Paper_The occurrence of rare earth elements in South African coal ash- identification and characterisation.pdf

Nicola Wagner, University of Johannesburg
Vhonani Rerani, Mintek
Christopher Baiyegunhi, University of Limpopo
Sanki Biswas, University of Johnannesburg

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The occurrence of rare earth elements in South African coal ash: identification and characterisation Authors Prof. Nicola Wagner - South Africa - University of Johannesburg Ms. Vhonani Rerani - South Africa - Mintek Prof. Christopher Baiyegunhi - South Africa - University of Limpopo Dr. Sanki Biswas - South Africa - University of Johnannesburg Ms. Happy Mabowa - South Africa - Mintek Abstract South Africa's coal-fired power generation results in significant amounts of ash. Coal ash is considered a potential secondary resource for rare earth elements (REEs). Thus, there is growing interest in researching the occurrence of REEs in South African coal and ash. In this study, laboratory-derived coal ash, power station coal ash (fly ash and bottom ash) and corresponding feed coals collected from different coalfields in South Africa were analysed for their chemical and mineralogical characteristics. ICP-MS results revealed varying REE values, ranging from 400-900 ppm in the ash samples. It is apparent that the REE occurrence differs between the different sources / coalfields, related to sediment source in the peat swamp and subsequent mineralogical and elemental precipitation and alteration. Ash samples with high total REE values were examined using the Mineral Liberation Analyser (MLA). In one sample set, four rare earth-bearing particles were identified using the bright phase search mode and grouped as monazite-REE, xenotime-REE, REE-silicates, and REE-cerium. The back-scattered electron (BSE) detector images revealed a combination of locked, middling, and liberated REE-hosted particles. This information is useful when determining appropriate REE extraction techniques.

 
May 15th, 11:30 AM May 15th, 12:00 PM

Paper_The occurrence of rare earth elements in South African coal ash- identification and characterisation.pdf

Grand Rapids, Michigan

The occurrence of rare earth elements in South African coal ash: identification and characterisation Authors Prof. Nicola Wagner - South Africa - University of Johannesburg Ms. Vhonani Rerani - South Africa - Mintek Prof. Christopher Baiyegunhi - South Africa - University of Limpopo Dr. Sanki Biswas - South Africa - University of Johnannesburg Ms. Happy Mabowa - South Africa - Mintek Abstract South Africa's coal-fired power generation results in significant amounts of ash. Coal ash is considered a potential secondary resource for rare earth elements (REEs). Thus, there is growing interest in researching the occurrence of REEs in South African coal and ash. In this study, laboratory-derived coal ash, power station coal ash (fly ash and bottom ash) and corresponding feed coals collected from different coalfields in South Africa were analysed for their chemical and mineralogical characteristics. ICP-MS results revealed varying REE values, ranging from 400-900 ppm in the ash samples. It is apparent that the REE occurrence differs between the different sources / coalfields, related to sediment source in the peat swamp and subsequent mineralogical and elemental precipitation and alteration. Ash samples with high total REE values were examined using the Mineral Liberation Analyser (MLA). In one sample set, four rare earth-bearing particles were identified using the bright phase search mode and grouped as monazite-REE, xenotime-REE, REE-silicates, and REE-cerium. The back-scattered electron (BSE) detector images revealed a combination of locked, middling, and liberated REE-hosted particles. This information is useful when determining appropriate REE extraction techniques.