This paper has investigated a new desulfurizer for iron and steel industry to make up the lackness of magnesium-based desulfurizer. In order to explore the desulfurization process of hot metal by the new desulfurizer, both the thermodynamics and experiments have been studied.. The results of thermodynamics indicated that, under the standard condition,the lowest reaction temperatures of MgO + C and MgO +Si were 1846℃ and 2132℃ and the pressure of Mg vapor at the hot metal temperature were 0.2-0.5kPa and 0.005-0.01kPa, respectively. In the case of reaction between MgO and Al, the calculated starting reaction temperature under standard condition was 1475 ℃, and the pressure of Mg vapor was distributed from 27 kPa to 45kPa at the hot metal temperature, showing that it was easy to happen the reaction of MgO+Al. The experimental results displayed that the desulfurization efficiency was only 42.31% by the desulfurizer of MgO and C, while the effect of MgO+ Al and MgO+ Al-Si was good, since the desulfurization efficiencies were above 85%, and the lowest sulfur content was below 40×10-6.
ZHANG Ting-an, REN Xiao-dong, LIU Yan, DOU Zhi-he, LV Guo-zhi, HE Ji-cheng (School of Material and Metallurgy, Northeastern University, Shenyang 110004, Liaoning, China)
This paper presents a new idea about desulfurization with in-situ mechanical stirring method on the basis of desulfurization by single blow grain magnesium and KR method, that is, the inner gases carry the magnesium vapor formed in-site in molten iron by magnesium-based desulfurization, and bubble dispersed and disintegrated under the condition of mechanical stirring, thence to improve the efficiency of desulfurization by single blow grain magnesium .It has been proved by research of cold water model experiment that the bubble dispersion and disintegration can not only improve the desulphurization efficiency but also increase the utilization rate of magnesium. Obviously, the bubble dispersion and disintegration of magnesium vapor is the key problem in improving the desulphurization efficiency and increasing the utilization rate of magnesium. Thus the research focus on exploring the performance of bubble dispersion and disintegration on the base of refining process and gas-liquid mass transfer. According to the literature and cold water model experimental result basing on principle of similitude, the influencing factors and interaction of bubble dispersion and disintegration have been studied from the perspectives of physical and numerical simulation. The study would provide the theoretical and experimental data for the new method of desulfurization with in-situ mechanical stirring.
For the lack of the present hot metal desulfurization processes in iron and steel industry, our group has proposed the in-situ mechanical stirring method for external desulfurization of molten iron and researched this new method. This paper investigated this new in-situ mechanical stirring hot metal desulphurization process on desulphurization experiments of one-ton scale by using the new desulfurizer. The experimental results indicated that the desulfurization efficiency of in-situ mechanical stirring desulfurization process is 90% and the lowest sulfur content in the treated hot metal is 23ppm. By comparing with the methods of direct throwing desulfurizer and in-situ injecting desulfurization, in-situ mechanical stirring desulfurization process is the suitable desulfurizaton method.
REN Xiao-dong, ZHANG Ting-an, DOU Zhi-he, LIU Yan, Lü Guo-zhi, HE Ji-cheng (School of Material and Metallurgy, Northeastern University, Shenyang 110004, Liaoning, China)
