Abstract
Lithium is an alkali metal that offers excellent thermal and electrical conductivity. Its many compounds are abundantly used in the manufacturing of a wide variety of products, including: glass, ceramics, batteries, and refrigerants. Locatelli Saline di Volterra has shown interest in the process of recovering lithium from brine. They decided to collaborate with the CPTM research centre to identify a chemical process as selective as possible for extracting lithium from brines. In particular, the main goal is to recover lithium from the mother liquors obtained from the sodium salt production process (i.e. from a process effluent), fully in line with the dictates of the circular economy. The recovery process mentioned above is difficult due to the low concentration of lithium compared to the other elements. Recovering lithium in low concentration solutions is possible, however, by taking advantage of the low solubility of some of its salts. Precipitation of lithium phosphate from salt solution, with initial lithium concentrations around 200 ppm, yielded excellent results, showing a maximum lithium recovery yield of 84 %. These results can be achieved operating at a temperature close to the boiling point of the solution (108 °C), for a reaction time of 2 h and a PO4/Li molar ratio of 0.91.
