Migration and distribution of saline ions in bauxite residue during water leaching

淋溶条件下赤泥盐分离子的迁移与分布（英文）

Bauxite residue,a highly saline solid waste produced from digestion of bauxite for alumina production,is hazardous to the environment and restricts vegetation establishment in bauxite residue disposal areas.A novel water leaching process proposed here was used to investigate the dynamic migration and vertical distribution of saline ions in bauxite residue.The results show that water leaching significantly reduced the salinity of bauxite residue,leaching both saline cations Na+,K+,Ca2+and anions CO32-,SO42-,HCO3-.Na+and K+migrated from 40-50 to 20-30 cm of the column,presenting a high migration capacity.The migration capacity of Ca2+was lower and accumulated at 30-40 cm of the column.CO32-initially distributed at 20-30 cm of the column,subsequently transported to 30-40 cm of the column,and finally returned to 20-30 cm of the column along with evaporation.SO42-was originally distributed at 40-50 cm,but finally migrated to 20-30 cm of the column.Nevertheless,HCO3-remained at the bottom of the column,and its migratory was less affected by evaporation.

赤泥是氧化铝工业生产过程产生的强碱性固体废物,其盐分含量高,对环境有害且制约着赤泥堆场的植被重建。通过土柱模拟淋溶实验,研究赤泥盐离子的动态迁移及垂直分布情况。结果表明:淋溶不同程度地将赤泥中的Na^+、K^+、Ca^(2+)、CO_3^(2-)、SO_4^(2-)和HCO_3^-等盐分离子浸出到渗滤液中,显著降低了赤泥的盐度。赤泥中Na^+和K^+呈现出较高的迁移能力,从柱体的40~50 cm处向上迁移至20~30 cm处;而Ca^(2+) 的迁移能力较弱,主要分布在柱体的30~40 cm处。淋溶刚结束时,CO_3^(2-)主要分布在柱体的20~30 cm处,随后向下迁移至30~40 cm处,最终受蒸发作用迁移至20~30 cm处。SO_4^(2-) 最初主要分布在柱体的40~50 cm处,最终向上迁移至20~30 cm处。HCO_3^-主要停留在柱体的下部,其迁移特性受蒸发的影响较小。