A cleaner electrolysis process to recover alumina from synthetic sulfuric acid leachate of coal fly ash

The realization of clean extraction of aluminum hydroxide from high-alumina coal fly ash would be beneficial to achieve better overall coal utilization, and renders environmental and economic benefits. The current study mainly aimed to develop a nonhazardous approach to conduct electrolysis for alumina extraction from sulfuric acid leachate of high-alumina coal fly ash. The XRD, SEM, LPSA, FT-IR and ICP-AES results revealed that aluminum hydroxide was a main electrolysis product, with current efficiency of 83.25% under the optimized conditions as t = 1 h, J = 600 A/m(2). The median particles of aluminum hydroxide after 1-h and 6-h electrolysis were 35.3 and 40.1 mu m, respectively. The electrolysis mechanism was analyzed by cyclic voltaminetry, which showed that the H2O gained electrons on the cathode to form OH- and H-2. The OFF reacted with Al3+ to form Al (OH)(3). In addition, the effluent of electrolysis was sulfuric acid and can be reused as a leaching reagent to promote zero pollution discharge. Hence, the electrolysis process provided an environment-friendly and efficient approach for alumina extraction from high-alumina coal fly ash.