Abstract:
Monazite concentration in Pulmoddai mineral sand deposit in Sri Lanka is 1.38%. Its Rare
Earth Elements (REE) composition is about 61%. Currently, only heavy minerals are
separated and cerium rich monazite is discarded. Therefore, the study is focused on finding
feasibility of extraction of CeO2 from Pulmoddai monazite. The research was conducted
under four stages, removal of phosphate ions, removal of radioactive elements, purified
Rare Earth oxide (REO) preparation and selective separation of CeO2. The optimum
concentration of NaOH solution is found as 80% (w/v)/ 20M. Alkaline digestion was done
for 4hrs at 150oC by adding 25 ml of NaOH to 25 g of monazite, followed by acid leaching
with 50 ml of 60%(w/v) HCl at 90°C for 1hr. Concentration of 20 g/L (0.22M) oxalic acid
should be added to the RE chloride mixture until the complete precipitation of RE oxalates.
Purified REO was obtained by calcination at 900°C for 2hrs using RE oxalate precipitated.
Purified REO was used to recover CeO2 by subjecting to selective precipitation. Selective
precipitation of CeO2 was carried out using solid form of KMnO4 and (15wt%) Na2CO3
solution with maintaining average pH value 4 by manual addition of Na2CO3 solution ([15
g /100 L]/0.001M).
Citation:
Rasanjalee, P.H.A.U., Delaksana, S., Sampath, M.D., Dushyantha, N.P., Batapola, N.M., Dissanayake, D.M.D.O.K., & Rohitha, L.P.S. (2020). Feasibility of extraction of cerium dioxide (CeO2) from monazite at Pulmoddai. In D.M.D.O.K. Dissanayake & A.B.N. Dassanayake (Eds.), Proceedings of International Symposium on Earth Resources Management & Environment 2020 (pp. 78-85 ). Department of Earth Resources Engineering, University of Moratuwa.