Fundamental Study On Reduction Process Of Coupled Charge Of BF

In this paper, sinters, pellets and lump ore are studied as the research object. By studying the reduction behavior of iron burden in the blast furnace and soft melting zone, analyzing the behavior change of the wustite in the process of reduction and depending on the reflow characteristic of different charging structure, the reasonable structure of blast furnace is found. The results indicates that firstly in the area of low temperature, with the temperature increasing gradually, the weight loss rate of the three iron ores increased linearly. Secondly the reduction rate of the three iron ores showed the same law to the weight loss rate. When the temperature is 950 deg.c, weight loss curve of three iron ores tends to be gentle, suggesting that when the reduction is carried out to a certain extent, even if time of the reduction reaction is extended, the weight loss rate is also very difficult to upgrade.In high temperature zone of 1100~1400?, with the increase of temperature and alkalinity, the weight loss rate of the ore increases linearly. From 1100? to1400?,with the increase of temperature, the content of FeO in the charge decreases gradually but the metallization ratio increases;. With the increase of alkalinity from 1.16 to 1.39,the weight loss of the charge, the content of FeO and its metallization rate increases gradually. The soft melting temperature of the charge is higher when the alkalinity rate is 1.39.At the same time the relationship between the melting temperature and the properties of liquid phase formation and composition of FeO-CaO-SiO2-MgO-Al2O3 five slag is analysed by Fact Sage software. The results show that with the increase of temperature, area of slag liquid increases significantly, improving the fluidity of slag.The melting temperature of slag increases with the increase of two element alkalinity.When two element alkalinity is less than 1, the melting temperature varies very little with the increase of FeO content. When two element alkalinity is greater than 1, the melting temperature varies obviously with the increase of FeO content. With the increase of the content of Al2O3, the melting temperature of the slag decreases firstly and then increases, and the melting temperature of the slag increases with the increasing of FeO content. Therefore, in order to ensure the slag fluidity, the mass fraction of Al2O3 in slag should be kept at about 16%.. When the mass fraction of FeO is less than 15%, the melting temperature of slag decreases firstly and then increases with the increase of MgO content. When the mass fraction of Fe O is greater than 15%,the melting temperature of slag increases with the increase of MgO content. Therefore,in order to ensure the reasonable and good fluidity of the slag melting temperature,the MgO mass fraction in the slag is kept at about 11%.