冶金渣非牛顿流变特性对其泡沫化的影响

实验得到的冶金过程熔渣的一维本构方程的发泡性能方程都是幂律型的。本文对温度和添加物引起溶渣流变特性变化的原因进行了分析。对比熔渣的流变特性的发泡高度曲线,发现除加入较大颗粒的焦炭外,两者的变化趋势非常一致。对Ｆｒｕｅｈａｎ泡沫化指数不适合非牛顿体溶渣的原因进行了解释。     

冶金渣发泡性能及添加剂对其影响的研究

研究了冶金过程中一些常见渣在不同温度和加入不同粒度的添加物（煤、焦炭、石墨、ＣａＯ）条件下,发泡层高度和吹气量的关系。试验得出下述结论：Ｆｒｕｅｈａｎ给出的泡沫化指数只适用于外生气源时温度较高的情况,对温度较低或加入添加物时不适用;较大颗粒的含碳物质能抑制发泡;而细粉状的含碳物质促进发泡;氧化钙粉剂会促进熔渣发泡,发泡的程度与原熔渣的碱度有关。     

LF熔渣发泡剂的研究

讨论了白云石、石灰石、碳酸钡组成的碳酸盐发泡剂对ＬＦ熔渣发泡的影响。在实验室用两种熔渣进行了９种发泡剂试验。测定了熔渣的发泡时间和发泡高度，计算了熔渣的发泡指数。试验结果表明：因为碳酸盐的分解温度不同，单组分发泡剂发泡特性也不同；在９种发泡剂中，白云石、石灰石、碳酸钡配比相等的３组分发泡剂的发泡指数最大，     

保护渣的物性对熔渣摩擦力的影响

介绍了利用结晶器与铸坯之间的模拟装置对熔渣摩擦力测定的结果，分析和讨论了保护渣的粘度，熔化温度，结晶温度等物性对熔渣摩擦力的影响，测定的结果对研制新的保护渣具有一定的指导意义。     

电磁场对连铸保护渣流变特性的影响

采用自制的电磁场中保护渣黏度测试装置和HF-201型黏度仪,分别对有、无磁场时保护渣的流变特性进行试验研究,并通过Scigress分子动力学模拟研究有、无磁场时连铸保护渣的微观结构,分析保护渣流变特性与微观结构之间的关系。结果表明,在电磁场作用下,连铸保护渣黏度增大,转折温度升高,而其Si-O键长不发生变化,键长为0.162 5 nm,但Si与O的结合能力增强;施加磁场后,熔渣中四配位Si、桥氧以及复杂结构单元Q3的含量增多,熔渣网络结构聚合度增大且复杂、稳定。     

高速连铸结晶器保护渣流变特性的研究

用改进的可变转速粘度仪测定了连铸保护渣(％：1.47MgO，12．98Al2O3，47．57SiO2，7．71Na2O，28．52CaO，1．75TiO2)的流变特性，以试验总误差为测量牛顿流体时所容许的最大偏差，由试验得到不同转速下剪切速率D和剪切应力τ，作出τ～D对数曲线，经回归得出熔渣本构方程，以判别熔体是否为非牛顿流体。结果表明，在1200℃较低温度下，该保护渣仍为牛顿流体，如再加入较多的CaO，则保护渣变为非牛顿流体。     

高炉熔渣制备矿渣棉调质剂的研究

针对高炉渣制备矿渣棉的调质过程,研究铁尾矿、碱度、MgO和Al2O3含量对高炉渣黏度和熔化性温度的影响规律。结果表明:铁尾矿能够使高炉渣由短渣特性向长渣特性转化,黏度变化更加平稳,但铁尾矿加入量超过20%后,熔渣黏度和熔化性温度增加,不利于熔渣直接制备矿渣棉;采用化学纯试剂对高炉渣进行调质时,碱度升高使得熔渣黏度向短渣特性进一步转化,熔化性温度升高,不利于熔渣流动性的提高;随着MgO含量增加,熔渣黏度和熔化性温度均呈现先降低后增加的趋势,MgO含量在8%~10%时,熔渣流动性较好;研究中Al2O3含量相对较小,Al2O3含量变化时,熔渣黏度和熔化性温度变化较小,对熔渣流动性影响较小。     

TiO2对含氟熔渣粘度和熔化性温度的影响

对添加ＴｉＯ２的含氟熔渣的粘度和熔化性温度进行测定，并对其凝固渣显微组成和结构进行研究发现，ＴｉＯ２具有提高含氟熔渣粘度和熔化性温度的作用，尤其在提高含氟熔渣熔化性温度方面更显著。当ＴｉＯ２含量增加到５．０％时，熔化性温度可提高９８℃。这主要是由于生成了高熔点矿物钙钛矿，并使低熔点矿物枪晶石减少，这对低熔点、低粘度的含氟铁矿冶炼有重要意义。     

铝钙型预熔精炼渣的黏温特性和熔化温度

通过黏流活化能与温度的关系分析了wMg O、wCa O/wAl2O3和wSi O2对铝钙型预熔渣液相线温度的影响,并通过熔点实验和Fact Sage热力学计算软件对研究结果进行验证,对比分析熔化温度和黏温特性的区别和联系。结果表明:铝酸钙型预熔精炼渣中,wMg O、wCa O/wAl2O3和wSi O2对黏温特性估算的液相线温度的影响比较显著,总体趋势表现为先降低后升高,其中,wMg O为4%~6%,wCa O/wAl2O3为0.8~1.0,wSi O2为6%~10%时,能显著改善熔渣的熔化性能,变化规律与理论分析一致。通过熔渣黏温特性可以较为准确地估算液相线温度,估算的液相线温度介于Fact Sage计算的液相线温度与实验测定的半球点温度之间。     

直接还原-渣金熔分法富集白云鄂博主东矿铁精矿粉中的稀土

对于白云鄂博主东矿铁精矿粉,采用直接还原-渣金熔分法将其中的稀土富集在脉石形成的熔渣中,测定了熔渣的化学成分、结构、熔化温度,考察了熔渣的微观形貌及其组成,探明了熔渣中稀土的富集状况。研究结果表明,海绵铁渣金熔分后脉石形成的熔渣的熔化温度为1350℃,熔渣中稀土元素显著富集,且稀土以氧化物形态优先结晶析出,稀土富集区中稀土氧化物的含量在60%左右。     

Dephosphorization Thermodynamics of Crude Steel Using CaO-Based Flux

Thedephosphorizationofhotmetalandliquidsteelisanimportantoperationduringthesteelmak ingprocess .Searchingforfluxeswithhighrefiningcapacityandlowcostisalwaysofgreatinterestinferrousmetallurgy .Inthelasttwodecades ,agreatefforthasbeenmadebymetallurgiststostudynewdephosphorizationreagents .Thecompoundscon tainingsodiumandbariumhavebeenprovedaspow erfuldephosphorizationreagents[1 3 ] .Thesefluxes ,however ,arenotoftenusedinproductionduetolowavailability ,highcostandenvironmentalpollutionproblems.…     

Investigation into rheological characteristic and foaming behaviour of molten slags

The rheological characteristic and foaming behaviour of molten slags have been investigated at different temperatures and with different additives, such as coke, coal and CaO. In the experiment of rheological characteristic, a modified rotational viscometer with variable revolution's speed was applied. Therefore, constitutive equations and rheological parameters of molten slags have been established. The tolerance-analysis method is applied to judge whether a molten slag belongs to Newtonian fluid or not. The results of foaming behaviour in the blowing gas show that addition of coarse grain coke and coal decreases the foam height. However, the carbonaceous materials of fine grain and CaO powder can cause the increase in foam height. It has also been found from the experimental results that the foam index ∑ is only available for slag of Newtonian fluid in blowing gas. The reason may be well explained with the rheological characteristic of molten slags.     

The Thermodynamics of Some Transition Metals in Molten Slags

In the present paper, the thermodynamic behaviour of transition metals, such as Cr, Ti, Nb and V in molten slags is systematically analysed based on a literature survey. These metals exist in molten slags with multi valences. Oxygen partial pressure, slag basicity, total content of each transition metal, content of each component in slag, and temperature are the influential factors on their thermodynamic properties in molten slags. Higher basicity and strong oxidative atmosphere are generally favourable for the stable existence of transition‐metal ions with higher oxidation states. Temperature is a factor that is less influential than the above‐mentioned ones. For a transition metal in molten slag, the concentration ratio of ions of different valences depends on the activity coefficient ratio of their oxides. The present paper summarizes the activity studies regarding the transition metal oxides in various molten slags. For chromium and titanium oxides, information on CaO? SiO₂ based systems is involved. For titanium oxides, its thermodynamic behaviour in MnO? SiO₂ based slags is introduced. For niobium and vanadium, the information in Na₂O? SiO₂, CaO? CaF₂? SiO₂ systems is provided. Thermodynamic studies are described for Nb₂O₅? MnO? SiO₂ molten slag equilibrated with liquid iron at 1828 K.     

Smelting Oxidation Desulfurization of Copper Slags

 According to the mechanism of sulfur removal easily through oxidation, the process of smelting oxidation desulfurization of copper slags is studied, which supplies a new thinking for obtaining the molten iron of lower sulfur content by smelting reduction of copper slags. Special attention is given to the effects of the holding temperature, the holding time and CaF2, CaO addition amounts on the desulfurization rate of copper slags. The results indicate that the rate of copper slags smelting oxidation desulfurization depends on the matte mass transfer rate through the slag phase. After the oxidation treatment, sulfur of copper slags can be removed as SO2 efficiently. Amount of Ca2+ of copper slags affects the desulfurization rate greatly, and the slag desulfurization rate is reduced by adding a certain amount of CaF2 and CaO. Compared with CaF2, CaO is negative to slags sulfur removal with equal Ca2+ addition. Under the air flow of 0. 3 L/min, the sulfur content of copper slags can be reduced to 0. 00467% in the condition of the holding time of 3 min and the holding temperature of 1500 ℃. The sulfur content of molten iron is reduced to 0. 0008% in the smelting reduction of treated slags, and the problem of high sulfur content of molten iron obtained by smelting reduction with copper slag has been successively solved.     

UV/VIS-spectroscopy of molten and solid CaO-MgO-SiO2 - slags

The previously developed high temperature set-up has been used to monitor the redox state of molten slags at 1500°C directly by UV/VIS spectroscopy. Slags of the CaO-MgO-SiO₂-system were doped with Fe₂O₃ mass contents of 0.80 and 5%. Spectroscopical results at different oxygen partial pressures of the investigated Fe³⁺ charge-transfer (CT) transitions in the wavelength range between 200 and 800 nm were found to be representative for the redox state of the slag. The peak positions and shifts give further information about the optical basicity and the structure of molten slags. The time dependence of the oxidation/reduction equilibrium process was measured and evaluated concerning diffusion mechanisms. In Cr₂O₃-doped silicate-slags in the liquid state CrO₃ - and Cr³⁺- species occur. The different CrO₃-species (CrO₄^2- and Cr₂O₇^2-) in silicate slags have been indicated spectroscopically and registed quantitatively. Further investigations on Cr₂O₃-doped slags uncovered the well known evaporation of chromium out of molten slags as a decrease in the CrO₃ concentration in time. In the molten slag the CrO₃ slowly evaporates, which can be seen spectroscopically as a decrease in the CT-band intensity. The results obtained on numerous optical parameters of molten slags will establish the application of reflection spectroscopy at high temperatures.     

镁质中间包冲击板的研制和试用

以电镁砂为主要原料，加入短钢纤维，促凝剂和分散剂等外加物，研制出镁质中间包中击板预制块。该板钢水，熔渣冲刷性能好，不污染钢水，烘烤时无爆裂，使用方便。     

Density of Na2O-Li2O-SiO2-B2O3 Molten Slag at 1 803——1 873 K

The density of three kinds of molten slags was measured by modified sessile dropmethod at 1 803 1 873 K. The density of molten slag is found to decrease with increasing tem-perature. The temperature coefficients of Na2 O-Li2--SiO2 and Li2O-SiO2-B2O3 slag are smallerthan that of Na20-B2O3 slag. The molar volume of slags increases with increasing temperature.     

熔渣中氧传递机理的研究

介绍了熔渣中氧的扩散系数以及气-渣、气-渣-金及渣-金体系中氧的传递现象,分析了电子电导对熔渣中氧传递的影响,总结了熔渣中氧的传递机理,并认为改变电化学因素可以控制渣相中氧离子的迁移。     

Manganese Distribution between FeO‐MnO‐SiO2–CaO–MgO‐Al2O3 Slags and Molten Iron

Pretreatment of high manganese hot metal is suggested to produce hot metal suitable for further processing to steel in conventional LD converter and rich manganese slags satisfy the requirements for the production of silicomanganese alloys. Manganese distribution between slag and iron represents the efficiency of manganese oxidation from hot metal. The present study has been done to investigate the effect of temperature, slag basicity and composition of oxidizer mixture on the distribution coefficient of manganese between slag and iron. Ferrous oxide activity was determined in molten synthetic slag mixtures of FeO‐MnO‐SiO₂–CaO–MgO‐Al₂O₃. The investigated slags had chemical compositions similar to either oxidizer mixture or slags expected to result from the treatment of high manganese hot metal. The technique used to measure the ferrous oxide activity in the investigated slag systems was the well established one of gas‐slag‐metal equilibration in which molten slags contained in armco iron crucibles are exposed to a flowing gas mixture with a known oxygen potential until equilibrium has been attained. After equilibration, the final chemical analysis of the slags gave compositions having a particular ferrous oxide activity corresponding to the oxygen potential of the gas mixture. The determined values of ferrous oxide activity were used to calculate the equilibrium distribution of manganese between slag and iron. Higher manganese distribution between slag and iron was found to be obtained by using oxidizer containing high active iron oxide under acidic slag and relatively low temperature of about 1350°C.     

Desulphurization of Hot Metal and Ferronickel With Calcium Aluminate Fluxes

Traditionally, fluxes containing calcium fluoride and other additives are used for the treatment of hot metal and molten steel. Recently, magnesium powder or lime-Mg mixture is used more popularly in hot metal desulphurization. However, the use of calcium fluoride has been restricted due to environmental concerns, and the supply of magnesium is uncertain for the countries, which are short of magnesium resource. For those reasons, calcium aluminate fluxes are a possible alternative to replace slags containing calcium fluoride or magnesium. Calcium aluminate fluxes can be produced from three different raw materials: (1) high-quality bauxite, (2) residuals from aluminum dross treatment processes and (3) waste products from alumina production. Due to the limited amount and high cost associated with high-quality bauxite, the other two sources are preferred based on both economic and environmental considerations. The objective of this paper is to examine the use of waste slags and by-products from the aluminum industry as potential refining fluxes for the steel industry so that waste disposal from the aluminum industry can be reduced with economical and environmental benefits for both industrial sectors.