Université de Toulon, Aix Marseille Univ., CNRS, IM2NP, CEDEX 9, Toulon, 83041, France.
French National Institute for Industrial Environment and Risks (formely Ineris), BP 2, F-60550, Verneuil-en-Halatte, France.
Environ Sci Pollut Res Int. 2023 Sep;30(42):96486-96498. doi: 10.1007/s11356-023-29297-9. Epub 2023 Aug 14.
The ALTEO company produces approximately 300,000 tons per year of bauxite residue after alumina extraction, which is washed and dried in a press filter to produce Bauxaline®. In this study, different ways for recovering and reusing this residue were explored, namely transformation into a vegetated soil, use in acid mine drainage depollution, and application in sulfide-mine tailings remediation. The Bauxaline® was therefore transformed into modified bauxite residue (MBR), resulting in reduced alkalinity, salinity, and sodicity. To counterbalance the net acid generation potential of two sulfidic mine tailings with 1 mol H kg (1.5% sulfide) and 3.3 mol H kg (5.3% sulfide), respectively, various treatments were applied. These treatments included the addition of 10% MBR or 10% MBR plus limestone, or by limestone only, within 40-l lysimeters. Six lysimeters were monitored over a 5-year period to assess the long-term emissions from treated materials. Vegetation was tested under various conditions, and its impact on emission was evaluated. The emissions of mine tailings treated with MBR and limestone were very low. The mine tailings with limestone showed intermittent peaks of emission, probably due to the coating of calcite grain by ferric oxide, hindering contact with percolating water. Vegetation successfully grew in the treated tailings. This study demonstrated that the alkalinity of limestone can temporarily immobilize elements in sulfidic mine tailings, with a reduction factor of emissions of 300 and 40 for the two mine tailings, respectively. For long-term immobilization, the alkalinity provided by both limestone and MBR and the Al and Fe oxides of MBR are more effective and necessary for long-term immobilization, with a reduction factor of 300 and 900, respectively.
奥乐公司每年从氧化铝提取后产生约 30 万吨铝土矿残渣，这些残渣经过压滤机洗涤和干燥后制成 Bauxaline®。在本研究中，探索了回收和再利用这种残渣的不同方法，即将其转化为植被土壤、用于酸性矿山排水的净化，以及应用于硫化矿山尾矿修复。Bauxaline®因此被转化为改性铝土矿残渣（MBR），从而降低了碱度、盐度和钠度。为了中和两个含硫矿山尾矿的净酸化潜力，每个尾矿分别添加了 1 mol H kg（1.5%硫化物）和 3.3 mol H kg（5.3%硫化物）。这些处理方法包括添加 10% MBR 或 10% MBR 加石灰石，或仅用石灰石，在 40-L 淋滤器中进行处理。六个淋滤器在五年期间进行监测，以评估处理材料的长期排放情况。在不同条件下进行了植被测试，并评估了其对排放的影响。用 MBR 和石灰石处理的矿山尾矿排放非常低。用石灰石处理的矿山尾矿显示出间歇性的排放峰值，可能是由于方解石颗粒被氧化铁包裹，阻碍了与渗滤水的接触。处理后的尾矿中成功生长了植被。本研究表明，石灰石的碱度可以暂时固定硫化矿山尾矿中的元素，两个矿山尾矿的排放量分别降低了 300 和 40。为了长期固定，石灰石和 MBR 的碱度以及 MBR 的 Al 和 Fe 氧化物对于长期固定更有效和必要，排放量分别降低了 300 和 900。
