Two-stage kinetics study of cadmium dissolution from Cd–Ni filter cake with sulfuric acid

Abstract

In this research, the effects of temperature (25, 40, and 80 °C) and time (0–15 min and 15–40 min) on Cd dissolution from the Cd–Ni filter cake containing 24.5 wt-% cadmium and 8.3 wt-% nickel were investigated. It was found that temperature raising has little positive effect on the Cd dissolution. The Cd dissolution was 82%, 85%, and 92% at 25, 40, and 80 °C, respectively, for a leaching time of 40 min. Based on the kinetics evaluation, acidic dissolution of Cd follows the shrinking core model (SCM). Depending on the dissolution time, the rate-controlling step was diffusion through the product layer (for the time range of 0–15 min) and chemical reaction (for the time range of 15–40 min). The activation energy of the Cd dissolution process is calculated as 5.5 kJ/mol and 27 kJ/mol for the time ranges of 0–15 min and 15–40 min, respectively.