Title : From bauxite waste to value: Technologies for red mud reuse
Abstract:
Red Mud (RM), the highly alkaline, iron and alumina rich residue generated during the Bayer refining of bauxite, presents a persistent environmental challenge due to its large volumes, caustic pH and potential for metal mobilization. This review synthesizes recent advances in converting RM from an industrial liability into a versatile secondary resource. It summarizes how targeted physico chemical treatments — including acidification, neutralization/carbonation, thermal activation and composite formation with biochars, clays or polymers — alter RM surface chemistry, porosity and stability to create materials suitable for adsorption, coagulation, catalysis and incorporation into construction products. Acid treatments and surface functionalization increase available binding sites and enhance uptake of anionic species (phosphate, fluoride) and certain heavy metals; neutralization and carbonation reduce alkalinity and soluble alkali leaching, improving environmental safety for land applications; thermal activation and sintering increase surface area and catalytic activity for organic pollutant degradation; and composite approaches combine RM’s metal oxide functionality with complementary matrices to broaden contaminant selectivity and mechanical performance. Reported laboratory and pilot studies demonstrate promising removal efficiencies for dyes, phosphates, heavy metals and emerging contaminants, effective catalytic degradation of organics, and successful partial replacement of cement or aggregate in bricks, tiles and glass ceramics with acceptable mechanical properties when leachability is controlled. Nevertheless, significant barriers remain to widescale adoption. Key gaps include limited long term field data on leaching and ecotoxicity under variable climatic conditions, inconsistent pre treatment and modification protocols that hinder comparability, energy and cost penalties associated with thermal routes, and a lack of standardized testing and regulatory pathways for RM derived construction materials. To realize RM’s circular economy potential, future work should prioritize low cost, low energy modification strategies, rigorous life cycle and techno economic assessments, harmonized leaching and performance standards, and demonstration projects that integrate RM reuse with existing industrial processes (e.g., coupling thermal activation to waste heat streams). Policy incentives and cross sector partnerships will be essential to scale safe applications while protecting human and ecosystem health. In summary, modified red mud offers a suite of environmentally beneficial uses that can substantially reduce disposal impacts, but responsible deployment requires coordinated research on long term stability, standardized processing methods and clear regulatory frameworks to ensure both performance and safety.
