酸法铁黄脱水过程微观机制

Micromechanism of Acidic Geothite Dehydration

采用ＤＴＡ、ＴＧ、ＴＥＭ、ＸＲＤ、ＨＲＥＭ等研究了酸法铁黄脱水过程中相变及孔洞产生的变化机理。发现α－ＦｅＯＯＨ在２７５～３１０℃完成向α－Ｆｅ＿２Ｏ＿３的转变，沿颗粒针形方向形成片状α－Ｆｅ＿２Ｏ＿３相与狭长脱水通边交替排列的组织，且随温度升高，狭长通道缩短变粗，至５００℃左右时，则转变成零星分布的圆孔。通过分析α－ＦｅＯＯＨ与α－Ｆｅ＿２Ｏ＿３的拓扑转变过程，认为交替组织是α－ＦｅＯＯＨ沿［１００］方向收缩至２５％的结果。颗粒内部空位浓度梯度的存在是导致空洞形态衍变主要原因。

The mechanism of phase transformation and Dores formation and development during acidic geothite dehydration was studied by using DTA,TG,TEM,XRD and HREM. Geothite was transformed into hematite at 275～310℃.The alternative structure of slit-shaped pores and plate-like hematite was formed along the acicular direction of the particle during the dehydration process.The slit-shaped pores became shorten and widen with in-creasing the temperature and at about 500℃,they were transforformed into scattered round pores.The investigation of the topotatic transformation between geothite and hematite showed that the alternative structure was created as a result of 25% contraction along the[100] crystal direction of geothite. The existence of voil concentration difference in the particle primarily caused the shape development of the pores.