Solidstate Conversion of Scandium Phosphate to Oxide With

Solid-state Conversion of Scandium Phosphate to Oxide With Sodium Compounds Bengi Yagmurlu, Wenzhong Zhang, Risto Koivula, Carsten Dittrich, Bernd Friedrich MEAB BR 2018 7 -10 May Athens, Greece

Motivation • 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 • Sc. PO 4 concentrate can be produced by selective precipitation • No discovered use of Sc. PO 4 • Phosphate has stricter regulations • Sc 2 O 3 is preferred • Conversion of the synthesized concentrate into oxide • Best candidates: Na compounds BR 2018 7 -10 May Athens, Greece

Results Sc. PO 4 + Na. OH Sc. PO 4 • Pyrophosphate formation after 800⁰C • No formation of pyrophosphate when reacted with Na. OH • Further verification needed BR 2018 7 -10 May Athens, Greece

Results • Verified conversion into oxide and mixed oxide depending on the heating rate in case of Na. OH and Na. NO 3 additon • Unsuccessful in case of Na. Cl and Na 2 SO 4 • Low temperature processing is needed BR 2018 7 -10 May Athens, Greece

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. • Sc 2 O 3 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 Na. Al. O 2 is soluble in water. BR 2018 7 -10 May Athens, Greece

BR 2018 7 -10 May Athens, Greece