CaO-Al_(2)O_(3)-MgO-SiO_(2)-Ce_(2)O_(3)渣系活度计算模型

Development of activity calculation model for the CaO-Al_(2)O_(3)-MgO-SiO_(2)-Ce_(2)O_(3)slag system

稀土钢冶炼过程中,含稀土钢液与熔渣间存在强烈的渣金反应,导致钢中溶解态稀土含量波动严重,影响其在钢中的作用效果。然而,由于含稀土渣系热力学数据的缺失,限制了相关研究工作的开展。依据分子离子共存理论,建立了CaO-Al_(2)O_(3)-MgO-SiO_(2)-Ce_(2)O_(3)渣系的活度计算模型,并绘制组元的等活度线图,讨论w(CaO)/w(Al_(2)O_(3))、w(Ce_(2)O_(3))等成分变化对渣系中各组元活度的影响。计算结果表明,CaO-Al_(2)O_(3)基精炼渣的SiO_(2)活度范围(4×10^(−19)~7×10^(−18))远小于CaO-SiO_(2)基精炼渣的活度范围(0.003~0.4),即对于稀土钢而言,CaO-Al_(2)O_(3)基精炼渣更为适用;对于CaO-Al_(2)O_(3)基精炼渣,提高熔渣的w(CaO)/wAl_(2)O_(3)和w(Ce_(2)O_(3))可增加(Ce_(2)O_(3))活度、减小Al_(2)O_(3)活度,能够减弱含稀土钢液与熔渣中Al_(2)O_(3)间的反应。

During smelting steel containing rare earth elements,there exists strong reaction between the molten steel and the slag,which may result in significant content fluctuation of dissolved rare earth and then reduce its effect in steel.However,the lack of thermodynamic data of rare earth-containing slag system limits the development of related research work.In this paper,based on the ion and molecule coexistence theory,an activity calculation model of the CaO-Al_(2)O_(3)-MgO-SiO_(2)-Ce_(2)O_(3)slag system has been established,which can be used to construct the iso-activity diagram and investigate w(CaO)/w(Al_(2)O_(3)),w(Ce_(2)O_(3))and other composition changes on the activity of each component of the slag system.The results show that the SiO2 activity range(4×10^(−19)~7×10^(−18))of CaO-Al_(2)O_(3)-based refining slag is much smaller than that of CaO-SiO_(2)-based refining slag(0.003~0.4),that is,CaO-Al_(2)O_(3)-based slag is more suitable for rare earth steel.For CaO-Al_(2)O_(3)-based refining slag,increasing the w(CaO)/w(Al_(2)O_(3))and w(Ce_(2)O_(3))of the slag can increase the activity of Ce_(2)O_(3) and decrease the activity of Al_(2)O_(3),which may restrain the reaction between the rare earth-containing molten steel and Al_(2)O_(3) in the slag.