| The Oolitic hematite is abundant in our country, accounting for1/9of the total iron ore resources. However, this type iron resource has not been widely exploite for its fine particle distribution, complex structure and compostion. With the high comsumption of high grade ore for easy separation continually, steel industry is facing tremendous pressure from raw material supply. The job of exploring and processing the grade and refractory hematite ore is quietly urgent.In this paper, the samples samples were high phosphorus Oolitite from Guizhou. Firstly, conventional physical benefication methods which include shaking table, high-intensity magnetic separation and floation were used to separate this Oolitite hematite, mainly to study the constraints of conventional separation. Secondly, magnetic roasting-magnetic separation process was used to separate Oolitite hematite and dephosphorization, to find out the affecting factors and appropriate technology systems of this process. Thermodynamics analysis, kinetic analysis, X-ray diffraction and microstructure annlysis were also used to study the mechanism of magnetic roasting-magnetic separation. The results were as followed:(1)The results of physical separation methods indicate that shaking table separation can obtain a relatively good index, with a concentrate of 54.22%Fe grade and 33.74% Fe recovery. Sliming in grinding process and fine particle embedment were the main reasons to restrict Oolitite hematite separation.(2)The results of magnetic roasting-separation show that pellet magnetic roast can obtain a higher grade of iron concentrate than that of powder magnetic roasting with TFe 52.31% growing to 54.20%, but the recoveries were almost the same, keeping at about 80%. Additive can improve the iron recovery of concentrate, but has no more effect on iron grade.(3) the results of dephosphorization indicate that iron concentrate leached by acid can significantly reduce the phosphorus content and increase the iron grade. Under the appropriate acid leaching process, the P content of iron concentrate can be reduced from 0.258% to 0.065% and the Fe grade increased from 54% to 57%.(4) The mechanism research of magnetic roasting-magnetic separation results indicate that the reduction of hematite to magnetite was extremely easy to happen and the Kinetics rate of Magnetic roasting process was fast. So the kinetic was not the restrictive factor of Magnetic roast. However, magnetic roast can only change the phase of iron rather than the microstructure of ore, which means that the magnetic roast ore has the same microstructure to the raw ore. This is the internal reason to restrict magnetic roasting-magnetic separation. Additive can not change the control unit of the reaction, have little effect on the reaction rate of hematite reducing to magnetite, have little effect on the change of the microstructure of ore and promotion of the grain growth and ctystallization of magnetite, so it has little effect to improve the magnetic roasting-magnetic separation. The results of magnetic roasting-magnetic separation depend on the dissemination size and embedment relationship of iron mineral in the ore.This paper, on the basis of magnetic roasting-magnetic separation study, presented the view that magnetic roast can only change the phase of iron rather than the microstructure, especially the dissemination size and distribution of the ore, which revealed the underlying reasons to limit the magnetic roasting-magnetic separation. In addition, additive effect on the separation and the mechanism of Oolitite hematite magnetic roast was studied for the frist time. This reaseach project enriched the magnetic roasting-magnetic separation theory and has a good guidance for the industrial applications of Oolitite hematite with the magnetic roasting-magnetic separation.
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