Binders and the Bonding Mechanism of Fly Ash and Coke Pelletization

Fly ash is an industrial by-product generated during the combustion of coal in power plants and it could represent a very important source of minerals particularly alumina. Extracting alumina by pelletization and carbo-chlorination of fly ash is an effective utilization process. However, the strength of fly ash and coke pellets is very low, therefore the application of binders to the pellets should be investigated. In this study, physical and chemical characteristics of fly ash and coke were investigated followed by experiments with different binders to make pellets with a focus on pellet strength. The results of studies indicated that of all the binders evaluated, the organic binders generally produced pellets with greater strength than the inorganic binders, with carboxymethyl cellulose (CMC) being the most effective. Based on the results, it was concluded that a blend of CMC with pre-gelatinized starch was the best compromise for strength of the pellets and the cost point of view. The bonding mechanisms of the best binder have been discussed.