Rare earth element enrichment in intrusive rocks of Sri Lanka as a potential low-grade source

Abstract

Owing to the crucial role-playing in the decarbonization of the global economy, the demand for rare earth elements (REEs) is burgeoning while the supply is highly uncertain. This lack of secure supply coupled with high-grade resource depletion has led to increased explorations on potential low-grade resources of REEs. Thus, the present study focuses on the enrichment of REEs in intrusive rocks in Sri Lanka – a prospective low-grade REE resource. We analyzed fifty-five rock samples from a few granitic bodies (Massenna, Thonigala, Arangala), Eppawala Phosphate Deposit (EPD), and Ratthota pegmatite for their REE concentrations. Amongst the studied prospects, EPD (4185 mg/kg), Arangala granite (2183 mg/kg), and Massenna granite (937 mg/kg) had high REE concentrations with increased LREE enrichments over HREEs. However, EPD contains processable REE minerals (apatite and monazite), and REEs can be extracted as a by-product after developing the phosphate fertilizer production flow. Thus, EPD is the highest prospective of all the studied intrusive rocks of Sri Lanka. Compared to global occurrences, although it is low-grade (0. 48 wt% REO, 0.29 million tons REE reserve), such low-grade REE resources could become viable in the future due to the ever-increasing demand and the expected resource depletion of REEs.