采用烧结法处理高铁赤泥回收氧化铝

Alumina recovery from red mud with high iron by sintering process

利用氧化铝热力学数据库,对高铁赤泥炉料烧成过程中的相关化学反应进行热力学计算,并在此基础上,研究烧成温度、烧成时间、炉料配比等烧成工艺条件对高铁赤泥炉料烧成效果的影响。研究结果表明:赤泥炉料的配钙量可以在较宽的范围内变化,并且在烧成过程中可能生成不溶盐类,导致熟料中氧化铝的溶出率降低;延长烧成时间和增加配料铁酸钠含量均有利于烧结;高铁赤泥炉料的最佳配料是:熟料中Na2O.Fe2O3质量分数为10%～12%,钙铁摩尔比为1.0～1.2;烧成工艺条件是:温度为1 000～1 050℃,烧成时间为30～40 min。在最佳配料和烧成工艺条件下,当熟料中氧化铝含量为15%左右时,熟料中Al2O3回收率可达85%～90%。

By employing the thermodynamic database of alumina production, relevant chemical reactions involved in the sintering process of red mud furnace charge with high iron were analyzed. Based on the thermodynamic analyses, influences of factors, such as sintering temperature, sintering duration time and prescription of red mud furnace charge on the sintering process were investigated. The results show that addition amount of calcium oxide can vary in a wide range, possible formation of indissoluble compound salts thermodynamically results in the decline of alumina recovery in the sinter, which prolongs sintering duration time and increases calculated sodium ferrite （Na2O-Fe2O3） mass fraction in the sintering process of red mud with high iron. The optimized prescription of red mud furnace charge with high iron and its suitable technological condition are as follows： the mass fraction of calculated sodium ferrite in sinter is 10%-12%, molar ratio of calcium oxide to ferric oxide is 1.0-1.2, sintering temperature is 1 000-1 050℃, and sintering duration time is 30-40 min. Under the optimal prescription of furnace charge and sintering technological conditions, alumina recovery can reach 85%-90% when mass fraction of alumina in sintering is 15%.