Abstract SYMPHOS 2011

Results
REE elements recovery is excellent whatever the treatment undergone by the aqueous refinate. After treatment by
ammonia only, the lanthanides recovery proves to be optimal (near the100%).
But, the lanthanides concentrate obtained presents some phosphates impurities, mainly found in the residue
obtained. The CaO content of this residue remains very low. After treatment by the ammonia and the oxalic acid, REE
recovery is total whatever the ammonia volume added. The major limitation related to this treatment of aqueous
refinate is the presence in the residue of high quantities of CaO (more than 90% of the CaO contents presents in
the aqueous refinate, already very rich in this oxide). For cost reasons, it seems obvious to recover REE by one-stage
Ammonia treatment. In this way we were able to recover as REE-phosphate nearly 80% of REE initially present in
the phosphate ore.
Figure 4 - CaO, P 2 O 5 and (REE)2O3 recovery in solid phase
(calcined residue) according to the ammonia volume added –
aqueous refinate treated by ammonia (ICP/AES analyses).
Conclusions
The mineralogical composition of the phosphate Angico dos Dias/Caracol ore is relatively simple and easy to
treat. In addition to apatite and quartz grains, mixed grains of kaolinite, crandallite and iron oxides/hydroxides
(with apatite and quartz inclusions) predominate. Fe minerals (magnetite/hematite with or without associated
ilmenite), feldspaths, titanite and goethite were also detected.
Phosphoric acid can be extracted from the hydrochloric leachate by the tributylphosphate. Three stages are
theoretically necessary to recover all the phosphoric acid in the organic extract. The extraction experiments
undertaken, in continuous as discontinuous way, led to the comparable results. Lanthanides and calcium chloride
being mainly distributed in the aqueous refinate. The aqueous phase can also be treated by ammonia in order to
recover the lanthanides (as phosphate concentrate), initially presents in phosphate ore.
In the phosphate sector, even almost 100% REE recovery is a realistic target, the technology is available. It is
dependent to a great extent on the various standards imposed by lawmakers and on the investment and operations
costs involved.
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Figures 2 & 3 - CaCl 2 and lanthanides recovery in refinate.
Figure 5 - CaO, P 2 O 5 and (REE) 2 O 3 recovery in solid phase
(calcined residue) according to the ammonia volume added
– aqueous refinate treated by ammonia and oxalic acid (ICP/
AES analyses).