一水硬铝石矿—氢氧化钠体系加热过程中的相变规律

Phase Transformation of Diasporic Bauxite-Sodium Hydroxide System during Heating Process

研究了焙烧温度和氢氧化钠添加量对一水硬铝石矿—氢氧化钠体系相变规律的影响。利用DTA-TG、XRD和SEM技术对焙烧产物的加热性能、物相转变和微观形貌进行了分析。结果表明,当焙烧温度较低、氢氧化钠添加量较少时,大量AlOOH没有转变,主要反应是高岭石和白云母与氢氧化钠反应生成沸石、方钠石、霞石等不同物相。温度升高利于沸石和方钠石换成钙霞石。氢氧化钠添加量增多利于AlOOH与NaOH反应生成铝酸钠物相。当温度升高到500℃以上时,主要反应是AlOOH脱水形成Al2O3。

Effects of roasting temperature and NaOH addition on phase transformation of diaspore-sodium hydroxide system were investigated. Heating performance, phase transformation, and microstructure of roasting ore were comparatively analyzed with DTA-TG XRD and SEM. The results show that AlOOH is not changed to a large extent with low roasting temperature and a small amount of NaOH dosage, and kaolinite and muscovite reacts with NaOH to form zeolites, sodalite, and cancrinite respectively. Raising temperature facilitates conversion of zeolite and sodalite into cancrinite. Increasing NaOH dosage promotes reaction of AlOOH with NaOH to form sodium aluminate phases. When temperature rises to 500 ℃ above, AlOOH is decomposed into Al2O3.