This document specifies the requirements, test methods, inspection rules, marking and accompanying documents, packaging, transportation, storage, etc. of magnesium sulfate heptahydrate, a by-product of tetrabromophthalic anhydride and ethylene bis-tetrabromophthalimide. This document is applicable to the sulfuric acid solution produced during the production of tetrabromophthalic anhydride and ethylene bis-tetrabromophthalimide. After pretreatment, it is neutralized with magnesium oxide to form a magnesium sulfate solution. After refining treatment, magnesium sulfate heptahydrate is obtained. , mainly used in building materials, tanning, printing and dyeing, papermaking, plastics, etc.