Optimization of major elements recovery from thermal power plant fly ash using Taguchi experimental design

In this study, aluminum, iron, calcium and magnesium existing in thermal power plant fly ash were leached by the method of hydrochloric acid with 20% acetic acid. Then, solvent extraction and precipitation methods were applied for recovery processes. The effects of acid concentration, reaction time, and temperature on leaching of iron, aluminum, calcium, and magnesium were investigated considering the Taguchi experimental design. The optimal leaching efficiencies of these elements were obtained under the experimental condition of 5 molar acid concentration, a 240 min reaction time, and 90 °C reaction temperature and removal efficiencies were obtained for iron, aluminum, calcium and magnesium as 95%, 87%, 87%, and 96%, respectively. Almost all the tested elements were successfully recovered from leaching solution of elements by solvent extraction and precipitation processes, which are considered as recovery processes. This study indicated that the proposed methods could be applied in recovery of metals from fly ash samples successfully.