石灰石在转炉炉渣中分解行为的机理

针对转炉使用石灰石代替石灰炼钢造渣速度加快的现象,研究将FeOx、SiO2和MnOx按照一定的配比与CaCO3混合来模拟石灰石在转炉炉渣中的环境,通过热重-差热（TG-DTA）同步热分析试验探寻其分解规律。研究结果表明,炉渣组分能够明显降低石灰石的分解温度,提升石灰石的分解速度。将混合试样在管式炉煅烧后经X射线衍射分析后发现,CaCO3的分解产物能够与炉渣组分结合生成氧化物或者固溶体,从而降低CaO的活度。     

Decomposition,Reduction and Dissolution Mechanism of Calcium Sulfate in Iron Oxide Dust Pellet

Iron oxide dust generated during oxygen blowing in the BOF process contains a high content of iron. This iron oxide dust can be used as a material of iron source in the BOF slag reduction process or as de‐siliconisation flux or dephosphorization flux of hot metal pretreatment. One of the most practical uses of iron oxide dust is recycling as a form of pellets in the BOF considering easy application and the amount that can be recycled. In the process of making iron dust pellets cement is used as a binder that contains a lot of calcium sulfate. This calcium sulfate is reduced and dissolved in the molten metal during refining in the BOF. If the oxygen content in slag and molten steel is high enough, the reduced sulfate cannot be dissolved into molten metal and it can be removed as SO_x gas. The behaviour of calcium sulfate has been studied using of 50kg high frequency induction furnace and industrial‐scale plant tests were carried out at a 300ton BOF. The results show that for low carbon steels the evaporation of decomposed sulfate increases with increasing oxygen content in the slag while for high carbon steels the decomposed sulfate is reduced into the molten metal.     

100t转炉用含钛铁水冶炼高碳钢的留渣+单渣操作实践

针对100t转炉用含钛铁水冶炼高碳钢的前期成渣难于熔化、脱磷率低的问题,分析了含钛铁水转炉炼钢的成渣过程和炉渣的物理特性,开发了留渣+单渣工艺技术。循环利用终点炉渣,充分发挥渣中10%～13%FeO高（FeO）含量的特点,快速把含钛铁水冶炼前期的CaO-TiO₂-SiO₂三元渣系转变为CaO-TiO₂-SiO₂-FeO四元渣系,脱除钢中大部分磷。控制终渣碱度大于3.2、（TiO₂）含量小于5%,使转炉出钢[C]≥0.20%、[P]≤0.014%,转炉炼钢脱磷率达到88%～92%,石灰消耗下降到28 kg/t钢。     

提高钒钛铁水转炉冶炼废钢比工艺研究

废钢比是转炉生产的重要经济技术指标,其值大小直接影响转炉冶炼钢铁料消耗及热平衡,提高入炉废钢比是实现节铁增钢、降本增效的重要技术手段。然因冶炼低硅含钛铁水成渣难、脱磷难等问题,对应入炉废钢比持低不高,直接影响转炉生产成本。为此,基于低硅含钛铁水冶炼特点及难点分析,结合水钢生产实践,通过氧枪喷头优化、枪位优化、添加提温剂等工艺优化和技术开发,使入炉废钢比由优化前7.41%提高至13.48%,优化效果较为明显。     

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.     

Parameters Affecting Energy Consumption for Producing High Carbon Ferromanganese in a Closed Submerged Arc Furnace

The power consumption is considered to be the most important factor affecting the production cost of fer romanganese alloy. Different parameters affecting the energy consumption for industrial production of high carbon ferromanganese HCFeMn were investigated in a closed submerged arc furnace. The analysis of industrial data revealed that the most energy consumed factors were the direct reduction by solid carbon, Boudouard reaction, metal and slag formation, and decomposition of fluxing materials （limestone and dolomite）. To reduce the energy con- sumption and minimize the energy losses in the production process of HCFeMn, it was recommended to use Mn blend with minimum Mn to Fe ratio of 6 and lower SiO2 content or higher basicity. The added coke must be adjusted according to the material balance to prevent the over-coke and to minimize the highly endothermic ＂Boudouard reac tion＂. In addition, it was recommended to work at basic slags with the ratio of （CaO＋MgO） to Si（）2 equal to 1.0- 1.2 instead of much higher slag basicity. Furthermore, the mass losses had to be minimized through adjusting the handling and charging process and to take care of all metal produced.     

浅析水钢100t转炉喷溅的控制措施

喷溅是转炉炼钢吹炼过程中经常出现的一种现象,喷溅不仅带走大量的金属损失,而且冒烟污染环境。水钢为了进一步降低铁前成本,炼铁采用部分价格相对较低的钒钛磁铁矿,铁水中钛含量大幅上升,Ti氧化生成TiO2的过程,对转炉喷溅影响较大,导致喷溅的进一步增加。本文分析了喷溅产生的根本原因尧铁水中Ti氧化的反应机理等问题,通过转炉冶炼过程的操作调整,进一步降低了转炉喷溅,水钢100 t转炉金属喷溅率从5.23%降低至2.85%,取得了良好的经济效益和社会效益。     

含铌铁水直接冶炼含铌微合金钢的试验

 含铌铁水通过脱碳保铌探索作为合金化元素回收铁水中铌并直接冶炼为含铌微合金钢的方法。试验在真空碳管炉内进行,铁水温度为1 500 ℃,氧化剂为Fe2O3,真空度为10 Pa,分别进行有SiO2-CaO-Al2O3系造渣剂、无渣真空氧化冶炼研究。结果表明：在无渣条件下,加入Fe2O3铁水中硅、铌和碳同时氧化,不能脱碳保铌;加入造渣剂时,造渣剂的碱度越低,铁水中的硅氧化量越低,碳氧化量越高,碳质量分数最低下降到0.032%,铌质量分数最低值从0.09%下降到0.082%;碱度越高,铁水中硅氧化量越高,铌的氧化量也越高;真空氧化冶炼能够促进碳氧化,减少硅的氧化,抑止铌氧化。在50 kg级真空感应电炉内成功进行了回收铁水中铌直接冶炼为含铌钢试验,为回收含铌铁水中的铌提供新方法,也为工业化直接冶炼含铌钢提供试验依据。     

铁水用复吹转炉脱磷脱硫预处理的热模拟研究

通常的铁水预处理是铁水罐或鱼雷车内进行。近年来，日本一些钢厂利用转炉作为铁水脱磷脱硫专用预处理炉。１００ｋｇ试验复吹转炉铁水预处理结果：脱磷率达到９２．０％，脱硫率达到４７．９％。处理时间仅１９ｍｉｎ。与通常的铁水预处理工艺相比，显示了本工艺具有脱磷硫效果好，处理时间短的特点。     

用矿热炉和摇炉生产金属锰的工艺探讨

该工艺是在矿热炉中用焦炭还原锰铁矿石,将还原反应的温度控制为1500℃以下,渣碱度ω(CaO)/ω(SiO2)为0.16,SiO2的质量分数为18%,生产出的富锰渣中MnO的质量分数不小于70%,同时有副产物碳素锰铁产生。然后将富锰渣热兑入摇炉中,加石灰精炼生产调和渣,使其碱度提高到2.0,这样有利于脱除磷、硫,并降低SiO2的活度。最后在摇炉中加入工业硅还原调和渣中的锰,获得锰质量分数不小于99%的金属锰,节能效果明显。     

LF热态渣循环利用技术

 LF热态渣的循环利用可减少废渣排放,降低对环境的危害。对LF热态循环渣的脱硫能力及可回收性进行了分析,热态循环渣返回LF炉和转炉参与冶金反应后,可大幅降低渣料消耗,LF炉每罐回收热态循环渣1～1.5 t,平均节省石灰及其他助溶剂用量5 kg/t（钢）,转炉每罐回收热态循环渣3～5 t,渣料消耗平均降低10～15 kg/t（钢）。采用热态循环渣配加石灰的LF炉造渣制度后,在相同的处理时间内,处理终点钢水中硫质量分数与常规处理几乎相同,同时节省了能源消耗,但必须考虑对钢水增硅、增锰的影响。热态循环渣返回转炉后导致入炉铁水温度低及吹炼过程渣量较大,因此转炉吹炼全程以低枪位操作更为适宜。在不影响生产组织的情况下,热态渣以返回转炉循环利用为最佳途径。     

模拟复吹转炉脱钛预处理的理论和试验

 采用具备顶底复吹功能的500 kg感应炉模拟了转炉预脱钛工艺,分析了钛的氧化反应机理。试验结果表明：终点铁水钛质量分数平均为0.008 2%,脱钛率平均为71.3%。脱钛率随铁水温度升高而降低,随熔池供氧量增加而增加。铁水的终点钛质量分数与终点硅、锰质量分数存在平衡关系,与过程中碳的氧化没有相关性。渣铁间钛分配比为0.6～1.6,随渣中氧化亚铁质量分数的提高而提高,随铁水温度的升高而降低。试验结果和低温下有利于脱钛的理论分析一致。     

A Novel Process Control Model for Extracting Vanadium Semi‐Steel in Basic Oxygen Furnace Based on Steelmaking Mechanism

A novel process control model for basic oxygen furnace (BOF) steelmaking is proposed based on metallurgy mechanism, with lower contents of carbon, manganese, silicon, and lower temperature in semi‐steel after extracting vanadium. According to mass balance and heat balance, a static control model is built up, with slagging model, temperature model, and oxygen supply model. When actual amount of oxygen supply reaches 85% of theoretical value calculated by static model, quasi‐dynamic control model is activated to predict carbon and temperature in later period of steelmaking. A steelmaking process control system for semi‐steel smelting on 120 tonne BOF is developed in a steelmaking plant in China. Based on test of three steel grades, this model acts a guide for BOF steelmaking with semi‐steel, not only providing tactic, but also pointing out a feasible method for BOF process control without sub‐lance or off‐gas analyzer.     

SiO2-Al2O3-Fe2O3渣在铁水脱硫处理中的应用

为了改善铁水脱硫扒渣操作的效果,进行了在铁水喷镁脱硫结束时,将SiO2-Al2O3-Fe2O3系合成渣作为凝渣剂加入铁水脱硫罐内的半工业试验.结果表明,这种凝渣剂具有成渣速度快、铺展性好、吸附脱硫产物能力强的特性,有利于干净扒渣、缩短扒渣时间、降低铁损、减少温降和转炉回硫.     

含钒转炉钢渣中钒的提取与回收

针对攀钢目前含钒铁水的工艺流程和含钒转炉钢渣中V2O3含量,提出了从含钒钢渣提钒的新的技术思路和工艺,并对新工艺的关键环节——含钒钢渣冶炼和高钒铁水提钒进行了试验研究。结果表明：采用矿热炉冶炼含钒钢渣,生铁中钒的质量分数达7．45％,对含钒生铁进行提钒,钒渣中V2O3;的质量分数达35．06％,实现了钒资源的有效提取和综合回收。     

石灰石代替石灰造渣炼钢减排CO2 的研究

为了分析石灰石代替石灰造渣炼钢这项技术在节能环保方面产生的效果,本文将石灰石直接进转炉造渣 炼钢模式和原有的“煅烧石灰-造渣炼钢”模式的CO 2 排放进行详细的对比计算,结果得到用石灰石替代1 kg石 灰,在冷料为废钢和生铁块的情况下,分别能够减排1.29 kg和1.12 kg CO 2 。该技术为钢铁行业节能减排带来的 效益巨大。     

SiO2-TiO2-CaO-MgO-FeO-MnO渣系与脱钛过程铁水中Ti-Si平衡热力学模型

 为降低铁水中钛含量,采用烧结矿或球团矿进行铁水包脱钛预处理。基于共存理论,采用Matlab编程软件,建立了铁水包脱钛典型渣系SiO2-TiO2-CaO-MgO-FeO-MnO中TiO2活度计算模型。结果表明,随着MgO、FeO、MnO摩尔分数和炉渣碱度的增大,脱钛渣中TiO2活度下降;随着TiO2摩尔分数的增大,TiO2活度提高。脱钛终点铁水中的钛含量与硅含量呈线性关系,其斜率受温度、铁水成分以及炉渣中SiO2和TiO2活度的影响。计算结果与试验结果及实际生产数据十分吻合。     

Limestone dissolution and decomposition in steelmaking slag

Based on thermal simulation experiment, SEM analysis and mathematical simulation, limestone dissolution and decomposition mechanism in steelmaking slag were studied. The results showed that limestone decomposition and dissolution happen simultaneously in molten slag, and influence each other. Owing to high-activity lime product and CO₂ from limestone decomposition, the dissolution rate of limestone is greater than that of lime under the same conditions in slag, and the calculated activation energy of limestone dissolution is 226.8?kJ?mol^?1. On the other hand, as decomposition product lime dissolves into slag, a sloughing-type unreacted shrinking core model was proposed to describe limestone decomposition behaviour in slag. In addition, mathematical simulation results showed that heat transfer is the rate-controlling step for limestone decomposition in slag.     

Cost and Life Cycle Analysis for Deep CO2 Emissions Reduction for Steel Making: Direct Reduced Iron Technologies

Among heavy industrial sectors worldwide, the steel industry ranks first in carbon dioxide (CO₂) emissions. Technologies that produce direct reduced iron (DRI) enable the industry to reduce emissions or even approach net-zero CO₂ emissions for steel production. Herein, comprehensive cradle-to-gate (CTG) life cycle analysis (LCA) and techno-economic analysis (TEA) are used to evaluate the CO₂ emissions of three DRI technologies. Compared to the baseline of blast furnace and basic oxygen furnace (BF–BOF) technology for steel making, using natural gas (NG) to produce DRI has the potential to reduce CTG CO₂ emissions by 33%. When 83% or 100% renewable H₂ is used for DRI production, DRI technologies can potentially reduce CO₂ emissions by 57% and 67%, respectively, compared to baseline BF–BOF technology. However, the renewable H₂ application for DRI increases the levelized cost of steel (LCOS). When renewable natural gas (RNG) and clean electricity are used for steel production, the CTG CO₂ emissions of all the DRI technologies can potentially be reduced by more than 90% compared to the baseline BF–BOF technology, although the LCOS depends largely on the cost of RNG and clean electricity.     

Artificial neural nets for prediction of silicon content of blast furnace hot metal

Conventional models for prediction of silicon content of blast furnace hot metal are briefly reviewed. Four different artificial neural net (ANN) models, namely, back propagation algorithm (BPA), dynamic learning rate algorithm, functional link network (FLN) and fuzzy neural network (FNN), are trained and tested on operational data from blast furnace (BF1) at Visakhapatnam Steel Plant. FNN can predict silicon mass content of hot metal with a standard error (actual versus predicted) of 0.09% and correlation coefficient of 0.86; standard back propagation predicts with a standard error of 0.08 % and correlation coefficient of 0.79.