1. Solid-state Conversion of Scandium Phosphate to Oxide With Sodium Compounds Bengi Yagmurlu, Wenzhong Zhang, Risto Koivula, Carsten Dittrich, Bernd Friedrich
MEAB
BR May Athens, Greece

2. Motivation
ScPO4 concentrate can be produced by selective precipitation
No discovered use of ScPO4
Phosphate has stricter regulations
Sc2O3 is preferred
Rare primary sources
Generally produced as a by-product
Complex processing
High purification costs
Classified as a critical metal
>90% of whole bauxite residue value
Conversion of the synthesized concentrate into oxide
Best candidates: Na compounds
BR May Athens, Greece

3. Results ScPO4 ScPO4 + NaOH Pyrophosphate formation after 800⁰C
No formation of pyrophosphate when reacted with NaOH
Further verification needed
BR May Athens, Greece

4. Results
Verified conversion into oxide and mixed oxide depending on the heating rate in case of NaOH and NaNO3 additon
Unsuccessful in case of NaCl and Na2SO4
Low temperature processing is needed
BR May Athens, Greece

5. Conclusions
Low Tm Na compounds succeeed the conversion while high Tm Na compounds were unsuccessful.
Different oxide species are formed as a result of heating rate.
Sc2O3 formation was observed even in low temperatures as 350⁰C as a result of solid-state conversion.
This process can also be used as purification since NaAlO2 is soluble in water.
BR May Athens, Greece

6. BR May Athens, Greece