Study on separation and recycling of iron from Bayan Obo tailings

A method using reduction roasting and magnetic separation to separate and recycle the iron resource from Bayan Obo tailings was proposed in this paper. The variation tendency of the grade and recycling rate of iron in the iron concentrate powder under different conditions of coal powder addition and temperature was studied, meanwhile, the kinetic characteristic of carbon thermal reduction reaction was investigated by weight loss experiment. The results indicated that, given that the mass of the coal powder addition is 62.5% of the tailings, after roasting under the temperature of 1150~1250°C for 180 minutes, the iron concentrate powder can be obtained after magnetic separation, which can be employed as excellent iron-making raw materials. The grade of iron concentrate powder can reach up to 80% and recycling rate of iron can reach up to 75%. At 950°C, during 0~14min the reduction rate was controlled by the gasification of carbon, during 25~60min it was controlled by the diffusion of CO in the product layer, and during14~25min it was controlled by the both; At 1150°C, during 0~12min the reduction rate is controlled by the interface chemical reaction, during 21~44min it was controlled by the diffusion of CO in the product layer, and during 12~21min it was controlled by the both; At 1350°C, during 0~5min the reduction rate was controlled by the interface chemical reaction, during 10~27min it was controlled by the diffusion of CO in the product layer, and during 5~10min it was controlled by the both.