Manganese sulfate monohydrate: 1. Physical and chemical properties of manganese sulfate monohydrate: melting point begins to decompose at 850 ℃. Very soluble in water, insoluble in ethanol. Its aqueous solution is nearly neutral. It begins to lose crystal water above 200 ℃, most of the crystal water is lost at 280 ℃, and all crystal water is lost at about 500 ℃. It becomes a melt at 700 ° C, it starts to decompose at 850 ° C, and it decomposes completely at about 1050 ° C. When the temperature is below 27 ℃, the solubility increases with the increase of temperature. Afterwards, as the temperature rises, the solubility gradually decreases to only 0.7% at 200 ℃. 2. Synthesis method of manganese sulfate monohydrate 1. Manganese sulfate monohydrate method: Pyrolite ore powder is mixed with pulverized coal powder in a batching ratio of 100: 20 (mass ratio) and reduced roasted in a roaster at 800 ° C to produce Manganese oxide. Cool to room temperature under the condition of air isolation, perform acid hydrolysis in 15% to 20% dilute sulfuric acid, use manganese dioxide powder as oxidant to make Fe2 + → Fe3 +, control Ph≤5.2, and press filter to remove Fe3 +, aluminum and other Acid insoluble matter, and then settling to further remove calcium impurities. The manganese sulfate fine filtrate is concentrated by evaporation, crystallization, centrifugal separation, and hot air drying to produce a manganese sulfate finished product, whose MnO2 + C → MnO + CO MnO2 + CO → MnO + CO2 MnO + H2SO4 → MnSO4 + H2O 2. Roasting method of two ores ： Pyrogenite and pyrite are dried and crushed separately, then the ingredients are mixed, roasted at 500-600 ℃ for 0.5-1.0h, the clinker is leached with dilute manganese sulfate solution, and the wet slag is separated for fine filtration, then After evaporation, concentration and centrifugal separation, the wet material is dried and crushed to obtain a manganese sulfate product. Its 8MnO2 + 4Fe2S2 + 11O2 → 8MnSO4 + 2Fe2O3 3. Reducing leaching method: mixed reaction of pyrolusite, sulfuric acid and a certain amount of reducing agent, after aging, leaching with water, filtering and removing slag to obtain manganese sulfate solution, then concentrated, Separate and dry the manganese sulfate product. The reducing agent used in the reaction can be selected from ferrous sulfate, pyrite, iron filings, starch, sawdust, etc. according to the conditions. At present, ferrous sulfate and pyrite are widely used. Using pyrite as reducing agent, leaching water directly to prepare manganese sulfate solution, its FeS2 + H2SO4 + 6H2O → FeSO4 + 2H2SO4 + 5H2 ↑ MnO2 + H2SO3 → MnSO4 + H2O H2 + H2SO4 + MnO2 → MnSO4 + 2H2O 2FeSO4 + 2H2SO4 + MnO2 → MnSO4 + Fe2 (SO4) 3 + 2H2O 4. Rhodochrosite method: Rhodochrosite is crushed and reacted with sulfuric acid leaching. The resulting manganese sulfate solution is filtered to remove slag. In the finished manganese sulfate. When leaching rhodochrosite with sulfuric acid, in order to promote the reduction of high-priced manganese and the oxidation of low-priced ferrous iron, a small amount of catalyst needs to be added and the air is ventilated to achieve this purpose, or the waste electrolytic solution of electrolytic manganese dioxide and sulfuric acid leaching minerals are used. The iron is removed by neutralization and filtration to prepare a manganese sulfate solution. Its MnCO3 + H2SO4 → MnSO4 + H2O + CO2 ↑ 5. Hydroquinone by-product recovery method: by the oxidation reaction of aniline and manganese dioxide to produce hydroquinone, a large amount of waste liquid containing manganese sulfate and ammonium sulfate is produced by The impurities are removed by neutralization of lime milk, and then heated to deamination to obtain a manganese sulfate solution, which is then concentrated, crystallized, dehydrated, separated and dried to obtain a manganese sulfate product. Its 2C6H5NH2 + 4MnO2 + 5H2SO4 → 2 (OC6H4O) + 4MnSO4 + (NH4) 2SO4 + 4H2O (NH4) 2SO4 + Ca (OH) 2 → CaSO4 ↓ + 2NH3 ↑ + 2H2O 6. In the ferromanganese alloy powder (containing 70% of manganese) and To the water mixture, add a small amount of sulfuric acid with a density of 1.84 (make the manganese slightly excessive) in small portions to carry out the reaction: during the reaction, a small amount of water should be added frequently to make up for the evaporated water. . After filtering off the precipitate, add an appropriate amount of manganese dioxide to the filtrate, and heat to 50 ° C with stirring to completely oxidize the Fe ions to Fe ions, and hydrolyze, and remove the precipitate by filtration. Add an appropriate amount of sodium carbonate paste to the filtrate to further precipitate Fe ions. After filtration, the filtrate is heated and evaporated to be re-filtered. After the filtrate is acidified with sulfuric acid, the temperature is controlled not to exceed 60 ° C to evaporate and concentrate until crystals appear, and then crystallize below 0 ° C. The crystals are washed with ice water, spin-dried and dried with hot air to prepare crystalline manganese sulfate. 7. First soak industrial manganese dioxide with nitric acid, and then wash with water to prepare manganese dioxide free of alkali metal salts. In the qualified mixture of manganese dioxide and water, the sulfur dioxide gas was introduced while stirring until the precipitate changed from black to light gray: then a small amount of manganese dioxide was added until the black precipitate no longer changed color. Continue stirring until the odor of sulfur dioxide in the mixture disappears, filter, the filtrate is acidified with 10% sulfuric acid, evaporated to dryness in a water bath and burned at 450 ° C for several hours until the sulfur dioxide no longer escapes. The resulting burned material was anhydrous manganese sulfate. Use of manganese sulfate monohydrate: Manganese sulfate monohydrate is one of the important trace element fertilizers, used as base fertilizer, seed soaking, seed dressing, top dressing and foliar spraying. It is used as feed additive in animal husbandry and feed industry. It is also a raw material for the preparation of driers in the coating industry. It is used as a catalyst in the synthesis of fatty acids. raw material.
