Na_2O-Al_2O_3-Fe_2O_3系烧结过程中铝、铁的反应行为

Reaction Behavior of Al_2O_3 and Fe_2O_3 in Na_2O-Al_2O_3-Fe_2O_3 Systems during Sintering

以Al2O3,Fe2O3和Na2CO3为原料,对Na2O-Al2O3-Fe2O3系烧结过程中的反应行为进行了详细研究.基于溶出率与时间、温度的关系,证明Na2O-Al2O3和Na2O-Fe2O3的生成反应动力学都服从Zhuralev-Lesokin-Tempelman模型,表观活化能分别为186.59和80.92kJ/mol,表明Na2O-Fe2O3比Na2O-Al2O3在动力学上更易形成;Al2O3易与Na2O-Fe2O3反应形成Na2O-Al2O3和Fe2O3,在1273K烧结30min,所得熟料Al2O3溶出率达98.51%;Fe2O3对Na2O-Al2O3的形成有双重作用,在1273K下可加速Na2O-Al2O3的形成,超过1323K,促使Na2O-Al2O3分解成Na2O和β-Al2O3,且随着温度升高或时间延长,分解程度增高,从而导致熟料中Al2O3溶出率显著降低.

The reaction behavior of Al2O3 and Fe2O3 in Na2O-Al2O3-Fe2O3 system was investigated in detail with Al2O3, Fe2O3 and Na2CO3 as raw materials. Both NaEO.Al2O3 and Na2O·Fe2O3 formation reactions are in accordance with the Zhuralev-Lesokin- Tempelman diffusion-controlled model in kinetics based on the relationship between Al2O3/Na2O extraction rate and sintering temperature or time, and the apparent activation energy is 186.59 and 80.92 kJ/mol, respectively, and the formation of NaO2·Fe2O3 is prior to that of Na20.Al2O3. The results also indicate that Al2O3 reacts easily with Na20.Fe2O3 in sintering process, and Na20.Al2O3 and Fe2O3 occur in clinker. For example,Al2O3 extraction rate of the clinker reaches to 98.51%. Fe2O3 has double effects on the formation of Na2O.Al2O3. On the one hand, it can accelerate the formation of Na2O-Al2O3 at 1273 K. But on the other hand, at the temperature higher than 1323 K, Fe2O3 can accelerate the decomposition of Na20.Al2O3 due to the decrease of Al2O3 extraction rate in clinker leaching operation and existence of β-Al2O3 in residue, and temperature increasing or time prolongation favors the reaction between Fe2O3 and Na2O·Al2O3.