熟料烧结过程中氧化铁反应行为的热力学分析

通过对Fe2O3与碳酸钠、氧化钙以及硅酸钙反应的热力学分析,明确Fe2O3在铝土矿炉料烧结过程中的热力学反应规律。热力学计算、分析结果表明:Fe2O3在正常烧结温度范围内能与Na2CO3或CaO发生反应,但更易与CaO反应形成2CaO.Fe2O3或CaO.Fe2O3,Fe2O3和Na2O.Fe2O3能使2CaO.SiO2和3CaO.2SiO2转变为CaO.SiO2,CaO.SiO2进一步与Na2O.Al2O3或Na2O.Fe2O3反应生成不溶的三元化合物而造成烧结法生产氧化铝过程中Na2O和Al2O3的损失。4CaO.Al2O3.Fe2O3不能由铁酸钙和铝酸钠相互反应产生,而可能是CaO、Al2O3和Fe2O3三者直接反应的产物,且在烧结条件下Na2O.Fe2O3可分解4CaO.Al2O3.Fe2O3。

Thermodynamics of reaction behavior of ferric oxide during sinter-preparing process

Based on the thermodynamic analyses of the reactions of ferric oxide(Fe2O3) with sodium carbonate,calcium oxide and calcium silicates,respectively,the thermodynamic of those reactions was determined.The results show that ferric oxide can react with sodium carbonate and calcium oxide respectively,but be more likely to react with calcium oxide to form calcium ferrite in the industrial sintering temperature range.Ferric oxide and sodium ferrite(Na2O.Fe2O3) can transform 2CaO.SiO2 and 3CaO.2SiO2 into CaO.SiO2,and CaO.SiO2 can further react with Na2O.Al2O3 or sodium ferrite to form insoluble ternary compounds,which results in the loss of sodium oxide and alumina during the alumina production by the sintering process.Calcium ferrite aluminate(4CaO.Al2O3.Fe2O3) can not form from the reaction of calcium ferrite(CaO.Fe2O3,2CaO.Fe2O3) and sodium aluminate but rather is the direct product of the reaction of calcium oxide,alumina and ferric oxide.And calcium ferrite aluminate can be decomposed by sodium ferrite under the condition of sintering.