REUSE OF COAL COMBUSTION ASH AS SORBENT: THE EFFECT OF GASIFICATION TREATMENTS

Beneficiation through gasification of coal combustion ash coming from an industrial power plant aimed at its reuse as adsorbent is addressed. The raw ash was gasified in a tubular reactor at 850 degrees C for times ranging from 10 to 60 min, using either steam or CO2 as gasifying agents. The relationships among ash properties, gasification treatments, and properties of the gasified ashes deserve investigation. Therefore, ash characteristics (such as carbon content and porosimetric, diffractometric, and granulometric properties) were correspondingly determined. In the light of a critical analysis of the obtained results, gasification conditions able to make the parent ash a potentially better adsorbent material were defined, with a particular emphasis on similarities and differences between steam and CO2 gasification. Finally, preliminary results concerning cadmium adsorption from aqueous solutions have been reported.