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.