... directly used as fertilizer for rubber, palm trees ;2. In industries: used in tanning, porcelain, pigment, match, fireproof materials, Mg- ... salt, dyeing, medicine and food additives;3. Extensively used in food, pharmaceutical and animal remedy industries. ITEMSSpecialty gradesFine gradeMgSo4.7H2O,≥99.599 ... ,%,≤11Water insoluble,%,≤0.050.05 Magnesium Sulphate Heptahydrate used in food, Medicine