1. Alkalinity stabilization behavior of bauxite residue: Ca-driving regulation characteristics of gypsum.
- Author
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Li, Xiao-fei, Guo, Yin, Zhu, Feng, Huang, Long-bin, Hartley, William, Li, Yi-wei, Kong, Xiang-feng, and Xue, Sheng-guo
- Abstract
Alkaline anions, include CO
3 2- , HCO3 - , Al(OH)4 - , OH- , continuously released from bauxite residue (BR), will cause a potential disastrous impact on surrounding environment. The composition variation of alkaline anions, alkaline phase transformation pathway, and micro-morphological transition characteristics during the gypsum addition were investigated in an attempt to understand alkalinity stabilization behavior. Results demonstrated that alkaline anions stabilization degree in leachates can reach approximately 96.29%, whilst pH and alkalinity were reduced from 10.47 to 8.15, 47.39 mmol/L to 2 mmol/L, respectively. During the alkalinity stabilization, chemical regulation behavior plays significant role in driving the co-precipitation reaction among the critical alkaline anions (CO3 2- , HCO3 - , Al(OH)4 - , OH- ), with calcium carbonate (CaCO3 )) being the most prevalent among the transformed alkaline phases. In addition, XRD and SEM-EDX analyses of the solid phase revealed that physical immobilization behavior would also influence the stability of soluble alkali and chemical bonded alkali due to released Ca2+ from gypsum which aggregated the clay particles and stabilized them into coarse particles with a blocky structure. These findings will be beneficial for effectively regulating strong alkalinity of BR. [ABSTRACT FROM AUTHOR]- Published
- 2019
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