Slag foaming in smelting reduction processes

In order to understand the effect of slag composition on foaming in the smelting reduction process, slag foaming was quantitatively studied for CaO–SiO₂–FeO slags in the temperature ranging 1250–1400 °C. It was found that slag foaming could be characterized by a foaming index Σ which is equal to the retention or travelling time of the gas in the slag and by the foam life. The effects of P₂O₅, S, MgO and CaF₂ on foaming were studied. As expected slag foaming increased with increasing viscosity and decreasing surface tension. The results were extrapolated to bath smelting process to predict the foam height. Slag foaming heights as high as 3–5 meters are predicted for a typical operation.     

40t钢包炉泡沫渣埋弧作业

在实验室条件下研究了ＣａＯ－ＳｉＯ２－ＭｇＯ－Ａｌ２Ｏ３渣系的发泡性能与熔渣物性的关系，并在４０ｔ钢包炉上进行了埋弧作业的生产试验，据此对泡沫渣埋弧加热的工艺因素和溶渣发泡机理进行了探讨。     

Slag foaming in bath smelting

Slag foaming measurements in terms of the foaming index (∑) were conducted on bath smelting-type slags (CaO-SiO₂-FeO, CaO-SiO₂-MgO-Al₂O₃-FeO) at 1773 K. It was found that the slag foam stability decreases with increasing FeO (FeO > 2 pct) content and basicity. For the slag system (CaO-SiO₂-FeO), no stable foam was observed at very low FeO content (<2 pct). As pct FeO increases, the slag foaming index goes through a maximum and then decreases; a similar phenomenon was observed for CaO-SiO₂-NiO slags with respect to the NiO content. The foaming index determined from the normal small-scale experiments (3.8-cm ID diameter) were confirmed on a larger scale (9.2-cm ID diameter), indicating that the foaming index is independent of container size. Measurements were also made for the actual compositions for bath smelting slags. For these slags, the foaming index is higher than those of simple CaO-SiO₂-FeO slags, because MgO and Al₂O₃ may increase their viscosities. The foam index is believed to be a function of the physical properties of the slag. Consequently, a dimensional analysis was performed, and a correlation was developed relating the foaming index to the viscosity, surface tension, and density of the slag. An estimation of slag foaming in actual pilot plant trials was also made from the results of the present study. Good agreement was observed between the predicted and observed foam heights and indicated coke in the slag can reduce the foam height by more than 50 pct. R. Jiang, Formerly Graduate Student, Carnegie Mellon University, is deceased.     

脱硅工艺参数对泡沫渣的影响

用X－光透视装置,观察分析了脱硅工艺参数对泡渣的影响,结果表明,铁水温度过高,过低都会助长泡沫渣,均匀加入适量脱硅剂对缓解泡沫渣是有益的。提高脱硅渣碱度有利于降低泡沫渣,也有利于脱硅。     

氩站钢包顶渣起泡性能的实验研究

在实验室条件下采用钼丝挂渣法对氮微合金化HRB400钢筋氩站顶渣的发泡指数进行了测定。研究表明:当碱度在0.6~1.2之间,ω(MgO)为7%~20%时,碱度升高或ω(MgO)增加,能够有效抑制炉渣的起泡;高含量的CaF2(﹥6%)有利于抑制炉渣的起泡;Al2O3对炉渣的发泡指数影响并不明显。具有较弱的起泡性能的顶渣成分范围是:ω(CaO)/ω(SiO2)为0.8~1.2,ω(MgO)=10%~20%,ω(Al2O3)=9.45%,ω(CaF2)=2%,ω(FeO)2.02%。向顶渣中加入适量的CaO和MgO,可有效抑制顶渣的起泡。     

Slag conditions in electrosmelting: A review

The literature on the foaming of electrofurnace slag is reviewed. On that basis, recommendations for improvement in slag foaming are formulated. Inconsistencies in the published data are noted, and some principles are elaborated. It is evident that two key factors have been ignored in the existing research: the temperature of the slag; and its content of small gas bubbles.     

70tDC电弧炉泡沫渣操作技术的改进

分析了直流电弧炉炉渣的理化性能及其炉渣泡沫化的影响。对新疆八一钢铁集团公司70tDC电弧炉泡沫渣的操作进行了总结和分析,同时介绍了优化泡沫渣的方法。     

精炼炉熔渣泡沫化的实验研究

对精炼炉深渣的泡沫化进行了实验室研究了半工业性的实验研究。实验在硅化钼棒炉和１０００ｋｇ感应炉内进行,考究了熔渣碱度、熔渣中ＣａＦ２含量及发泡剂配比对发泡效果的影响。在分析大量实验数据的基础上,对熔渣发泡机理进行了探讨。研究结果表明：所研究的ＣａＯ－ＳｉＯ２－ＭｇＯ－Ａ１２Ｏ３渣系,在碱度为１．０～１．２、ＣａＦ２含量为６％～８％和碳加入量过剩指数为１．４～１．５时,发泡效果较好。     

LF埋弧泡沫渣实验研究

测定了碱度从２．６到３．４的精炼渣系的炉渣发泡性能,得到了具有较好发泡性能的精炼渣系,并通过离差分析方法,得出了炉渣组成对炉渣泡沫化程度的影响顺序为：ＣａＦ２→ＭｇＯ→Ａｌ２Ｏ３→Ｂ（ＣａＯ／ＳｉＯ２）。     

直流电弧炉长弧泡沫渣技术

本文指出了直流电弧炉采用长弧泡沫渣技术的必要性及该技术的发展现状，总结了炉渣物理性质，化学成分，温度和气源等对炉渣泡沫化的影响，并介绍了电炉泡沫渣的操作工艺及实际应用效果，对宝钢三期１５０ｔＤＣ－ＵＨＰ电弧炉的泡沫渣工艺提出了看法。     

Foaming in Electric Arc Furnace Part I: Laboratory Studies of Enthalpy Changes of Carbonate Additions to Slag Melts

In the present work, a modified thermal analysis technique was used for studying the heat effect of slag foaming with carbonates addition. Experiments were conducted by sinking limestone and dolomite pieces of defined shapes (together with iron sinkers) in molten slag and monitoring the temperature changes accompanying the decomposition of carbonates. The heat effects of dolomite and limestone decompositions were determined at 1623 K (1350 °C) and 1673 K (1400 °C). It was found that the decomposition energy for dolomite and limestone for the studied slag composition is in the range of 56 to 79 pct of theoretical values, which is linked to the energy-saving effect of slag foaming. No influence of sample shape on decomposition energy was found for both limestone and dolomite.     

LF埋弧精炼渣发泡剂实验研究

实验了多种物质作为发泡剂的使用效果。实验结果表明，碳酸钙作为LF精炼渣的发泡剂是适合的，SiC单独使用效果不佳，但作为复合发泡剂的组成可以明显改善发泡过程。发泡剂的粒度对泡沫渣的形成有重要作用，不同粒度的发泡剂混合使用可以得到较理想的结果。     

LF精炼渣发泡性能研究

从发泡剂、精炼渣发泡性能、精炼渣成分优化3个方面综述了精炼渣发泡性能的研究现状，最后展望了精炼渣的发展前景和方向，为今后精炼渣的研究和使用提供依据和参考。     

熔渣泡沫化与熔渣性质的关系

对ＣａＯ－ＳｉＯ２－Ａｌ２Ｏ３－ＭｇＯ四元熔渣系进行了发泡性能的研究,测试了熔渣碱度,ＣａＦ２含量,和发泡剂组成对渣发泡效果的影响,对实验结果从熔渣的表在张力和粘度的变化予以分析,阐明熔渣泡沫化程度与熔渣泡沫化性能和供气量之间的关系。     

LF泡沫精炼渣研究和发展现状

介绍了LF泡沫精炼渣的提高热效率，降低炉衬消耗等功能，重点分析了炉渣物理性质、炉渣成分、工艺条件等对熔渣泡沫化性能的影响．指出精炼渣的脱硫性能和泡沫化性能存在一定冲突，发泡剂机理应该从提供气源以及改变熔渣物理性质两方面来考虑。     

还原泡沫渣用发泡剂的实验研究

测定了以碳酸盐为基的发泡剂在特定基渣中的“发泡指数”，研究了发泡剂型泡沫渣的涨泡规律和影响因素及泡沫对钢水的精炼效果，结果表明，运用复合型发泡剂并采用原生矿态是发泡剂的理想选择，泡沫渣具有较强的脱硫能力。     

LF精炼渣泡沫化半工业性试验

在1t中频炉中进行了LF精炼渣泡沫化半工业性实验，测定基础渣发泡实际状况和渣发泡高度和持续时间，研究了CaF2含量和发泡剂成分对发泡率和发泡指数的影响。     

Control of Slag Formation, Foaming, Slopping, and Chaos in BOF

Decarburization, slag formation, foaming, and slopping in basic oxygen furnace (BOF) can now be partly understood, and to some extent predicted with the help of several on-line measurements and on-line control models. The principal reaction in BOF is decarburization. The bulk of the decarburization takes place in the turbulent region of jet impact irrespective of the fact whether the slag is solid, liquid or foamy. Metal droplets are ejected from the jet impact zone but it is difficult to distinguish the decarburization occurring in the bulk metal from that occurring in the droplets. Slag in BOF is heterogeneous and always contains some entrained gas bubbles and solid material (either un-dissolved or precipitated). At no stage the slag is 100 % liquid. A significant part of the metal droplets fall back and travel through the semi liquid slag. Through this mechanism the droplets can cause slag foaming and slopping in the BOF. Phenomenon of slag foaming and slopping can be monitored and controlled by following, dynamically, the audio signals, gas flow rate and composition, by tracking ‘Chaos’ in chemical reactions, by manipulating the chaotic attractors, and by monitoring the lance water temperature and weight. Relative stability potential (RSP) diagrams are found to be a good indicator of the dynamics of process inside the BOF and help in advance prediction of the impending chaos.     

转炉泡沫渣抑制剂的应用实践

介绍了转炉冶炼中的喷溅原因,分析了转炉喷溅对安全、生产、设备、消耗的影响,探讨了三安炼钢厂对抑制炉渣喷溅的措施与方法。对转炉使用泡沫渣抑制剂进行了探讨、实验,在生产实践中表明:优化枪位控制、加料时机控制、熔池温度控制、提高操作水平、正常合理使用泡沫渣抑制剂可以减少83%左右的喷溅,可以补吹不倒炉直接出钢并获得了较好的溅渣护炉效果,采用该技术工艺为三安创造了显著的经济效益和社会效益。     

A Study on the Copper Recovery from the Slag of the Outokumpu Direct-to-Copper Process

The work was aimed at the investigation of the influence of the carbon reducer’s surface on the rate of copper removal from the slag obtained from the flash direct-to-blister process at the G?ogów smelter in Poland. It was found that, under our experimental conditions, the copper recovery from the slag slightly increases as the slag/carbon interface increases. It is very likely that the results depend on the geometry of the investigated system as well as the slag foaming phenomenon. The increase of the slag/carbon interface does not noticeably change the final copper content in the slag. The obtained results do not follow any of the reaction rate equations. Therefore, it can be suggested that the slag foaming plays the key role in the experiments by increasing the reduction surface. In addition, the investigated slag has a high viscosity, which hampers the mass transfer in this slag. This hypothesis is supported by the fact that the slag layer situated below the graphite penetrator was found to be of a different color than the slag in the vicinity of that penetrator, where it was agitated by the CO and CO₂ gases generated by the reactions of the slag reduction. Also, the slag in the layer under the penetrator contained more copper than the slag above this layer.