Abstract

Batch experiments were conducted to collect data for obtaining insights into the chemical mechanisms and kinetics of red mud neutralization by both atmospheric (passive treatment) and injected CO2 (active treatment) in the absence and presence of gypsum. Active treatments allowed effective sequestration of CO2 within 1 h. A mixing ratio of gypsum to red mud at 0.04–0.06 enabled effective control of pH rebound, completely eliminating the causticity of the red mud by reducing the pH value of red mud to < 9. The carbonation of red mud was realized through the formation of carbon-containing minerals, mainly basic aluminium carbonates (largely dawsonite), sodium bicarbonate, sodium carbonate and calcite. The importance of calcite as a carbon carrier increased when gypsum was added. Passive treatments also allowed simultaneous causticity reduction and carbon sequestration but at a much slower rate compared to the active treatments. The research findings obtained from this study have implications for developing strategies to cost-effectively manage red mud. Where flue gas is available, active treatment could be a feasible option for simultaneously reducing the harmfulness of red mud and CO2 emission. Passive treatment can be used as a natural attenuation process for low-cost management of red mud. Where off-site utilization of red mud is feasible, gypsum addition at an optimal rate could be a more appropriate option. For future study, industrial-scale experiments are required to validate the research findings obtained from this laboratory-scale study.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.