Alternative Process for Recovering Zirconium and Rare Earth Elements from Pre-processed Gabal El-Faliq Concentrate Pegmatite

Another approach for recovering zirconium and rare earth elements has been proposed. This process is based on the separation of Zr-sulfide from the prepared chloride leach liquid of the hydrous oxide cake (obtained following the previous alkaline breakdown of Gabal El-Faliq pegmatite concentrate). At the optimal conditions of pH 3, 10% Na₂S concentration, precipitation period of 25 min, and precipitation temperature of 80 °C, zirconium sulfide precipitated almost completely. The filter chloride solution, free of Zr ions, was then treated with oxalic acid to separate the REE-oxalate cake. Finally, a flow sheet for preparing pure products from the metals of interest was established. The chloride leaching experimental data were well interpreted using a shrinking core model with diffusion control across a porous product layer. The activation energy was measured to be 2.31 kJ/mol. The low activation energy supported the discovery that the chloride leaching rate is determined by a diffusion-controlled process. The experimental data were graphically and statistically examined, and the aforementioned model proved to suit the results satisfactorily.