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中南大学学报(英文版)

Journal of Central South University

Vol. 26    No. 2    February 2019

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Alkalinity stabilization behavior of bauxite residue:Ca-driving regulation characteristics of gypsum
LI Xiao-fei(李晓飞)1, GUO Yin(郭颖)1, ZHU Feng(朱锋)1, HUANG Long-bin(黄隆斌)2, William HARTLEY3, LI Yi-wei(李义伟)1,KONG Xiang-feng(孔祥峰)1, XUE Sheng-guo(薛生国)1

1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2.The University of Queensland, SMI, Centre for Mined Land Rehabilitation, Brisbane, Qld 4072, Australia;
3. Crop and Environment Sciences Department, Harper Adams University, Newport, Shropshire,TF10 8NB, United Kingdom

Abstract:Alkaline anions, include CO32–, 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 (CO32–, 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.

 

Key words: bauxite residue;gypsum;alkalinity stabilization;phase transformation;Ca-drivenregulation

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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