Abstract: In order to efficiently develop and utilization of magnesium from high-magnesium copper tailings，technical conditions for the hydrochloric acid leaching process were studied，and the leaching kinetics model was established.The results showed that under conditions of hydrochloric acid 1 mol/L，reaction temperature at 353 K，liquid to solid ratio of 3〖DK（〗∶〖DK）〗1，reaction time 4 h，stirring speed of 300 r/min，the magnesium leaching rate reached 75.55%; Avrami model can better describe the leaching process.XRD，SEM analysis of leaching residue under different conditions showed that:when the magnesium leaching rate is 75%，the serpentine's structure has been completely destroyed，thus diffraction peaks of serpentine in leaching residue disappeared; High temperature and high pressure only makes the crystal structure of some calcium-magnesium garnets unstable and reaction with hydrochloric acid,which is the reason for lowering the leaching rate of magnesium acid.

Key words: High-magnesium copper tailing, Serpentine, Hydrochloric acid leaching, Kinetics model