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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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Improvement of alkaline electrochemical characteristics ofbauxite residueamendment with organic acid and gypsum
KONG Xiang-feng(孔祥峰)1, LI Chu-xuan(李楚璇)1, JIANG Jun(江钧)1, HUANG Long-bin(黄隆斌)2, HARTLEY William3, WU Chuan(吴川)1, XUE Sheng-guo(薛生国)1

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

Abstract:Neutralization of alkaline properties of bauxite residue (BR) by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation. Mineral acids, citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential, isoelectric point (IEP), surface protonation and active alkaline —OH groups, which are critical factors for further improvement of physicochemical and biological properties later. Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods. Electrochemical characteristics were significantly improved by the amendments used, resulting in reduced IEP and —OH groups and decreased surface protonation for transformed residues. XRD results revealed that the primary alkaline minerals of cancrinite, calcite and grossular were transformed by the treatments. The treatments of citric acid and gypsum promoted the dissolution of cancrinite. From the SEM examination, citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of —OH groups on particle surfaces. The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.

 

Key words: bauxite residue; alkalinity regulation; organic acid; gypsum; electrochemical characteristic; soil formation in bauxite residue

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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