中國有色金屬學(xué)報(bào)(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 28 No. 6 June 2018 |
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Central South University, Changsha 410083, China;
3. Crop and Environment Sciences Department, Harper Adams University, Newport, Shropshire, TF10 8NB, United Kingdom）
Abstract:Bauxite residue is a highly alkaline waste containing soluble alkaline anions, which can cause environmental concerns. The optimal leaching conditions, distribution of alkaline anions, types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment. Using a two-stage leaching, 86% of the soluble alkaline anions ( , , , OH-) were leached with a L/S ratio of 2 mL/g, at 30 °C, over 23 h. During the first stage of leaching, approximately 88% of alkaline anions were leached from the dissolution of free alkali (NaOH, carbonate, bicarbonate, NaAl(OH)4) with the rest originating from the dissolution of alkaline minerals (calcite, cancrinite and hydrogarnet). Supernatant alkalinity was 69.78 mmol/L with accounting for 75%. Furthermore, carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol.
Key words: bauxite residue; alkaline anions; carbonate; leaching optimization; dissolution behavior
