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?