氧气转炉采用石灰石替代部分石灰冶炼的应用分析

湘钢炼钢厂成功地开发了转炉采用石灰石替代部分石灰的冶炼新工艺。应用该工艺后,转炉热平衡、前期成渣、造渣效果等能够满足转炉炼钢生产的需求。从而降低了能耗和生产成本,取得了良好的经济和社会效益。     

转炉炼钢过程工艺控制的发展与展望

 转炉炼钢过程控制是转炉自动化控制的重要内容。介绍了转炉自动化控制的发展状况以及国内目前常用的转炉冶炼控制方法,从自动化控制角度分类讨论了转炉冶炼过程中枪位、氧气流量和投料控制的特点,并结合转炉炼钢过程工艺控制的特点,对工艺控制的优化途径进行了论述。对转炉自动化控制的发展趋势进行了简要分析和展望。     

Free CaO stabilisation by mixing of BF slag and BOF slag in molten state

Reducing free CaO (f-CaO) in basic oxygen furnace (BOF) slag effectively and efficiently is the prerequisite to achieve the goal of BOF slag's volume stability. In this work, Taguchi experimental design method was used to explore the influencing factors effect on stabilising f-CaO by mixing BOF slag with blast furnace (BF) slag and probe into the relevant mechanism. The results show that, in the setting conditions of this work, the most influential factor on the stabilisation ratio of f-CaO is mass ratio between BF slag and BOF slag, and then mixing temperature and duration time as a queue. The reasonable conditions are obtained as follows: mass ratio of BF slag to BOF slag is 6:1, temperature of mixing is 1783?K and duration time for mixing is 20?min. The f-CaO stabilised mechanism on BF slag and BOF slag molten mixing was regarded as mutual coupling effects of stabilisation reactions and dilution.     

Influence of ladle slag additions on BOF process under production conditions

Abstract

The influence of recycled ladle slag on the basic oxygen furnace (BOF) process under production conditions was investigated in plant trials. More specifically, 25 heats with ladle slag additions and 23 heats without ladle slag additions were studied. Both steel and slag samples were collected, from which the chemical compositions were determined. In addition, several process parameters were monitored. Overall, it was found that recirculation of ladle slag during normal production conditions works fine. On the positive side, it was seen that the steel quality concerning the phosphorus and sulphur contents of liquid steel has, in accordance with previous studies, not been affected by the ladle slag additions. Furthermore, no major differences in the slag composition occur when the recycling of ladle slag to BOF is performed. Finally, in comparison to previous studies, the increased tendency for slopping when adding ladle slag could be eliminated with a change in the lance schedule. However, on the negative side, it was seen that the addition of ladle slag leads to an increased blowing time due to lower iron ore additions. Moreover, the slag weight at tapping increased due to an increased weight of added slag formers.     

Effect of operation parameters on supersonic jet behaviour of BOF six-nozzle oxygen lance

Abstract

A three-dimensional mathematical model of compressible supersonic free surrounding jets from six convergent–divergent nozzles oxygen lance was developed based on the Reynolds averaged Navier–Stokes equations. The modelling results were validated by experiment. A comparison between the standard k～ω turbulence model and realisable k～? was carried out, and it shows that the standard k～ω turbulence model is superior in being able to depict the flow characters of multiple jets. The effects of nozzle inclination angle and operation pressure on jet flow characteristics and coalescence behaviour were investigated, and the mechanism of jet coalescence is discussed. The results show that coalescence patterns of six nozzle jets are strongly affected by the inclination angle but hardly by the operation pressure. When jets impinge on the melt surface in a BOF, the nozzle inclination angle plays also an important role in the splashing phenomena and the shape of cavity. It can be expected that when the nozzle inclination angle reduces from 17·5 to 10°, the cavities impinged by jets evolve from several scattered small craters to one large cavity. The change of jet coalescence pattern leads to different splashing patterns of the melt.     

弹簧钢60Si2CrVAT的生产工艺实践

采用90tBOF→100tLF→＋100tRH→大圆坯连铸工艺生产60Si2CrVAT弹簧钢,轧制成Ф517～28mm棒材。通过控制转炉出钢终点成分、温度和下渣量,控制LF精炼渣碱度R≥4,渣中ω（T．Fe＋MnO）≤0．5％,保证RH真空处理时间不小于20min,采用全程保护浇铸等工艺措施生产高洁净弹簧钢。检验结果表明,弹簧钢中ω（T．O）≤10×10^-6,ω（H）≤1．1×10^-6,A细类、C细类夹杂在0．5级以下,B细类、D细类夹杂在1．0级以下,制品的抗疲劳寿命达到500万次。     

300t转炉自动化炼钢应用实践

介绍了Danieli Corus公司研究开发的自动化炼钢系统的基本原理、功能及马鞍山钢铁股份有限公司300t转炉自动化炼钢技术的应用情况,在生产应用中,通过原辅料管理、提高基础数据精度、完善数据采集功能、优化动静态模型参数等,进一步提高了转炉炼钢过程和终点控制水平。     

120 t BOF-LF-Φ200mm坯连铸工艺试制X52管线钢

由于方圆连铸机浇铸X52管线钢（%:0.14～0.18C、0.30～0.50Si、1.25～1.40Mn、≤0.025P、≤0.025S、0.03～0.06Nb）易发生水口堵塞和难控制铸坯质量,故采用转炉出钢时根据钢中的碳含量加入200～500kg/炉Fe-Al脱氧剂进行脱氧,在LF用高碱度渣（%:≥70CaO、≤5Al₂O₃、≤5SiO₂、≥5CaF₂、≤5MgO、≤0.05N）进行精炼,精炼结束软吹氩≥5 min等技术措施生产X52管线钢。结果表明,LF平均脱硫率37%,钢中S≤0.011%、P≤0.015%,Φ200 mm连铸圆坯表面质量良好,低倍各项评级均小于1.0级。     

样本自选择回归分析算法在转炉炼钢中的应用

针对转炉炼钢静态控制模型广泛采用的常规回归分析算法采用目标炉次的前几炉次冶炼数据作为样本,模型预测准确度低的问题,提出了一种基于样本自选择的回归分析算法。该算法从实际生产数据中自动选取一定数量的合适样本来构建回归分析预测模型,实现吹氧量、冷却剂加入量、终点温度和终点碳含量的预测。通过某钢厂120t转炉Q235B钢种的实...     

高磷铁水顶底复吹转炉双渣法冶炼工艺实践

舞钢在没有铁水预脱磷设备的条件下,为了提高转炉钢冶炼前期的脱磷效率,结合转炉不同吹炼时期特点,通过生产实践,探索高磷铁水顶底复吹转炉双渣法冶炼工艺生产低磷钢的方法,确定了吹炼过程中合理的氧枪枪位和原料投放时机,总结出一倒时间、碱度、温度等关键操作制度,最终开发出直接利用高磷铁水生产低磷钢的转炉双渣法冶炼工艺技术,满足了低磷钢种对钢水洁净度的要求,达到了降本增效的目的。