Gregory V. Lowry

Bauxite Residue (Red Mud) Treatment/Neutralization using Fly Ash and Direct Carbonization

Funding Agencies
National Science Foundation
Alcoa, Inc.

Collaborators
David Dzombak, CMU

Publications

Khaitan, S., Lowry, G., Dzombak, D. Identifying the solid and dissolved species responsible for the acid neutralizing capacity of Bauxite residue (Red Mud). Environ. Eng. Sci.

Khaitan, S., Lowry, G., Dzombak, D. Neutralization of Bauxite Residue with Acidic Fly Ash. Environ. Eng. Sci.

Khaitan, S., Dzombak, D., Lowry, G. Red Mud Neutralization by CO₂, Environ. Sci. Technol.

Khaitan, S., Lowry, G., Dzombak, D. Field evaluation of the effects of carbon dioxide/vegetation/amendment on neutralization of bauxite residue,” J. Environ. Eng.

Abstract

Safe treatment and storage of high volume industrial waste streams pose unique waste management challenges. Land disposal of these materials often has negative environmental impacts such as contamination of soil and groundwater, and consumes vast areas of land. Bauxite residue (Red Mud) from aluminum production, fly ash from coal combustion, and waste water treatment plant (WWTP) biosolids are three examples of high volume waste streams. Approximately 3 million tons of Red Mud are produced in the U.S. each year (30 M/yr globally), and are disposed in land-based impoundment reservoirs. Approximately 63 million and 7 million tons of fly ash and biosolids are generated annually in the U.S., respectively, much of which is disposed of in landfills. Another high volume (Gigatons/yr) waste stream with serious environmental impacts is CO₂. Safe disposal of these wastes are a requisite. New methods for sustainable management and ways to find beneficial use for these wastes are highly desirable.

Red Mud is usually managed by discharge into engineered or natural impoundment reservoirs, with subsequent dewatering by gravity consolidation and sometimes with capping for closure. Revegetation of dewatered Red Mud is not possible without addition of amendments because of the high pH, high salinity, and absence of nutrients and organic constituents.

This proposal investigates the potential of using high volume waste materials, specifically CO₂ and acidic fly ash, to neutralize Red Mud for the purpose of soil building and revegetation. The potential of Red Mud to safely sequester CO₂ will also be determined. Bench scale batch experiments will be used to evaluate the rate and extent of Red Mud neutralization by contacting with dilute carbon dioxide waste streams, and by addition of acidic fly ash. The properties of the resulting mixture will be evaluated including pH, heavy metal leaching potential, carbonate mineral content, texture, bulk density, and water holding capacity. The additional neutralization capacity and reduction in heavy metal leaching afforded by WWTP biosolids, a common organic soil amendment needed to aid revegetation of surficial neutralized Red Mud, will also be determined. Various Red Mud to ash ratios, CO₂ concentrations, and organic amendment concentrations will be used to determine which ratio provides optimal soil properties for revegetation. Lastly, engineering schemes to implement this technology will be evaluated for a possible Phase II field demonstration.

Greg Lowry Home | Dept. Civil & Env. Eng.

.

Last Modified: Jan 2004