Effect of Foaming Slag on Removal of Nitrogen in Liquid during 120t BOF Steelmaking Process

Abstract

Abstract: The bottom blowing argon is carried out in commercial production of 40 heats 120t BOF steelmaking process, at blowing 15% the C content in metal is 4.0% with slag ingredient (/%) ： 21.2FeO, 2.6A1₂O₃, 5.3MnO, 31.2CaO, 11.2MgO, 23.7SiO₂ , 3.2P₂O₅ and basicity 1.3, and at end blowing the C content in liquid is 0.1% with slag ingredient (/%) : 14.5FeO, 2.0Al₂O₃ , 3.9MnO, 49.5CaO, 8.0MgO, 13.5SiO₂,2.2P₂O₅ and basicity 3.4. The effect of slag foaming level on removal of nitrogen in BOF liquid is studied by gas and composition analysis and optical microscope ,and the mechanism of secondary removal of nitrogen in slag is discussed. The analysis results show that in earlier blowing period the removal of nitrogen in BOF metal is weaker, the removal of nitrogen is concentrated in 15%~80% blowing process, in last period of BOF blowing the liquid has some nitrogen increment. As the metal droplets exist in slag, the slag foaming level is better and the retained time of CO in slag is longer to increase the change of collision between CO bubbles and metal droplets, the effect of secondary removal of nitrogen is obvious. With N content in charging metal being 53 x 10^-6, with regard to heats with better slag foaming level the BOF end N content average in liquid is 13.7 x 10^-6 and the average removal rate of nitrogen reaches 74.2% , while to heats with lower foaming level the BOF end N content average in liquid is 25.2 x 10^-6 and the average removal rate of nitrogen in liquid is only 52.5%.

Key words: 120t BOF, Foaming Slag, Removal Nitrogen in Liquid, Secondary Removal of Nitrogen in Liquid

摘要： 120t转炉40炉工业试验的冶炼过程全程底吹氩,吹炼15%时钢中C含量为4.0%,炉渣成分为（/%）:21.2FeO，2.6Al₂O₃，5.3MnO，31.2CaO，11.2MgO，23.7SiO₂，3.2P₂O₅,碱度1.3，吹炼终点钢中C含量0.1%,炉渣成分为（/%）:14.5FeO，2.0Al₂O₃，3.9MnO，49.5CaO，8.0MgO，13.5SiO₂，2.2P₂O₅，碱度3.4。采用气体、成分分析和光学显微镜等方法研究了炉渣泡沫化程度对转炉钢液脱氮的影响，讨论了炉渣二次脱氮机理。分析得出，吹炼初期转炉钢液脱氮很微弱,脱氮主要集中在吹炼15%到80%的过程中，转炉吹炼末期钢液有所增氮。炉渣中存在金属液滴，炉渣泡沫化程度好，CO在炉渣中的停留时间长，CO与金属液滴的碰撞机会多，二次脱氮作用明显。入炉铁水N含量为53×10^-6，炉渣泡沫化程度较好的炉次，转炉终点平均N含量13.7×10^-6，平均脱氮率为74.2%；泡沫渣程度较差的炉次，转炉终点平均N含量为25.2×10^-6，平均脱氮率为52.5%。

关键词: 120t转炉, 泡沫渣, 钢液脱氮, 二次脱氮

Chi Yunguang , Deng Zhiyin , Zhu Miaoyong. Effect of Foaming Slag on Removal of Nitrogen in Liquid during 120t BOF Steelmaking Process[J]. Special Steel, 2017, 38(2): 40-43.

迟云广, 邓志银, 朱苗勇. 泡沫渣对120t转炉钢液脱氮的影响[J]. 特殊钢, 2017, 38(2): 40-43.

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