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

Abstract

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.

Keywords

zinc metallurgy / extraction / ammonium sulfate / ore roasting / thermodynamics / kinetics

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