vacuum evaporation method: After natural mirabilite is dissolved and clarified, the clarified liquid is subjected to vacuum evaporation dehydration, thickening, centrifugal separation and drying to obtain anhydrous sodium sulfate.
    calcium Mirabilite Method: The calcium mirabilite ore is crushed, ball-milled with water, and leached. The leaching solution is filtered to remove impurities, and the filtrate is clarified, anhydrous sodium sulfate was obtained by drying.
    The conversion method is to prepare anhydrous sodium sulfate by using high and low temperature salt produced by potassium chloride as a raw material. Under certain temperature and mixing conditions, after three-stage conversion, magnesium sulfate and sodium chloride are firstly converted into white sodium magnesium alum, then converted into anhydrous sodium magnesium alum, and finally converted into anhydrous sodium sulfate. The entire conversion process is a continuous counter-current operation. The slurry is driven and lifted mechanically, and the liquid flows backward according to the difference, and the segments are linked and influenced each other. The first stage of conversion is controlled to react at a pH value of 3-4 and a temperature of 55-70 ℃, the white sodium magnesium alum slurry is thickened by a one-stage settler and then sent to a two-stage conversion tank; The pH value of the two-stage conversion is 4-5, and the temperature is about 100 ℃; in the third stage, the conversion conditions are controlled to pH 5~6, and the temperature is about 55 ℃. Under stirring, anhydrous sodium magnesium alum reacts with sodium chloride aqueous solution to generate anhydrous sodium sulfate, which is centrifuged and dried, anhydrous sodium sulfate was obtained. This method has high cost, low recovery rate, consumption of sulfuric acid, impurities are not easy to remove, the color of the product is poor, but the equipment is simple.
    rayon by-product method: After crystallization, dissolution, neutralization, filtration, concentration, cooling, separation and drying of the wastewater from the coagulation of rayon, anhydrous sodium sulfate is obtained.