| The oolitic hematite is abundant in our country and its prospective reserve is more than ten billion ton which accounts for1/9of the total iron ore resourees. However, this kind of iron ore resource around the world has not been widely exploited for its fine particle distribution, complicated structure, complex compostion and a high P content. With the high consumption 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 low grade and refractory hematite ore is quite urgent, which is propitious to ease the contradiction between supply and demand and has great practical significance.Based on the research of mineral technology of the oolitic hematite in Hubei, this paper mainly studies on magnetizing roasting-low intensity magnetic separation-reverse flotation flowsheet for high grade iron concentrate and mainly examines influence of magnetizing roasting temperature and time towards magnetizing roasting effect. Then through observation and statistics of roasted production and XRD qualitative and quantitative correlation analysis, the results show that:Through the reasearch of magnetizing roasting-low intensity magnetic separation-reverse flotation process, determine the optimum conditions as following: magnetizing roasting temperature for800degrees centigrade, magnetizing roasting time for60min, magnetizing roasting reducing agent amount for8percent; magnetic field stength of weak magnetic roughing separation for79.58kA/m, weak magnetic cleaning separation for63.66kA/m, grinding fineness of-0.045mm accounting for84.15percent; pH of reverse flotation for11.0～11.5, activating agent dosage for500g/t, inhibitor dosage for350g/t, collector dosage of1300g/t for reverse roughing flotation, collector dosage of650g/t for reverse cleaning separation. Based on those conditions, the result of magnetizing roasting-low intensity magnetic separation-reverse flotation closed-circuit test process is for: the iron grade of60.24%, the total recovery rate of74.54percent, phosphorus content of0.28percent for the final iron concentrate. The final iron concentrate can be used as ingredients for smelting iron. It needs further study to reduce P content.Observations and statistics for roasted production under optical microscope show that magnetizing roasting reaction is from outside to inside. The particle size and particle distribution of the crude ore has a direct influence on magnetizing roasting process. The smaller the particle size is, the easier the reducing reaction will occur. Magnetizing roasting process can only change iron phase rather than oolitic microstructure, which means that the magnetizing roasted ore has the same microstructure as the crude ore. This is the internal factor that restricts magnetizing roasting effect. XRD quantitative analysis of roasted ore shows that when magnetizing roasting temperature is800℃and magnetizing time is60min, there will be highest magnetite content generated and a small amout of weakly magnetic iron silicate generated. Meanwhile, there is only slight over-reducing reaction and only a small amount of weakly magnetic wustite generated, which means the roasting effect is good. |
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