超低氧冶炼过程镁铝尖晶石形成的热力学分析与控制

Thermodynamics Analysis and Control of Formation of Magnesia-Alumina Spinel During Refining of Ultra-Low Oxygen

对超低氧试验钢精炼过程中镁铝尖晶石的形成机制和生成热力学计算分析表明:1873K时,MgO-Al2O3二元系夹杂物中MgO的质量分数超过17%时就能生成镁铝尖晶石;采用高碱度、w((CaO))/w((Al2O3))≈1、强还原性精炼顶渣对铝终脱氧钢液进行LF精炼时,在LF精炼中前期就实现Al2O3向MgO·Al2O3尖晶石的转变;钢液中的镁则是实现Al2O3向MgO·Al2O3尖晶石转变的中介和桥梁。而钢中镁含量是由酸溶铝控制的。因此,保持钢液中足够的铝含量是镁铝尖晶石生成的前提。生产过程中,当钢液的w([Al])达到0.03%时,w([Mg])只需要1.32×10-7以上就能生成MgO·Al2O3尖晶石。

The analysis and calculation to the formation mechanism and producing thermodynamics of magnesia-alumina spinel in refining process of ultra-low oxygen experimental steel shows that magnesia-alumina spinel can be formed when the contents of w（（MgO）） exceeds 17% in MgO-A12 03 binary system in 1873 K, and the AI2 03 inclusions can transform to magnesia-alumina spinel in front of middle period of LF refining when the aluminium deoxidation molten steel is refined by high basicity and ω（（CaO））/ω（（A12 03 ）） ≈ 1 and strong reducibility top slag in LF refining. The magnesium in molten steel is the medium and bridge of realizing A1203 to magnesia-alumina spinel, but the w（[Mg]） is controlled by acid-soluble aluminium. Therefore keeping sufficient aluminium in molten steel is the precondition of producing magnesia-alumina spinel. Only more than 1.32 × 10 7 of w（[Mg]） can produce magnesia alumina spinel when ω（[AI]） exceeds 0. 03% in productive process.