The characteristics of Huimin high phosphorus limonite ore and the beneficiation of this iron ore by sodium-carbonate-added carbothermic reduction, ultrafine grinding and magnetic separation were investigated. Iron particle size in reduced ore without Na2CO3 additive is tiny and the fayalite is abundant. It is indicated that the formation of fayalite is the main hindrance to accelerate the reduction of limonite. With a mass ratio of Na2O3 to ore of 10% additive, the reduction of limonite can be reinforced. The reinforcing affect may be caused by the increase of the reducing reaction activity of FeO and the acceleration of the carbon gasification reaction rate. Fluorapatite were not reduced in the low temperature reduction process and entered to gangue phases, after ultrafine grinding-magnetic separation process, a qualified iron concentrate with 76.47% Fe, a recovery of 73.20% is obtained with simultaneous decrease in the phosphorus content down to 0.25%.

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The characteristics of Huimin siderite ore with high content of phosphorus and the reduction of this ore bearing pulverized coal and sodium carbonate were investigated. The study focuses on the influence of Na2CO3 dosage on the carbothermic reduction process. Iron particle size in reduced ore is tiny and the fayalite is abundant without Na2CO3 additive. With ratio of Na2CO3 to ore at 1:20 or 1:10, iron particle size in reduced ore is coarse and the diffraction intensity of metallic iron increases obviously in the XRD pattern. The reduction of siderite can be catalyzed by adding an appropriate amount of Na2CO3. The catalyzing activity may be caused by the increase of the reducing reaction activity of FeO and the acceleration of the carbon gasification reaction rate. The phosphorus compounds were not reduced in the low temperature reduction process and remained as fluorapatite in the gangue phases. Ultrafine grinding-magnetic separating of magnetic minerals is an efficient way to obtain qualified iron concentrate.

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