Research On Sintering Property And Dezincification Of Magnetite Containing Zinc

Sintering practice can remove some harmful impurities, which provides sinter with good metallurgical property for blast furnace smelting and greatly improve economic and technical index of blast furnace production. Therefore, the index of blast furnace production depends to a large extent on the quality of sinter.There are rich magnetite containing zinc in a certain area, which is mainly made up of Fe3O4, Fe2O3, TFe, Zinc and etc. The content of TFe and Zinc is high, respectively, 62.5% and 0.0845%. Reduction temperature of zinc is low; boiling point of liquid zinc is low. So, zinc compounds are easy to be reduced. When the temperature is increasing, liquid zinc will be gasified. Mixed with coal gas, gasified zinc rises up to the top of and low-temperature area of blast furnace, and then, gas is oxidized and become sediments. When zinc sediments become more and more, sediments could form zinc tumor, which have bad effects on blast furnace, even cause accidents in the sintering practice. Therefore, only through the sintering process, can this kind of zinc-containing magnetite that be selected carefully be used in blast furnace smelting. On the one hand, the content of zinc is reduced; on the other hand, metallurgical property of zinc-containing magnetite is greatly improved, which meet the needs of blast furnace production.This paper, based on sinter pot experiment through basic experimental study, draws a conclusion that physical strength and reduction of this zinc-containing magnetite are low; low temperature reduction degradation is good. The results also be found that adding additives, such as CaCl2, is helpful to dezincification, however, improving carbon addition is not a good way to achieve dezincification. Through observations of mineral phases, conclusions are made:the internal reasons why sinter has the property of bad strength and reduction is that the content of calcium ferrite is low and that the content of magnetite is high; the cause that sinter has good property of low temperature reduction degradation is that the content of hematite is low.Through the quantitative analysis of iron ore powder and additives, conclusions are made:20%of Australian mining are added, the results of dezincification is not good. At the same time, if 0.3%CaCl2 is added, the rate of dezincification is higher, which can reach above 20%. From the perspective of sintering process, the influences of basicity, fuel ratio, stock thickness, exhausting pressure, sinter return ratio, particle size composition, sinter ratio on physical strength of sinter. The optimum proportion through experiments is confirmed as follow:basicity 2.0, fuel ratio 5.5%, stock thickness 616, exhausting pressure 9～10kPa, sinter return ratio 16%, particle size composition 3/7 (coarse/fine), sinter ratio 6/4, (magnetite/hematite).