1. Sulfuric acid method This method uses dolomite, serpentine, and bittern as raw materials. Add water or mother liquor in the neutralization reactor, and then gradually add sulfuric acid and bitter soil powder containing more than 85% magnesium oxide into the reactor according to a certain ratio for neutralization reaction, control Ph=5, and the concentration is 39-40° Be. Stir for 30 min to make the reaction proceed fully. The reaction equation is as follows: keep the neutralization solution at 80°C, send the filtered filtrate into a crystallizer, add an appropriate amount of crystal seeds, then cool, filter, centrifuge and separate, and dry at 50-55°C to obtain magnesium sulfate. . The mother liquor is returned for batching.

2. The bittern obtained in the salt lake is naturally evaporated and concentrated into crude magnesium (crude magnesium sulfate). Using crude magnesium as raw material, add water to dissolve at 80-90°C, clarify at 60-70°C, crystallize by cooling at 20-25°C, separate by centrifugation, and dry to obtain industrial magnesium sulfate products. The industrial magnesium sulfate is immersed in distilled water, the pH value is adjusted with sulfuric acid, centrifuged, dried and dehydrated, and then recrystallized to obtain the magnesium sulfate for medicine.

3. The seawater salting bittern method The seawater is salted to obtain bittern, and after transpiration with the brine method, high-temperature salt is produced, and its composition is MgSO4>30%, NaCI<35%, MgCl2 is about 7%, KCl is about 0.5 %. Bitter bittern can be immersed in 200g/L MgCl2 solution at 48℃, NaCl dissolves less, and MgSO4 dissolves more. After separation, the immersion solution was cooled to 10°C to precipitate coarse MgSO4·7H2O, and the product was obtained by secondary recrystallization.

Under vigorous stirring, gradually add 30% hot sulfuric acid solution to magnesium carbonate until the liquid no longer foams. Check the filtrate with NH4SCN solution, if there is red, add some magnesium carbonate until it can't dissolve. Filter while hot, cool the filtrate and let stand overnight. The precipitated crystals were drained and washed with a small amount of ice water. Finally, it is recrystallized with 40 mL of water per 100 g of salt.

4. Purification method: Using the co-deposition effect of newly deposited Mg(OH)2, impurities such as Ni, Co, Fe, Zn, Cu can be removed from MgSO4. Add NaOH solution to the solution containing 2g MgSO4·7H2O in a polyethylene cup to form Mg(OH)2 deposit, wash it, and add this deposit to the euphoria containing 200～240g MgSO4·7H2O (analytically pure) In the solution, the mixture was vigorously stirred for 30 min, left standing overnight, and the clear liquid was sucked out by the siphon method. A highly pure MgSO4 solution can be obtained. From this solution, purer MgSO4·7H2O crystals can be crystallized. It is obtained by adding sulfuric acid to natural magnesium carbonate (magnesite), and after removing carbon dioxide, it is obtained by recrystallization;

5. After heating and dissolving 20kg of industrial magnesium sulfate (the lower the chlorine content, the better) with 30kg of distilled water, add a slight excess of silver sulfate solution (determined by the chlorine content of the raw material), after stirring, check the chlorine content in the solution to pass, filter , Add an appropriate amount of magnesium carbonate while stirring in the clear magnesium sulfate solution to make the solution slightly alkaline to remove the M-like 2+ ions, pass hydrogen sulfide for 15min, and filter after standing for 24h. Slowly add 0.25-0.5 mol/l sulfuric acid solution, continuous sampling and analysis: 4 drops of bromothyme blue indicator are added dropwise to the 10ml H sample, and the addition of acid is stopped when the solution turns blue. The solution is evaporated and concentrated (about 110°C), crystallized by cooling, centrifuged and dried, and dried at 50-60°C (the temperature should not be exceeded) to obtain the reagent magnesium sulfate.

6. In a small white porcelain jar, stir 1kg of high-purity magnesium oxide into a paste with 1000ml of conductive water, and slowly drop 30% high-purity sulfuric acid into the magnesium oxide to react. When there is less foam, stop adding acid, leave a little magnesium oxide, stand for 15 minutes, and filter. The filtrate is placed in a glass-lined pot, evaporated and concentrated to form a film, directly cooled with cold water for crystallization, and centrifuged to dry. Wash twice with cold conductive water, crystallize in a white porcelain plate and dry at low temperature in an oven to obtain spectrally pure magnesium sulfate heptahydrate. If the quality index is not reached, it can be recrystallized again. To prepare anhydrous magnesium sulfate, magnesium sulfate heptahydrate can be carefully heated to 238°C to obtain anhydrous magnesium sulfate.

    Liaoning Shibo Tianze Fertilizer Industry Co., Ltd. adheres to the concept of "customer, honesty and cost", adheres to the belief of "creating a brand with quality, and occupying the market with a brand", in line with the thought of serving agriculture wholeheartedly, sincerely hopes to have friends from all over the world. , develop friendship and cooperation, and achieve a win-win situation.