| The usage of high-aluminum iron ore causes the Al2O3 content in the blast furnace(BF)slag high,resulting in an increase in the viscosity of the slag,a decrease in fluidity,and a decrease in desulfurization ability.Changing the MgO content or the binary basicity(R2)of slag both are major recourses to adjust the metallurgical properties of slag.However.at present,there are few studies on the quantitative addition of MgO to BF slag with high Al2O3.Therefore,the effects of R2,w(MgO)/w(Al2O3)and Al2O3 contents on the metallurgical properties of BF slag with high Al2O3 was studied,furthermore,a viscosity prediction model suitable for high Al2O3 slag was established.It is of great significance to study the slag making system and slag composition of BF slag with high Al2O3.Relevant research and achievements are as follows.(1)With the increase of M/A in slag,the viscosity of slag decreases.When R2 is 1.15,the viscosity decreases remarkably with the increase of M/A under the same w Al2O3),under the condition that R2=1.15,w(Al2O3)=15%,the viscosity of slag decreases from 0.43 Pa·s to 0.243 Pa·s when M/A increases from 0.25 to 0.45 at 1500?;while R2=1.20 or R2=1.25,the viscosity of slag decreases slightly with the increase M/A at 1500?;when M/A and w(Al2O3)are fixed,at 1450? and 1500?,with the increase of the viscosity of slag generally decreases.The relationship between viscosity and w(Al2O3)is related to R2.The Al2O3 content has an obvious effect on the slag stability,the higher Al2O3 content is,the weaker slag stability is.(2)When R2 is in the range of 1.15-1.25 and Al2O3 content is fixed,the melting temperature almost increases with the increase of M/A.When M/A is 0.45,the change of melting temperature from 12%to 15%in w(Al2O3)is more obvious than that from 15%to 18%in w(Al2O3)with the increase of R2.(3)Urbain model is improved by introducing quaternary basicity(R4)and the ratio of M/A.The improved viscosity model has a good applicability to the high Al2O3 slag,and the calculated value of the model has a good linearity with the measured value of viscosity.Iso-viscosity contours of C-S-A-M system were plotted by using the data from the improved Urbain model;iso-viscosity contours showed that the slag viscosity centers at the point of R2=1 and M/A=0.6,then gradually increases in the process of diffusion from center to the periphery,the lowest viscosity at the center is 0.28Pa·s;with the increase of M/A,the slag viscosity first decreases and then increases.The turning point is related with R2;the turning point of low basicity(R2=1.15)is 0.5,while that of high basicity(R2=1.25)is 0.4.(4)Comprehensive consideration of the relationship between slag viscosity and composition,under the condition of R2=1.10-1.25 and w(Al2O3)=15%,the suitable M/A of BF slag should be 0.35-0.55.(5)There is a negative correlation between the desulfurization rate of slag and the viscosity of slag.Within 15 minutes of desulfurization reaction,the composition points with desulfurization rate over 70%account for 78%of the total composition points,indicating that the first 15 minutes of desulfurization reaction is the key to high efficiency desulfurization of slag.The average desulfurization rate of 27 groups of experiments is 75.6%,and the corresponding average slag viscosity is 0.314 Pa·s.Increasing M/A and R2 of slag can increase the desulfurization rate of slag.The R2 of slag plays a decisive role in the desulfurization capacity.The increase of R2 can significantly improve the desulfurization capacity of slag,not only improve the kinetic conditions of desulfurization reaction,but also increase the distribution coefficient of sulfur in thermodynamics.Improve the desulfurization capacity of BF slag. |
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