Zinc Concentrates Oxygen-rich Jet Stream Leaching Kinetics

On the basis of the review of the development of zinc smelting techniques and the researches on leaching kinetics of zinc sulfides, the new technology of oxygen-rich spray leaching is proposed in this dissertation to achieve high leaching efficiency of zinc sulfide concentrate. This dissertation focuses on the oxygen-rich spray leaching kinetics of zinc sulfide concentrate and the discussion on the leaching mechanism. The main subjects in this dissertation are as follows:The mineral presence as well as the existence of zinc and iron in zinc concentrate is analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), energy spectrum and optical microscope.The atmospheric leaching kinetics of zinc concentrate is studied in the temperature range of 348 K to 368 K in order to clarity the leaching behavior of zinc concentrate on the top of the oxygen-rich spray leaching tank. The results show that the leaching of zinc is controlled by the interface chemical reaction and the kinetic regression equation follows the shrinking core model under the atmospheric leaching conditions.Different slurry-spray pressures in the oxygen-rich spray leaching tank are simulated by autoclave and the leaching kinetics as well as the leaching behavior of zinc concentrate is studied under the conditions of slurry pressure from 0.3 MPa to 0.5 MPa and leaching temperature from 358 K to 378 K. The apparent activation energy values of leaching reaction under the different slurry pressures are calculated respectively. The results show that the leaching of zinc during the oxygen-rich spray leaching is controlled by interface chemical reaction and the kinetic regression equation follows the shrinking core model. While the temperature is increased to 393 K, the controlling step for the leaching of zinc will probably change into inner-diffusion.The kinetic equation for the oxygen-rich spray leaching of zinc concentrate is established under the conditions of slurry pressure of 0.3 MPa to 0.5 MPa and leaching temperature of 358 K to 378 K by quadratic regression.The mineral phase in the oxygen-rich spray leaching residue of zinc concentrate is further studied by mineralogical analysis methods. The leaching mechanism is discussed on the basis of the analysis of the phase transformation of sphalerite, pyrite and pyrrhotite during the leaching.