Comparison of the Concentrations of REE & Lithium in Coal Ash Collected from Impoundments in the Southeastern United States

Comparison of the Concentrations of REE & Lithium in Coal Ash Collected from Impoundments in the Southeastern United States

Grand Rapids, Michigan

COMPARISON OF THE CONCENTRATION OF REE & LITHIUM IN COAL ASH COLLECTED FROM IMPOUNDMENTS IN THE SOUTHEASTERN UNITED STATES Authors Mrs. Kalyn Tew - United States - University of Alabama Dr. Rona Donahoe - United States - University of Alabama Abstract This study compares REE, REE+ and Li concentrations in coal ash (N>350) collected from ten impoundments in the southeastern United States. Historical data (N=170) was compiled from 8 power plants. New samples (N=180) were collected from 8 impoundments, then digested (ASTM D6357) and analyzed via ICP-OES (EPA 200.8) for REE+ and Li concentrations. The average REE content for all samples is 385.64 ppm and the average REE+ content is 487.22 ppm. REE content varies significantly between impoundments, with a range of 893.70 - 131.0 ppm. The average lithium content for all samples is 220.25 ppm. For selected samples, major and minor element content was determined via XRF, and elemental mapping was performed via micro-XRF. Results indicate correlations between bulk coal ash composition, mineralogy, and REE content. A strong positive correlation exists between Li and REE content (r = 0.75). There is a weak positive correlation between K and REE content (r = 0.3). A weak negative correlation exists between Ca and REE content (r = -0.3). Micro-XRF mapping indicates that REEs partition into crystalline phosphate grains. These results give insights into the ease of extractability of REEs in coal ash, which is vital to understanding their viability as a resource.