Study On Improving The Charge Ratio Of Pellet At Yigang Steel Blast Furnace

With the development of economy progress, the scale of the steel industry hasexpanded quickly. With the decrease of world iron ore resource and the expanded scaleof iron and steel making industry, the demand for iron ore is increasing, which lead tothe rising of the price of iron ore. It is the common problem of world steel enterprisefaced currently to realize the ironmaking development of high yield, high quality, andhigh efficiency production, and to achieve the rational use of blast furnace burden at thelimited mineral resources.The method of pelletizing is developed with the progress of the ironmakingtechnology and the lack of rich ore iron in recent decades. The pellets is a kind of idealbeneficiated burden material, so improving the charging ratio of the pellets in blastfurnace is the development trend of blast furnace burden structure. And because ofproblems that the Yigang steel sintering production can not meet the needs of the blastfurnace, therefore, on the basis of the study Yigang steel blast furnace burden chargingmetallurgical properties, the improvement of pellets ratio of blast furnace in Yigangsteel and achieving the rationalization of blast furnace burden structure are studied inthis paper, which have an important instructive significance and realistic significance ofYigang blast furnace.This paper analyzes the changing of pellets ratio in furnace charging effect on themain technical and economic index of the Yigang steel blast furnace, throughmetallurgy performance test on furnace burden (sinter, pellets and lump ore) of theYigang blast furnace used at present and combined with a large number of productiondata. The conclusions can be made as follows: (1) The reductibility of pellets are general, the index of reductive degree RI of thepellets sample is no more than60%; but the low temperature reduction desintegrationproperties of pellets are better, RDI+3.15are higher than70%, and the reductionexpanding properties of pellets are stable relatively, and the reduction inflation rate isessential in normal extent, rarely exceed, but it will not affect the regularly operate ofblast furnace.(2) The blast furnace burden structure of Yigang steel is changed from70%sinter+25%pellets+5%Australian ore to59%sinter+35%pellets+6%Australian ore.With the increased pellet ratio of10%，the production of blast furnace was in goodcondition, and each index reached preferably level, with the coke ratio dropped15kg/t,comprehensive coke ratio dropped15kg/t, and the charged grade of blast furnacewas improved gradually, from55percent to59percent; And the output and quality ofblast furnace also had improved in different degrees.(3) To meet the need of improvement of pellets ratio in the blast furnace, Yigangsteel blast furnace had improved sinter basicity, increased the air supply and improvedthe wind temperature; it had taken the combination of obverse and reverse chargingsystem, which restrained the development of edge air flow; in order to stabilizing theheat system and slagging system, the low silicon smelting is practiced on the basis ofslag heat supply, which reduced [Si] lower to0.6%,controlled the binary alkalinity ofslag in1.1and the (MgO) about6%.