Investigation of dissolution behavior of scandium and lithium from red mud

In this study, scandium and lithium extractions were investigated using the atmospheric pressure agitation leaching method at acidic medium. The leaching tests were carried out at two stages. To remove the ionic impurities such as Na and Al first stage leaching was performed at relatively higher pH. Following solid-liquid separation of leach cake of the first stage leaching, it was subjected to the second stage leaching. The second stage leaching resulted in 95.1% Sc and 94.7% Li extractions. The overall Sc and Li recoveries were determined as 82.4% and 86.5%, respectively. Regarding the kinetic studies, it was understood that scandium and lithium leaching processes were controlled by a combination of chemical reaction and ash diffusion models. In this case, the activation energies were determined as 29.52 and 30.22 kJmol^-1, respectively for scandium and lithium. As a result, while direct H₂SO₄ leaching of red mud is a challenge due to physical and chemical problems, an alternative solution was suggested using H₂SO₄ even at high solids ratios.