Dissolution behavior and partitioning of rare earth elements in coal fly ash particles into dilute acids

近年来，世界范围内稀土资源的供应将受到严重限制。另一方面，燃煤电厂排放的飞灰颗粒含有较高浓度的稀土元素。煤飞灰中稀土元素的含量一般在几百ppmw左右。为了从煤飞灰颗粒中提取和回收稀土元素，我们首先研究了它们在稀硫酸中的溶解行为。准确测定了燃煤飞灰样品中的稀土元素含量，提出了原煤的灰分中稀土元素的存在及其在燃烧过程中在飞灰颗粒中的富集性。随着时间的推移，飞灰中的稀土元素逐渐在硫酸中溶解，这意味着在飞灰颗粒中存在两种类型的稀土元素。通过将未反应核模型应用于稀土在硫酸溶剂中的溶解行为，我们可以解释这两种类型的发生。

Recently, the worldwide supply of rare earth element (REE) resources will be severely restricted. On the other hand, coal fly ash particles emitted from coal-fired electric power plants contain relatively high concentrations of REEs. The contents of REEs in coal fly ash are regularly several hundreds of ppmw. In order to extract and recover REEs from coal fly ash particles, as a first step, we have investigated their dissolution behavior in a dilute H2SO4 solvent. The REE content of coal fly ash specimens has been precisely determined, and their presence in the ash component of the original coal and their enrichment in coal fly ash particles during coal combustion have been suggested. REEs in coal fly ash dissolve gradually in H2SO4 over time, and this implies two types of occurrences of the REEs in coal fly ash particles. By applying the unreacted core model to the dissolution behavior of REEs in a H2SO4 solvent, we can explain both types of occurrences.