Pelletizing ash

A method for pelletizing ash from a combustor in which carbonaceous fuel is burned in the presence of calcium, and wherein fly ash is generated as a by-product of the combustion process, comprising the steps of:

• obtaining fly ash generated during the combustion process;
• adding water to the fly ash to form a mixture;
• forming pellets from the fly ash-water mixture;
• drying the surfaces of the pellets;
• and
• curing the pellets.

A method for pelletizing ash from a fluidized bed combustor in which limestone particles are suspended in the presence of carbonaceous fuel being burned, wherein lime-containing fluidized bed combustion residue (FBCR) is produced in the combustor, and wherein fluidized bed combustion (FBC) fly ash is generated as a by-product of the combustion process, comprising the steps of:

• obtaining FBCR from the combustor;
• obtaining FBC fly ash generated during the combustion process;
• adding water to the lime-containing FBCR so as to convert about 50-95% of the lime to hydrated lime and thereby form hydrated FBCR;
• adding water to the FBC fly ash to form a mixture;
• forming pellets from the FBC fly ash-water mixture;
• applying the hydrated FBCR to the surfaces of the pellets to form coated pellets;
• curing the coated pellets by nesting them in a bed of hydrated FBCR;
• separating the cured, coated pellets form the bed of hydrated FBCR;
• and
• mixing the separated, hydrated FBCR with FBC fly ash and water prior to forming additional pellets.