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磷石膏改良作用下赤泥的碱性变化(英文)
Variation of alkaline characteristics in bauxite residue under phosphogypsum amendment
【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CO32–>OH–>AlO2–>HCO3–;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Ca2+,抑制结合碱的溶解;磷石膏促进团聚体形成,表面Ca2+含量增加, Na+、Al3+含量降低,有利于加快赤泥土壤化进程。
【Abstract】 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 CO32–>OH–>AlO2–>HCO3–. 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 Ca2+, decreased Na+ and Al3+ on the surface of bauxite residue significantly, ultimately promoting soil formation in bauxite residue.
【Key words】 bauxite residue; alkaline regulation; free alkali; phosphogypsum amendment; soil formation in bauxite residue;
- 【文献出处】 Journal of Central South University ,中南大学学报(英文版) , 编辑部邮箱 ,2019年02期
- 【分类号】X758
- 【被引频次】8
- 【下载频次】230