电炉短流程高品质钢生产控氮技术探索与创新实践

Exploration and innovation practice of nitrogen control technology in short process high quality steel production of electric furnace

电炉短流程炼钢是实现钢铁工业减碳的重要路径,但传统电炉短流程炼钢以废钢为原材料,以电能为主要能量来源,熔池内碳氧反应不足,电弧持续放电电离空气致使钢液氮质量分数偏高且氮的脱除与控制较为困难。由于氮对钢质量的影响,长期以来钢中氮质量分数控制是电炉短流程高品质钢生产的重点和难点,目前对于钢中氮质量分数有严格要求的高品质钢种几乎全部由长流程生产制造。为扩大电炉短流程生产钢种,提高电炉短流程行业竞争力,综述了钢中氮的危害以及电炉炼钢控氮难点,总结了钢液脱氮机理和电炉炼钢控氮技术研究进展,并结合本团队的研究和实践,提出了CO_(2)复合喷吹控氮技术和中空电极富氢气体喷吹控氮技术。CO_(2)复合喷吹控氮技术将CO_(2)载气喷吹碳粉和CO_(2)-Ar混合底吹相结合,一方面通过降低炉内氮分压并优化泡沫渣形成减少钢液吸氮量,另一方面利用CO_(2)-Ar混合底吹高效吸附脱氮原理降低钢液氮质量分数。中空电极富氢气体喷吹控氮技术在隔绝电弧周围空气的同时,利用电极产生的电弧将多元气体电离成富氢等离子体和钢中氮结合逸出钢液实现脱氮。工业实践结果表明,CO_(2)复合喷吹控氮技术可将全废钢电炉出钢平均氮质量分数由0.00814%降至0.00508%;应用中空电极富氢气体喷吹控氮技术后可将电炉出钢平均氮质量分数从0.00585%降至0.00466%,最低仅为0.00299%。可有效降低电炉冶炼出钢氮质量分数,助力电炉短流程高品质钢生产进一步发展,推动实现钢铁行业绿色低碳的发展目标。

Electric furnace short process steelmaking is an important way to realize carbon reduction in iron and steel industry.However,the traditional electric furnace short process steelmaking takes scrap steel as raw material and electric energy as the main energy source.The carbon-oxygen reaction in the molten pool is insufficient,and the arc continues to discharge and ionize the air,resulting in high mass percent of nitrogen in molten steel and difficult removal and control of nitrogen.Due to the influence of nitrogen on the quality of steel,the control of nitrogen mass percent in steel has long been the key and difficult point in the production of high-quality steel with short process of electric furnace.At present,almost all high-quality steel grades with strict requirements for nitrogen mass percent in steel are manufactured by long process.In order to expand the production of steel in the short process of electric furnace and improve the competitiveness of the short process industry of electric arc furnace,the harm of nitrogen in steel and the difficulty of nitrogen control in electric furnace steelmaking were reviewed.The mechanism of nitrogen removal in molten steel and the research progress of nitrogen control technology in electric furnace steelmaking were summarized.Combined with the research and practice of our team,CO_(2) compound injection nitrogen control technology and hollow electrode hydrogen-rich gas injection nitrogen control technology were proposed.CO_(2) compound injection nitrogen control technology combines CO_(2) carrier gas injection carbon powder with CO_(2)-Ar mixed bottom blowing.On the one hand,the nitrogen absorption of molten steel is reduced by reducing the nitrogen partial pressure in the furnace and optimizing the formation of foam slag.On the other hand,the nitrogen mass percent of molten steel is reduced by using the principle of efficient adsorption and denitrification of CO_(2)-Ar mixed bottom blowing.The hollow electrode hydrogen-rich gas injection nitrogen control technology isolates the air around the arc while using the arc generated by the electrode to ionize the multi-component gas into a hydrogen-rich plasma and combine the nitrogen in the steel to escape the molten steel to achieve denitrification.The results of industrial practice show that the average nitrogen mass fraction of electric furnace tapping of all scrap steel can be reduced from 0.00814%to 0.00508%by CO_(2) compound injection nitrogen control technology.After the application of hollow electrode hydrogen-rich gas injection nitrogen control technology,the average nitrogen mass percent of electric furnace tapping can be reduced from 0.00585%to 0.00466%,and the lowest is only 0.00299%.It can effectively reduce the nitrogen content of steel produced by electric furnace smelting,help the further development of high-quality steel production with short process of electric furnace,and promote the realization of green and low-carbon development goals of iron and steel industry.