Epsom salt $(\ce{MgSO4})$ is really cheap (less than 0.5 €/kg), whereas $98\,\%$ or better grade magnesia $(\ce{MgO})$ is much more expensive (3 to 4 €/kg).

Is it possible to convert magnesium sulfate $(\ce{MgSO4})$ back to magnesium oxide $(\ce{MgO})$ and sulfuric acid $(\ce{H2SO4})?$ How difficult and economically viable would that be given the necessity of the efficient separation of the products $(\ce{MgO}$ and $\ce{H2SO4})$ from each other?


1 Answer 1


Yes, at 1124 °C magnesium sulfate decomposes to magnesium oxide without melting producing sulfur trioxide as the side product. [1]

Magnesium sulfate can also be reduced to magnesium oxide using a reducing agent like hydrogen or carbon monoxide. [2]


  1. Scheidema, M. N.; Taskinen, P. Decomposition Thermodynamics of Magnesium Sulfate. Ind. Eng. Chem. Res. 2011, 50 (16), 9550–9556. DOI: 10.1021/ie102554f.
  2. Plewa, J.; Steindor, J. Kinetics of Reduction of Magnesium Sulfate by Carbon Oxide. J. Therm. Anal. 1987, 32 (6), 1809–1820. DOI: 10.1007/BF01913973.
  • $\begingroup$ Thanks for your answer. In example 2, is it sufficient for me to add as a Carbon source the fuel I use to burn the Magnesium Sulfate? Say for example I use a propane fire to burn the Magnesium Sulfate, is the added Carbon from the propane enough? Or for that matter any other hydro-carbon fuel? $\endgroup$
    – made2hack
    Commented Feb 5, 2017 at 8:14
  • 1
    $\begingroup$ You have to use pure carbon $\endgroup$ Commented Feb 5, 2017 at 13:53

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