Carbon removal flotation performance and economic analysis of different coal fly ash using waste fried oil as a collector

• Circulating fluidized bed furnace fly ash is more sensitive to WFO dose. • Circulating fluidized bed furnace fly ash has more strongly hydrophilic groups. • WFO improves the hydrophobicity of fly ash with oxygenated groups. • WFO flotation of pulverized coal furnace fly ash is more profitable. Collector consumption in flotation is significant, and petrochemicals like kerosene, being non-renewable and expensive, are commonly used collectors; therefore, finding suitable alternatives to reduce costs is essential. Waste fried oil (WFO) possesses properties similar to those of kerosene, making it a viable substitute for flotation processes. In this study, the flotation performance was analyzed and economic analysis of WFO as a collector was performed for circulating fluidized bed furnace fly ash (CFBFA) and pulverized coal furnace fly ash (PCFFA). The interaction mechanism between WFO and fly ash was analyzed using contact angle, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) tests. The findings revealed that the optimal WFO dosage for coal fly ash closely correlates with the combustion technology used to obtain it. The study also established well-fitted curves for the loss on ignition (LOI) of CFBFA and PCFFA with changes in WFO dosage. FTIR and XPS analyses revealed that the interaction of WFO carbon chains with nonpolar regions on the surface of unburned carbon in coal fly ash resulted in an increase in hydrophobic carbon chain groups on the surface of unburned carbon, and the combination of oxygen-containing groups in WFO with the hydrophilic sites on the surface of unburned carbon were the main reasons for the enhancement of hydrophobicity of unburned carbon particles. Moreover, the economic analysis revealed that flotation of 1 t of CFBFA and PCFFA with WFO can yield profits of 1.91 USD and 1.11 USD more, respectively, compared with kerosene, which has practical applications in industry.