Kinetics of Sulfuric Acid Leaching of High Silica Low-grade Zinc Oxide Ore

The effects of the acid value,acid ways,solid-liquid ratio,particle size and reaction temperature on the leaching rate of zinc have been investigated by experiments to solve the problems of difficult filter pressing pulp,low solid-liquid ratio and low leaching rate of Zn occurred while routine processing high silica natural zinc oxide ore.The results show that when the solid-liquid ratio is 1∶6 and the ores size is 0.15～0.212 mm react with H2SO4 of which the concentration is 8% for 120 min at a normal temperature,the leaching rate of zinc can reach 96.07%.The leaching rate of zinc can increase by 99.02% while the temperature raised.The leaching process can be explained by the model of contractibility and unreacted core,that is the leaching rate conforms to the leaching equation 1-(1-α)1/3 ～ k·t.Leaching kinetics indicate that the rate of the reaction process can be controlled by controlling the diffusion of the mineral layer during the reaction.The activation energy is the character which control the diffusion process and the value of it is aproximately 6.385 kJ/mol.