Fundamental study on zinc sulfation roasting reaction

Zinc sulfide has been sulfation roasted in a closed reactor where the materials involved in the reaction are conserved and the reacting gas is being circulated. In this closed system, the atmosphere for zinc sulfate formation is being gradually produced as shown in a phase stability diagram calculated by thermodynamic analysis coupled with material conservation in the system. The zinc sulfate formation takes place in the following sequence: ZnS → ZnS → ZnO · 2ZnSO₄ → ZnSO₄, which is in agreement with thermodynamic predictions. However, it could not be clarified whether the formation of these intermediate compounds take place within the particle or not.