Conversion of Coal Fly Ash into Zeolite Materials: Synthesis and Characterizations, Process Design, and Its Cost-Benefit Analysis

In this work, coal fly ash (CFA) – a byproduct of coal combustion, has been successfully converted into a value-added product— zeolite. This study focuses on the production of the Na-A zeolite phase via the fusion method. The effects of fusion reaction temperature, hydrothermal reaction temperature, reaction time, and the concentration of alkaline were investigated. The synthesized products were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) and studied for their purity and yield. A fusion temperature of 550 °C, fusion duration of 1.5 h, and a subsequent hydrothermal temperature of 100 °C for a reaction of 12 h were found to be the optimal conditions. Based on the synthesis conditions found, an up-scale production process was designed and simulated with aid from the Aspen Plus program. It was found that zeolite production via the fusion method obtained high profitability. For a 5000 kg/h coal fly ash feed, a payback period of 7.1 years is feasible over a 20-year operation period. A cost-benefit analysis was studied to compare the improved environmental performance and economics of zeolite production from CFA with current CFA disposal practices.