Research On Appropriate FeO Content For Sinter Of Chongqing Iron & Steel Company

Sinter is one of the principal materials of blast furnace ironmaking production; its performance and quality directly affect the operation and techniqal economic index of blast furnace smelting. The sinter of CQISCO had bad reducibility and high low-temperature reduction degradation index because of the condition that low sintering concentrate rate, more kinds of imported ore, heterogeneous particle size of mixed ore and instability of component and quantity of sintering fuel. So there was significance of optimizing sintering and ironmaking production in, by means of controlling the FeO content of sinter, improving structure and metallurgy property of sinter, increasing smelting index and reducing the cost of sintering and ironmaking process.The effect of fuel ratio, basicity and material layer on FeO content was studied and the effect of fuel ratio on sintering process and metallurgy property of sinter was investigated based on the two most commonly used ore blending scheme of CQISCO. The quality of sinter was improved and an appropriate FeO content for current sintering ore blending structure of CQISCO was found while every sintering process index of CQISCO was optimized through the research. The conclusion had been successfully applied to guiding actual CQISCO sintering production.Using orthogonal test the effect of fuel ratio, basicity and material layer on FeO content of sinter and the change of sintering property index of ore blending scheme A, B were analyzed. The relationship among FeO content, strength, reducibility and low-temperature reduction degradation index of sinter was studied. The relationship among mineral phase structure, FeO configuration and sinter metallurgy property was researched.The results showed: FeO content and solid fuel would increase as fuel ratio increased; FeO content would decrease as basicity increased and FeO content would be affected less by material layer. When the FeO content increased, the calcium ferrite decreased, the property of reduction turned worse, the RDI+3.15 index increased, the softening temperature of sinter turned lower, the dropping temperature turned higher, the soften-melting zone turned wilder and the pressure of column turned higher. The mineral phase showed that lots of magnetite and calcium ferrite were born and their structures were mainly melting and particles while most of calcium ferrite existed as acicular. Ore blending scheme A was adopted under current sintering condition of CQISCO with fuel ration 4.24%～4.32%, basicity 2.0, material layer 700mm, FeO content about 8.4%. Since 2007 the actual application in CQISCO showed that: the sinter particle size≤10mm reduced from 28.12% to 22.60%; the sinter return rate reduced from 13.40% to 12.65%; the sinter reducibility increased by 1% and low-temperature reduction degradation reduced by 2%.