About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Alumina & Bauxite
|
| Presentation Title |
Field and laboratory evaluation of bauxite residue partial neutralization with gypsum |
| Author(s) |
Caio Melo, Alexandre Rezende de Freitas, Ronaldo Pantoja, Ruben Ostertag, Antônio Neto |
| On-Site Speaker (Planned) |
Caio Melo |
| Abstract Scope |
This study evaluates the partial neutralization of bauxite residue (BR) using gypsum, aiming to reduce alkalinity for safer storage and potential reuse in Hydro Alunorte. Laboratory tests assessed gypsum dosages (GD) from 1–10% (w/w) under different conditions, including compaction and simulated rainfall. GD ≥5% reduced pH to ~11.0 within 7 days. Field trials in BR disposal site tested 12 experimental units (~306 tons each) with varying caustic concentrations and GD. A 5% dosage consistently maintained pH <12.5 after 105 days, with stabilization observed after 30 days. Geotechnical properties (permeability, compaction, plasticity) remained largely unchanged. Runoff analyses showed lower pH and sodium, higher sulfate, and metal concentrations within regulatory limits. Pre-commissioning results confirmed the technical feasibility of applying 5% gypsum at scale. Despite changes in waste classification regulations, the findings support future applications in BR reuse or revegetation. |
| Proceedings Inclusion? |
Planned: Light Metals |
| Keywords |
Other, Other, Other |