钠硅渣在氧化铝熟料烧结过程中的物相变化

摘要

According to the thermodynamic calculation, the multistage reaction and the product composition of sodium hydrate alumino-silicate were proposed in alumina sintering process. The presence of Na2-xAl2-xSixO4and the differences of dissolution performance were confirmed by the reactions of sodium hydrate alumino-silicate under different conditions. The results show that all the Na2-xAl2-xSixO4(x=0, 0.05, 0.25, 0.35, 0.45, 0.55, 0.85) can be formed in the alumina sintering process. And the composition of sintering products were influenced by sintering temperature and raw material proportioning. The silicon coefficient (x) of Na2-xAl2-xSixO4can reduce from 0.85 to 0 gradually with the sintering temperature ranging from 750 ℃ to 1200 ℃ (mole ratio of CaO to SiO2is 2), or the mole ratio of CaO to SiO2 increasing from 1 to 2.5 (sintering temperature 900 ℃). The dissolution performance of Na2-xAl2-xSixO4was determined by the silicon coefficient (x), and the Na2-xAl2-xSixO4can be dissolved in sodium aluminate solution with x≤0.25.%结合相关热力学计算结果,推测钠硅渣在氧化铝熟料烧结法处理过程中存在的多级反应及其产物组成,并通过研究钠硅渣在不同条件下的反应行为,验证中间相Na2-xAl2-xSixO4的存在及其溶出性能的差异.结果表明:在烧结过程中,硅系数x为0、0.05、0.25、0.35、0.45、0.55、0.85的Na2-xAl2-xSixO4均可以生成;烧结产物组成形态受反应温度和生料配比影响;当配钙比为2、烧结温度由750 ℃升高至1200 ℃时,或当配钙比由1.0升高至2.5、温度为900 ℃时,反应产物的硅系数x均可由0.85逐渐下降至0;硅系数决定反应产物的溶出性能,当x≤0.25时,Na2-xAl2-xSixO4中间相可以溶解于铝酸钠溶液.