Investigation on Kinetics and Mechanism of Energy Dissipation by Ultrasound-Assisted Leaching of Low-Nickel Matte

The effects of ultrasonic power, leaching time, reaction temperature, solution concentration and particle size in leaching process were investigated by univariate method, and the optimal leaching conditions were obtained with Fe 3+ concentration of 2.0 mol/L, ultrasonic power of 1500 W, particle size around 100 mesh (− 168 μm + 135 μm) and leaching temperature at 348 Κ for 180 min. The results showed that the leaching efficiencies of nickel, copper and cobalt were 96.3%, 98.2%, and 94.5%, respectively, which were 4–7% higher than those of the mechanical agitation leaching under the same conditions of time, temperature, concentration and particle size. Due to the cavitation effect of ultrasound, the sulfur layer changed from loose and porous labyrinth structure into spherical particles. The rate-determining step of ultrasound-assisted leaching of low-nickel matte was diffusion reaction, and the removal effect of ultrasound on sulfur layer was limited. The change of the micro-morphology of the product layer will cause energy dissipation of ultrasound, which will make the sulfur layer not completely separated from the matrix, and the growth of the leaching efficiency was limited in the macroscopic performance.