Thermodynamics and kinetics of extracting zinc from zinc oxide ore by the ammonium sulfate roasting method

Thermodynamic analyses and kinetic studies were performed on zinc oxide ore treatment by (NH₄)₂SO₄ roasting technology. The results show that it is theoretically feasible to realize a roasting reaction between the zinc oxide ore and (NH₄)₂SO₄ in a temperature range of 573-723 K. The effects of reaction temperature and particle size on the extraction rate of zinc were also examined. It is found that a surface chemical reaction is the rate-controlling step in roasting kinetics. The calculated activation energy of this process is about 45.57 kJ/mol, and the kinetic model can be expressed as follows:1-(1-α)^1/3=30.85 exp(-45.57/RT)·t. An extraction ratio of zinc as high as 92% could be achieved under the optimum conditions.