摘要
赤泥碱性转化是氧化铝工业处置固体废物面临的世界性难题。本文开展工业废弃物对赤泥碱性改良研究,结果表明:磷石膏最优添加量为1.50 wt%,处理91天后,赤泥pH由10.83降至8.70;自由碱去除率为97.94%,可交换性钠去除率为75.87%,自由碱、可交换性钠和赤泥pH存在显著正相关关系(P<0.05);自由碱的作用效果为CO_3~(2–)>OH–>AlO_2~–>HCO_3~–;化学结合碱含量从52.81%降至48.58%,固相中稳定性强的石膏为液相体系持续提供Ca~(2+),抑制结合碱的溶解;磷石膏促进团聚体形成,表面Ca~(2+)含量增加, Na~+、Al~(3+)含量降低,有利于加快赤泥土壤化进程。
Aiming at alkaline problem of bauxite residue, this work focused variation of alkaline characteristics in bauxite residue through phosphogypsum treatment. The results demonstrated that the p H of bauxite residue reduced from initial 10.83 to 8.70 when 1.50 wt% phosphogypsum was added for 91 d. The removal rates of free alkali and exchangeable sodium were 97.94% and 75.87%, respectively. Meanwhile, significant positive correlations(P<0.05)existed between p H and free alkali, exchangeable sodium. The effect of free alkali composition was CO_3~(2–)>OH–>AlO_2~–>HCO_3~–. In addition, alkaline phase decreased from 52.81% to 48.58% and gypsum stably presented in bauxite residue which continuously provided Ca2+ to inhibit dissolution of combined alkali. Furthermore, phosphogypsum promoted formation of macroaggregate structure, increased Ca~(2+), decreased Na+ and Al~(3+) on the surface of bauxite residue significantly, ultimately promoting soil formation in bauxite residue.
引文
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