Leaching Behaviors of Lithium-Rich Bauxite Flotation Tailings in Sodium Bicarbonate Solution

Multi-channel exploitation and utilization of lithium-bearing resources may be the future sustainable development trend of the lithium industry. Lithium-rich bauxite flotation tailings are a potential lithium resource. This study proposed a green and effective lithium extraction process employing sodium bicarbonate solutions to leach lithium-rich bauxite flotation tailings. 91.75% of lithium could be leached over a time of 60 min using a 300 g/L sodium bicarbonate solution at 280 °C with a liquid–solid ratio of 10. Notably, potassium’s leaching efficiency was lower than lithium’s, whereas other elements, such as aluminum and silicon, were difficult to leach. Furthermore, the experimental results verify the results of the thermodynamic analysis. The leaching mechanism of lithium and potassium in sodium bicarbonate solution is that sodium ions in the sodium bicarbonate solution substituted Li⁺ of cookeite and K⁺ of illite, respectively. Thus, this research could provide a new way to efficiently and economically utilize clay-rich lithium resources.

The mechanism of leaching lithium and potassium from tailings was considered to involve the ion-substitution reaction. Sodium ion in the sodium bicarbonate solution substituted Li⁺ of cookeite and K⁺ of illite, respectively.