Characterization of Unburnt Carbon Recovered from Fly Ash by Froth Flotation

Abstract

Coal based thermal power plants are the main source of power generation in India. Since Indian coals contain high percentage of ash, as much as 40% and above, these power plants produce about 150 million tons of fly ash per annum. Presence of significant amount of unburned carbon in these fly ashes can be attributed to inefficient comb-ustion of fuel coal in the boilers or the use of low-NO, burners to reduce power plant emission. The carbon amount in fly ash needs to be reduced, so that these fly ashes meet the requirements for maximum loss of ignition (L01) for various uses. On the other hand disposal offly ash containing appreciable amount of unburnt carbon is posing serious problems causing environmental damages. It is in this context an attempt has been made to recover the unbu-rnt carbon from fly ash by froth flotation and then chara-cterize it further to effectively utilize it. Such an effo-rt will find market for both the materials such as fly ash and the recovered unburnt carbon. In the present study the quality of recoverable carbon has been determined for two fly ashes collected from two thermal power plants. The raw ash ancrthe concentrate generated out of process have been characterized by SEM and XRF techniques besides dete-rmining their proximate analysis, particle size distribut-ion and surface area to estimate their adsorption capabil-ities.