Study On Harmful Trace Elements Distribution And Control Technology Of Large Blast Furnace In Handan Iron And Steel Co.ltd

The raw material supply becomes tension with the rapid growth of Chinese steelproduction recently. The K, Na, Zn and Cl contents in raw material increased graduallyof Handan Company of Hebei Iron&Steel Group (following called Hangang), and slagquantity decreased greatly, the problems of harmful trace elements to blast furnacesmelting occur frequently, affects its anterograde and longevity.The balance calculation of harmful trace elements for Hangang iron making systemshows: the harmful trace elements load of large blast furnace is higher, and the sinter,pellets and coke are the main sources. The limited value of harmful trace elements loadfor each blast furnace was put forward. The zinc and chlorine are discharged mainly bygas, slag is the main medium of alkali metal exhausting blast furnace. Harmful traceelements have adverse effects on the metallurgical properties of blast furnace burden, thecompound influence of alkali metal and chlorine for the coke metallurgical properties isthe biggest.The results of joint experiments on dealkalization and desulphurization of blastfurnace slag reveal, the basicity increasing is beneficial to the desulphurization but not tothe dealkalization. The MgO or Al2O3content increasing are beneficial to thedealkalization but have the opposite affect on the desulphurization. The reactiontemperature or reaction time increasing are advantageous to desulphurization but not todealkalization. The slag-iron ratio increasing is favorable to both desulphurization anddealkalization, but the iron-making cost will increase. The suitable ranges of eachparameter on dealkalization and desulphurization are: CaO/SiO2is from1.01~1.15, MgOcontent is10.28%~14.28%, Al2O3content is14.67%~15.67%, slag temperature is1480~1500℃, tapping time is110~120min, and slag-iron ratio is0.33~0.36, which canmeet the qualified iron request, and the alkali removal rate is higher than80%meanwhile.The harmful trace elements load reduced gradually and the harm to blast furnacewas controled, the smooth operation and each technical index of BF were good by usingthe measures of controlling harmful trace elements load, optimizing blast furnaceoperation and classifying the dust recycle.