A green extraction process of lithium from clays

Abstract

One of the possibilities for mitigating global climate change is to replace the burning of hydrocarbons with cleaner wind and solar energies, but the problem is storing the energy efficiently. To solve this problem, one of the most promising alternatives is the use of rechargeable and efficient lithium batteries. The importance of this work is that a green method to extract lithium from clays (the third major source of this element) is demonstrated at a laboratory scale. This is done through an electrodialysis process, placing the clay slurry in the anodic section and water in the cathodic section. In this work, the effect of temperature and percentage of solids of the slurry on the lithium extraction kinetics is studied and it is found that the temperature favours the extraction kinetics, but the solids percentage affects it negatively. The extraction of lithium from clay-type carbonates is feasible under the following initial operating conditions: temperature close to 25 °C, solids content at 10 % (weight/weight, w/w) and natural pH of the clay slurry (pH_natural 10, approximately). The small particle size and high surface charge of clays makes them very difficult to separate from water (by filtration or sedimentation) but this method allowed settling of the processed clays.