Cenospheres are one of many valuable
components within coal combustion ash.
Traditionally, only particles having
densities < 1 gm/cm have been 3 called ‘cenospheric’.
This terminology is probably because
cenospheres float on water, allowing
harvesting from wet ash impoundments. In
combustion fly ashes, the relative amount of
cenospheres is typically around 1%. However,
cenospheres are really gas bubble-containing
particles independent of their bulk density.
Hence, their density may be greater than 1
gm/cm3 and their concentration in combustion
ash much greater than 1%.