Improved bauxite residue dealkalization by combination of aerated washing and electrodialysis
Journal
Journal of Hazardous Materials
Journal Volume
364
Pages
682-690
Date Issued
2019
Author(s)
Abstract
Bauxite residue, a major by-product of the alumina-producing Bayer process, is a serious environmental pollutant due to its high alkalinity. Here, we reported an operation system designed in our laboratory that included washing and electrodialysis dealkalization systems with aeration pipes. Washing with aeration releases a substantial amount of free alkali and attached alkali into water and increases the dealkalization efficiency. The washing liquid was treated with five steps of batch-mode electrodialysis. The average removal of total dissolved solids (TDS) after the aeration and non-aeration electrodialysis processes were 61.30% and 39.61%, respectively. The average removal of OH− under aeration conditions was 76.62%, a value that was greater than the value produced under non-aeration conditions (68.48%). This efficiency was also higher than that of some other reports (64.90–68.50%). Aeration decreased the energy consumption to a greater extent than the non-aeration condition. NaOH was recovered in terms of the concentration chamber, and the NaAl(OH)4 present in the dilution chamber was separated for the electrodialysis treatment. Membrane scaling was generated to a lesser amount under aeration conditions than that of non-aeration conditions, which would improve the dealkalization efficiency. The high repeatability of the experiments was indicated by the intraclass correlation coefficient (P < 0.05). © 2018 Elsevier B.V.
Subjects
Aeration; Bauxite residue; Dealkalization; Electrodialysis; Membrane
Other Subjects
Alumina; Aluminum oxide; Electrodialysis; Energy utilization; Membranes; Sodium Aluminate; Sodium hydroxide; Washing; Water aeration; Bauxite residue; De-alkalization; Environmental pollutants; Intraclass correlation coefficients; Membrane scaling; Operation system; Total dissolved solids; Washing liquids; Dialysis membranes; alkali; aluminum oxide; aeration; alkalinity; bauxite; byproduct; chemical reaction; concentration (composition); drag coefficient; efficiency measurement; electrochemical method; experimental study; inorganic compound; laboratory method; membrane; pollutant; pollutant removal; aeration; Article; bauxite residue; cation exchange; dealkalization; electrodialysis; energy consumption; fluid intake; ion exchange; pollutant; surface property; waste component removal
Type
journal article