A Study on Preparation of Mn_3O_4 by Oxidizing Hydrolysis of Manganese Sulfate with Air in Ammonia Alkalescence Media

The mechanism of manganese ion hydrolysis and precipitation rate of manganese ion in ammonia alkalescence media were investigated,and the experiments for oxidization of hydrolysates of manganese sulphate were carried out further.The results indicate that the hydrolysate of manganese sulphate is a mixture containing manganese hydroxide and manganese hydroxysulfate,the manganese hydroxide in mixture is oxidized more easily than manganese hydroxysulfate,the high level of sulphate in Mn3O4 product is caused by manganese hydroxysulfate that is oxidized difficultly.At pH value 10.4 and 30℃,rate of manganese ion precipitation is 87.3%,the complex reaction of manganese ion with ammonia molecule is main reason for a lower manganese ioo precipitation rate.