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摘要:
本文以铁尾矿为研究对象，以草酸和EDTA-2Na作为浸提剂对铁尾矿中的Pb、Zn、Cu、Cr和Ni进行震荡浸提实验，研究不同浸提液浓度、液固比和震荡时间对重金属去除效果的影响，并对浸提前后重金属形态的变化进行分析，探讨了浸出含量与重金属形态的相关性。结果表明，Pb、Cu、Cr在草酸浓度分别为250、100、200 mmol/L时去除率达到最高，分别为19.9%、43.9%、4.2%；Zn和Ni在EDTA-2Na浓度分别为100、200 mmol/L时去除效果最好，去除率分别为33.2%和39.4%。草酸浸提过程中，Cu和Pb的去除率随震荡时间的增加逐渐提高，Zn、Ni和Cr的去除率在120 min后基本趋于稳定。EDTA-2Na对重金属的去除率随震荡时间的延长变化不大，当震荡时间为60 min时基本趋于稳定。当液固比为30∶1时，草酸和EDTA-2Na对重金属的去除效果相对较好。对草酸浸提前后重金属的形态进行分析，发现浸提不仅能够有效去除重金属的易迁移形态，还能使重金属形态发生迁移转化。相关性分析发现重金属浸出含量与可交换态和碳酸盐结合态的相关系数分别为0.930*和0.996**。浸提后铁尾矿中重金属的可交换态和碳酸盐结合态比例降低，残渣态、铁锰氧化物结合态和有机结合态比例增加，提高了铁尾矿在环境中的稳定性，降低了其污染环境的风险，为铁尾矿的无害化提供了新的思路和理论依据。
Abstract:In this paper, oxalic acid and EDTA-2Na were used as leaching agents to perform shock leaching tests on Pb, Zn, Cu, Cr and Ni in iron tailings. The effect of different leaching solution concentrations, liquid-solid ratios and shaking times on the removal effect of heavy metals were studied. The changes of heavy metal morphology after leaching were analyzed, and the correlation between leaching content and heavy metal morphology was discussed. The results showed that the removal rates of Pb, Cu, and Cr reached the highest when the oxalic acid concentration was 250, 100, and 200 mmol/L, respectively, and the removal rates were 19.9%, 43.9%, and 4.2%, respectively. The removal effect of Zn and Ni was best when the concentration of EDTA-2Na was 100 and 200 mmol/L, respectively, and the removal rates were 33.2% and 39.4%, respectively. During the oxalic acid leaching process, the removal rates of Cu and Pb gradually increased with the increase of shaking time, and the removal rates of Zn, Ni and Cr tended to be stable after 120 min. EDTA-2Na had little effect on the removal rate of heavy metals with the extension of the shaking time, and it basically stabilized when the shaking time was 60 min. When the liquid-solid ratio was 30:1, the removal effect of heavy metals was relatively good. The morphology of heavy metals after oxalic acid leaching was analyzed, and it was found that the leaching can not only effectively remove the easily migrated forms of heavy metals, but also caused the migration and transformation between heavy metal forms. Correlation analysis found that the correlation coefficients of heavy metal leaching content with exchangeable state and carbonate binding state were 0.930* and 0.996**, respectively. After leaching, the ratios of the exchangeable state and the carbonate-bound state of heavy metals in the iron tailings decreased, and the proportion of the residue state, the iron-manganese oxide-bound state and the organically bound state increased. This improved the stability of iron tailings in the environment, reduced the risk of iron tailings polluting the environment, and provided new ideas and theoretical basis for the harmless iron tailings.
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Key words:
- Iron tailings /
- Leaching /
- Heavy metal /
- Oxalic acid /
- EDTA-2Na
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表 1 铁尾矿中重金属的总含量/（g·t−1）
Table 1. Total amount of heavy metals in iron ore tailings
Pb Zn Cu Cr Ni 1655.0 2006.3 2527.9 422.7 37.8 
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表 2 草酸浸提前后铁尾矿中重金属形态含量对比/（g·t−1）
Table 2. Comparison of various heavy metal forms in iron tailings before and after leaching
重金属元素 浸提
前后可交换态 碳酸盐结合态 铁锰氧化物结合态 有机结合态 残渣态 总量 Pb 前 74.9 59.4 80.1 60.1 1380.5 1655.0 后 15.8 11.1 67.9 59.0 1187.1 1340.9 Zn 前 576.0 133.6 81.2 56.1 1159.4 2006.3 后 92.1 105.0 86.2 54.2 1138.8 1476.3 Cu 前 729.8 277.8 68.6 175.0 1276.7 2527.9 后 56.3 73.1 14.0 155.7 1127.3 1426.5 Cr 前 12.1 11.2 8.0 78.2 313.2 422.7 后 4.6 4.0 7.9 82.1 304.8 403.4 Ni 前 9.3 2.8 3.3 2.6 19.8 37.8 后 2.3 1.0 3.1 7.1 14.9 28.4
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表 3 铁尾矿重金属形态与浸提含量相关性分析结果
Table 3. Correlation analysis results of morphology and leaching effect of heavy metals in iron tailings
可交
换态碳酸盐
结合态铁锰氧化物
结合态有机
结合态残渣态 Pearson
相关性0.930* 0.996** 0.685 0.846 0.733 显著性
（双侧）0.022 0.000 0.202 0.071 0.159 N 5 5 5 5 5 注：*在0.05级别（双侧）相关性显著；**在0.01级别（双侧）相关性显著。
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