Difference in BOF Slag Splashing in US and China

Some differences in slag splashing between BOF steel works in US and China were investigated. The slag composition,melting point, and mineralogical phases of final slags from both countries were studied. The control of slag superheat is important to an effective slag coating.

Simulation on Slag Splashing for LD Converter

SeveraL parameters affecting slag splashing in LD converter have been discussed. Using parffin and starch model, a simulated test about 30 t converter has been made in laboratory and the modified Frode numberwas chosen as the main similar basis of the system. It was results that the optimized slag splashing parameters wasobtained through data treatment The nitrogen gas flow rate is about 8 500 m3/h, the splashing time is of 3 min,and the lance height is of 0.8 m. It is necessary to add MgO or carbon into the slag to adjusting slag composition.Also, it is difficult for the splashed slag condensing on the line when the slag temperature is much higher

Slag Splashing in a Basic Oxygen Furnace under Different Blowing Conditions

The influence of three different blowing conditions on the slag splashing process in a basic oxygen furnace for steelmaking is analyzed here using two-dimensional transient Computational Fluid Dynamics simulations. Four blowing conditions are considered in the computer runs: top blowing, combined blowing using just a bottom centered nozzle, combined blowing using two bottom lateral nozzles, and full combined blowing using the three top and the three bottom nozzles. Computer simulations show that full combined blowing provides greater slag splashing than conventional top blowing.

Slag Melting Characteristic of Slag Forming and Slag Splashing for BOF Less Slag Smelting

The slag melting characteristic of slag forming and slag splashing for 300 t BOF less slag process is researched by combining the methods of the slag chemical composition, the melting point determination and the petrographic analysis. The results show that the melting point of final slag for less slag smelting is 20 ~C lower than that for conventional smelting. According to results of the petrographic analysis, the C3S （3CaO ~ SiO2） and C2S （2CaO · SiO2） content for less slag smelting are lower than those for conventional smelting, while the RO （FeO, MgO, MnO, etc） phase and C4AF （4CaO · Al2O3· Fe2O3） phase are higher than those for conventional smelting. According to results of the chemical analysis, the （CaO） content and slag basicity for less slag smelting are higher than those for conventional smelting, while （FeO） and （MgO） content in slag for less slag smelting are almost equal to those for conventional smelting. The reason why slag melting point for less slag smelting is lower than that for con- ventional smelting is that the quantity of added fluorite for less slag smelting is more than that for conventional smel- ting. According tO the analysis results the slag melting point is determined by the C3S, C2S, RO phase and C4AF content. According to the results of slag melting characteristic before and after slag splashing for less slag smelting, the present adjusting slag process has little effect. It is important to adjust the composition of BOF final slag. The （FeO） content in slag is to be reduced at the slag splashing and adjusting slag process for less slag smelting.

A Novel Method of Recycling CO_2 for Slag Splashing in Converter

Converter off-gas, an important energy resource for steel industries, is one of the weak points in the recov ery and utilization of secondary energy resources. To improve the level of recycling converter off-gas in steel plants, a novel approach to the recycle of CO2 separated from converter off-gas or other off-gas for the green slag splashing technique was developed, and the CO2 equilibrium conversion ratio of the green CO2 slag splashing under different technological conditions was calculated by the program of enthalpy （H）, entropy （S）, and heat capacity （C）, i.e. HSC software. Furthermore, the experiments of CO2 injected into molten converter slag were carried out, and the influencing factors of the green slag splashing technique using CO2 were analyzed. The experimental results showed that the carbon content for smooth slag splashing using COs was about 4.0%.

Characteristics of Nitrogen Jet and Its Effect on the Bath in Slag Splashing

The measured results show that the overexpanded supersonic jet velocity produced by low stagnation pressure (0.53 MPa) attenuates quickly, deviates greatly with smaller impact area and large energy loss. According to the measured results and the analysis of lashing energy of jet on the bath, the technological parameters of nitrogen flow in slag splashing were proposed.

CFD Analysis of Influence of Slag Viscosity on the Splashing Process in an Oxygen Steelmaking Converter

Physical properties of molten slag such as viscosity, density and surface tension have a significant influence on the slag splashing process in an oxygen steelmaking converter. Particularly, viscosity determines the shear forces that rule droplets formation. Besides, stirring of the molten slag bath strongly depends on this property. In this work, the influence of viscosity on the efficiency of slag splashing is explored by means of transient Computational Fluid Dynamics simulations. Several values of viscosity are employed in the computer experiments. In order to quantify the splashing efficiency as function of slag viscosity, an average slag fraction on the converter walls is defined and calculated. CFD results are compared with those of an empirical expression, and at least qualitative agreement is found.

120 t转炉热态渣循环利用工艺研究

唐山中厚板材有限公司为提高转炉热态渣的利用率,对转炉冶炼过程炉渣产生机理进行分析,探索热态渣循环利用的途径。试验全留渣双渣法,即第一炉按原单渣法冶炼出钢和不倒渣溅渣护炉,根据铁水硅含量将数据固化在模型中,保证终点二元碱度控制在3.5~3.8,第二炉加入废钢和铁水进行双渣冶炼,出钢后倒出40%~50%炉渣再溅渣护炉,完成一组正常的冶炼。同时,通过优化副枪自动炼钢模型、增强转炉底吹强度、改造双渣氧枪等措施,保证第一炉碱度控制在3.0以上,实现循环渣造渣方法的自动控制。实施热态渣循环利用后,渣中FeO含量降低2.1%,钢铁料消耗降低4.355 kg/t,稳定了低P高端品种钢的生产工艺,提高命中率22.5%。

连续光纤激光切割金属薄壁材料工艺研究

随着工业领域金属薄壁构件设计的多样化,在高速激光切割的同时,对切口形貌质量也提出了更高的要求。本研究采用连续光纤激光器对0.2 mm厚度304不锈钢薄板进行切割实验,研究了毛刺和熔渣飞溅区产生的机理,重点讨论了加工工艺参数中的激光功率、切割速度、离焦量对毛刺堆积量和熔渣飞溅区宽度的影响关系,通过实验分析获得了最佳加工参数组合。研究结果表明,毛刺厚度随着激光功率、离焦量的增大而增加,随着切割速度的增大先降低后增加。熔渣飞溅区宽度随着激光功率的增大而增加,随着切割速度的增大而降低,随着离焦量的增大出现小范围波动。根据加工结果分析,当激光功率为125 W,切割速度为10 m/min,辅助气体压强为1.2 MPa,离焦量为-0.3~-0.5 mm,可以获得0.2 mm厚304不锈钢薄板较好的加工效果。

减少转炉补炉的策略及其效果分析

针对马鞍山钢铁股份有限公司65 t转炉补炉频率高的问题展开原因分析,并进行相应的改进。结果表明:转炉吹炼终点渣的成分超出合理范围、吹炼过程返干比例高及终渣过氧化比例高是补炉次数多的主要原因。通过对溅渣护炉工艺、枪位和加料模式、装料制度等几个方面的优化,终渣中TFe、MgO和碱度值均有所降低,更接近理论渣系成分;溅渣时间不合格比例降低了15.8%,返干比例降低了26%;转炉炉衬厚度逐渐变厚,炉况变好,平均每月减少补炉17.7次。

唐钢新区200 t转炉炉况维护技术应用实践

分析了转炉炉衬侵蚀机理,提出转炉炉衬侵蚀现状,介绍了溅渣护炉动态控制技术、前大面维护技术、自动挂渣技术、转炉底吹风口图像识别技术,通过以上护炉技术的应用,炉龄在1000炉时大面的侵蚀速率由上炉役的0.49 mm/炉降低至0.25 mm/炉,炉底侵蚀速率由上炉役的0.74 mm/炉降低至0.45 mm/炉,转炉炉龄由7500炉提高至8800炉,为延长转炉炉龄提供了理论指导。

提钒转炉耐材损毁原因及炉衬维护探讨

基于钒渣与钢渣不同性质及物相分析的基础上,提出钒渣的温度、粘度、碱度、CaO及MgO含量与钢渣存在着较大差异,炼钢转炉炉衬维护技术不能完全应用于提钒转炉。分析了提钒转炉炉衬耐材损毁的主要影响因素,提钒转炉的冶炼工艺、冶炼周期、所处的工作环境、形成的炉渣成分及物相组成与炼钢转炉有较大差异,指出提钒转炉炉衬耐材维护应根据其损毁原因及结合钒渣的特性,采用综合砌炉、渣补及改质钒渣后的溅渣护炉技术,可大幅提高提钒转炉炉衬寿命。

半钢炼钢条件下转炉护炉技术探讨

钒钛磁铁矿经过高炉炼铁得到含钒铁水,转炉炼钢时利用碳与钒的选择性氧化,将铁水中的钒富集后进入炉渣,然后从钒渣中提取钒,是目前国内主流的提钒方法。含钒铁水的冶炼,转炉的成渣条件及渣相与常规铁水冶炼差异较大,对护炉技术提出挑战,因此掌握半钢炼钢条件下转炉护炉技术,在生产过程中才能不影响生产组织,保证一座提钒转炉对应两座半钢冶炼转炉的顺行。本文基于半钢炼钢条件下钒渣与钢渣的成分和岩相结构分析研究的基础上,总结了影响转炉护炉的主要因素,针对性的提出改进措施,在某厂半钢炼钢条件下,转炉护炉取得了较好的冶金效果。

Mechanism of Fractional Melting in the Splashed Coating on BOF Lining

With the self-made equipment, the benavior of the splashed slag coating was studied by the thermo-simulation. The influenceof TFe, basicity and heating rate of slag on the occurrence of fractional melting was investigated. Furthermore, the composition variationof slag in different stages of the heating process was also discussed, and the mechanism of fractional me1ting was explained. In addition,the exploitation of this phenomenon in practice was also discussed.

120 t复吹转炉炉型稳定控制技术的开发应用

为提高120 t顶底复吹转炉炉型控制的整体稳定性,通过引进炉体测厚仪对转炉炉型进行数字化描述,并根据炉型状态通过研究应用各项炉型控制技术,不仅保障了整个炉役期间的安全稳定生产,且使整个炉役期间碳氧积始终处于稳定状态。

转炉吹炼过程喷溅机理及预报模型研究进展

转炉作为一个高温高压、多元多相的反应容器,容易发生喷溅或溢渣事故.良好的熔池搅拌可以增大渣–金反应面积,提高炼钢效率;异常的熔池搅拌则会造成金属损失,毁坏炉体及其附属设备,甚至威胁到炉前工作人员的人身安全.本文总结了前人对喷溅机理及影响因素的研究结果,转炉喷溅按产生的原因可以分为爆发性喷溅、泡沫性喷溅、金属性喷溅和其他喷溅,其中爆发性喷溅的危害最大,泡沫性喷溅的发生频率最高.喷溅事故的产生总体可以归结为炉内激烈化学反应产生气泡驱动的高温熔体喷溅和顶底复吹为熔池提供的流动能量所产生的喷溅,且一次喷溅事故的发生常常是多种因素耦合引发,从单方面分析喷溅事故原因过于片面,研究出一套适用于转炉喷溅的安全评价模型是当务之急.并对现有的喷溅预报模型进行了综述,总结了炉气分析法、音频分析法、图像分析法的预测原理及部分应用结果,指出现有预测模型没有得到广泛应用的原因,未来喷溅预测模型会朝着更加智能化、精细化的方向发展.

转炉终渣成分和溅渣时间数据驱动预测模型开发

基于260 t转炉实际生产数据,通过机器学习算法XGBoost(eXtreme Gradient Boosting,极限梯度提升树)、弹性回归、线性回归、AdaBoost(Adaptive Boosting,自适应提升树)四种算法建立了终渣主要成分CaO、SiO_(2)、TFe和MgO的预测模型。通过优化调参,XGBoost终渣成分预测模型的决定系数R^(2)均在0.8以上。溅渣时间模型采用SVR(Support Vector Regression,支持向量机回归)、LGBM(Light Gradient Boosting Machine,轻量梯度提升机回归)、GBDT(Gradient Boosting Decision Tree,梯度提升树回归)、RF(Random Forest,随机森林)和XGBoost五种算法进行建模。通过探究,将SVR、XGBoost、GBDT算法使用集成方法得到Stacking集成溅渣时间预测模型,Stacking集成溅渣时间预测模型提升了单个模型的预测效果,偏差为±20 s的预测命中率达89.95%。

低铁耗条件下120 t转炉护炉工艺研究与实践

为了保证钢产量,提高废钢用量,降低护炉的成本以及提高经济效益,通过理论及生产实践,从冶炼护炉、溅渣护炉、日常补炉三方面着手对转炉低铁耗冶炼进行研究,并针对炉况侵蚀情况提出了改进措施。通过降低铁水比,减轻了因转炉冶炼热量不足、终点命中率低、后吹率高、终点钢水过氧化多而造成的转炉炉衬侵蚀严重和转炉漏钢事故。结果表明,通过低铁耗生产模式的运行,使得转炉操作技能得到质的飞跃。

转炉熔渣气化脱磷与循环利用工业试验

为深入研究转炉渣气化脱磷后循环利用的工艺效果,在承钢公司100 t转炉上采用焦粉进行气化脱磷试验并分析了焦粉还原P的可行性.试验结果表明:在溅渣护炉阶段添加焦粉进行气化脱磷,熔渣中先被还原的是P2O5,试验炉次平均气化脱磷率为36.78%;应用气化脱磷渣循环利用工艺后,试验炉次冶炼终点钢液成分合格,钢液中P质量分数呈现降低趋势;试验中吨钢的钢铁料消耗量平均降低0.04 kg,吨钢的石灰消耗量平均降低5.54 kg,吨钢的CO_(2)排放量降低约1 kg.