Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada.
Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada.
Chemosphere. 2024 Nov;367:143562. doi: 10.1016/j.chemosphere.2024.143562. Epub 2024 Oct 19.
Coal ashes in Canada have gained attention as a potential source for recovering rare earth elements (REE) from industrial waste. However, the complex chemical properties of coal ashes have made it difficult to determine the desirability, feasibility, and viability of REE recovery. To address this issue, this study systematically investigated distribution and structural information, speciation and chemical-binding state, and purity and extraction capacity of REE in multiple Canadian coal ashes (i.e., 2 fly ash and 1 bottom ash samples) through synchrotron-based X-ray fluorescence mapping and adsorption spectrum analyses, as well as high-resolution REE sequential extraction quantitation. The results showed that Y, Ce, and La were present in the glass phase of the bottom ash, and the distributions of these REE elements correlated with Ca. The XANES analysis revealed that the dominant form of REE in coal fly ash (CFA) was REE oxides, indicating a transformation during combustion, while YO and Y(CO) were the predominant Y species identified in CFA. The study found that there is no correlation between P and REEs, suggesting that REEs in CFA may exist as discrete particles rather than being associated with amorphous glass. The extractability of REEs in bottom ash samples was lower than that in fly ash samples. Additionally, the benefits of REE recovery were estimated to be USD 99.82 to 215.21 per ton of fly ash through life cycle analysis, indicating that REE recovery from fly ashes is a promising path to supplement the REE supply chain in Canada.
加拿大的煤灰作为从工业废料中回收稀土元素（REE）的潜在来源引起了关注。然而，煤灰的复杂化学性质使得确定 REE 回收的可取性、可行性和生存能力变得困难。为了解决这个问题，本研究通过同步辐射 X 射线荧光映射和吸附光谱分析以及高分辨率 REE 顺序提取定量，系统地研究了加拿大多个煤灰（即 2 个飞灰和 1 个底灰样品）中 REE 的分布和结构信息、形态和化学结合状态以及纯度和提取能力。结果表明，Y、Ce 和 La 存在于底灰的玻璃相中，这些 REE 元素的分布与 Ca 相关。XANES 分析表明，飞灰（CFA）中 REE 的主要形式是 REE 氧化物，表明在燃烧过程中发生了转化，而 YO 和 Y(CO)是在 CFA 中鉴定出的主要 Y 物种。研究发现，P 和 REE 之间没有相关性，这表明 CFA 中的 REE 可能以离散颗粒的形式存在，而不是与无定形玻璃结合。底灰样品中 REE 的提取率低于飞灰样品。此外，通过生命周期分析估计，从飞灰中回收 REE 的收益为每吨飞灰 99.82 至 215.21 美元，这表明从飞灰中回收 REE 是补充加拿大 REE 供应链的有前途途径。
