机械搅拌法铁水预脱硅的动力学研究

在实验室进行了模拟铁水预处理机械搅拌法脱硅的动力学试验,考察了铁水温度、搅拌方法、初始硅含量、脱硅渣碱度等因素对脱硅反应速率的影响.试验表明：铁水温度对脱硅速率影响较小;机械搅拌可显著提高脱硅速率;脱硅反应初期的限制环节是硅在铁水侧的传质,当渣中FeO含量降低到一定程度后,FeO在渣相侧的传质成为脱硅过程的限制环节,或与硅在铁水侧的传质共同控制速度;脱硅渣碱度在0.32 ～0.65变化对脱硅速率无显著影响.     

铁水脱硅过程机理的探讨

经脱硅实验与计算表明,脱硅反应的表观活化能不大（４３．９ｋＪ／ｍｏｌ Ｓｉ）,温度对脱硅反应影响。脱硅初期,脱硅受铁水侧传质所控制。ＥＰＭＡ显示了构硅元素在渣铁相本体与渣铁界面存在明显浓度差。所以,一次性投入过多脱硅剂不会增加脱硅速度。加强搅拌有利于提高脱硅效率。     

渣洗法铁水脱硅的工业试验

重庆钢铁股份公司开展了铁水渣洗脱硅的工艺试验,结果表明:采用渣洗法进行铁水脱硅,脱硅率可达52.69%;脱硅剂加入量、铁水原始硅含量及脱硅剂加入速度是铁水脱硅效果的主要因素。讨论了试验中铁水温降、脱硅渣泡沫化的问题。     

转炉渣在铁水脱硅领域的应用研究

在实验室及工业大牛产条件下采用宝钢转炉渣作熔剂配制脱硅剂进行铁水脱硅实验。结果表明：用转炉渣替代石灰作熔剂生产脱硅剂脱硅效果更佳;脱硅剂中转炉渣(质量分数)在15％～30％的范围内时,脱硅剂具有良好的脱硅效果和经济效益。     

KR铁水脱硫剂逸散及搅拌器黏渣分析

 为进一步提高KR机械搅拌铁水脱硫效率,对KR机械搅拌铁水脱硫时脱硫剂加入过程中的逸散和搅拌器叶桨上方黏结渣块产生原因进行分析。结果表明,脱硫剂粒度和成分、加料方式、铁水带渣是引起加料逸散和搅拌器黏结渣块的主要原因。采取控制脱硫剂粒度小于0.1 mm的比例小于10%、控制加料时的搅拌速度不大于40 r/min、优化萤石粒度避免脱硫剂中局部CaF₂质量分数高、采取脱硫前扒除铁水带渣等方法,有效改善脱硫剂逸散和搅拌器黏渣,进而提高脱硫剂的利用率和铁水脱硫率。     

含铌铁水预处理脱硅保铌的研究

 为防止铁水预处理脱硅过程中脱铌,通过中频感应电炉底吹氧气冶炼含铌铁水,研究了铁水预处理吹氧过程中不加渣和加入造渣剂吹炼过程中脱硅保铌的行为及铁水中各元素含量的变化规律。试验结果表明：在铁水温度1623K加入碱度为4的CaO-SiO2-CaF2的造渣剂、供氧强度为0. 5m3/(t·min)时吹氧冶炼,铁水中的硅含量降低到0. 012%(质量分数,下同)时,铌才开始氧化,脱硫率为83%,磷含量不变;在相同的温度和供氧强度,不加造渣剂吹炼时,铁水中的硅降低至0. 16%时,铌开始氧化,硫和磷含量不变;有渣吹炼脱硅保铌终点硅含量是无渣吹炼脱硅保铌终点硅含量的10%,显著脱硫。     

含钒硅铁水CO_2脱硅保钒实验研究

以含钒生铁为原料,进行脱硅保钒处理,得到低硅含钒生铁,为下一步转炉提钒获得高品位钒渣奠定基础.本文利用MoSi_2炉和石墨坩埚以CO_2为氧化剂,研究了温度和CO_2气体流量等因素对含钒硅铁水中硅和钒含量的影响.结果表明:当温度在1 450℃左右、CO_2流量控制在1 L/min、一定强度的搅拌时,对脱硅保钒有利,脱硅率高达68.62%,而钒氧化率仅为0.73%.     

Development of Slag Recycling Process in Hot Metal Desulfurization with Mechanical Stirring

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.     

脱硅工艺参数对泡沫渣的影响

用X－光透视装置,观察分析了脱硅工艺参数对泡渣的影响,结果表明,铁水温度过高,过低都会助长泡沫渣,均匀加入适量脱硅剂对缓解泡沫渣是有益的。提高脱硅渣碱度有利于降低泡沫渣,也有利于脱硅。     

Study of New Hot Metal Desulfurization Process on 1t Desulfurization Experiments

For the lack of the present hot metal desulfurization processes in iron and steel industry, our group has proposed the in-situ mechanical stirring method for external desulfurization of molten iron and researched this new method. This paper investigated this new in-situ mechanical stirring hot metal desulphurization process on desulphurization experiments of one-ton scale by using the new desulfurizer. The experimental results indicated that the desulfurization efficiency of in-situ mechanical stirring desulfurization process is 90% and the lowest sulfur content in the treated hot metal is 23ppm. By comparing with the methods of direct throwing desulfurizer and in-situ injecting desulfurization, in-situ mechanical stirring desulfurization process is the suitable desulfurizaton method.     

Effects of BOF top blowing and bottom stirring conditions on suppressing excessive oxidation

Abstract

The effects of top blowing and bottom stirring conditions during steelmaking in a 6 t basic oxygen furnace (BOF) were investigated in studies with the aim of suppressing excessive oxidation. With low oxygen feed rate and high stirring energy, the apparent partial pressure of CO P′_CO was calculated from the equilibrium of carbon and oxygen in molten steel as being <1 atm. The relationship between top blowing/bottom stirring conditions and mass transfer at the slag/metal interface was analysed. It is proposed that mass transfer at the hot spot is significantly affected by the reaching rate of oxygen to the steel bath and bottom stirring. Mass transfer at the slag/metal interface, outside the hot spot, is sufficient to allow equilibrium to be attained in combined blowing BOF processes. Thus, the oxygen that is not consumed for decarburisation is distributed between steel and slag, i.e. deoxidation from steel to slag takes place, which makes it possible to obtain P′_CO <1 atm under atmospheric conditions. The decarburisation model developed based on the analysis reproduces the suppression of excessive oxidation under a decreased, top blown oxygen feed rate and is in good agreement with results from both 6 t BOF experiments and 350 t commercial BOF operation.     

铁沟喷粉工艺及应用

利用喷射冶金的方法,在高炉出铁过程中进行铁沟喷粉,可实现高炉铁水的多项处理。该工艺具有投资少、操作简便、反应温度高、不单独占用处理时间、渣处理方便及反应效率高等优点。工业生产和试验证明,用此方法进行铁水脱硅、脱硫、脱磷及增硅是有效的。严格地过程控制是保证高反应效率的关键。     

铁水脱硅过程泡沫渣的基本特征

采用Ｘ光透视装置,直接观察了铁水脱硅过程泡沫渣现象,结果表明：当脱硅剂投入铁水,泡沫渣随即升腾,以烧结矿为脱硅剂时,泡沫渣从激烈、平缓、再升高,最后塌落,以富矿粉、铁鳞为脱硅剂,泡沫渣起始激烈、逐渐衰减。泡沫渣的孔隙度高,后期脱渣中有铁珠悬浮。     

Effect of in-mould electromagnetic stirring on the flow,initial solidification and level fluctuation in a slab mould: a numerical simulation study

In-mould electromagnetic stirring (M-EMS) is a widely used technique during slab continuous casting. To investigate the effect of M-EMS on the flow and initial solidification in a slab mould, a three-dimensional model coupling electromagnetic field, flow and solidification was developed. To track the steel/slag interface, the volume of fraction (VOF) model was coupled in the model. The electromagnetic force presents a centrally symmetrical distribution on the cross-section. The influences of stirring current and stirrer position on flow, initial solidification and level fluctuation have been discussed. M-EMS enhances the transversal flow and shrinks the lower recirculation in mould. The results indicate that both a higher stirring current and a lower stirrer position produce a reduction of the temperature in the mould centre. Furthermore, a higher stirrer position and a lower stirring current are favourable to the solidified shell growth. However, M-EMS aggravates the level fluctuation, which may lead to slag entrainment.     

移动电磁场对铁水预处理脱硫速度的影响

 为探讨移动电磁场对冶金反应速度的影响作用,本研究对电磁搅拌下的铁水预处理脱硫进行了实验研究。将CaO-10 mass%CaF2脱硫剂加至铁水的自由表面或用载气带入铁水内部,并采用不同的搅拌方式和强度进行了电磁搅拌下的实验,得到了铁水中硫浓度随时间的变化曲线。研究发现电磁搅拌通过改变渣金界面状态及边界层厚度从而提高铁水脱硫速度,并得到了不同搅拌强度和不同搅拌方式的容量传质系数。最后提出一种环保和易操作的电磁搅拌下铁水预处理脱硫工艺。     

机械搅拌法与镁喷吹法铁水搅拌能和混匀时间的关系

采用永田进治公式和全浮力模型计算了机械搅拌法和喷吹法的铁水搅拌能,研究了搅拌能和混匀时间的关系,并和水模型的结果进行了比较,分析了两种搅拌能影响混匀时间的原因。结果表明,机械搅拌法的搅拌能力比喷吹法大数倍,在同一搅拌能下机械搅拌方式的混匀时间比喷吹法短。搅拌优势使得机械搅拌法比喷吹法的脱硫率比喷吹法平均高18.61%,带来的副作用是铁水温降要高于喷吹法15℃,以及对耐火材料的侵蚀速度为喷吹法的3倍。     

KR脱硫效果影响因素的水模实验研究

通过常规搅拌器与设计的异型叶片搅拌器在不同结构搅拌罐上的水力学模拟实验,探讨铁水罐结构等不同因素对脱硫剂卷吸深度的影响规律,实验结果表明,铁水罐结构对KR脱硫效果有较大影响;设计异型搅拌器模型对不同结构搅拌罐适应性较强。     

铁水预处理与纯净钢冶炼(一)

铁水预处理特别是铁水三脱处理技术自获得工业化应用以来，已成为纯净钢冶炼必不可少的最经济工序。综述了国内外铁水深度预处理以及转炉生产纯净钢冶炼工艺的发展现状和部分工业规模生产的操作结果，论述了铁水预处理对纯净钢生产的意义，分析了冶炼纯净钢的铁水深度预处理技术。认为在目前我国调整钢铁产业结构、开发品种、提高质量的关键时期，大力发展和推广铁水深度预处理技术，辅以钢水炉外精炼，必将为钢铁企业扩大纯净钢种冶炼、改善质量、降低成本、提高产品竞争力和附加值发挥巨大作用，带来显著经济效益。     

Study of the Effect of Hellenic Diasporic Bauxite Addition on Blast Furnace Operations

The blast furnace (BF) operation, as well as the steel‐shop downstream, can derive benefits from adjusting the slag alumina content with the proper addition of bauxite flux to its burden. Additions of 5‐15 kg of bauxite/t hot metal lead to a raise of the alumina content of the resultant BF‐slag from 10% to the level of about 12%. In Hellas extensive deposits of diasporic bauxite exist which, however, are under‐utilized by the alumina refineries due to their rather low solubility during the Bayer‐process. The above BF application, therefore, as an alternative use of the diasporic bauxite, is of great interest to the bauxite producers of Hellas. The influence of the bauxite additions on the metal/slag reactions under BF‐conditions was simulated in the laboratory by smelting BF‐slag with diasporic bauxite additions in a graphite crucible. It was achieved the production of BF‐slags with higher alumina contents under the condition of constant slag basicity. The results show the beneficial effect of the bauxite addition to the quality of the produced hot metal. In accordance to its desulphurization and desiliconization as well as the increase of BF‐slag sulphur capacity and fluidity, a thermodynamic evaluation of the metal/slag reaction in respect of SiO₂ reduction and S‐transfer to the slag in relation to its Al₂O₃ content was carried out. This evaluation led to simple algebraic functions and graphs easily applicable by the BF operators. The attained metallurgical results were verified in comparison to industrial test heats with bauxite additions in the BF‐burden in USA, Canada and Europe.     

转炉铁水预处理脱磷的影响因素

 基于炉外铁水深度预脱硫+转炉铁水预脱磷的铁水预处理工艺是当今低磷或超低磷钢冶炼的重要工艺平台,其中转炉铁水预处理脱磷是关键的技术环节。以国内“双联转炉炼钢法”预脱磷炉实践为出发点,在实验室高温炉上通过顶加脱磷剂、浸入吹氧进行了铁水模拟转炉预脱磷影响因素的试验研究,比较了铁水温度、铁水初始硅质量分数w(Si)_i、脱磷渣碱度、供氧制度、搅拌强度、萤石加入量对脱磷效率的影响。结果表明,各因素对脱磷率影响的顺序为铁水温度＞w(Si)_i＞供氧制度＞脱磷渣碱度、搅拌强度＞萤石加入量;适宜的工艺参数为铁水温度为1 300 ℃,w(Si)_i 为0.10%～0.26%或低于0.30%,脱磷渣碱度为2.9～3.0,供氧制度中气氧与固氧各占50%或固氧稍偏多,维持较高的搅拌强度;转炉内铁水预脱磷处理可不加萤石。