Preparation technique of magnesium dinitrate hexahydrate

The invention discloses a preparation technique of magnesium dinitrate hexahydrate, wherein the preparation method includes steps of step S1, using a magnesium hydrate filter cake formed in salt lake brine lithium extraction technique as a raw material, and removing impurities so as to extract magnesium hydrate material, wherein the mass percent of Cl- in the magnesium hydrate material is 0.02% below; step S2, mixing magnesium hydrate material with salpeter solution, generating neutralization reaction and forming magnesium nitrate solution; step S3, crystealizing the magnesium nitrate solution and forming a crystal initial body of magnesium dinitrate hexahydrate; preparing the magnesium dinitrate hexahydrate crystal through separating and drying. The preparation technique of the magnesium dinitrate hexahydrate can produce high-quality magnesium dinitrate hexahydrate crystal, and is applicable to industry and agriculture. The method solves the problem of burying the waste magnesium hydrate filter cake in the s