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 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 2018 7-10 May Athens, Greece

Results ScPO4 ScPO4 + NaOH Pyrophosphate formation after 800⁰C No formation of pyrophosphate when reacted with NaOH 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 NaOH and NaNO3 additon Unsuccessful in case of NaCl and Na2SO4 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. 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 2018 7-10 May Athens, Greece

BR 2018 7-10 May Athens, Greece