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Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
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Red mud with enhanced dealkalization performance by supercritical water technology for efficient SO2 capture
Zimeng Nie1, Qun Zhao1, Qilin Zhao2
1Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province, 650500, China.
Journal of Environmental Management
|July 2, 2023
Summary
Supercritical water treatment effectively de-alkalizes red mud (RM) and enhances its use for sulfur dioxide (SO2) removal. This sustainable approach aids red mud utilization and pollution control in the aluminum industry.
Area of Science:
- Materials Science
- Environmental Engineering
- Chemical Engineering
Background:
- Industrial solid waste red mud (RM) presents a global challenge due to its high alkalinity.
- Sustainable utilization of RM requires effective de-alkalization and removal of insoluble alkali fractions.
- Existing methods for RM treatment are often insufficient for complete alkali removal.
Purpose of the Study:
- To investigate the novel application of supercritical water (SCW) and leaching agents for de-alkalizing Bayer RM.
- To assess the efficacy of de-alkalized RM slurry in removing sulfur dioxide (SO2) from flue gas.
- To elucidate the mechanisms behind alkali removal, iron leaching, and desulfurization performance.
Main Methods:
- Treatment of red mud with supercritical water (SCW) and calcium oxide (CaO) as a leaching agent.
- Analysis of alkali removal and iron leaching rates.
- Evaluation of desulfurization performance of treated red mud slurries using flue gas containing SO2.
- Microscopic and chemical analysis to understand the structural changes in red mud.
Main Results:
- Optimal alkali removal (97.90%) and iron leaching (82.70%) achieved with RM-CaO-SW slurry.
- SCW treatment disrupted aluminosilicate bonds, converting insoluble alkalis to soluble forms.
- RM-SCW slurry demonstrated superior desulfurization performance (88.99% over 450 min) compared to other treatments.
- Mechanisms include neutralization, redox reactions, and iron-catalyzed oxidation.
Conclusions:
- Supercritical water treatment is a highly effective method for de-alkalizing red mud.
- De-alkalized red mud shows significant potential for SO2 capture from flue gas.
- This integrated approach offers a sustainable solution for red mud waste utilization and environmental protection.
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