不同矿种H2-C熔融还原过程中CaO-SiO2-Al2O3-MgO系熔渣的起泡行为

 在1400℃下,通过300kg级氢碳熔融还原热模拟试验,用渣线测定装置研究了不同矿种在氢碳熔融还原过程中CaO-SiO2-Al2O3-MgO系熔渣的起泡行为,测定了熔渣的起泡高度、泡沫渣厚度、熔渣起泡率等参数。通过计算得到了气泡大小和熔渣的物理化学性质。结果表明,泡沫渣厚度随表观气体流速(反应速率)的增加而增加,表观气体流速相近时又随熔渣的黏度增大而增加。熔渣起泡率最高的矿种为生矿,为3.4。通过对泡沫渣厚度的因次分析,得到了泡沫渣厚度与熔渣黏度、密度、表面张力、气体表观流速、气泡大小及重力加速度的关系。     

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7～15mm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～l.0mm的球形气泡堆积而成,泡沫化高度随气体...     

含铬转炉渣黏度和表面张力的计算模型

为预测含铬转炉渣的黏度和表面张力,基于炉渣离子与分子共存理论,并结合前人实测的系列含铬转炉渣黏度和表面张力数据,建立含铬转炉渣黏度和表面张力关于温度和结构单元之间的计算模型。模型的计算值与文献的实测值吻合较好,通过模型,有助于预测含铬转炉渣的黏度和表面张力。结果表明,随着Cr₂O₃含量的增加,炉渣黏度升高,表面张力增大,Cr₂O₃对表面张力的影响最大;随着FeO含量的增加,炉渣黏度降低,表面张力减小;随着碱度的增加,炉渣黏度升高,碱度对黏度的影响最大,而对表面张力的影响是先增加后减小,在碱度为1.8时存在极大值。     

固体颗粒含量和形状对流体黏度的影响

实验采用蓖麻油作为流体,近似于长方体的ABS塑性颗粒及近似于圆盘状的石蜡颗粒作为固体颗粒,以旋转黏度仪为实验仪器,研究固体颗粒含量和形状对流体黏度的影响。结果表明:当蓖麻油中颗粒含量≤10%时,颗粒流体为牛顿流体,当蓖麻油中颗粒含量≥15%时,颗粒流体为非牛顿流体;蓖麻油的黏度随颗粒含量增加而增大,近似于圆盘状的石蜡颗粒比近似于长方体的ABS塑性颗粒对蓖麻油黏度的影响更显著。此外,引入形状系数因子,对Einstein-Roscoe模型进行修正,将修正模型预测结果与实验结果对比分析,验证了修正模型的准确性。     

泡沫渣中CO还原FetO的实验研究

考察了ＣＯ流量、添加焦炭颗粒和表面活性组元Ｐ２Ｏ５对泡沫渣中ＣＯ还原ＦｅｔＯ的影响。在浸没喷吹ＣＯ条件下，ＣＯ还原ＦｅｔＯ速度随溶渣泡沫化程度增大而增大。添加灰颗粒有抑制泡沫化的作用，ＦｅｔＯ还原速度降低，而添加Ｐ２Ｏ５促进了熔渣泡沫化，还原速度增大。     

黄铜矿浮选体系晶态/无定形二氧化硅的流变特性与夹带行为

硅酸盐类脉石夹带是制约贫杂难选矿高效浮选分离的难题之一。借助分批浮选试验、流变学测试、冷冻扫描电镜测试、颗粒沉降试验，探究了黄铜矿浮选体系晶态/无定形二氧化硅的流变特性与夹带行为。结果显示，随着脉石中无定形二氧化硅含量的增加，矿浆表观黏度呈指数型增大，黄铜矿回收率持续降低，脉石回收率先升高后降低。脉石回收率发生变化是脉石夹带率、水回收率共同作用的结果:在黏度低增长区，脉石夹带率上移对脉石回收率升高起主导作用，而在黏度中、高增长区，水回收率减少是脉石回收率由升转降的主要原因。总脉石夹带率和各粒级脉石夹带率均随无定形二氧化硅含量增加而升高，且各粒级脉石夹带率呈现出明显差异性，细粒脉石夹带率增幅最大。冷冻扫描电镜与沉降试验表明，无定形二氧化硅与石英颗粒形成了聚集体结构，导致矿浆体系黏度增大，因而脉石颗粒沉降减缓、泡沫排液“洗涤”脉石作用弱化，单位泡沫水中的脉石质量增大，脉石夹带率升高。      

Fe-Si-B-P-C熔体性质对非晶薄带质量的影响

分别采用振荡杯法和座滴法研究了Fe-Si-B-P-C合金体系熔体黏度及表面张力随温度的变化规律,确定了黏度的温度敏感性差异最大的2个合金成分。用平面流工艺制备了该2种合金的非晶薄带,分析了薄带的厚度和贴辊面表面质量随熔体温度的变化。结果表明,非晶薄带的厚度随熔体温度的升高而近似线性减小;对于熔体黏度对温度不敏感的合金来说,熔体温度变化对薄带厚度的影响也相对较小;薄带贴辊面的气坑尺寸和数量均随熔体温度的升高先减小(减少)后增大(增多)。最后,分别从黏度及表面张力对熔潭的影响角度对实验结果进行了分析。     

臭氧强化氧化氧化锌法脱硫过程中产生的亚硫酸锌

氧化锌法脱除低浓度二氧化硫过程中副产物亚硫酸锌的氧化回收利用是影响脱硫工艺发展的重要步骤,同时也是解决脱硫系统设备管道结垢堵塞问题的关键,文中提出利用臭氧强化氧化亚硫酸锌生成可溶性硫酸锌的新方法。研究了亚硫酸锌初始含量、搅拌转速、臭氧流量、溶液初始pH以及温度对臭氧氧化亚硫酸锌的影响。结果表明氧化过程中溶液的pH先升高后降低,溶液中锌离子浓度随氧化时间的增加而增加。亚硫酸锌臭氧氧化速率随初始亚硫酸锌含量的增加先增加后降低,随搅拌转速的增加而增大,随臭氧流量的增加先增加后减小,随溶液初始pH的增加而增加,温度对氧化速率的影响较小。研究结果为氧化锌法高效脱硫及副产物的回收利用提供了理论基础。      

非离子型表面活性剂对风化壳淋积型稀土矿浸出过程的影响

为了缓解风化壳淋积型稀土矿浸取过程存在的浸取周期长、浸出剂用量大和稀土拖尾等问题,以非离子型表面活性剂为助浸剂,氯化镁为浸出剂,对稀土浸出过程进行研究,研究复配浸出剂溶液性质,分析浸矿前后矿物粒径分布,探讨表面活性剂的促渗机理。研究结果显示,加入表面活性剂后,稀土浸出率提高,渗透速度加快,溶液的表面张力和接触角均减小,黏度增大,矿物颗粒的中值粒径明显减小,矿物表面Zeta电位增大,其中加入吐温40后稀土浸出率提高至86.38%,表面张力减小19.00%,接触角减小53.19%,溶液黏度减小4.29%,溶液性质变化最大。加入表面活性剂后可使溶液更容易润湿矿物,进入孔隙的阻力变小,扩散层厚度减小,黏土矿物的膨胀受到抑制,使得溶液浸出稀土的效果更好,其中吐温40对溶液浸出稀土的渗流效果影响最大,助渗效果最好。     

CaF2-SiO2-Al2O3-CaO-MgO五元渣系黏度的试验研究

为了研究含氟渣系成分变化对黏度的影响,根据五因素二次正交旋转回归法设计渣系配方,使用RTW-10熔渣物性测定仪,采用旋转柱体法,在1 600～1 300℃降温过程中对CaF2-SiO2-Al2O3-CaO-MgO渣系的黏度进行连续测定;建立了1 600℃下五元含氟渣系黏度的回归模型,研究了各组元对熔渣黏度的影响.结果表明:当CaF2的含量(质量分数,下同)在10％～70％时,随CaF2含量增加,黏度减小,随SiO2、Al2O3和MgO含量增加,黏度增大,CaO易受其他组元的作用而对黏度产生不同影响;在w(SiO2)=10％、w(MgO) =10％和w(CaF2)=50％时,随w(CaO)增加,黏度先增大后减小,w(CaO)=10％时黏度最大.在w(Al2 O3) =20％、w(MgO)=10％和w(CaF2)=50％时,随着w(CaO)增加,当w(SiO2)＜20％时,黏度先增大后减小;当w(SiO2)＞20％时,黏度持续减小.     

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.     

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.     

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.     

高铝渣物性及发泡性能的试验分析

以Al₂O₃质量分数为30%的高铝渣为原料,研究了该渣系下的液相比例、黏度、表面张力和密度在不同n(CaO)/n(Al₂O₃) (C/A=1.4、1.5、1.6)、MgO质量分数(0%、5%、10%)下与温度变化(1 550、1 600、1 650 ℃)的关系,并分析了不同n(CaO)/n(Al₂O₃)下高铝渣特性对发泡行为的影响及与发泡指数之间的关系。结果表明,不同n(CaO)/n(Al₂O₃)下,MgO质量分数不同,则熔渣成为全液相时的温度均有所差异;渣的黏度和表面张力随温度的升高而减小,并且温度越高,黏度减小的幅度越小,表面张力减小的幅度越大,而渣的密度随温度升高而增加,但幅度较小,因此温度对密度的影响较小。在温度为1 650 ℃、MgO的质量分数分别为0%和5%的渣系中,改变w(CaO)/w(SiO₂)可以影响熔渣的起泡性能,因此确立了该渣系下熔渣特性与发泡指数的关系。综合分析熔渣特性结果发现n(CaO)/n(Al₂O₃)不宜过高,最佳比值为1.4。通过对不同条件下高铝渣物性及发泡性能的试验分析,掌握高铝渣物性参数的变化规律及发泡指数,为高铝渣在冶金过程中的应用提供一定参考。     

Experimental study on resistance characteristics in vertical tank for recovering sinter waste heat

The resistance characteristics of gas flowing through sinter bed layer were tested in different cases on the homemade experimental platform. The pressure drop of gas flowing through sinter bed layer was measured, and the influence of relevant parameters was fully studied. Also, the experimental correlation formula of dimensionless number to reflect sinter layer resistance characteristic, was derived from applying dimensional analysis. The regression analysis was used to determine the coefficient and index of the empirical correlation. The results show that for a given particle size distribution, pressure drop of unit bed layer height in sinter bed layer increases as a form of power function whose power exponent is 1. 681 with the increase of gas superficial velocity. For a given gas superficial velocity, pressure drop of unit bed layer height increases as an exponential relationship with the decrease of particle size distribution. The pressure drop formula is adapted for the whole experimental data. The pressure drop can be accurately predicted while using dimensional formula whose mean error is 12% comparing with former modifier Ergun formula.     

冶金熔体泡沫分类的研究

冷态和热态模拟实验结果证实冶金熔体产生的泡沫化现象与水溶液-气泡系统的泡沫化现象有相似规律。铁水熔池终还原阶段形成的泡沫渣和熔融发泡法制备的铝合金泡沫,均存在球状泡沫型和多面体泡沫型2种不同形态的泡沫结构。气源类型、泡沫形成环境和熔体的物理化学性质是影响冶金熔体泡沫结构及其稳定性的主要因素。     

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.     

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。     

Study on the foaming of CaO-SiO2-FeO slags: Part I. Foaming parameters and experimental results

In order to understand the effect of slag composition on foaming in iron and steelmaking processes, slag foaming was quantitatively studied for CaO-SiO₂-FeO slags in the temperature range of 1250 °C to 1400 °C. It was found that slag foaming could be characterized by a foaming index (Σ), which is equal to the retention or traveling time of the gas in the slag, and the average foam life ( τ). The effects of P₂O₅, S, MgO, and CaF₂ on foaming were studied. As expected, slag foaming increased with increasing viscosity and decreasing surface tension. It was found that suspended second-phase solid particles such as CaO, 2CaO SiO₂, and MgO stabilized the foam and had a larger effect on foaming than changes in viscosity and surface tension for the slags studied. Kimihisa Ito, Research Associate, formerly with the Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University