Study On Sinter Production Process Optimization Of Low Silicon Mine

Sinter is one of the main man-made rich ores used in blast furnace smelting in modern iron and steel enterprises,and has the advantages of high iron grade and excellent metallurgical properties.In this paper,the fine powder of iron which has low SiO₂ from Xi'ning Iron and Steel Company was used as the main raw material to produce sinter.The optimum proportion of sinter production in low silicon ore and the factors affecting metallurgical properties were explored.The mineral composition and microstructure of sinter were analyzed by means of XRD?X-ray diffraction?analysis and phase microscope scanning.The following conclusions were drawn:The SiO₂ content of the ores was only 2.1%,which was lower than general iron ores,and the content of MgO was higher.There was little liquid phase formation in the sinter preparation in which the low content of SiO₂ of the ores,which led to the bond strength was too small,the yield of sinter decreased,and the performance of low temperature reduction degradation deteriorating.Therefore,it was necessary to optimize the proportioning structure of sinter raw materials.At the same time,MgO has a certain effect on the droplet property of sinter.When MgO in sinter is more than2.2%,the range of softened temperature increased,but the softened temperature decreased at the beginning.Because the main form of iron in Qinghua iron fans is Fe₂O₃,when the proportion of iron concentrate powder to material was too large,the content of Fe₂O₃ increases.Fe₂O₃,which is not involved in the formation of calcium ferrate,resolidification in the process of cooling and consolidation of sinter to produced the crystal shape of Fe₂O₃,which is mostly in the shape of fish ridge.Serious powdering occurred when the sinter is reduced at low temperature.In the process of sintering experiment,it was the amount of carbon which has great influence on the product rate,sintering rate,drum strength and sintering rate of sintering technical index,and a large amount of chemical heat produced by combustion reaction under high carbon content,which can accelerate the sintering rate and improve the rate of finished product.In terms of metallurgical properties of sinter,the proportion of CO in sintering atmosphere was increased because of the high carbon content,that was,the reduction atmosphere is thick.The reaction of high iron elements in sinter with CO to form FeO,results in a sharp decreased in reducibility of sinter.The content of CaO in sinter had obvious influence on its pulverization rate.CaO·Fe₂O₃ series compounds were second only to calcium silicate in their mineral phase structures,and the reducibility index was high,but the melting point of calcium silicate was too high.When the basicity is low,the interlaced sinter calcium ferrate can not be melted to liquid as the bonding phase of the sinter at this reaction temperature,so it was the best choice to use the interwoven sinter calcium ferrate as the bonding phase of the sinter at this reaction temperature.During sintering,sufficient calcium ferrate liquid phase could not be used as binder for sinter.When the alkalinity is too high,the excess CaO in the sinter exists in a free state,and CaO can absorb the moisture in the air to make the sinter.The compressive strength,pulverization index and wear resistance index of sinter become worse.The sintering raw materials should be mixed and the pellets with particle size in6mm¹0mm should be formed to improve the air permeability of the sinter layer.When the carbon content was 5.0%,the alkalinity adjusted to about 2.0,and the proportion of Qinghua iron powder 49.1%,the technical index and metallurgical properties of the sinter can be improved greatly.