Study On Distribution Law Of Chlorine Between Iron And BF Slag

The effects of chlorine on blast furnace(BF) smelting had been widely concerned. Study on the distribution law of chlorine in different zones of BF, it can provide a theoretical basis for the study on its trend in BF, and reduction the harm of chlorine. Using the thermodynamic software, the probable chemical reactions of chlorine in BF were investigated. The distribution law of chlorine in lumpy zone, in the slag and iron of soft melting zone, and in the BF slag were studied by experiments. The results show that:Thermodynamic analysis shows that, the chlorine brought in by raw material and fuel mostly generate HCl gas and alkali-chlorine. The obtained chlorine products rise with gas. A part of chlorine occur adsorption on iron burden and coke. Some of chlorine discharge with gas, and small amount of chlorine is absorbed by BF slag and iron.With rising temperature, the chlorine content of sinter and coke rises, and then falls, the chlorine content of pellet has no obvious change, and the chlorine content of lump ore falls. With the increase of HCl rate, the chlorine content of sinter, lump ore and coke rise, which in pellet rises slowly. The chlorine distribution coefficient of gas in lumpy zone is maximum, next are sinter, coke and lump ore, pellet is minimum. The increase of chlorine distribution coefficient of gas is most significant with the increase of HCl rate.With rising chlorine content of burden, the chlorine content of slag and iron in soft melting zone increase. The chlorine content increased in slag is more obvious than that in iron. The S and the chlorine content of coke decrease. With rising basicity of burden, the chlorine content of iron and coke have no obvious change, and it increases in slag.The chlorine content of BF slag rises with increasing basicity. It rises firstly, and then falls with rising Mg O content. It also increases with increasing Al2O3 content less than 16%. The chlorine content falls with rising temperature and prolonging the time in high temperature. The basicity of BF slag should be enhanced, the Mg O and Al2O3 content should be maintained at about 11% and 16%, the temperature should be reduced, and the BF production should increase the number of discharge slag appropriatly, to improve the dechlorination capacity of BF slag.