Assessing the potential of critical metals and rare earth elements in lateritic soils of the Southwestern region of Sri Lanka

Abstract

Laterites are currently considered potential targets for critical metals (CMs) exploration considering their near-surface occurrence, large dissemination, and enrichment of CMs in lateritic soil during weathering. Although prominent lateritic formations are found in Sri Lankan geological terrain, the potential for CMs has not been explored yet. Therefore, the present study assesses the potential of CMs in laterites of the southwestern part of the country. 60 samples were collected covering the overall study area and processed for critical metal analysis. The metal concentrations of CMs: Al, Ni, V, Cr, As, Sr, Co, Sc, and REEs were determined from inductively coupled plasma-mass spectrometry (ICP-MS) and Li, Fe, and Al concentrations were determined from atomic absorption spectroscopy (AAS). According to the analysis, critical metals such as Cr, V, Ni, and Th were significantly high in laterite samples ranging from 42-419, 116-583.4, 274 – 1498, and 33 – 472 mg/kg, respectively. REE and other critical metals considered in the study including Co and Cu, showed comparatively low potential. The findings of the study emphasise that laterite soil has significant potential for Ni, V, and Cr, especially in low grades. The conclusion is this analysis will benefit future CMs' exploratory investigations by providing insights into the potential of CMs in Sri Lankan laterite deposits.