Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue
(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. Institute for Future Environments, Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane Qld 4000, Australia)
2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Central South University, Changsha 410083, China;
3. Institute for Future Environments, Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane Qld 4000, Australia)
Abstract: This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride treatment. The results showed that the pH of bauxite residue decreased from 10.49 to 8.93, total alkaline anion ( , , OH-, ) concentration reduced from 38.89 to 25.50 mmol/L, leaching rate of soluble sodium was 80.86% with ammonium chloride addition of 0.75%, liquid/solid (L/S) ratio of 3 (mL/g), temperature of 30 °C and reaction time of 18 h; L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of sodium. Furthermore, ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive structure. The findings of this work will contribute to achieve soil-formation of bauxite residue.
Key words: bauxite residue; ammonium chloride; leaching behavior; alkaline regulation; soil formation