Preparation And Mechanism Of Manganese Tetroxide

Manganous manganic oxide is a kind of structural materials of high performance,and mainly used for producing of manganese zinc soft magnetism ferrites as one of good raw materials in the electronic industry.In recent years,with the rapid development of the electronic industry,the demand of Mn₃O₄ of high quality increases day after day.Manganous manganic oxide can be prepared by taking electrolytic metal manganese as raw material and adopting aqueous solution oxidation method.This paper studied the process conditions of preparing Mn₃O₄ by oxidating from metal manganese powder suspension through a series of orthogonal test.The product has been characterized with the XRD,SEM,TEM and the composition of the material is analysed by the chemical method..The process conditions were discussed in the end. The amount of ammonium chloride is the greatest in various factors condition;the optimum conditions of preparating Mn₃O₄ are as follows:manganese powder 20g, ammonium chloride 2g,reaction time 4h,feeding time 20 min,temperature 80℃, the amount of hydrochloric acid is 6ml,ethanol is 8ml,and water is 500ml.The total manganese content analysis indicated that it conforms to the request of manganic manganic oxide used to soft magnetism ferrites;the determination of manganese ions confirmed the Mn₃O₄ molecular formula is 2MnO·MnO₂;XRD test results for high-purityγ-Mn₃O₄,lattice constant a=b≠c show that Mn₃O₄ is distortional spinel structure.On the base of producing excellent physical and chemical indicators of Mn₃O₄, the mechanism in the reaction process is discussed.In view of the different chemical additives in connection with potential-pH diagram of Mn-H₂O system,the chemical action mechanism and the electrochemical action mechanism were concerned. Mn(OH)₂ is intermediate product in the reaction process,its oxidation process into Mn₃O₄ is analysed theoretically in this article.According to the reaction mechanism,ammonium salt,hydrochloric acid, amino acid and other substances only play a role of catalyst and medium in the system.This article has also studied the situation of taking the oxidation mother liquor to carry on the circular using,which is helpful to reduce environmental pollution and lower production costs.