Trimanganese tetroxide is one of the important raw materials for preparing soft magnetic materials such as manganese-zinc ferrite. The existing technologies for preparing manganese tetroxide include roasting method, reduction method, oxidation method and electrolysis method. The method of preparing manganese tetroxide using manganese sulfate solution is to add alkaline substances to the manganese tetroxide solution to convert it into Mn(OH)2, and then oxidize the manganese hydroxide in the solution with oxidant or oxygen or air to prepare manganese tetroxide. manganese.
Manganese tetroxide began to be produced in China in 1997 and has developed rapidly. Nowadays, it has formed a production scale with an annual output of nearly 40,000 tons. However, due to poor quality, the products are mainly supplied to the domestic market, with only a few Partially exported. At present, the domestic production method of manganese tetroxide can only be produced by metal manganese powder oxidation method. The technical principle is derived from the US patent (US4812302). The main problems existing in the current technology are: low technical content; high production cost, about 13,000 yuan per ton, and the selling price is about 15,000 yuan per ton, which is almost unprofitable; uneven particle size, large particle size, about 2mm; the content of various impurities is generally high, and only ordinary-level products can be produced. The high impurity content is mainly caused by the raw material electrolytic manganese metal powder itself. The production of electrolytic metal manganese powder requires complex process links. It is difficult to effectively avoid the entry of certain impurities in each link, so this method is difficult to Fundamentally reduce the content of impurities in manganese tetroxide. The method for producing manganese tetroxide abroad is mainly the metal manganese powder oxidation method. In addition, there is a method for preparing ultra-high purity manganese tetroxide, but the technology is strictly confidential and the specific method is not yet known.