H2-C熔融还原条件下渣金间磷的分配比的试验研究

 通过300kg级氢-碳熔融还原热模拟试验,从热力学角度分析了氢-碳混合熔融还原条件下磷的分配比,运用熔渣规则溶液模型计算了氧化钙、二氧化硅、氧化镁、氧化铝、氧化亚铁、五氧化二磷六元熔渣组分的活度、活度系数,进而计算出一定温度条件下熔渣的磷容量以及渣金平衡时磷分配比的理论值。通过比较理论计算得出的磷分配比与试验中磷的分配比的差异,解析产生差异的原因,进而为氢-碳混合熔融还原炼铁新工艺冶炼高磷铁矿提供参数。试验结果表明：用熔渣规则溶液模型计算渣金间的磷的分配比是合适的,氢-碳熔融还原工艺可以利用高磷铁矿。     

不同气源条件下熔渣泡沫化的高温模拟

熔渣泡沫化的有效控制对冶金工艺的稳定控制具有重要的现实意义。开展了外引和内生两种气源条件下熔渣泡沫化的高温模拟研究,得到如下结论:在外引气源条件下,泡沫渣由尺寸为7～15 mm的多面体气泡堆积而成,泡沫化高度随气体流量增加先升高后降低;在内生气源条件下,泡沫渣由尺寸为0.5～1.0 mm的球形气泡堆积而成,泡沫化高度随气体产生量的增加和熔渣碱度的降低而升高。典型炼钢辅料的消泡效果对比如下:活性石灰纯碱石灰石白云石菱镁矿。     

原位合成多孔凝渣材料机理研究

含钛高炉渣特殊的物理化学性质是产生多孔凝渣层的基础条件,在降温过程中黏度提高很快,气泡被迅速“冷冻”;高熔点TiC、TiN及其固熔体Ti(C,N)的存在,显著降低了熔渣的表面张力,使炉渣黏度增加、变稠,阻碍渣中气泡的长大和放出;含钛高炉渣中TiO2组分,尤其是以四配位离子团存在的阳离子Ti4+,其增加熔体黏度、稳定泡沫的作用明显;TiO2及其高熔点还原产物是表面活性物质,具有稳定气泡的马拉戈尼效应。多孔凝渣层的形成是由于反应物质产生气体,气体上浮逸出的速度小于气体生成的速度,以及渣急速冷却凝固,使部分气泡“冷冻”存留在凝渣中。     

CaO-SiO2-MgO-Al2O3-Cr2O3渣系黏度结构分析及Iida模型应用

 为了实现冶炼铬铁合金过程中含铬渣系黏度的精准控制,从微观结构方面研究了碱度及Cr2O3质量分数变化对铬铁冶炼渣系黏度的影响并优化了Iida黏度预测模型。通过转筒法测量CaO-SiO2-MgO-Al2O3-Cr2O3渣系黏度,结合拉曼光谱从熔渣微观结构方面阐述了Cr2O3质量分数及碱度变化对CaO-SiO2-MgO-Al2O3-Cr2O3渣系黏度的影响。结果表明,熔渣黏度与其表征聚合度的BO参数值均随Cr2O3质量分数的增加而升高,随二元碱度值的增大而降低,熔渣黏度与渣系聚合度变化趋势相一致。根据测量得到的含Cr2O3熔渣黏度数据,进一步优化了Iida黏度预测模型。经过优化后的模型计算黏度值与实际测值吻合较好,利用Iida黏度模型可在较大的温度与成分范围内进行含铬渣黏度的预测。     

固体碳还原熔融氧化铁的动力学

介绍了用体系的初、终态浓度,结合反应过程还原剂失重速度测定动力学参数的方法,测量了周体碳还原熔融PeO-CaO—SiO_2-MgO和FeO-CaO-SiO_2两种渣系中FeO的还原速度。结果表明,在本试验条件下测出的还原反应速度是总(FeO)重量百分浓度的表观一级反应,表观活化能为53.174kcal/mool。在本试验范围内,测得固体碳还原熔融氧化铁的经验速度方程式为: 还原反应的速度限制步骤是FeO热量向反应界面的对流扩散和气泡脱离石墨表面。发现添加少量碱金属氧化物能十分显著地加快碳还原熔融氧化铁的速度。     

含钛高炉渣泡沫稳定性的研究

测定了CaO-SiO_2-TiO_2-Al_2O_3-MgO五元系熔渣中TiO_2含量(10～40%)对熔渣表面张力的影响,指出该渣系中TiO_2是表面活性物质。在还原条件下,测定了TiO_2含量及还原时间与熔渣泡沫稳定性的关系,并讨论了表面张力及钛的碳氮化物和碳化物对泡沫稳定性的影响。     

高锌含量下ZnO-FeO-SiO2-CaO-Al2O3渣系黏度研究

ZnO-FeO-SiO₂-CaO-Al₂O₃是铅锌火法冶炼过程中重要渣系,本文研究高锌含量下ZnO-FeO-SiO₂-CaO-Al₂O₃渣系的黏度,为进一步优化铅锌氧化渣还原熔融设计提供理论支撑。研究过程中采用内旋转圆柱法测量了不同组成成分下ZnO-FeO-SiO₂-CaO-Al₂O₃渣系的黏度,采用傅里叶红外光谱仪测定了高温淬冷渣的结构,并计算了不同熔渣成分下的表观活化能。研究结果表明：初始ZnO含量(16%～32%)的增加可降低ZnO-FeO-SiO₂-CaO-Al₂O₃系炉渣黏度;进一步增加ZnO含量(>36%)则会使黏度大幅增加;当ZnO含量为36%时,温度较高(>1 623 K)时,Fe/SiO₂和CaO/SiO₂的增加可以降低炉渣黏度,但随着温度的降低,Fe/...     

添加剂CaO、Al_2O_3和Cu_2O对铜渣黏度的影响

调控铜渣黏度是提高铜渣贫化效果、促进渣-铜分离的关键因素,本文通过采用高温黏度计测定铜熔渣的黏度,研究了添加剂CaO、Al_2O_3和Cu_2O在不同温度下对铜渣黏度的影响规律。研究结果表明:在相同温度条件下,铜渣的黏度随CaO含量的增加先降低后升高,当CaO含量增加到6%时,铜渣的黏度降至最低,当CaO含量达到7%时,CaO与渣中物质生成难熔化合物,导致渣黏度升高;在渣贫化过程中,Al_2O_3被认为是一种酸性物质,加入Al_2O_3可形成高熔点化合物并提高铜渣的液相温度,从而导致铜渣黏度的增加;在渣贫化过程中,Cu_2O与渣中的Fe~(2+)离子反应生成Fe_3O_4,使铜渣黏度增加;随着添加剂Al_2O_3和Cu_2O含量的增加,改变了铜渣物相组成,提高铜渣的黏度流变表观活化能。     

甘油溶液的泡沫化行为

采用常温甘油溶液体系模拟高钛型高炉渣,通过系统的实验研究了黏度、表面张力和固体颗粒掺杂对泡沫化行为的影响。实验结果表明:随黏度的增加,溶液泡沫化指数先增加后减小,也即涨泡性能先增强后减弱,黏度为93.6mPa·s时达到最大。相同的气体表观速率下,泡沫高度随表面张力的减小而增加;表面张力相同时,泡沫高度随表观速率的增加而增加。表观速率一定时,泡沫高度随固体颗粒PPS含量的增加而增增加,随固体颗粒PPS粒径的减小而增大。同一表观速率下,随着滤板孔径的增大,泡沫高度显著降低。     

高炉粉尘造泡沫渣过程中FeO还原动力学的研究

为了循环利用高炉粉尘,研究了用宝山钢铁股份有限公司高炉粉尘与沥青焦粉混合后加入电弧炉造泡沫渣过程中FeO的还原动力学。结果表明,随粉尘加入量的增加和温度的升高,FeO的还原速率加快;用固体碳还原渣中FeO的反应为表观二级反应,其表观活化能为276kJ／mol;用固体碳还原渣中FeO的反应总速率由CO还原FeO的界面化学反应和炉渣的流动传质共同控制。     

Physical modelling of slag-foaming phenomenon resulted from inside-origin gas formation reaction

Slag foaming is a common phenomenon in the metallurgical process that negatively influence the blast furnace when smelting some special ores such as V-Ti-magnetite. Inside-origin gas plays a leading role during this foaming phenomenon. This study performed a room-temperature simulation of slag foaming from inside-origin gas. Results showed that foaming height increased with increased the amount of inside-origin gas. Higher liquid viscosity caused lower foaming height, which was opposite to the slag-foaming regularity caused by outside-origin gas. Higher surface tension benefited the suppression of the foaming phenomenon and shortened the foaming elimination time. The effect of solid particles on the foaming phenomenon was not monotonic, i.e. the maximum foaming height initially increased and then decreased with increased number of particles. Particles with better solution wettability caused higher foam because they can easily adhere onto film, thereby enhancing elasticity and extending film life. Small particle size benefited the foam. The experimental data were in accordance with the model predictions based on the estimated bubble sizes, which proved that the model developed by Zhu and Du helped predict foaming height caused by chemical reaction.     

全钒钛矿冶炼时含钛高炉渣起泡现象的研究

从配加添加剂的角度研究全钒钛矿冶炼时，含钛高炉渣起泡现象。试验结果表明，含钛高炉中配加适量的添加剂能抑制的还原，降低钛渣粘度，改善钛渣的起泡性能，使全钛钛矿冶时的起泡高度同攀钢现场条件对应的起泡高度接近。     

Study on Foaming Behaviour of Molten Slag during Smelting Reduction with Iron Bath

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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.     

酸性含钛炉渣泡沫化问题的研究

为解决攀钢熔分深还原电炉冶炼钒钛磁铁矿金属化球团过程中出现的泡沫化严重的问题,采取提高炉渣二元碱度、控制金属化球团w(FeO)和残碳量、减少低温电炉加料量等措施,使炉内泡沫化严重的现象得到控制,保证了冶炼过程的连续进行。同时钒还原率提高了13%,冶炼时间缩短了45min。     

Smelting reduction reactions by solid carbon using induction furnace: foaming behaviour and kinetics of FeO reduction in CaO–SiO2–FeO slag

Abstract

Smelting reduction process technology is progressing rapidly, and research to understand the reduction of FeO in molten slag and the associated foaming behaviour has gained importance. The present paper reports experimental data on the reduction of FeO in molten slag generated in a 30 kW capacity induction furnace. The influence of FeO content in the slag and temperature on the foaming and kinetics is discussed. The foaming index, a parameter describing the travel time of gas in the reactor, is shown to decrease with an increase in the superficial gas velocity. The quantitative dependence of the foaming index on slag properties viscosity, surface tension and density has been studied. The data have also been analysed to give an estimation of the activation energy for the reduction reaction. The reduction reaction, initiated by direct slag–graphite contact, produces CO gas, which spreads into the molten slag bath causing foaming of the slag; further reduction of FeO proceeds mostly via indirect reduction. The rate of reduction is found to depend directly on the initial FeO content. An increase in temperature increases the rate of reduction, which has an activation energy of 118 kJ mol^?1 of FeO. The results indicate that transport of FeO in the liquid phase is the rate controlling step. The major findings are in agreement with those reported by earlier investigators.     

Modelling of slag foaming

Abstract

In this work, silicone oils of different viscosities were used to simulate slag foaming. The experimental results showed that the variations of foaming height with superficial gas velocity and liquid viscosity do not show simple increasing trends. At a constant viscosity, foaming height increased first and then started decreasing with increasing superficial velocity. Similarly, a maximum foaming height was observed at an optimum viscosity when a constant gas flowrate was applied. The foaming height started decreasing with further increasing viscosity. Based on the experimental data, a semiempirical equation of foaming height was developed. The predictions of the model agreed well with experimental data. The model could also reasonably well explain the industrial pilot trial experiments. The experimental results with paraffin particle additions indicated that a small amount of particle addition moved the onset of foaming to lower superficial velocity. However, the increase in viscosity due to the presence of solid particles was found not the main reason for the increase in foaming height.     

Study on the foaming of CaO-SiO2-FeO slags: Part II. Dimensional analysis and foaming in iron and steelmaking processes

An empirical equation for the foaming index Σ of a CaO-SiO₂-FeO slag was obtained by dimensional analysis. The effect of second-phase particles on slag foaming was well described by calculating the viscosity of the mixture using the modified Einstein equation. The anticipated foaming in basic oxygen furnace (BOF), electric arc furnace (EAF), and bath-smelting processes was estimated using the parameter Σ for various operating conditions and slag compositions. For BOF operations, it is predicted that foaming is most extreme in the middle of the blow, and a stable foam in EAF is achieved with less basic slags with low FeO contents. For bath smelting, foam heights of 5 m are possible, and a higher degree of prereduction prior to smelting will reduce foaming (because of smaller gas evolution) and possibly increase production rates. Running the process at a higher pressure will also reduce foam heights, because the volume of gas generated is less. Kimihisa Ito, Research Associate, formerly with the Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University