Magnesium Sulfate (MgSO4) back to Magnesium Oxide (MgO) + Sulfuric Acid (H2SO4)?
Yes, magnesium sulfate can be converted back to magnesium oxide by thermal decomposition or use of reducing agents.


Thermal decomposition


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


  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)



Use of reducing agent


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


  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.