Manganese dioxide+carbon → manganese dioxide+carbon monoxide
Manganese dioxide+carbon monoxide → manganese dioxide+carbon dioxide
MnO+H2SO4→MnSO4+H2O
2. Two-ore roasting method: pyrolusite and pyrite are dried, respectively crushed, then mixed with ingredients, roasted at 500-600℃ for 0.5-65438±0.0h, leached with dilute manganese sulfate solution, separated from wet slag, finely filtered, evaporated, concentrated, centrifugally separated, and dried and crushed with wet materials to obtain manganese sulfate products. that
8 MnO 2+4 fe2s 2+ 1 1o 2→8 mnso 4+2 fe2o 3
3. Reduction leaching method: pyrolusite, sulfuric acid and a certain amount of reducing agent are mixed and reacted, aged, leached with water, filtered and deslagging to obtain manganese sulfate solution, and then concentrated, crystallized, separated and dried to obtain manganese sulfate product. The reducing agent used in the reaction can be ferrous sulfate, pyrite, iron filings, starch, sawdust, etc. According to the conditions. At present, ferrous sulfate and pyrite are widely used. Manganese sulfate solution was directly prepared by leaching pyrite with water as reducing agent.
Fe S2+h2so 4+6H2O→feso 4+2h2so 4+5h 2↑
Manganese dioxide+sulfuric acid → manganese sulfate +H2O
H2+ sulfuric acid+manganese dioxide → manganese sulfate +2H2O
2feso 4+2h2so 4+MnO 2→mnso 4+Fe2(SO4)3+2H2O
4. Rhododendron process: pulverizing Rhododendron, leaching with sulfuric acid, filtering the generated manganese sulfate solution to remove residues, heating and concentrating the filtrate, cooling and crystallizing, centrifuging and drying to obtain the finished manganese sulfate product. When leaching rhodochrosite with sulfuric acid, in order to promote the reduction of manganese with high valence and the oxidation of ferrous with low valence, it is necessary to add a small amount of catalyst and introduce air to achieve this goal, or leach minerals with the waste electrolyte of electrolytic manganese dioxide and sulfuric acid, and then neutralize and filter to remove iron to make manganese sulfate solution. that
Manganese carbonate+sulfuric acid → manganese sulfate +H2O+ carbon dioxide
5. Hydroquinone by-product recovery method: the oxidation reaction of aniline and manganese dioxide produces a large amount of waste liquid containing manganese sulfate and ammonium sulfate, which is usually neutralized with lime milk to remove impurities, then heated for deamination to obtain manganese sulfate solution, and then concentrated, crystallized, dehydrated, separated and dried to obtain manganese sulfate products. that
2c 6 H5 NH 2+4 MnO 2+5 h2so 4→2(OC6H4O)+4 mnso 4+(NH4)2so 4+4H2O
(NH4)2so 4+Ca(OH)2→caso 4↓+2nh 3 ↑+ 2H2O
6. In the mixture of ferromanganese alloy powder (containing 70% manganese) and water, add a small amount of sulfuric acid with the density of 1.84 (slightly excessive manganese) for reaction:
During the reaction, a small amount of water should be often added to make up for the evaporated water, and after the reaction, the same amount of water should be added to stand. After filtering to remove the precipitate, an appropriate amount of manganese dioxide was added to the filtrate, which was heated to 50℃ while stirring to completely oxidize Fe2+ ions into Fe3+ ions, and then hydrolyzed and filtered to remove the precipitate. Adding proper amount of sodium carbonate paste into the filtrate, further precipitating iron ions, filtering, heating and evaporating the filtrate, and filtering again. After the filtrate is acidified with sulfuric acid, the temperature is controlled not to exceed 60℃ and evaporated and concentrated to crystallize, and then crystallized below 0℃, washed with ice water and dried with hot air to prepare crystalline manganese sulfate.
7. Firstly, industrial manganese dioxide is soaked in nitric acid, and then washed with water to prepare manganese dioxide without alkali metal salts. Adding sulfur dioxide gas into the qualified mixed solution of manganese dioxide and water under stirring until the precipitate changes from black to light gray;
Then add a small amount of manganese dioxide until the black precipitate no longer changes color. Continue stirring until the smell of sulfur dioxide in the mixture disappears, filter, acidify the filtrate with 10% sulfuric acid, evaporate in a water bath, and burn at 450℃ for several hours until sulfur dioxide no longer escapes. The obtained calcined product is anhydrous manganese sulfate.