残留CO<sub>2</sub>对石灰在转炉初渣中溶解的影响

doi:10.13228/j.boyuan.issn0449-749x.20220147

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Abstract In the process of converter steelmaking, the rapid dissolution of lime is of great significance for efficient dephosphorization of converter. The calcium silicate product layer formed at the slag/lime interface in the process of lime dissolution is considered to be the key factor hindering lime dissolution. Two kinds of partially calcined limestone with different CO₂ content were prepared. The dissolution behavior of partially calcined limestone in the primary slag of converter was studied by immersion method, and compared with that of pure lime and limestone. The results show that the mass transfer coefficient of CaO in the liquid slag during the dissolution of limestone is 2.1 times that of lime, and the mass transfer coefficient of partially calcined limestone with 10% residual CO₂ is as high as 6.7 times that of limestone. When the mass fraction of CO₂ is in the range of 0-43.5%, the dissolution rate of lime firstly increases and then decreases. The 2CaO·SiO₂ layer formed in the process of lime dissolution seriously hinders the diffusion of FeO_x, so it slows down the dissolution rate of lime. Significantly different from lime, CO₂ produced by limestone decomposition can destroy the 2CaO·SiO₂ layer and internal structure, which is conducive to the penetration of slag. This is also applicable to partially calcined limestone with residual CO₂. In the process of preparing pure lime, in order to ensure the complete calcination of the lime core, it is very easy to cause over-burning on the outer surface of lime, and the preparation of partially calcined limestone can solve the problem of over-burning on the surface. Furthermore, compared with limestone, the temperature drop of slag near the surface of partially calcined limestone is relatively lower because the surface is lime shell, which can avoid the stagnation stage at the initial stage of dissolution. When the surplus heat of converter is limited, the lime replacement ratio of partially calcined limestone is higher than that of limestone, which depends on the CO₂ residue in partially calcined limestone.

Key words： residual CO₂ dissolution 2CaO·SiO₂ layer partially calcined limestone lime shell slag temperature drop lime replacement ratio converter

Received: 02 March 2022

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	TIAN Yu-feng
	LI Guang-qiang
	XIAO Yong-li
	LIU Yu

Cite this article:

TIAN Yu-feng,LI Guang-qiang,XIAO Yong-li等. Effect of residual CO₂ on dissolution of lime in converter slag[J]. Iron and Steel, 2022, 57(10): 84-90.

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http://www.chinamet.cn/Jweb_gt/EN/10.13228/j.boyuan.issn0449-749x.20220147 OR http://www.chinamet.cn/Jweb_gt/EN/Y2022/V57/I10/84

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