Distribution of rare earth elements in the pilot-scale processing of fly ashes derived from eastern Kentucky coals [electronic resource] : Comparisons of the feed and processed ashes

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Tác giả:

Ngôn ngữ: eng

Ký hiệu phân loại: 553.8 Gems

Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Office of the Assistant Secretary of Energy for Fossil Energy ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2021

Mô tả vật lý: Size: Article No. 120562 : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 267682

 Beneficiated fly ash from the combustion of Central Appalachian high volatile bituminous coals was extracted with HNO<
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  in a pilot-scale processing plant. Several major oxides (notably CaO and SO<
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 , but also including Fe<
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 O<
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 , MgO, K<
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 O, and P<
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 O<
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 ) and minor elements (Mn, As, Sr, Ba, and Pb) are depleted in the post-HNO<
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 -extraction spent ash. The total lanthanides, Y, and Sc concentration is reduced by about 20% in the spent ash, with Gd showing the greatest decrease. Along with Gd, Nd and Dy are also well differentiated between the feed and spent ashes, with La and Sm showing minimal partitioning. The Gd decrease is correlated with the depletion of Fe<
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 O<
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 . The heavy rare earth elements (REE heavier than Eu) and Y are disproportionately concentrated in the HNO<
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 -leachate compared to the light REE. For the ashes studied, Sc did not partition between the feed and spent ashes. Pozzolanicity tests show that the compressive strength and strength activity indices of the spent ash + ordinary Portland cement (OPC) mixes are comparable to 100% OPC, indicating that the spent ashes produced in the pilot-scale runs have the potential to be sold as a Class F fly ash. Finally, the beneficiated ash chemistry influences the chemistry of the post-HNO<
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 -extraction spent ash and the HNO<
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 -leachate. A 500-ppm-REE fly ash will presumably be a more economically favorable feedstock than an ash with a significantly lesser concentration.
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