderite, Stepped flotation, Direct flotation, Reverse flotation, Collector DTX-1