Simultaneous Leaching and Kinetics of Cu and Zn from Malachite Ore in NH3-NH4NO3 Solutions

The simultaneous leaching behavior and kinetics of copper and zinc from malachite were investigated in NH3-NH4NO3 buffer solutions at pH 9.8. The effects of solution concentration, temperature, stirring speed, average particle size, and solid to liquid ratio on the leaching rate were examined. It was observed that the leaching rate of copper and zinc increased with an increase in the solution concentration, temperature, stirring speed, and with a decrease in the solid to liquid ratio and particle size. The findings showed that copper was leached nearly completely depending on the experimental conditions while zinc was dissolved partially. While the concentration of NH3-NH4NO3, temperature, stirring speed, average particle size, solid to liquid ratio, and time were 0.38/0.11 M, 40°C, 500 rpm, 214 µm, 5/500 g/mL, and 240 min, respectively, and the amount of the leached copper and zinc was calculated to be 83.0% and 43.4%, respectively. It was determined that the leaching kinetics fit a mixed-kinetic model. The activation energy values were found to be identical for both copper and zinc leaching (16.22 kJ/mol). The process was determined to be weakly dependent on temperature, with diffusion playing a significant role in the overall leaching process.