LAUSR

With the aim of high-efficiency utilization of carbonate iron ore, a new beneficiation process of preoxidation-reduction-magnetic separation is proposed. This work focuses on the oxidation and decomposition behavior of carbonate iron ore during the preoxidation. Based on the single factor experiment and non-isothermal analysis results, it shows that with the increasing of oxidation temperature and time, the oxidation degrees of carbonate iron ore increase rapidly. After oxidizing at 773 K for 30 min, the oxidation degrees OX0, D, and y0 reach 97.36%, 99.12%, and 1.475, respectively. Besides, a porous structure forms with a large amount of cracks after oxidation which is beneficial to the gas diffusion. Then both the oxidation and the decomposition of carbonate iron ore are enhanced consequently. And the main phase and structure transformation of carbonate iron ore during the preoxidation is proceeded as follow as FeCO3 (rhombohedral crystal) → Fe3O4 (cubic crystal) → γ-Fe2O3 (cubic crystal) → α-Fe2O3 (rhombohedral crystal). Moreover, the nearest mechanism for carbonate iron ore decomposition within 650–950 K is F1 model, which is random nucleation and subsequent growth. And the values of activation energy and pre-exponential factor are 220.64 kJ mol−1 and 1.510 × 1014 min−1, respectively.