Hydrothermal synthesis of zeolites from Polish coal fly ash

A method for the synthesis of NaPl-type zeolite and analcime from Polish fly ash derived from hard coal combustion in pulverized-fuel boilers is applied in this paper. The zeolite synthesis was performed from Opole Power Plant fly ash (Elektrownia Opole S. A.), which were activated with aq 3.6% Na₂O (1.16 M NaOH) solution within 80 to 320°C. The NaPl-type zeolite and analcime crystallize at 120°C. As the synthesis temperature increases, the NaPl-type zeolite content rises, and for temperatures of 200 to 320°C the analcime share in the synthesis products becomes significant. The synthesizing capability of zeolites from fly ash has a positive impact on utilization of wastes coming from solid fuel combustion by converting the fly ash into valuable raw material and, simultaneously, accomplishing the lithosphere protection effect.