STUDY ON IMPROVING DEGASSING EFFICIENCY OF IRON MELT WITH VACUUM SUCTION DEGASSING METHOD

为提高铁液真空抽吸除气的效率，进行了脱碳、脱碳和脱氧的试验研究。这种脱气方法基于使用多孔耐火材料，其在真空条件下将熔体与外部空间分离。脱气反应发生在熔体-多孔材料界面处，并且气态产物通过渗透多孔材料而容易地从界面移除。必要的条件是熔体不应渗透材料。由于熔体-多孔材料界面面积可以任意增大，因此可以任意提高脱气速率.对于铁液脱碳，采用固体氧化物，将Al_2O_3-2-30%Fe_2O_3多孔管浸入熔体中，试图获得较高的脱碳速率.脱碳是通过C与Fe_2O_3（和/或O）的反应进行的。脱碳 ...更多信息 随着管坯中Fe_2O_3含量的增加，钢管的抗渗性增强，但熔体中的氧含量也随之增加。此外，由于高Fe_2O_3含量的钢管热强度不足，在较低的内压下，钢管发生变形，透气性降低。在这种情况下，脱碳速率也降低。因此，Al_2O_3-Fe_2O_3管的脱碳速度并不优于我们以前所用的Al_2O_3-SiO_2管的上级。结果表明，气液两相传质过程控制着反应速率。采用混合控制模型计算了管-液界面的传质系数。采用浸渍式MgO-10-30%C多孔管对铁液进行了脱氧实验。熔体中的氧与炉管中的C反应生成CO和/或与MgO-C反应生成的Mg蒸气反应生成MgO，脱CO反应有效进行。还用浸渍法对装有MgO-C粉的MgO多孔管进行了脱氧实验。在这种情况下，熔体中的氧只能与Mg蒸气反应，并且Mg蒸气对脱氧化的贡献是清楚的。少

Experimental studies on decarburization, dehydrogenization and dcoxidation have been performed for improving the efficiency of degassing of iron melt with applying the vacuum suction degassing method. This degassing method is based on using a porous refractory material, which separates the melt from the outer space under a vacuum condition. The degassing reaction takes place at the melt-porous material interface and the gascous products are easily removed from the interface by permeating the porous material. The necessary condition is that the melt should not permeate the material. Since the area of the melt-porous material interface can be arbitrarily increased, it is possible to increase the degassing rate optionally.As for decarburization of iron melt, with using solid oxide, an attempt was made to obtain a high decarburization rate by immersing an Al_2O_3-2-30%Fe_2O_3 porous tube in the melt. The decarburization proceeded by the reaction between C and Fe_2O_3 (amd/or O). The decarb … More urization increased with increasing Fe_2O_3 content of the tube, but the oxygen content of the melt also increased. In addition, since the hot strength of the tube of high Fe_2O_3 content was not sufficient, deformation of the tube took place during the experiment at lower internal pressure of the tube, and the gas permeability of the tube decreased. In this case, the decarburization rate also decreased. Hence, the Al_2O_3-Fe_2O_3 tube was not superior in the decarburization rate to the Al_2O_3-SiO_2 tube used in our previous experiments.Experiments on dehydrogenization of iron melt were made with blowing Ar gas onto the melt surface and with or without immersing an Al_2O_3 prorous tube. It is shown that the dehydrogenization rate is controlled by gas-and liquid-phase mass transfers. The mass transfer coefficients for the tube-melt interface and obtained by applying a mixed control model. The gas-phase mass transfer coefficients is larger for the tube of higher gas permeability.Dcoxidation experiments of iron melt were made with immersing MgO-10-30%C porous tube. Oxygen in the melt reacted with C of the tube to form CO and/or with Mg vapor produced by the MgO-C reaction to form MgO,and the dcoxidation proceeded effectively. Dcoxidation experiments were also made with immersing a MgO prorous tube filled with MgO-C powder. In this case, oxygen in the melt could react only with Mg vapor, and contribution of the Mg vapor to the dcoxidation is made clear. Less