Research and industrialization progress of recovering alumina from fly ash: A concise review.

Fly ash, a by-product of high temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amount of industrial solid wastes generated in China. Its improper disposal has become an environmental problem. Now it is widely realized that fly ash should be considered as a useful and potential mineral resource. Fly ash is rich in alumina, making it a potential substitute for bauxite. With the diminishing reserves of bauxite resources, as well as the increasing demand for alumina, recovery of alumina from fly ash has attracted extensive attention world-wide. The present review describes, firstly, the generation and physicochemical properties of high alumina fly ash found in northern China and then focuses on the various alumina recovery technologies, the advantages and disadvantages of these processes, and in particular, the latest industrial developments. Finally, the directions for future research are also considered.