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Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent
Published on: February 21, 2017
Alkalinity conversion of bauxite refinery residues by neutralization
M Johnston1, M W Clark, P McMahon
1Environmental Science and Management, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia. max.johnston@scu.edu.au
Journal of Hazardous Materials
|July 20, 2010
Summary
Neutralizing red mud, a major industrial waste, improves its environmental profile and opens reuse possibilities. Different neutralization methods offer distinct geochemical outcomes, enhancing red mud
Area of Science:
- Environmental Science
- Geochemistry
- Materials Science
Background:
- Red mud, a byproduct of alumina refining, poses significant environmental challenges due to its high pH, fine particle size, and high alkalinity.
- These characteristics limit its transport and reuse, necessitating effective treatment methods.
- Neutralization is a key process to mitigate these issues, potentially transforming waste into a resource.
Purpose of the Study:
- To investigate the geochemical effects of different red mud neutralization techniques.
- To evaluate the potential for converting red mud waste into a usable resource through neutralization.
- To compare the outcomes of carbon dioxide (CO(2)) neutralization, Basecon neutralization, and a hybrid approach.
Main Methods:
- Three red mud neutralization treatments were studied: CO(2)-neutralized red mud (CNRM), Basecon-neutralized red mud (Basecon), and a hybrid CO(2) followed by Basecon neutralization.
- Geochemical analysis was performed to assess changes in pH, alkalinity speciation, and the presence of specific mineral precipitates.
- Carbon dioxide sequestration and changes in acid neutralization capacity (ANC) were quantified.
Main Results:
- Neutralization treatments resulted in two distinct geochemical groups based on alkalinity precipitation.
- Each treatment exhibited unique alkalinity speciation (hydroxide-dominant or carbonate/bicarbonate dominant) and varying residual elements (Ca, Mg, Al).
- Approximately 17 g/kg of CO(2) was sequestered in CNRM and hybrid treatments, and no Dawsonite precipitation was observed, contrary to other studies.
Conclusions:
- Red mud neutralization significantly alters its geochemical properties, reducing alkalinity and pH.
- The choice of neutralization method influences alkalinity speciation and the potential for CO(2) sequestration.
- All investigated treatments demonstrated potential for improved red mud transport and reuse options, contributing to waste valorization.
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