Phase characteristics and comprehensive regulation technology of slag crust on cooling staves of BF body
The bosh,belly and lower part of the shaft the furnace body area is one of the limitations of efficient and longevity operation of the blast furnace,the formation of a stable slag crust is the key to ensuring the safety of the cooling stave operation in this area.In order to explore the essential characteristics of slag crust,firstly,the slag crust samples were obtained from the bosh,belly and lower part of the shaft through the anatomy and the investiga-tion of cooling stave breakage in several blast furnaces.Secondly,the phase composition and microstructure evolu-tion of the slag crust were studied through analysis methods such as XRF,XRD,and SEM-EDS.Based on the com-positional characteristics of slag crust,a category system of slag crust was established,focusing on comparing the phase and morphological characteristics of cooling stave slag crust of blast furnace with different volumes and differ-ent cooling stave materials.Finally,the cooling stave slag crust regulation measures were formulated.The results show that the cooling stave slag crust can be mainly divided into two categories,the slag crust mainly composed of slag-iron and the harmful element binder mainly composed of ZnO and carbon.Among them,harmful element bind-ers have poor thermal stability and are prone to detachment,which is not conducive to the safe operation of the cool-ing stave.The basicity of the slag in the slag crust first increases and then decreases with the decrease of height.The composition of cooling stave slag crust of blast furnace with different capacity under the same cooling stave material does not differ much,while the difference of slag crust of blast furnace body with different cooling stave materials is large.The copper stave slag crust has a clear layered structure,and its slag composition shows the characteristics of high aluminum and low magnesium slag system,the main precipitation phase is Ca2Al2SiO7.While the cast iron stave slag crust has no layered structure,the content of Al2O3 and MgO is slightly lower than that of blast furnace slag,and its main precipitation phase is Ca3MgSi2O8.Finally,it is clarified that the formation and control of slag crust should be carried out from the aspects of edge gas flow temperature and slag composition,in order to ensure the crystallization kinetics conditions of slag hanging on the surface of the cooling stave and provide a theoretical basis for the long-term operation of the cooling stave of the blast furnace.
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