The leaching kinetics of K-feldspar in sulfuric acid with the aid of ultrasound

The leaching kinetics of K-feldspar in H2SO4-CaF2 system with the assistant of ultrasound was investigated. The effects of various factors, such as sulfuric acid concentration, liquid-to-solid ratio, CaF2 dosage and leaching temperature were comprehensively studied. The dissolution fraction of potassium can reach more than 83% under the optimum operation conditions with ultrasound. Because of the cavitation effect, the intensified effect with ultrasound has more obvious at lower temperature than higher temperature. The leaching kinetics of K-feldspar with and without ultrasound was successfully modeled by a classic shrinking core model with the product layer diffusion as the rate-controlling step. The activation energies over the temperature range from 60 to 90 °C with and without ultrasound were found to be 55.67 kJ mol−1 and 72.33 kJ mol−1, respectively. It was found that the rate constant increases greatly in the presence of ultrasound due to the decreased apparent activation energy, resulting in the improved dissolution fraction of potassium.