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

The leaching kinetics of K-feldspar in HSO-CaF system with the assistant of ultrasound was investigated. The effects of various factors, such as sulfuric acid concentration, liquid-to-solid ratio, CaF 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 55.67kJmol and 72.33kJmol, 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.