Abstract
Monazite, a rare earth phosphate mineral, is the second most important primary source of rare earth elements (REEs). Current technologies for processing monazite ore using sulfuric acid are primarily focused on REEs recovery. However, these technologies result in the loss of phosphorus in waste streams. Therefore, there is a need for efficient processing methods that could recover both REEs and phosphorus from monazite ore. This study presents a method for recovering both REEs and phosphorus as potential feed material for iron phosphate battery precursor from monazite ore by sulfuric acid baking with the addition of sulfate salts. The leaching efficiency of REEs and phosphorus varied depending on the additive used, with the highest efficiencies observed for the ferric sulfate system. As the temperature increased, the leaching efficiency of REEs and phosphorus decreased when baking with no additive. However, the addition of ferric sulfate salt to the baking reactants improved leaching efficiency of REEs and favourably enriched P in the residue for subsequent processing. The XRD confirmed the successful constraining of P and Fe in the residue while more than 95% REEs were selectively leached. The results suggest that this method could be a promising alternative to conventional methods for processing monazite ore. An integrated flowsheet was proposed to produce a marketable rare earth oxide product of over 99% purity.