用空气直接氧化游离二价锰离子制备高纯四氧化三锰

Preparation of trimanganese tetroxide by air oxidizing free divalent manganese ions

一定温度下,根据锰离子浓度变化严格控制溶液pH的条件下,研究了用空气直接氧化游离二价锰制备高纯四氧化三锰的新方法.结果表明,碱式硫酸锰的氧化速度比氢氧化锰慢,碱式硫酸锰的包裹夹带是造成四氧化三锰产品中硫含量高的根本原因.该法与用空气直接氧化锰的水解物制备四氧化三锰的方法相比较,前者能大幅度降低四氧化三锰产品中的钙、镁和硫含量,部分解决了锰盐氧化法制备四氧化三锰过程中钙、镁和硫分离的难题.

A new method for the preparation of trimanganese tetroxide （Mn3O4） by air direct oxidizing free divalent manganese was made at a certain temperature and pH value varying correspondingly according to the change of manganese ion concentration. The results show that the rate of oxidization of manganese hydroxysulfate is slower than that of manganese hydroxide, and the package of manganese hydroxysulfate is a basic reason for high sulfate content in Mn3O4. In comparison with the method in which Mn3O4 is prepared by air direct oxidizing the hydrolyzates of manganese, the proposed method can efficiently reduce impurity contents of Ca^2 ＋ , Mg^2＋ and SO4^2- in Mn3O4.