(ECIC-31)Effect of mixing coke to ferrous burden on permeability of ironmaking blastfurnace – A cold model study

摘要

The charging pattern may affect the permeability of the blast furnace, coke rate and the freedom of selection of lowgrade raw materials. Ore-coke mixed charging is known as one of the potential techniques for optimizing thecharging pattern. In recent years, charging small sized coke (nut coke) into the burden layer is applied for saving rawmaterials and decreasing the cost. Various studies indicate that mixing nut coke to ferrous burden could improve thepermeability of the cohesive zone, enhance the reduction kinetics and have a positive effect on the softening andmelting behaviour. Although the mixed charging, especially adding nut coke into the burden layer, may have manyadvantages, for various reasons, the mechanisms and side effects for using nut coke are not well understood andthe mixing ratio is still limited in actual blast furnace operation.In this paper the status of mixed charging, especially nut coke used in the blast furnace is investigated. A cold flowmodel is established to study the permeability of the packed bed in the blast furnace dry zone under differentconditions. It is aimed to better understand the mechanisms of mixing coke and nut coke into the burden layer. Theeffect of coke size, mixing coke ratio, layer numbers, different types of ore, and gas flow rate on the pressure drop ofthe packed bed were investigated. Experimental results show that mixing the nut coke in the ore layers decreasesthe pressure drop to a different extent for the small size of the nut coke.