Electrochemical reaction of ions in molten slags with electron in thermal plasma

本文研究了用氩弧等离子体熔化氧化物FeO-SiO_2的行为。采用直流转移/非转移混合型发电机。在等离子体弧斑处形成空腔，空腔的深度取决于流体静压与电弧和气流压力之和之间的平衡。表面熔渣在空气动力学阻力的作用下从中心向边缘流动。用Ar-O_2等离子弧熔制了含Zn的FeO-SiO_2玻璃。从光谱测量，锌蒸气的平均压力随时间呈指数下降。Zn在等离子体点处的蒸发速率受气相扩散控制，并随氧分压的增加而减小。用Ar等离子弧熔炼40 CaO-40SiO_2-20Al_2O_3（质量%）渣系和含氧化铁渣系。熔渣中的Fe^<3+>迅速还原为Fe^<2+>.然后，蒸发速率受氧分压的影响。采用转移弧等离子体技术，以铁板为阳极，对25mol%Na_2O-75mol%SiO_2熔渣进行了电分析。铁在阳极的氧化量符合法拉第定律。然后发生Na_2O+Fe→FeO+2Na^++2e反应。Na/Si比增加，SiO气体蒸发量比法拉第定律预期的大100至1000倍。熔渣表面发生SiO_2（渣）+2e SiO（g）+O^<2->（渣）反应，电中性反应为SiO_2（渣）+2e+2Ar^+→SiO（g）+（1/2）O_2+2Ar。

The behavior of oxides FeO-SiO_2 melted by Ar arc plasma has been investigated. A direct-current transfer/non-transfer-hybrid-type generator was employed. A cavity was formed at the arc spot of plasma and the depth was determined by the balance between the hydrostatic pressure and the sum of the pressure caused from both of the arc and the gas flow. Molten slag on the surface flowed from center to the edge of melt because of aerodynamic drag force. FeO-SiO_2 glasses cont aining Zn were melted by Ar-O_2 plasma arc. From spectroscopic measurement, the parial pressure of Zn vapor exponentially decreased with time. The evaporation rate of Zn at the plasma spot is controlled by diffusion in gas phase and decreases with increasing the partial pressure of oxygen. 40CaO-40SiO_2-20Al_2O_3 (mass%) slag and that containing iron oxide were melted by Ar plasma arc. Fe^<3+> in molten slag was rapidly reduced to Fe^<2+>. Then, the evaporation rate is affected by the partial pressure of oxugen. 25mol%Na_2O-75mol%SiO_2 molten slag was electrically analyzed by transfere-arc plasma with ironplate as a anode. The amount of oxidation of iron at the anode was according to Faraday's law. Then, the reaction of Na_2O+Fe→FeO+2Na^++2e takes place. The ratio of Na/Si increased and the amount of SiO gas evaporated in 100 to 1000 times larger than that expected by Faraday's law. Then, the reaction of SiO_2(slag)+2e→SiO(g)+O^<2-> (slag) would take place at the surface of molten slag with the electro-neutrality reaction of SiO_2(slag)+2e+2Ar^+→SiO(g) +(1/2)O_2+2Ar.