Experimental parameter optimization study on the acid leaching of coal fly ash

AbstractCoal fly ash from a power plant was leached using HCl. Factors that influenced the leaching process, such as the ratio of coal fly ash to Na2CO3, the HCl concentration, the leaching time, and the temperature, were investigated, and an orthogonal test was used to determine the optimal conditions for acid leaching the coal fly ash. The coal fly ash samples before and after acid leaching were analyzed by scanning electron microscopy, energy dispersive spectroscopy, and Brunauer–Emmett–Teller adsorption analysis. An aluminum leaching rate of 90.68% was obtained using the optimal values of 6 g Na2CO3, 100 g coal fly ash, 4 mol L−1 HCl, 1.5 h leaching time, and a temperature of 100°C. The concentrations of Al3+ and Fe2+ plus Fe3+ in the leaching liquid were 34.21 and 30.67 g L−1, respectively, using the optimal conditions. The coal fly ash residue had certain specific surface area and absorption features that are described. The results suggest that acid leaching offers benefits in terms of the comprehen...