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The rates of desulfurization of Fe-O-S melts by CaO crucibles and by CaO-saturated liquid iron oxide have been measured at
1600 ‡C. It was found that irons containing 1.62 wt pct and 0.64 wt pct sulfur and 0.070 wt pct oxygen are desulfurized by
a reaction with the containing CaO crucible which does not involve the formation of a CaS product layer. The rate of desulfurization
reaction is controlled by diffusion of sulfur in the iron melt, and a value of 6.7 ±1.7 × 10-5 cm2 per second was obtained for the diffusion coefficient of sulfur in liquid iron. Iron containing 0.088 wt pct sulfur and 0.070
wt pct oxygen is not desulfurized by solid CaO. The rate of desulfurization of liquid iron containing 0.088 wt pct sulfur
and 0.070 wt pct oxygen by CaO-saturated liquid iron oxide is significantly greater than that calculated on the assumption
of diffusion control in the metal phase, and evidence is presented in support of speculation that the reaction rate is enhanced
by Marangoni turbulence at the slag-metal interface. The addition of 4 wt pct CaF2 to the CaO-saturated liquid iron oxide has no influence on the rate of desulfurization of the melt.
A. Saelim formerly Lecturer, Faculty of Engineering, Prince of Songkla University, Thailand 相似文献
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采用高温硅钼炉和常规化学分析法对高硫含量的硅锰合金进行了系列脱硫研究,分析了CaO-BaO-MgOSiO2-CaF2渣系中MgO、CaO、BaO含量的变化对脱硫效果的影响。结果表明:当MgO的质量分数大于8%时,脱硫率会随着MgO含量的增加而升高。用(MgO+CaF2)代替CaO不利于脱硫;用(MgO+CaF2)代替质量分数为0~4%的BaO有利于渣系脱硫,但代替量过多时不利于脱硫。得到了最佳硅锰合金脱硫的渣系,wCaO/wBaO为1.25时脱硫率最高。 相似文献
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承钢独特的资源特点决定了铁水硫含量高,特殊的炼钢工艺造成渣系单一、化渣困难,转炉脱硫效率低,为保证大断面铸坯质量,须提高LF炉的脱硫效率。通过对LF炉脱硫效率影响因素的分析,在原操作基础上制定并试验了两种不同的脱硫方案。实践证明:提高LF炉的脱硫效率,关键在于提高渣中CaO的活度、降低炉渣氧化性等。 相似文献
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KR脱硫渣是KR铁水预处理脱硫工艺的副产品,其磁选后尾渣中CaO质量分数大于50%。可将其用作优质造渣原料返回到转炉炼钢工艺中,降低转炉炼钢的原料消耗。但KR脱硫渣中的硫(w((S))=1.0%~2.5%)成为转炉冶炼循环利用的障碍,直接将其用于转炉冶炼会使钢中的硫含量增加。因此,根据工业KR脱硫渣的化学成分,以合成渣的形式对KR脱硫渣中矿物组成及含硫相的析出行为进行研究,旨在明确KR脱硫渣中各矿物相组成及炉渣中硫的析出行为和赋存状态,为后续通过氧化性气氛有效脱除KR脱硫渣中的硫提供理论参考。采用热力学数据库FactSage 8.0的Equilib模块对CaO-SiO2-CaS-CaF2基熔渣的凝固过程进行模拟,利用XRD、SEM-EDS对合成渣样品的矿物组成及微观形貌进行分析、检测。热力学计算结果表明,CaS的析晶温度为1 320 ℃,低于MeO#1相、MeO#2相及2CaO·SiO2相的析晶温度。炉渣样品的面扫描分析结果表明,在实际凝固过程中,受残余液相黏度增大的影响炉渣中少量硫未能析出形成CaS晶体,则以非晶态的形式赋存在基质相中。KR脱硫渣主要由C3S相、MeO#1相(CaO固溶体)、MeO#2相(MgO固溶体)、基质相和CaS相等矿物组成。炉渣中的硫主要以游离态CaS晶体形式赋存,少量以非晶态硫的形式赋存。炉渣中CaS晶粒主要沿着先析出的高熔点硅酸盐(C3S)相边界析出。 相似文献
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Qing Cao Laurentiu Nastac April Pitts-Baggett Qiulin Yu 《Metallurgical and Materials Transactions B》2018,49(3):988-1002
A quick modeling analysis approach for predicting the slag-steel reaction and desulfurization kinetics in argon gas-stirred ladles has been developed in this study. The model consists of two uncoupled components: (i) a computational fluid dynamics (CFD) model for predicting the fluid flow and the characteristics of slag-steel interface, and (ii) a multicomponent reaction kinetics model for calculating the desulfurization evolution. The steel-slag interfacial area and mass transfer coefficients predicted by the CFD simulation are used as the processing data for the reaction model. Since the desulfurization predictions are uncoupled from the CFD simulation, the computational time of this uncoupled predictive approach is decreased by at least 100 times for each case study when compared with the CFD-reaction kinetics fully coupled model. The uncoupled modeling approach was validated by comparing the evolution of steel and slag compositions with the experimentally measured data during ladle metallurgical furnace (LMF) processing at Nucor Steel Tuscaloosa, Inc. Then, the validated approach was applied to investigate the effects of the initial steel and slag compositions, as well as different types of additions during the refining process on the desulfurization efficiency. The results revealed that the sulfur distribution ratio and the desulfurization reaction can be promoted by making Al and CaO additions during the refining process. It was also shown that by increasing the initial Al content in liquid steel, both Al oxidation and desulfurization rates rapidly increase. In addition, it was found that the variation of the initial Si content in steel has no significant influence on the desulfurization rate. Lastly, if the initial CaO content in slag is increased or the initial Al2O3 content is decreased in the fluid-slag compositional range, the desulfurization rate can be improved significantly during the LMF process. 相似文献
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In order to develop an environment‐friendly steelmaking process, a slag recycling process for hot metal desulfurization by mechanical stirring was designed. The process was developed with 70 kg‐scale hot metal experiments and actual plant tests. The recycled slag has a 70% desulfurization ability compared with that of virgin flux (CaO‐5%CaF2). The lower efficiency of the recycled slag was caused by SiO2 contamination carried over from the previous process. There is no particular size requirement for the recycled slag, as the effect of the recycled slag size on the desulfurization ability is small. The ratio of CaO in the recycled slag to total CaO should be less than 60% in order to prevent an increase in the amount of slag. Slag recycling operation can be repeated more than twice when the optimum conditions are applied. The slag recycling process was established in an industrial operation, and consumption of desulfurization flux decreased by 40% with the process compared with that without slag recycling. Slag hot recycling was adopted at another plant where consumption of desulfurization flux decreased by 50% compared to operation without slag recycling. The positive effect of hot slag recycling is estimated to be a result of the temperature of the recycled slag. 相似文献
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为充分利用固废资源,降低脱硫成本,采用传统皮江法冶镁工艺中产生的金属镁渣为基质,利用实验室湿式脱硫系统,对不同镁渣粒径、烟气气体流速、二氧化硫浓度、固液质量比(简称固液比)以及氧气含量条件下的脱硫性能进行了研究。结果表明,样品粒径越小,流速越慢,二氧化硫流速越低,固液比越低,脱硫量越高;反之,则脱硫量越小。在粒径0.106 mm、烟气流速340 mL/min、二氧化硫流速10 mL/min、固液比0.1 g/g、饱和脱硫时间1 575 min的条件下,二氧化硫吸附量为1 354.62 mg/g。 相似文献
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为了实现LF热态钢渣的循环利用,对目前武钢LF热态钢渣两次循环利用工艺中精炼渣的组成、脱硫能力及吸收夹杂能力的变化进行了分析研究。结果表明,LF热态钢渣循环利用后钢水的脱硫率可以达到90%以上,精炼终点w([S])可以达到0.001%的水平;相对于未循环工艺,钢中w(T[O])减少17.50×10-6,w([N])减少17.00×10-6,夹杂物数量减少4.47个/mm2。根据两次热循环利用结果得出:通过控制回收的渣量及补加石灰的量,可保证循环后初始炉渣中的w((S))小于0.20%,终渣碱度(w(CaO)/w(SiO2))在12.00~20.00范围,w(CaO)/w(Al2O3)为1.75~2.00,从而使精炼渣的脱硫效率、w((S))/w([S])不受循环次数的限制。 相似文献
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The use of Zn- and Pb-contaminated scrap in steelmaking has led to a significant increase of the zinc and lead contents in dusts and sludges, especially produced in the electric arc furnace melting shops. To understand the behaviour of Zn and Pb, fundamental research on the thermodynamics and kinetics of zinc and lead reactions under steelmaking conditions is helpful. In the first part of the present work, the solubilities of lead and zinc in iron are discussed. Furthermore, the influence of several alloying elements, such as carbon, oxygen, sulfur and chromium on the dissolution behaviour of Zn and Pb was examined and compared with former studies. Measurements of the solubility of lead in liquid iron were made at elevated temperatures in the systems Fe-Pb-O, Fe-Pb-C and Fe-Pb-Cr under argon in a gas-tight Tammann furnace. An increase of lead solubility was found with increasing temperature and increasing oxygen content. On the other hand, higher contents of carbon and chromium led to lower solubilities of lead in liquid iron. In the second part, the partition ratios of zinc and lead between liquid iron and various selected slag compositions were investigated. It is shown that zinc partition is determined by oxygen activity and slag basicity. In SiO2-saturated slags, the partition ratio of zinc is considerably higher than in CaO-saturated slags. In comparison, the partition ratio of lead is significantly lower under the same experimental conditions. 相似文献
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Abstract: CaO-Al2O3-SiO2-CaF2-MgO was selected as the slag system for desulfurization in LF process. The reaction between steel and slag during desulfurization has been simulated by using Factsage software to study the influence of component on the sulfur distribution ratio. In order to research the influence of CaO content, aluminum powder content and its granularity on desulfurization, laboratory experiments have been carried out in a 200 kg inductive furnace. Results showed that the optimal composition of deep desulfurizer is wCaO=64% and aluminium powder 10% with a granularity of 30 μm. Industrial trials showed that the main composition range of final slag in LF process is wCaO=530%-570%, wAl2O3=234%-251%, wSiO2=81%-100%, and wCaF2=32%-47%. The sulfur mass percent in steel is lower than 00008% with a desulfurization rate above 89%. According to the result of industrial production, this desulfurizer could meet the production requirement for ultra-low sulfur steel, of which sulfur mass percent is under 00015%. 相似文献
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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. 相似文献
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利用热力学计算软件FactSage确定了精炼渣中MgO质量分数合理范围为4%~8%,以6%最佳。由工业取样结果结合FactSage分析了1873K时SiO2-CaO-Al2O3-6%MgO准三元系液相区及CaO饱和的固液两相区渣-钢平衡。结果表明:高碱度高w(CaO)/w(Al2O3)(C/A)精炼渣有利于钢液的低氧低硫和低硅控制,但并非造得越“白”越好,相反过高的CaO对脱氧和硅含量控制不利。通过钢渣平衡分析得到了酒钢SPCC精炼渣优化成分范围(质量分数)为:CaO为50%~55%,Al2O3为30%~36%,SiO2为1%~6%,MgO为4%~8%,6%为最佳,碱度为9.0~14.0,w(CaO)/w(Al2O3)为1.5~1.8,实验室渣-钢平衡试验和工业生产结果均验证了优化的渣系较原渣系精炼效果更加优越,能够同时降低钢中总氧、硫和硅含量,也能有效控制钢中夹杂物的成分。 相似文献
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以70 t EAF-GOR-LF-CC工艺生产304不锈钢为背景,分别对GOR冶炼过程初始钢液、终点钢液以及还原渣取样分析,重点考察了还原渣碱度、渣中残余Cr2O3质量分数(w((Cr2O3)))以及钢液初始硫质量分数(w([Ss]))对钢液深脱硫效果的影响规律,得出了以下结论:还原渣碱度对脱硫有较大影响,高炉渣碱度有利于钢液脱硫,但当炉渣碱度达到1.75以上时,炉渣碱度对终点硫质量分数(w([Sf]))的影响逐步变小。还原渣中残余Cr2O3对脱硫有阻碍作用,尽可能降低渣中w((Cr2O3))有利于提高GOR脱硫效果,当w((Cr2O3))降低到0.3%以下时,表观渣-钢间硫分配比(LS°=w((S))/w([S]))明显升高。GOR初始钢液硫质量分数越低,越容易获得最终低硫钢液,当w([Ss])<0.07%时,钢液中最低w([Sf])更容易降低到0.004%以下。根据GOR工业试验结果得出了冶炼终点时优化的表观渣-钢间硫分配比( LS°)随还原渣碱度、w((Cr2O3))和w([Ss])的变化关系。 相似文献
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低成本铁水在线脱硫工艺研究是水城钢铁公司(简称水钢)当前应对钢铁工业发展低迷,提高企业运营质量,强化质量管控的重点攻关课题研究.通过对铁水复合脱硫工艺热力学计算,优化复合脱硫剂成分配比并创造适宜的脱硫动力学条件为研究基准,通过对复合脱硫工艺的实验室研究,达到提高铁水脱硫效率,优化高炉炉料结构,提高钢材质量,降低生产成本的目的.研究得出:CaO和CaO/CaF2对Mg基脱硫剂的优化配料及强化脱硫的动力学条件对Mg3 N2基脱硫剂脱硫深度和脱硫率有明显的提升,实验最佳脱硫率达到63.8%.Mg3N2基脱硫工艺在水钢的工业化利用对水钢的质量管控、降本增效方面具有可观效益. 相似文献