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The sources of waste water in the number 4 tailings pond at the Dexing mine in Jiangxi, China, include alkaline flotation tailings and acid mine drainage from the nearby open cast mine. Acidification of the tailings due to the presence of acid mine drainage may result in the release of heavy metals which may potentially affect the aquatic environment and the re-use of the waste water. The tailings contained 31 750 mg/kg Fe, 20 070 mg/kg Ca, 215 mg/kg Zn, 775 mg/kg Mn, 83 540 mg/kg Al, 11 195 mg/kg Mg, 455 mg/kg Cu, up to 5 mg/kg each of Pb and Cd and 8 mg/kg Cr. Zn, Cu, Fe and Mn were determined to be the major heavy metals in the tailings, with gangue minerals such as quartz also being major constituents. Laboratory batch experiments were carried out to investigate the effects of pH, temperature, particle size and contact time on the leaching of the heavy metals. The tailings dissolution reaction was controlled by the presence of the acid and the kinetics could be expressed in terms of heterogeneous reaction models and followed a shrinking core model with surface chemical reaction as the rate-controlling step. The maximum leaching rates of Zn, Cu, Fe and Mn at pH 2 were 5.4%, 5.8%, 11.1% and 34.1%, respectively. Dissolution of all the metals showed a positive correlation with temperature. Particle size had little effect, but the concentrations of the leached heavy metals decreased to some extent with increasing particle size., The sources of waste water in the number 4 tailings pond at the Dexing mine in Jiangxi, China, include alkaline flotation tailings and acid mine drainage from the nearby open cast mine. Acidification of the tailings due to the presence of acid mine drainage may result in the release of heavy metals which may potentially affect the aquatic environment and the re-use of the waste water. The tailings contained 31 750 mg/kg Fe, 20 070 mg/kg Ca, 215 mg/kg Zn, 775 mg/kg Mn, 83 540 mg/kg Al, 11 195 mg/kg Mg, 455 mg/kg Cu, up to 5 mg/kg each of Pb and Cd and 8 mg/kg Cr. Zn, Cu, Fe and Mn were determined to be the major heavy metals in the tailings, with gangue minerals such as quartz also being major constituents. Laboratory batch experiments were carried out to investigate the effects of pH, temperature, particle size and contact time on the leaching of the heavy metals. The tailings dissolution reaction was controlled by the presence of the acid and the kinetics could be expressed in terms of heterogeneous reaction models and followed a shrinking core model with surface chemical reaction as the rate-controlling step. The maximum leaching rates of Zn, Cu, Fe and Mn at pH 2 were 5.4%, 5.8%, 11.1% and 34.1%, respectively. Dissolution of all the metals showed a positive correlation with temperature. Particle size had little effect, but the concentrations of the leached heavy metals decreased to some extent with increasing particle size.