CaO-Al2O3和CaO-SiO2-Al2O3渣系中组元活度的计算

根据分子和离子共存理论,建立了CaO-Al2O3和CaO-SiO2-Al2O3渣系的活度计算模型,并利用模型对渣中各组元的活度进行了计算,分析了w(CaO)对渣中组元活度的影响.结果表明,在CaO-Al2O3渣系中,当w(CaO)小于45%时,随着w(CaO)的增加,3CaO·Al2O3和12CaO·7Al2O3的活度不断升高,而CaO·Al2O3的活度变化不大;当w(CaO)大于45%时,随着w(CaO)的增加,CaO·Al2O3和12CaO·7Al2O3的活度不断降低,而3CaO·Al2O3的活度则略有升高.在CaO-SiO2-Al2O3渣系中,12CaO·7Al2O3的活度低于其在CaO-Al2O3渣系中的活度,随着w(CaO)的增加,CaO和3CaO·Al2O3的活度不断升高,2CaO·SiO2的活度则不断降低,CaO·Al2O3的活度呈现先升高后降低的趋势.     

82B硬线钢精炼渣和夹杂物研究

从A12O3活度和夹杂物成分两方面来研究精炼渣对夹杂物的影响．采用Factsage软件对CaO—A1203-SiO3-MgO（8％）-CaF2（8％）炉渣中A1203,活度进行了计算,并研究了碱度和（MgO）含量对A12O3度的影响．当炉渣碱度从1．0增加到2．0时,炉渣中A1203活度随着炉渣碱度的增加而降低;当炉渣碱度从2．0增加到3．8时,A1203活度变化幅度很小;（MgO）质量分数分别为5％和8％的渣,A1203活度差距较小;在碱度高的炉渣中[A1]。容易被从炉渣还原到钢水中．在使用高碱度精炼渣的盘条中发现许多含有MgO的硬性夹杂物,并对此进行了分析,最后得出最适宜的炉渣碱度为2．5—3．0．     

钙处理对铝镇静钢中非金属夹杂物变性效果的影响

通过对LF前—LF后—中间包—连铸工艺生产40Cr钢各环节系统取样,以及电子显微镜对夹杂物的形貌、尺寸及组成的分析,发现40Cr铸坯中含有大量CaO(CaS)-Al2O3-MgO类复合夹杂.采用Factsage计算得到的CaO-CaS-Al2O3三元相图对钙处理后CaO(CaS)-Al2O3夹杂形成过程进行了理论计算;并对实际发现的CaO(CaS)-Al2O3-MgO类复合夹杂物的面扫描分布进行描边处理,探讨了该类夹杂物的组成和形成过程.经Factsage理论计算发现,CaO-CaS-Al2O3三元相图中液相区各成分质量分数为CaO 32%～58%、CaS 0%～5%以及Al2O342%～65%,钙处理后CaO含量有逐渐增加,CaS含量有逐渐减小趋势.结合夹杂物的面扫描分布发现,CaO(CaS)-Al2O3-MgO类复合夹杂物的组成为xCaO·yAl2O3+mMgO·nAl2O3+Al2O3+CaS,钙处理后Ca能够使Al2O3变性为CaO-Al2O3,但同时夹杂物中也有很高的CaS成分,随着钙处理的充分进行,CaS将由内及外向CaO-Al2O3逐渐转变.     

精炼渣中FeO的活度模型

根据熔渣结构的分子离子共存理论,建立了SiO2-Al2O3-CaO-MgO-FeO-MnO六元渣系的活度计算模型。计算得到了LF精炼渣中FeO的活度值,并分析了炉渣成分Al2O3、FeO以及碱度w(CaO)/w(SiO2)对FeO活度的影响,为帘线钢精炼变渣过程中控制回硫提供指导。     

含钛高炉渣活度模型的建立及热力学分析

根据分子离子共存理论,建立了CaO-SiO2-MgO-Al2O3-TiO2含钛高炉渣活度模型,模型计算结果与实验测定结果吻合较好.利用该模型并结合相图计算分析了碱度和w(TiO2)对含钛高炉渣主要组元活度的影响.结果表明,含钛高炉渣中钛的主要赋存相是CaO·TiO2,1500℃时典型含钛高炉渣中CaO·TiO2的活度为0.18.随着碱度和w(TiO2)增加,CaO·TiO2活度先增后减.当碱度区间在1.08~3.08,w(TiO2)在26%~43%的条件下,有利于CaO·TiO2活度的增加,促进钛组分在钙钛矿中富集.CaO·TiO2活度最大值所需碱度随TiO2含量的增加而增加,当含钛高炉渣中w(TiO2)为20%~28%时碱度为1.34~1.63,对促进钛在钙钛矿中的富集是有利的.     

电铝热法冶炼钒铁渣熔化性能

利用FactSage热力学软件Phase Diagram和Equilib模块分别计算了CaO含量对CaO-Al2 O3-22%MgO-1%SiO2-2%FeO系液相线的影响以及CaO、调渣剂CaF2和B2 O3单独或复合添加对Al2 O3-MgO-25%CaO-1%SiO2-2%FeO系1700℃液相量的影响。通过差热分析测定了现场实验炉渣的熔化开始温度和结束温度,验证了理论计算变化规律。结果发现：电铝热法生产FeV的炉渣中CaO质量分数应该控制在25%左右,此时熔化性能较好;调渣剂CaF2的调渣效果好于B2 O3,且Al2 O3/MgO质量比较高时二者不能复合使用;考虑到工业应用效果和环境保护,CaF2添加量应控制在2%~5%。     

LF精炼对CSP集装箱钢T[O]和夹杂物影响

为提高武钢薄板坯连铸连轧产线集装箱钢水洁净度,通过工业试验考察了LF精炼过程炉渣成分、软吹氩以及钙处理工艺对钢中T[O]和夹杂物的影响.试验结果表明,适当提高(CaO+MgO)/SiO2有利于降低钢中T[O],但同时要考虑(CaO+MgO)/Al2O3的比值,适当增加钙处理前后软吹氩时间可明显提高钢水洁净度;将炉渣中(CaO+MgO)/SiO2和(CaO+MgO)/Al2 O3控制在合适范围不仅有利于提高钢水洁净度,而且有利于钢中低熔点CaO--MgO--Al2 O3系夹杂物的生成.根据相关热力学数据给出了实际生产钢中生成不同液态铝酸钙时[Ca]--[Al]平衡热力学计算模型.     

Influence of Na2O on Properties of CaO-AI2O3 Slag

分析了向CaO-Al2O3基熔渣中添加Na2O对熔渣性能的影响,并比较了几种不同的添加剂对渣系黏度的影响.研究表明：w（CaO）/w（Al2O3）=1.1时,渣系中随着Na2O含量的增加,CaO-Al2O3渣系的黏度先降低后升高,在Na2O质量分数为4%处出现极小值;Na2O的添加还会导致CaO-Al2O3渣系的熔化温度升高;Na2O,Li2O和MgO都可以降低CaO-Al2O3渣系的黏度,其降低渣系黏度的能力由大到小依次为Li2O〉Na2O〉MgO.综合考虑Na2O对渣系黏度和熔化温度的影响,Na2O在CaO-Al2O3渣系中的加入量以不超过4%为宜.     

CSP低碳铝镇静钢水可浇性控制

通过钢液-夹杂物的热力学基本理论,利用活度相互作用系数和Bjorkvall方法分别计算了CSP流程低碳铝镇静钢中钢和夹杂物的成分,详尽地分析了CaO-Al2O3二元系中中间相3CaO·Al2O3,CaO·A12O3,液态12CaO·7Al2O3和CaS夹杂的热力学性质,同时分析了钙处理过程中生成液态铝酸钙夹杂物,避免CaS夹杂析出的条件.模型的结果与工厂试验结果相符合.     

LF精炼过程中SAE8620钢所含MgO复合夹杂物分析

采用非水溶液电解的方法,萃取分离出SAE8620齿轮钢中含MgO复合夹杂物,利用扫描电镜、能谱分析仪对夹杂物的组成、类型和形貌特征进行分析。结果表明,SAE8620齿轮钢在LF精炼过程中,含MgO复合夹杂物中MgO、CaO含量逐渐增加,SiO2含量逐渐减少,Al2O3含量呈先上升后下降的趋势;夹杂物的形貌多不规则,呈块状且棱角分明;夹杂物类型主要为SiO2-Al2O3-MgO、SiO2-MgO、SiO2-Al2O3-CaO-MgO等,此类夹杂物的尺寸较大、熔点较高,直接影响钢材的质量和使用性能。     

Effect of slag composition on the cleanliness of 28MnCr5 gear steel in the refining processes

The equilibrium reaction between CaO—Al₂O₃—SiO₂—MgO slag and 28MnCr5 molten steel was calculated to obtain the suitable slag composition which is effective for decreasing the oxygen content in molten steel. The dissolved oxygen content [O] in molten steel under different top slag conditions was calculated using a thermodynamic model and was measured using an electromotive force method in slag–steel equilibrium experiments at 1873 K. The relations among [O], the total oxygen content (T.O), and the composition of the slag were investigated. The experimental results show that both [O] and T.O decrease with decreasing SiO₂ content of the slag and exhibit different trends with the changes in the CaO/Al₂O₃ mass ratio of the slag. Increasing the CaO/Al₂O₃ mass ratio results in a decrease in [O] and an increase in T.O. To ensure that T.O ≤ 20 ppm and [O] ≤ 10 ppm, the SiO₂ content should be controlled to <5wt%, and the CaO/Al₂O₃ mass ratio should be in the range from 1.2 to 1.6.     

LF炉合成精炼渣成分优化

通过建立二次回归正交设计模型,考察了合成精炼渣碱度w(CaO)/w(SiO2),Al2O3和CaF2质量分数对LF深脱硫效果的影响.结果表明,当渣中w(FeO)为0.5%,w(MgO)为9%时,随渣中w(CaO)/w(SiO2)增加,脱硫率均先增大后减小.当w(CaO)/w(SiO2)不同时,Al2O3和CaF2质量分数对脱硫效果的影响程度不同,主要原因是渣中有效CaO含量变化引起的.随渣中w(FeO)降低和渣量增加,脱硫率明显增大.实验优化的最佳脱硫渣系组成为w(CaO)/w(SiO2)=9~11,w(Al2O3)=27%~29%,w(MgO)=9%,w(CaF2)=8%~10%,w(FeO...     

莱钢高炉合理渣系的研究

为使莱钢高炉冶炼中具有合理渣系,保障高炉长期稳定运行,对其炉渣二元碱度及MgO、Al2O3、FeO含量对炉渣黏度的影响进行研究。结果表明,为保证较低的黏度,高炉渣保持二元碱度约为1.15、w(MgO)为8%~10%较适宜;当高炉渣Al2O3含量达到一定值时,其黏度会明显提高,高炉渣中Al2O3含量最好应控制在15%以内;高炉渣黏度随着FeO含量的增加而显著降低,初渣中较高FeO含量可改善其流动性能。     

Activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag and their application to the recycling of Ni-Co-Fe-based end-of-life superalloys via remelting

To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni-Co-Fe-based end-of-life (EoL) superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO-Al₂O₃-SiO₂ slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO-Al₂O₃-SiO₂ slag. The activity coefficients of NiO and CoO in CaO-Al₂O₃-SiO₂ slag both show a positive deviation from Raoult's law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B=(%CaO)/(%SiO₂)=1, where B is the basicity. We observed that controlling the slag composition at approximately B=1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.     

Top slag refining for inclusion composition transform control in tire cord steel

Controlling conditions for inclusion plasticization were calculated by FactSage, and the steel/slag reaction equilibration time was determined by pre-equilibrium experiments. Laboratory experiments with different top slags were carried out in 90 min, and industrial tests were performed based on the results of calculation and laboratory experiments. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to determine the morphology and composition of inclusions in tire cord steel. It is found that the shape of inclusions can be controlled well, and the composition of inclusions varies in the industrial test as the following transformation route:MnO-Al₂O₃-SiO₂→CaO-Al₂O₃-SiO₂→MnO-Al₂O₃-SiO₂. Inclusion plasticization can be achieved by controlling the binary basicity of top slag (CaO/SiO₂ by mass) around 1.0 and the (Al₂O₃) content in top slag below 10wt%. Under these controlling conditions in the industrial test, almost all of inclusions in the wire rods achieve plastic deformation.     

MgO对高铝高炉渣脱硫的影响及其动力学分析

随着廉价高铝铁矿石的不断使用,高炉炉渣内Al2O3含量也随之升高,这势必会影响高炉炉渣的各项冶金性能。为深入研究高铝高炉渣脱硫性能,明确MgO含量对高铝渣脱硫性能的影响,笔者通过改变高铝渣中MgO的含量,分别设定渣中MgO含量为5%、9%、13%MgO,研究不同MgO含量高炉高铝渣的脱硫性能及其脱硫动力学。结果表明:MgO含量不仅对高铝渣的黏度、脱硫能力有不同的影响,还使炉渣的脱硫速率发生了很大的改变。MgO含量越高对应的黏度越低,脱硫能力越大;但脱硫速率却表现出了不同规律,9%MgO的脱硫速率表现为最大;经过综合比较,当碱度固定为1.1、Al2O3含量固定为17%时,MgO含量为9%的炉渣同时具有较好的粘度和脱硫性能。     

高炉含碱金属氧化物炉渣性能的试验研究

对含有碱金属氧化物、TiO2的广钢高炉渣黏度、熔化性温度和脱硫能力进行了试验研究.结果表明:试验条件下,含碱炉渣黏度、熔化性温度比普通炉渣低,碱金属氧化物对酸性渣的熔化特性具有明显影响,碱度升高,影响减弱.MgO,Al2O3对含碱炉渣特性的影响规律与普通炉渣大体一致,碱度对含碱炉渣的脱硫能力具有明显影响.在广钢生产条件下,w(K2O)+w(Na2O)应控制在0.9%以下,w(CaO)/w(SiO2)控制在0.96~1.06之间,w(Al2O3)控制在14%以下,w(MgO)控制在12%~15%之间能够获得较好的炉渣黏度、熔化性温度和脱硫能力.     

Preparation of CaO-Al2O3-SiO2 system glass from molten blast furnace slag

To use the potential heat of molten blast furnace slag completely, a CaO-Al₂O₃-SiO₂ system glass (MSG) was prepared from the molten industrial slag. The corresponding method proposed in this study utilized both slag and its potential heat, improving the production rate and avoiding the environmental pollution. Using appropriate techniques, an MSG with uniform color and superior performances was produced. Based on the experimental results and phase diagram, the chemical composition of MSG by mass is obtained as follows: CaO 27%–33%, SiO₂ 42%–51%, Al₂O₃ 11%–14%, MgO 6%–8%, and Na₂O+K₂O 1%–4%. Thermodynamic processes of MSG preparation were analyzed, and the phases and microstructures of MSG were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that alkali metal oxides serve as the fluxes, calcium oxide serves as the stabilizer, and alumina reinforces the Si-O network. XRD and SEM analyses show that, the prepared MSG displays the glass-feature patterns, the melting process is more complete, and the melt viscosity is lowered with an increase in calcium oxide content; however, a continuous increase in slag content induces the crystallization of glass, leading to the formation of glass subphase. The optimum content of molten slag in MSG is 67.37wt%. With respect to bending strength and acid/alkali resistance, the performance of MSG is better than that of ordinary marble.     

Al2O3对高炉渣物化性能影响的理论分析

随着优质铁矿资源的消耗,钢铁企业可利用的铁矿原料品位逐渐降低。因此,高铝质铁矿资源越来越受到钢铁企业的关注,但高铝原料在高炉冶炼过程中会带来渣铁黏稠、炉温偏低、冶炼安全等一系列问题。本研究中采用FactSage热力学软件分析Al₂O₃质量分数对高炉渣平衡物相、熔化温度、相析出温度的影响以及高铝渣液相区变化和黏度变化,旨在为高炉冶炼高铝原料提供一定的基础支撑。研究发现：炉渣为低铝（5%～10%）含量时,随着Al₂O₃含量增加,炉渣熔化温度升高,析出相为黄长石相和纯物质相,高炉渣黏度变化不大,炉渣中SiO₂含量高,炉渣黏度过高,不适合高炉冶炼;炉渣为中铝（10%～15%）含量时,随着Al₂O₃含量增加,炉渣熔化温度升高,析出相为尖晶石相、黄长石相和纯物质相,高炉渣黏度增加幅度略有提高,Al₂O₃含量对高炉渣性质影响较小,增加炉渣二元碱度对炉渣黏度降低效果较明显;炉渣为高铝（15%～30%）含量时...