The Effection On Ironmaking Raw Materials And Metallurgical Process By High Content Of Al₂O₃ Iron Ore

At present,in order to reduce the cost of ironmaking in blast furnace,lots of iron and steel enterprises are vigorously unfolding the technology of beneficiated material and energy conservation。So they increased the propotion of import ore,which with high content of Al₂O₃。Accordingly the content of Al₂O₃ in BF slag farther increased and it goes beyond the limit of"15%",even over"20%"in some BFs sometimes,which badly impact the BF smelting。In this article,I systemicly study the influence to ironmaking by high content of Al₂O₃ ore with experiment in lab。The experiment adopt the raw material and fuel condition of Wuhan Iron and Steel Company。It started from sintering process,researched the impact on the sintering ore's resistance to tumbling,reductiondegree,low temperature breakdown index and soft heat nature by differ content of Al₂O₃。With the medium of microstructure observation to study the content of Al₂O₃ impact on the agglomerate SFCA's indigenous;In accordance with Wuhan Iron and Steel Company's scene slag composition to mix experimentize,to analyses the impact on BF slag'viscosity, melting point and desulphurizing ability by the three factors of Al₂O₃,MgO and alkalinity。The result of the research supply theory gist and experiment foundation to enlarge the content of high Al₂O₃ mine。Experimental result as follows:at the experiment condition,with the content of Al₂O₃ in the sintering ore increasing from 1.71% to 2.24%,agglomerate resistance to tumbling is maximal at the content of Al₂O₃ about 1.89%,and it is not evident that the impact on reductiondegree by the content of Al₂O₃,but give notable influence on low temperature breakdown index,which increase rapidly with the increased content of Al₂O₃。And Al₂O₃ is the essential condition of the creation of needle-shaped calcium ferrite。In the BF slag of high content of Al₂O₃ ,the more Al₂O₃ in slag,the higher slag viscosity,melting point and lower desulphurizing ability is;propriety content of MgO could depress the slag viscosity ,melting point and rise the desulphurizing ability ,but it's content shoudn't exceed 12% ;the slag alkalinity changed from 1.1 to 1.2,high alkalinity slag can depress slag viscosity,but it's thermostability is less,it's propriety alkalinity is at about 1.17。It can visibility depress the slag viscosity and melting point,improve slag's fastness with adding a few CaF2。In order to solve the problem of high slag viscosity and low desulphurizing ability resulting by high content of Al₂O₃ in slag,some countermeasures such as improving the coke quality,propriety rising the slag ratio,coal ratio and using high wind-temperature can be adopted,and it also can be optimized the rate of slag with increasing the content of MgO,and the increasing of MgO can be realized by adding magnesite or dolomite through the sintering process or in the pellet,but the content can't exceed 4% in sintering ore and 3% in pellet。...