转炉熔渣低温气化脱磷行为

doi:10.13228/j.boyuan.issn0449-749x.20220268

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Abstract The high phosphorus content in the dephosphorization converter slag at low temperature limits the recycling of the converter slag. Therefore, how to effectively reduce the phosphorus content in the slag has become one of the key issues that many iron and steel enterprises urgently need to solve. Based on this, the effects of theoretical thermodynamic conditions, melting point of converter slag, mineral phase structure and microstructure of slag on low-temperature gasification dephosphorization were further analyzed and studied from the perspective of theoretical analysis and industrial experiment, combined with XRD, SEM-EDS and Raman spectroscopy. Theoretical analysis shows that higher temperature, lower FeO mass fraction and alkalinity are beneficial to the low temperature gasification dephosphorization reaction; the industrial test results show that the gasification dephosphorization rate can reach over 30% when the terminal temperature, mass percent of FeO and alkalinity of converter slag are controlled in the range of 1 350-1 360 ℃, 25%-35% and 1.2-2.5 respectively. When the basicity and mass percent of FeO of slag are lower than 1.25 and 35% respectively, properly increasing the basicity and mass percent of FeO of slag can promote the melting point of slag to decrease, which is conducive to the occurrence of low-temperature gasification dephosphorization reaction. XRD and SEM-EDS analysis results show that the converter slag is mainly composed of phosphorus-rich phase, matrix phase and RO phase. Among them, the existence of Ca₂SiO₄-Ca₃(PO₄)₂ phosphorus-rich phase with high mass fraction of Si, P and Ca is not conducive to low-temperature gasification dephosphorization, while the existence of RO phase and matrix phase with high mass fraction of metal oxides such as Fe and Mn is conducive to low-temperature gasification dephosphorization. The Raman spectrum analysis of converter slag shows that when the relative content of the silicon-oxygen tetrahedral structure Qⁿ(n=1,2,3) in the converter slag is low, the degree of the polymerization in the slag decreases and the content of the Ca₃Si₂O₇ phase is less, so that the fluidity of converter slag is better. This slag structure is conducive to low temperature gasification dephosphorization. This study can provide reference for iron and steel enterprises to realize the secondary utilization of dephosphorization converter slag.

Key words： converter slag low temperature gasification dephosphorization thermodynamic conditions mineralstructure

Received: 22 April 2022

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	Articles by authors
	ZHOU Chao-gang
	CHEN Qing-gong
	AI Li-qun
	WANG Shu-huan
	XUE Yue-kai
	CHEN Hu

Cite this article:

ZHOU Chao-gang,CHEN Qing-gong,AI Li-qun等. Dephosphorization behavior by low temperature gasification of converter slag[J]. Iron and Steel, 2022, 57(11): 64-76.

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http://www.chinamet.cn/Jweb_gt/EN/10.13228/j.boyuan.issn0449-749x.20220268 OR http://www.chinamet.cn/Jweb_gt/EN/Y2022/V57/I11/64

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