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Location
Lexington, Kentucky
Start Date
5-5-2026 1:30 PM
End Date
5-5-2026 2:00 PM
Description
The global shift toward low-carbon energy systems, electric mobility, and digital technologies has sharply increased the demand for critical minerals, including rare earth elements (REY) vital for permanent magnets, batteries, wind turbines, photovoltaic cells, semiconductors, and modern defence applications. Coal by-products—particularly coal fly ash (CFA) and coal bottom ash (CBA)—are emerging as promising secondary sources of REY, but their economic viability depends on effective enrichment and extraction methods. South Africa’s coal-fired power plants generate nearly thirty million tonnes of coal-ash each year. This study investigates REY concentrations in CFA and CBA collected from five major power stations (PS-1 to PS-5) across the country. The REY concentrations in CFA range from 288.5 to 391.1 ppm (average 343.0 ppm), while CBA samples contain between 296.6 and 448.0 ppm (average 372.3 ppm). On average, both CFA and CBA exhibit lower REY abundances compared to World coal ash value. Light REY dominate the overall distribution in both ash types, followed by medium and heavy REY. Mineralogically, amorphous glass is the most abundant phase in CFA and CBA (averaging 58.5% and 64.9%, respectively), accompanied by quartz, mullite (formed through thermal alteration of clay minerals), and minor amounts of magnetite, hematite, and cristobalite. Samples with higher REY contents were further analyzed using a mineral liberation analyser (MLA) to understand the REY host minerals and modes of occurrence. In one dataset, three distinct REY-bearing particle types (10–30 μm) were identified using bright-phase search: monazite, xenotime, and REE-silicates. Back-scattered electron (BSE) imaging revealed a mixture of locked, middling, and liberated REY-hosting particles. This information is valuable for optimizing REY recovery strategies from coal-derived waste materials.
Document Type
Presentation
Archival?
Archival
Included in
Energy Systems Commons, Environmental Indicators and Impact Assessment Commons, Environmental Monitoring Commons, Mining Engineering Commons, Oil, Gas, and Energy Commons, Structural Materials Commons, Sustainability Commons
Rare Earth Element Distribution and Mineral Host in Coal derived Ash from South African Power Stations
Lexington, Kentucky
The global shift toward low-carbon energy systems, electric mobility, and digital technologies has sharply increased the demand for critical minerals, including rare earth elements (REY) vital for permanent magnets, batteries, wind turbines, photovoltaic cells, semiconductors, and modern defence applications. Coal by-products—particularly coal fly ash (CFA) and coal bottom ash (CBA)—are emerging as promising secondary sources of REY, but their economic viability depends on effective enrichment and extraction methods. South Africa’s coal-fired power plants generate nearly thirty million tonnes of coal-ash each year. This study investigates REY concentrations in CFA and CBA collected from five major power stations (PS-1 to PS-5) across the country. The REY concentrations in CFA range from 288.5 to 391.1 ppm (average 343.0 ppm), while CBA samples contain between 296.6 and 448.0 ppm (average 372.3 ppm). On average, both CFA and CBA exhibit lower REY abundances compared to World coal ash value. Light REY dominate the overall distribution in both ash types, followed by medium and heavy REY. Mineralogically, amorphous glass is the most abundant phase in CFA and CBA (averaging 58.5% and 64.9%, respectively), accompanied by quartz, mullite (formed through thermal alteration of clay minerals), and minor amounts of magnetite, hematite, and cristobalite. Samples with higher REY contents were further analyzed using a mineral liberation analyser (MLA) to understand the REY host minerals and modes of occurrence. In one dataset, three distinct REY-bearing particle types (10–30 μm) were identified using bright-phase search: monazite, xenotime, and REE-silicates. Back-scattered electron (BSE) imaging revealed a mixture of locked, middling, and liberated REY-hosting particles. This information is valuable for optimizing REY recovery strategies from coal-derived waste materials.
