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Magnesium Sulfate

Last updated: March 15, 2018

What Does Magnesium Sulfate Mean?

Magnesium sulfate is an inorganic chemical compound with the chemical formula MgSO4. It is a white crystal with a bitter, saline taste. It contains magnesium, sulfur and oxygen. It is glycerol soluble and used in fireproofing, textiles, ceramics, cosmetics and fertilizers.

It is often encountered with Epsom salt, which is the heptahydrate sulfate mineral epsomite (MgSO47H2O). Epsom salts are used as a bath salt and for isolation tanks.


Corrosionpedia Explains Magnesium Sulfate

Magnesium sulfate is an inorganic salt often encountered with Epsom salt. It is a colorless crystalline solid that decomposes at 1124 °C (2055 °F). During decomposition upon heating, it produces toxic and corrosive fumes including sulfur oxides. Magnesium sulfate has various industrial uses:

  • Adsorbents and absorbents
  • Agricultural chemicals (non-pesticidal)
  • Bleaching agents
  • Fillers
  • Pigments
  • Processing aids
  • A precursor to other chemicals
  • Drying and flocculation applications
  • Catalyst preparation
  • Rubber coagulation
  • Refractory bonding agents in bricks and oxysulfate cements

Magnesium sulfate causes sulfate-induced hot corrosion. After the protective oxide scale is dissolved from a metal by the molten salt, sulfur is released from the salt and diffuses into the metal substrate forming discrete grey/blue colored aluminum or chromium sulfides. Consequently, the steel cannot rebuild a new protective oxide layer and steel corrosion occurs.

It can also attack copper. The solutions of sulfates of sodium, potassium and magnesium corrode copper very slowly and the metal becomes slowly covered with a white precipitate containing bluish green flakes of basic sulfate.


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