Efficient extraction of lithium from Β-spodumene by direct roasting with NaF and leaching

Abstract

This research describes the study of a new process for the extraction of Li from β-spodumene by direct roasting with NaF and leaching. Various parameters including roasting temperature, β-spodumene/NaF molar ratio and reaction time were studied. The thermal behavior of the mixture β-spodumene/NaF was studied by simultaneous thermogravimetry and differential thermal analysis. The results indicate that the sample begins to react with NaF at around 540 °C. The optimal conditions for lithium extraction were found to be 600 °C, 1:2 β-spodumene:NaF molar ratio and 60 min of roasting. In these conditions, a lithium extraction degree of 90%, approximately, is reached. The products of the roasting reaction of the mineral with NaF are LiF, nepheline and albite, all identified by XRD. The unreacted NaF can be removed by water washing with minimal lithium loss of 0.36%. Finally, LiF was completely leached with a 10% v/v H2SO4 solution, remaining in the solid the compounds albite and nepheline.