Modeling and Simulation of Hot Metal Desulfurization by Powder Injection

The desulfurization of hot metal by the mono-injection of lime powder and the co-injection of lime, calcium carbide and magnesium powders is mathematically modeled. The mono-injection model is derived from the continuity equation and is validated using experimental results and data previously reported in the literature. The co-injection model and the rate constant of the injected mixture are determined from the molar fractions and rate constants of the individual powders. The effect of the lime content of the mixture on the desulfurization dynamics is studied and discussed.

Cold Model Study on Mg Desulfurization of Hot Metal Under Mechanical Stirring

The new method of in-situ desulfurization with mechanical stirring of new type impellers was introduced, in which the bubble＇s dispersion and disintegration of magnesium vapor were the key to boosting the desulfurization efficiency and increasing the utilization rate of magnesium. Effects of different new type of impellers on bubble dis persion and disintegration were studied through bubble image analysis, gas-liquid mass transfer, and power con- sumption levels of different impeller structures. The results showed that the sloped swept-back blade impeller-2 pro- duces optimal bubble＇s dispersion and disintegration, as well as higher volumetric mass transfer coefficient and CO2 gas utilization while consuming the least power. Numerical simulation result with Fluent software also showed that the sloped swept-back blade impeller-2 has higher turbulent kinetic energy and better velocity distribution than the other two impellers.

Kinetics of hot metal desulfurization by bottom blowing magnesium vapor

To solve the technical problems of hot metal desulfurization by injecting magnesium particulate,a new idea of hot metal desulfurization by bottom-blowing magnesium vapor was put forward.The reaction mechanism of hot metal desulfurization with magnesium vapor injection was analyzed,and the kinetic model of the desulfurization rate during the process of hot metal desulfurization with magnesium vapor injection was established.The dimensionless equation of the gas–liquid mass transfer coefficient under the injection conditions was obtained by the dimensional analysis method.And the theoretical calculation results were in good agreement with the experimental measurements.The results show that the diameter of the bubbles and the viscosity of the melt significantly affect the desulfurization rate of hot metal injected with magnesium vapor.When the temperature is 1573 K and the gas flow rate is 3 L/min,the desulfurization rate can reach 79%and the utilization rate of magnesium can reach 83%.

The Recent Progress of Hot Metal Desulfurization in CSC and DSC

There are two kinds of existing processes for hot metal desulfurization in CSC. One is the injection process in torpedo car, the other is the impelling process in transfer ladle. Lime-based fluxes have been used for both processes. The former was introduced to CSC in 1982. The latter was adopted by CSC and DSC respectively in 2004 and 2010. This paper comprises a theoretical analysis on lime-based flux as desulfurizing agent and an experimental evaluation on impelling process of Kambara (or Kikai) Reactor with a water model and a hot model established in 2001. The comparison of recent mass-production performance for both processes in steelmaking shop has also been included.

Effect of magnesium injection process on hot metal desulfurization

To solve the technical problems of hot metal desulfurization by injecting magnesium particulate, a new method of hot metal desulfurization by bottom-blowing magnesium vapor combined with mechanical agitation was put forward. The effects of three different desulfurization processes on the desulfurization efficiency were studied in view of thermodynamics and kinetics. It was found that the utilization efficiency of magnesium can reach 82.6% and desulfurization efficiency can reach 86.2% during the first 4 min using the method of magnesium vapor injection combined with mechanical agitation. The gasification of magnesium powder leads to significant splashing and magnesium losses in the process of magnesium powder injection, resulting in a low utilization efficiency of magnesium of 51.8% and a low desulfurization efficiency of 55.76%. Activation energy for a first-order kinetic relationship between magnesium powder and sulfur was measured from the experiments, which was 142.82 kJ/mol in the temperature range of 1573-1723 K. The activation energy of the reaction between magnesium vapor and sulfur was around 54.8-65.0 kJ/mol in the temperature range of 1573-1723 K, which indicates that the desulfurization with magnesium vapor proceeds relatively easier than the desulfurization with magnesium powder.

Kinetics of hot metal desulfurization using CaO-SiO2-Al2O3-Na2O-TiO2 slag

Kinetics of hot metal desulfurization were studied using CaO-SiO2-Al2O3-Na2O-TiO2 slag in the range of 1400-1500℃on a laboratory scale.The results of kinetic experiments indicate that the desulfurization rate increases as the temperature,Al2O3 content,Na2O content,and TiO2 content increase and basicity increases from 1.01 to 1.75,but decreases when basicity increases from 1.75 to 2.02.The melting effect of slag is promoted as the temperature,Na2O content,and TiO2 content increase and Al2O3 content increases from 12.13 to 17.17 mass%,but worsened as basicity increases and Al2O3 content increases from 17.17 to 22.27 mass%.A kinetic model of hot metal desulfurization has been developed to calculate the mass transfer coefficient and the mass transfer resistance of sulfur in slag.The mass transfer coefficient of sulfur increases as the temperature,Al2O3 content,Na2O content,and TiO2 content increase and basicity decreases.Total mass transfer coefficients of sulfur were in the range of(5.02-23.78)×10^-7 m s^-1.The activation energy was estimated to be 464.06 kJ mo1^-1 at the temperature from 1400 to 1450℃and 176.35 kJ mol-1 at the temperature from 1450 to 1500℃.The sulfur distribution at the slag-metal interface was observed using a mineral liberation analyzer.The result shows that the mass transfer of sulfur in slag is the controlling step at high temperature during the desulfurization process.

Kinetic modeling on hot metal desulfurization with mechanical stirring

A kinetic model on hot metal desulfurization with mechanical stirring was established using FactSage Macro Processing.The sulfur diffusion in the molten steel and reactions at the interface between the molten steel and the desulfurizer particle were considered.Calculated results agreed well with experimental results,indicating that the model can be used to predict the desulfurization rate and cost with various temperatures,chemical compositions,rotation speeds,and desulfurizer additions.The higher impeller rotation speed from 80 to 120 r/min,higher temperature from 1573 to 1673 K,smaller particle size from 2.5 to 1.5μm,and more desulfurizer addition from 0.35 to 0.64 kg/t were suggested to improve the desulfurization rate.Moreover,to synthetically increase the desulfurization efficiency and lower the cost,contours of S content and cost during the desulfurization process with various desulfurizer additions and time were calculated.Based on industrial cost data analysis of the added desulfurizer,the refractory erosion,and electric power consumption,the total cost of the hot metal desulfurization with time step(Δt)was fitted as Cost_(total)=0.066+1.58×10^(−7)·Δt.The less desulfurizer addition and longer desulfurization time contributed to lowering the cost,while more desulfurizer addition was conducive to improving the desulfurization efficiency.

基于集成学习的脱硫剂加入量预测方法

为解决铁水预脱硫过程中脱硫剂加入量控制问题,提出一种基于集成学习的脱硫剂加入量预测方法。首先,对原始数据进行预处理,将空值、重复值、0值以及不符合工艺规范的数据行删除,并使用LOF算法结合专家经验剔除异常值;其次,基于GBDT算法计算每个输入特征的重要性占比,进行特征筛选;最后,采用Optuna超参数自动寻优框架对预测模型调优,寻找最佳超参数组合,预测脱硫剂加入量。利用某钢厂铁水预处理过程中的实际生产数据,分别采用XGBoost、RF、GBDT以及LightGBM等方法构建预测模型并进行对比试验。其中XGBoost模型的拟合精度(R^(2))、均方根误差(RMSE)、平均绝对误差(MAE)以及平均绝对百分比误差(MAPE)分别为0.8962、198.245、119.726以及7.897%,相较于其它模型均是最优。

pH值对汽油吸附脱硫装置废吸附剂复活效果的影响

采用酸碱连续处理法对汽油吸附脱硫装置外排废吸附剂进行复活,利用15 mL固定床小试装置评价了其脱硫性能,研究了复活过程中pH值变化对复活效果的影响。结果表明:酸碱连续处理可以有效溶解废吸附剂中Zn_(2)SiO_(4)等非活性组分,并使其重新沉淀负载;随着反应体系pH值的升高,新生成的活性组分粒径更小;当反应体系pH值为8或9时,复活剂比表面积、孔体积及孔径分布与新吸附剂较为接近;当pH值为9时,反应滤液中锌离子、镍离子和铝离子质量浓度分别为0.92、0.79、0.51 mg/L;经过酸碱连续处理的复活剂的脱硫性能基本与新吸附剂持平;随着反应体系pH值的升高,复活剂脱硫率基本呈升高趋势;当pH值超过9时,脱硫率增幅减缓。因此,废吸附剂复活反应体系最佳pH值为9。

铁水预处理高效脱硫工艺

随着我国钢铁行业的发展,对钢中硫含量的要求越来越严格,一般要求钢中[S]的质量分数不大于0.02%,而一些对硫含量要求更为严格的钢种,则要求成品中硫含量小于0.005%。为了进一步提升铁水脱硫能力、降低铁水消耗,本文分析了KR预处理工艺过程中铁水温度、脱硫剂单耗、初始硫含量、搅拌时间对脱硫率的影响,针对KR工艺优化前存在的问题进行了分析,基于热力学平衡计算,建立了适宜的炉渣碱度、FeO以及温度的控制方式,更有利于获得碱度合适、流动性较好的炉渣,优化了渣钢反应的动力学条件。通过工艺优化,基于不同的铁水条件,调整装入量在78~80 t、优化搅拌头转速、搅拌时间以及搅拌深度,KR脱硫剂单耗为0.123 kg/(t·s),下降了13.38%,平均搅拌时间缩短了1.04 min,脱硫剂消耗减少了2.58 kg/t,吨钢脱硫渣量减少了1.97 kg/t,全天最高脱硫包数78包,全月有9次单班KR脱硫完成27炉,KR各项工艺指标均得到改善,形成了高效低成本KR冶炼工艺,降低了冶炼过程渣料消耗量,减少了冶炼成本,实现了KR高效低成本脱硫。

HMPT-BOF工艺生产低硫钢的硫控制与回硫分析

对涟钢HMPT-BOF工艺生产低硫钢的过程硫控制效果进行了分析,寻找出了转炉钢水回硫的主要原因,提出了有效的改进措施,满足了"HMPT-BOF-RH-CSP"工艺生产低硫钢的需要。

铁水脱硫渣固化土基层材料力学性能研究

基于土壤固化技术,将铁水脱硫渣、高炉矿渣微粉、普通硅酸盐水泥与素土按一定比例拌和制备铁水脱硫渣固化土基层材料,通过击实、无侧限抗压强度、劈裂强度等试验对其性能进行测定,并分析物料掺量对铁水脱硫渣固化土力学性能的影响,结果表明:提高铁水脱硫渣掺量和降低矿渣微粉掺量均会使混合料最大干密度增大、最佳含水率下降;铁水脱硫渣固化土基层材料具有较好的力学性能,7 d无侧限抗压强度均大于6 MPa;当矿渣微粉掺量为40%时,铁水脱硫渣固化土基层材料达到力学峰值,道路基层强度最佳。

硅钢铁水预处理脱硫工艺实践

结合脱硫理论和实际生产数据分析,对某厂硅钢铁水预处理脱硫进行了研究。结果表明,二次脱硫渣硫含量与前渣中的硫含量成正比、与前渣余量成反比、与一次脱硫渣余量成正比、与脱硫剂用量成反比。当脱硫剂总量一定时,二次脱硫渣中硫含量随着一次脱硫剂占比的增加呈先降后增的趋势,最佳一次脱硫剂占比为40%。铁水随着预处理前温度的升高,处理后的硫含量呈先降再升的趋势,最佳处理前温度为1370~1400℃。铁水通过3次扒渣,2次脱硫处理,硫的质量分数降至11.7×10^(-6),满足硅钢生产需求。

唐钢新区铁水KR高效脱硫的工业试验研究

通过在唐钢新区200 t铁水包中取样,研究了KR脱硫过程中铁水中[S]和脱硫渣中(S)含量的变化规律。结果表明,在KR 10 min的机械搅拌过程中,铁水硫从初始0.038%下降到0.002%,脱硫渣(S)从初始0.028%上升到3.28%。脱硫率从初始68%下降到33%。KR脱硫的限制性环节在后期的7~10 min,这是目前仍尚未明确的问题。为了提高KR处理过程末段脱硫效率,采用了阶跃式变化搅拌速度的工艺思路,并开展工业试验,在不增加搅拌时间的情况下,搅拌速度从90~110 r/min降低至45~90 r/min,脱硫剂用量从8~10 kg/t降至4.0~6.5 kg/t。阶跃控制搅拌速度的KR脱硫模式,在实际生产中具有较强的应用价值。

关于KR法铁水脱硫脱硫剂和投料方式的发展与探讨

介绍了铁水预处理的必要性及我国KR法铁水脱硫的发展过程,并对KR法铁水脱硫的脱硫剂发展进行阐述,提出脱硫剂未来研究方向和目标;同时对脱硫剂的投料方式进行对比,以便于更加清晰地进行投料方式的选择。

铁水炉外脱硫的新进展

综述了近年来高炉铁水炉外脱硫的发展现状和进展。对几种常用炉外脱硫剂的脱硫效果和利弊进行了对比分析，提出了目前采用镁基脱硫剂进行深度脱硫是我国发展优质钢材、提高企业竞争力的良好机遇。

Cu(I),Ag(I)/分子筛化学吸附脱硫的π-络合机理

应用DFT研究了一系列含硫的杂环化合物(噻吩、苯并噻吩、二苯并噻吩和4,6-二甲基二苯并噻吩)以及苯分子在Cu(I)-Y、Ag(I)-Y分子筛上的化学吸附.计算采用16T分子筛簇模型(H22Si15AlO22),对过渡金属采用了赝势基组,在BLYP/DNP水平上完成.相互作用能的结果表明,阳离子交换的分子筛对含硫杂环芳香族化合物吸附能力的顺序为Cu(I)-Y>Ag(I)-Y.两种吸附剂对噻吩类分子的吸附能力大于苯分子.噻吩衍生物的吸附能顺序依次为,4,6-二甲基二苯并噻吩<二苯并噻吩<噻吩<苯并噻吩,与实验结果相近.通过自然键轨道计算,研究了分子筛上担载的Cu(I)、Ag(I)金属离子与噻吩和苯分子之间的π-络合作用,分析比较了自然键电子给体-受体之间的二阶微扰稳定化能,并探索其络合机理.

KR法铁水脱硫的流动数值模拟分析

基于Fluent软件,采用VOF和DPM模型对KR脱硫搅拌槽内的流场和脱硫剂颗粒运动进行数值模拟,研究搅拌槽内的流场特性和搅拌头的转速对颗粒运动轨迹的影响。结果表明,搅拌初期槽内自由液面中心在下凹的过程中伴有上涌和回落的现象;流场稳定后,流体在壁面处形成上、下对称的两个涡流,而在搅拌头的底部容易形成死区;提高搅拌头的转速有利于提高槽内流场的轴向速度,有利于脱硫剂颗粒在槽内均匀悬浮,从而提高脱硫效果。

从热滤渣中富集贵金属的实验研究

针对含贵金属热滤渣物料的物相及元素组成,提出了氧化焙烧脱硫-硫酸选择性浸出贱金属铜和镍富集贵金属工艺,讨论了物料粒度、焙烧时间、焙烧温度、硫酸浓度、浸出时间、浸出温度等因素对贵金属富集比的影响。获得最佳工艺参数为：热滤渣粒度0.080~0.106 mm,焙烧时间6 h,焙烧温度700℃,硫酸浓度45%,浸出时间5 h,浸出温度95℃。在此条件下,脱硫率达到98.89%,铜、镍浸出率分别为98.33%和98.12%,硫酸浸出渣中Au含量1 198.60 g/t,Ag含量1 807.79 g/t,Pt含量1 801.27 g/t,Pd含量1 937.66 g/t。从原料到硫酸浸出渣,贵金属富集比达到14.19倍。该工艺流程操作简单、富集比高、回收率高、成本低,可为从热渣中富集贵金属提供借鉴作用。

复合ZnO高温煤气脱硫剂的物相、还原及硫化行为

通过热分解、沉淀法从硝酸盐或氯化盐制备出ZnO、Fe2O3、CuO、MnO2和CaO5种金属氧化物，并采用干混法制备出系列复合ZnO高温煤气脱硫剂。利用固定床反应器在500℃、3600h、40％H2、0．4％～0．6％H2S和N2平衡的条件下，评价了单一金属氧化物、复合gnO高温煤气脱硫剂的脱硫性能。采用程序升温还原（TPR）测试新鲜脱硫剂的还原性能，用XRD对新鲜和硫化后的脱硫剂进行表征。结果表明，复合ZnO高温煤气脱硫剂较单一金属氧化物脱硫剂，具有较高和稳定的脱硫效率、较长的反应时间、较大的硫容。ZnO与可还原金属氧化物复合改变了其还原性能，井在硫化前或后形成新的物相，显著提高了脱硫性能。