In order to reduce the temperature of the blast furnace shell surface and enhance the utilization efficiency of the blast furnace cooling column，the situation of installing cooling columns when the different cooling water pipes on the blast furnace cooling stave are damaged was analyzed， and the arrangement of one of the cooling columns was optimized. At the same time， a new method of plate-column combination was proposed to further reduce the temperature when the stave cooling water pipe were damaged. The numerical simulation results show that when the different cooling water pipes on the cooling stave are damaged， the surface temperature of the furnace shell with the cooling column is significantly lower than that without the cooling column. The cooling column arrangement obtained by genetic algorithm makes the maximum temperature of the furnace shell surface 60.9 °C and the average temperature 48.1 °C. Compared with the original arrangement in the factory， the maximum temperature of the furnace shell surface is reduced by 6.8% and the average temperature is reduced by 4.1%. The maximum temperature of the shell surface of the plate-column combination arrangement was 61.4 ℃， and the average temperature was 49.7 ℃. Compared with the original arrangement without cooling plates， the maximum temperature is reduced by 25.2% and the average temperature is reduced by 28.1%. The numerical simulation results can provide a theoretical basis for the installation of cooling columns when the cooling water pipe of the cooling stave is damaged.
赤铁矿是一种制备碳化铁的优质含铁原料,但是目前存在渗碳效率低下的问题.为了提高赤铁矿的渗碳效率,在赤铁矿中加入碱金属盐,并借助X射线衍射(XRD)、高频红外碳硫分析仪和扫描电子显微镜等揭示碱金属盐在赤铁矿球团渗碳过程中的作用机理.结果表明,碱金属盐(Na2CO3)能够促使致密的赤铁矿颗粒转变为疏松多孔的铁矿物颗粒,强化铁矿物的晶格畸变,提高CO在金属铁和碳化铁表面的吸附和分解能力,从而改善赤铁矿球团还原和渗碳效率;此外,预热处理是一种十分有效的强化Na2CO3添加剂作用的方法,不仅可以强化铁矿物的晶格畸变,还可以增强Na+离子的强化作用,显著提高赤铁矿球团的渗碳效率.当赤铁矿球团添加了质量分数为3％的Na2CO3并在1 000℃预热15 min后,球团的渗碳指数从13.23升高到28.99.研究结果可为提高赤铁矿的渗碳效率提供参考.
With the rapid development of computer hardware and software technology, the discrete element method（DEM） has been widely used for simulating blast furnace burden distribution, while its efficient and accurate calculation model has been accepted by domestic and foreign scholars. The influence of gas flow factor on burden surface was simulated by discrete element method, and the effect of gas flow factor was equivalent to the increase of friction coefficient based on mechanical analysis. The results show that there is an increase in size for inner and outer stack angles of coke burden surface after considering gas flow factor, and the increase extent in inner stack angle is larger than the increase in outer stack angle. The width of platform and the depth of hopper for burden surface also increase in varying degrees. Not only of ore but also of coke, the simulation result is closer to the practical data after considering the gas flow factor. Besides, gas flow factor also has some influence on particle size distribution, within the scope of 1.0 m from the center of furnace throat, the mass percent of 10 mm ore decreases, while that of 17 mm and 32 mm ore increases. Porosity near the hearth increases, and the ratio of ore to coke in the range of 0.85-1.80 m around the center also increases slightly, while the ratio decreases in the range of 1.80-3.45 m around the center.
为探索转炉喷吹石灰石粉造渣炼钢的最佳工艺条件,基于化渣脱磷基础试验,对小颗粒石灰石的化渣脱磷效果进行热力学分析.采用单变量试验方法,探究石灰石粒度、反应温度、配渣碱度及FeO含量对石灰石化渣脱磷的影响,进而得到最佳参数.结果表明,平均粒径为0.84 mm的石灰石颗粒化渣脱磷效果最佳,粒径过大或过小均会造成脱磷率降低;试验温度为1 400 ℃时化渣脱磷效果最佳,低于1 400 ℃时,化渣不充分且速度较慢,而高于1 400 ℃时会出现回磷现象.铁水脱磷率随碱度的升高而升高,当配渣碱度R=3.5时,熔渣状态较好,脱磷效果最佳;碱度过高时,熔渣黏度较高,泡沫渣量大,容易溢渣.铁水脱磷率随配渣FeO含量的升高而升高,FeO质量分数为20％时,熔渣状态最佳;当FeO质量分数达到30％时,反应过程中会出现溢渣现象.在试验得出的最佳工艺条件下,石灰石化渣脱磷过程前期脱磷速度快,泡沫渣状态好,渣中固溶体相种类多,终点脱磷率达到85％以上,钢中磷质量分数降到0.02％以下,可以完成脱磷任务.研究结果为开展转炉喷吹石灰石粉冶炼的工业应用提供了理论基础.
内部裂纹是特殊钢大圆坯常见缺陷之一.电磁搅拌是提高铸坯组织成分均匀性的常用技术手段,其中单绕组螺旋电磁搅拌器不仅结构简单、安装方便而且搅拌效果明显.为了探究凝固末端单绕组螺旋电磁搅拌(F-HEMS)对大圆坯内部钢液流动、凝固传热和裂纹形成的影响,采用试验和数值模拟方法进行研究,发现液相穴内钢液受电磁力作用,沿拉坯方向在电磁搅拌器高度范围内螺旋流动.F-HEMS使连铸坯内零塑性温度(TZD)至黏滞性温度(TLI)区间的温度梯度增大了 31.56％～42.27％,使TZD-TLI区间宽度减小了 6.6 mm.受F-HEMS影响,糊状区内的液相分数降低.连铸坯内的温度、Von-Mises应力与弹性等效应变分布均呈层状分布.在应用F-HEMS后,连铸坯TZD-TLI区间内的Von-Mises应力平均降低了 0.11 MPa,弹性等效应变平均降低了 0.02百分点.在数值模拟和试验的基础上,提出了一种开裂指数,以预测内部开裂风险.研究发现,应用F-HEMS时的开裂指数比未应用时的小0.158～0.280,证明F-HEMS有降低连铸坯裂纹形成概率的作用.然而,内部裂纹的形成受多种因素的影响,连铸过程中大圆坯的开裂预测仍需改进模拟方法并通过大量试验数据验证.F-HEMS影响连铸大圆坯内部的钢液流动和凝固传热,可降低内部裂纹的形成概率,本研究为工业生产提供了理论依据.
