Method for producing chemical manganese dioxide

Abstract

The invention relates to a method for producing chemical manganese dioxide, which comprises the steps of pressure crystallization of a manganese sulfate solution, dehydration and roasting, pyrolysis, oxidation-reduction, disproportionation and oxidation reaction, acid washing, repeated washing, neutralization, pressure filtration and drying, and is characterized in that oxygen-enriched air containing 70 to 55 percent of oxygen is passed through a manganic manganous oxide formed after pyrolysis for the oxidation-reduction reaction; during the disproportionation and oxidation reaction, the solid to liquid ratio is controlled to be 1:2.5-3 in each disproportionation reaction and the time of the oxidation reaction is kept between 4 to 5 hours in each oxidation reaction with an additional oxidizer. With the technical improvement, the manganese dioxide produced has the advantages of high utilization rate, large liquid absorption capacity, strong battery restoration capacity and so on, and is a high-quality raw material for the production of alkali manganese dry cells. The method improves main product content from 92 percent to 95 to 95.5 percent, greatly reduces the content of impurities, generates less environment pollution, requires low equipment investment, reduces production cost and achieves stable and reliable product quality.

Description

technical field [0001] The invention relates to the field of chemistry, in particular to a production method of chemical manganese dioxide. Background technique [0002] Manganese dioxide is the main positive electrode material of dry batteries, and its quality plays a decisive role in the performance of zinc-manganese dry batteries. Manganese dioxide produced by electrolysis can meet the quality requirements of high-capacity and high-power battery raw materials. Unfortunately, manganese dioxide produced by electrolysis has the disadvantages of high power consumption, large environmental pollution, large equipment investment, long production cycle, and high production cost. Lead to high product prices, to a certain extent, restricting the development of the battery industry. Since the 1970s, countries around the world have actively developed chemical manganese dioxide production, the most representative of which is the Belgian Saidema company, which uses the ammonium ammoni...

AI Technical Summary

Problems solved by technology

The chemical composition and crystal structure (mainly r-type) of the chemical manganese dioxide produced by this method are basically the same as those of the electrolytic manganese dioxide. It is twice as large, and the specific surface area is only half of that of chemical manganese dioxide. Therefore, compared with electrolytic manganese dioxide, chemical manganese dioxide has high manganese dioxide utilization rate, large liquid absorption capacity, strong battery recovery performance, and leak resistance. Good and other advantages, the disadvantage is that (taking Belgium as an example) the internal resistance of chemical manganese dioxide is relatively large, the short-circuit current and load voltage are slightly lower, the discharge performance of large current and heavy load is slightly lower than that of electrolytic manganese dioxide, and the investment in equipment is large. The production cycle is long, the production cost is high, and the product quality cannot be guaranteed (due to the ammonia cycle compression process, the entire production process requires high temperature and high pressure, and it is difficult to control various process indicators)