Removal of unburned carbon from fly ash using enhanced gravity separation and the comparison with froth flotation

摘要

Fly ash is the by-products of electric power, which has potential application in construction industry after removing the unburned carbon. The density difference and favorable dispersion characteristics of fly ash provide the feasibility using gravity separation method. The present study had investigated the removal of unburned carbon from fly ash using enhanced gravity separation under different operation parameters such as rotational angular velocity and backwash water pressure, and the decarbonization performance was compared with the froth flotation. The results showed that both the rotational angular velocity and backwash water pressure had evident effect on the removal of unburned carbon from fly ash, and the rotational frequency adjusted more accurate relative to the coarse adjustment of backwash water pressure. The enhanced gravity separation could yield qualified Level II and Level III ash products with yield of 12%-23% and 23%-69%, while the froth flotation yield Level I, Level II and Level III ash products. The decarbonization results of enhanced gravity separation was slightly lower than froth flotation, while it provided the application value in industry without complex reagent system and high cost on the premise that ma the requirements for Level II and Level III ash products.