Is it possible to go back from magnesium sulfate ($\ce{MgSO4}$) to magnesium oxide ($\ce{MgO}$) and sulfuric acid ($\ce{H2SO4}$) ?

How difficult or easy would it be?

The reason I ask is because epsom salts ($\ce{MgSO4}$) are really cheap (i.e. less than 50 euro cents / kg). Whereas magnesia ($\ce{MgO}$) of $98\%$ or better grade is much more expensive (i.e 3-4 euro / kg).

I was wondering how easy and cheap it would be to revert the reaction and separate out the sulfur from the magnesium oxide.


Yes, magnesium sulfate can be converted back to magnesium oxide by thermal decomposition or use of reducing agents.

  1. Thermal decomposition

$$\ce{2MgSO4 ->[\Delta] 2MgO + 2SO2 ^ + O2 ^}$$

The thermal decomposition of magnesium sulfate to produce magnesium oxide, sulfur dioxide and oxygen. This reaction takes place by heating to the temperature of 1137°C.(Chemiday 1)

  1. Use of reducing agent

$$\ce{2MgSO4 + C ->[\Delta] 2MgO + 2SO2 ^ + CO2 ^}$$

Magnesium sulfate react with carbon (as reducing agent) to produce magnesium oxide, sulfur dioxide and carbon dioxide. This reaction takes place at a temperature of 700-900°C. (Chemiday 2)

The products other than magnesium oxide are gaseous and escapes leaving behind pure magnesium oxide.

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  • $\begingroup$ 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 Feb 5 '17 at 8:14
  • $\begingroup$ You have to use pure carbon $\endgroup$ – Nilay Ghosh Feb 5 '17 at 13:53

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