Alkali Treatment Implications for Microwave-Assisted Rare Earth Elements Extraction from Coal Mine Tailings.

ABSTRACT: Coal tailings represent a promising secondary resource of rare earth elements (REEs), yet efficient extraction is limited by their complex mineralogy. This study investigated the impact of alkali pretreatment on aluminosilicate structures in coal tailings and its implications for REE extraction via acid digestion. Precombustion coal refuse was treated with 5 M NaOH at varying solid-to-liquid (S/L) ratios (5, 50 g/L) and reaction times (5, 15 min), including a multistep (five-cycle) treatment under microwave conditions. At 180 °C, XRD, ²⁹Si NMR, and thermodynamic modeling showed kaolinite transformed to hydrosodalite at high S/L ratios, while kaolinite completely dissolved at low S/L ratios. Quartz maintained crystallinity but slowly transformed to amorphous silica during prolong

SUBMITTER: Ajayi LO 

PROVIDER: S-EPMC12659421 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature