铬铁矿中杂质铝和铁对铬氧化率的影响及其机理

摘要

以实验室合成的尖晶石型化合物为原料,系统地研究铬铁矿无钙焙烧体系中杂质铁和铝对Cr(Ⅲ)氧化率的影响规律及其机理.结果表明:铬铁矿中杂质铁对Cr(Ⅲ)的氧化率无明显影响；焙烧过程中FeO被氧化后得到的Fe2O3先与Na2CO3反应生成中间产物NaFeO2,它在体系中仍能起着Na2CO3的作用,使铬的氧化反应继续进行,整个Cr(Ⅲ)氧化过程的反应速率均较快:而杂质铝能明显抑制Cr(Ⅲ)的氧化,其主要原因是:在焙烧过程中,Al2O3与Cr2O3和MgO反应生成相对稳定、难溶的多元复杂氧化物MgO·(Cr2O3)0.5·(Al2O3)0.5.此外,Al2O3与Na2CO3反应生成Na2O·Al2O3,但Na2O·Al2O3很难进一步与MgO·(Cr2O3)0.5·(Al2O3)0.5反应生成Na2CrO4.%Based on validating results by heat balance test for aluminum melting furnace, a reasonable mathematical model which considering the feature of the aluminum melting process was established. The numerical simulation of coupling field between combustion space and aluminum bath in a round aluminum melting furnace was carried out using CFD software FLUENT. The influence of the swirl number on melting process of the aluminum melting furnace was analyzed. According to optimizing criterion which is put forward in this work, the optimal melting performance is obtained when the swirl number is larger than 0.6.