Solubility Investigations in the MgSO4–Al2(SO4)3–(NH4)2SO4–H2O Quaternary System at 40 and 80 °C

Abstract

The separation of magnesium and aluminum bearing compounds from the (NH4)2SO4 aqueous solution is crucial for the ammonium sulfate roasting technique to extract Mg and Al from the magnesium–aluminum-bearing slag. Equilibrium solubility data for the quaternary system of MgSO4–Al2(SO4)3–(NH4)2SO4–H2O at 40 and 80 °C were therefore measured and compared with those of their ternary subsystems of MgSO4–(NH4)2SO4–H2O and Al2(SO4)3–(NH4)2SO4–H2O, respectively. The mutual salting-out effect between MgSO4 and Al2(SO4)3 in the quaternary system was further discussed. On the basis of the measured data, a strategy for effective separation of magnesium and aluminum compounds from the MgSO4–Al2(SO4)3–(NH4)2SO4–H2O system was developed.