High-End Reclamation of Coal Fly Ash Focusing on Elemental Extraction and Synthesis of Porous Materials
Tongyao Ju, Siyu Han, Yuan Meng, Jianguo Jiang
Abstract
Coal combustion accounts for a large proportion of the global energy supply due to its low cost and high heat value; however, pollution from the large amounts of coal fly ash (CFA) generated during the process causes many environmental problems. CFA has traditionally been used in construction and soil remediation, although there have been attempts to use CFA in response to the developing shortage of mineral resources. Numerous studies have investigated high-end recycling of CFA to obtain valuable products such as critical metals and porous materials, which are widely used in chemical engineering, ecological remediation, and other fields. In this study, we found that various extraction and synthesis methods summarized high value-added treatments of CFA. Dissolution and sintering processes were applied for extraction, while carbothermal and electrolysis techniques offered other unique advantages. The precursors and polymers used in the procedures were the two main factors influencing the synthesis of porous materials, providing a source of elements and inducing the formation of predictable structures. Considering the mechanisms involved, the complex methods used in state-of-the-art CFA recycling could be combed to develop high value-added CFA reclamation techniques.