TY - JOUR
T1 - Leaching of rare earth elements (REEs) from lake sediments around Eppawala phosphate deposit, Sri Lanka
T2 - A secondary source for REEs
AU - Dushyantha, N.P.
AU - Ratnayake, N.P.
AU - Premasiri, H.M.R.
AU - Ilankoon, I.M.S.K.
AU - Hemalal, P.V.A.
AU - Jayawardena, C.L.
AU - Chandrajith, Rohana
AU - Rohitha, L.P.S.
AU - Abeysinghe, A.M.K.B.
AU - Dissanayake, D.M.D.O.K.
AU - Dharmaratne, P.G.R.
AU - Ratnayake, A.S.
AU - Batapola, N.M.
N1 - Funding Information:
The authors wish to acknowledge the financial supports provided by the Accelerating Higher Education and Development (AHEAD) Operation of the Ministry of Higher Education of Sri Lanka funded by the World Bank ( AHEAD/DOR/6026-LK/8743-LK ) and SRC/CAP/2015/02 . The authors are thankful to Sandun Udayanga, Sathmi Wickramarachchi, Ranjani Amarasinghe, Sarath Perera and Duminda Wickramasinghe for the field and laboratory assistance and Mihiranga Jayaweera for XRD analysis.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/11
Y1 - 2021/11
N2 - Rare earth elements (REEs) are widely employed in a spectrum of high-tech applications. Since primary REE resources are limited, secondary REE sources will be crucial to reduce future supply chain gap between REE demand and supply, which is currently about 3000 t per year. In this context, lake sediments around Eppawala Phosphate Deposit (EPD) in Sri Lanka could be considered as a potential secondary REE source since a man-made water canal running across the EPD transports REE-rich materials to the lake sediments. The average total REE (ΣREE) concentration of the downstream surface lake sediments was 804 mg/kg. The REEs were present in lake sediments as 3 fractions, namely, ion-adsorbed, colloidal, and mineral bound fractions. Ion-adsorbed fraction was assessed using less expensive, easy, and environmentally friendly ion-exchangeable leaching by a solution of (NH4)2SO4 under optimum conditions. Experimental results revealed that 34% of ΣREE was leached as ion-adsorbed fraction. In addition, the maximum leachable REE content (i.e. ion-adsorbed and colloidal fractions) was determined as 78% of ΣREE through HCl leaching under optimum conditions. Therefore, acid leaching was proven to be the best leaching process and the results in this preliminary study could be useful to assess low-grade geological resources, especially sediments and soils around major phosphate deposits with similar geological settings.
AB - Rare earth elements (REEs) are widely employed in a spectrum of high-tech applications. Since primary REE resources are limited, secondary REE sources will be crucial to reduce future supply chain gap between REE demand and supply, which is currently about 3000 t per year. In this context, lake sediments around Eppawala Phosphate Deposit (EPD) in Sri Lanka could be considered as a potential secondary REE source since a man-made water canal running across the EPD transports REE-rich materials to the lake sediments. The average total REE (ΣREE) concentration of the downstream surface lake sediments was 804 mg/kg. The REEs were present in lake sediments as 3 fractions, namely, ion-adsorbed, colloidal, and mineral bound fractions. Ion-adsorbed fraction was assessed using less expensive, easy, and environmentally friendly ion-exchangeable leaching by a solution of (NH4)2SO4 under optimum conditions. Experimental results revealed that 34% of ΣREE was leached as ion-adsorbed fraction. In addition, the maximum leachable REE content (i.e. ion-adsorbed and colloidal fractions) was determined as 78% of ΣREE through HCl leaching under optimum conditions. Therefore, acid leaching was proven to be the best leaching process and the results in this preliminary study could be useful to assess low-grade geological resources, especially sediments and soils around major phosphate deposits with similar geological settings.
KW - Acid leachable REEs
KW - Ion-exchangeable REEs
KW - Lake sediments
KW - Rare earth elements
KW - Secondary rare earth resources
UR - http://www.scopus.com/inward/record.url?scp=85115269512&partnerID=8YFLogxK
U2 - 10.1016/j.hydromet.2021.105751
DO - 10.1016/j.hydromet.2021.105751
M3 - Article
AN - SCOPUS:85115269512
VL - 205
JO - Hydrometallurgy
JF - Hydrometallurgy
SN - 0304-386X
M1 - 105751
ER -