Leaching characteristics of trace elements in hetero-aggregation fly ash from coal-fired power plant
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摘要: 采集了燃煤电厂的异相凝并后飞灰，分析了其物理化学特性。并通过淋滤实验研究了飞灰中重金属As、Se、Pb的环境稳定性。结果表明，凝并飞灰的粒径峰值为138.04 μm，而粉煤灰为60.26 μm；凝并后细颗粒凝聚成了较大的颗粒；凝并飞灰中重金属As、Se、Pb含量均高于同工况下粉煤灰中的含量，且后序脱硫环节所产生石膏中重金属的含量有所下降；批淋滤实验研究结果表明，凝并飞灰中的重金属浸出能力受淋滤液的pH值影响较大，温和环境和碱性条件抑制了As的浸出，酸性和碱性条件抑制了Se的浸出，而碱性条件抑制了Pb的浸出。柱淋滤实验研究结果表明，在酸性溶液和水溶液中，凝并飞灰的重金属浸出能力均受到了抑制。Abstract: This paper studied physicochemical and leaching characteristics of three hazardous trace elements As, Se and Pb in hetero-aggregation fly ash (HAFA) and coal fly ash (FA)samples which were collected from coal-fired power plant. The results show that the peak of particle size of HAFA is 138.04 and is 60.26 μm of FA; the fine particles agglomerate into large particles after agglomeration; the contents of heavy metals of As, Se and Pb in HAFA are all higher than those of in FA. The content of heavy metals in gypsum produced in the subsequent desulfurization process is decreased. The batch leaching experiments show that leaching concentrations of three metals in HAFA are suppressed by mild and alkaline condition for As, by acidic and alkaline condition for Se, and by alkaline condition for Pb. The column leaching experiments show that the leaching abilities of the trace elements in HAFA are inhibited in both acidic and aqueous solution.
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Key words:
- fly ash /
- hetero-aggregation /
- particles /
- trace elements /
- leaching
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图 4 As的浸出质量浓度(a)和累积浸出质量分数(b)
Figure 4 Concentration of As in leachate (a) and cumulative (b) release
图 5 Se的浸出质量浓度(a)和累积浸出质量分数(b)
Figure 5 Concentration of Se in leachate (a) and cumulative (b) release
图 6 Pb的浸出质量浓度(a)和累积浸出质量分数(b)
Figure 6 Concentration of Pb in leachate (a) and cumulative (b) release
表 1 飞灰的化学元素组成
Table 1 Concentration of elements of fly ash
Sample Content w/% SiO2 Al2O3 CaO Fe2O3 SO3 TiO2 others FA 53.78 34.00 3.48 4.09 0.31 1.34 2.99 HAFA 53.68 34.10 3.49 4.20 0.36 1.29 2.87 
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表 2 样品的重金属含量
Table 2 Concentration of trace elements in samples
Sample Content w/(μg·g-1) As Se Pb FA 17.96 8.09 234 HAFA 19.53 9.19 243.96 DG 11.10 6.76 15.56 HA-DG 7.52 2.19 10.89
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表 3 元素累积浸出率
Table 3 Ratio of cumulative release
Element η/% As Se Pb FA/PW 0.02 15.51 0.0008 HAFA/PW 0.01 10.00 0.0003 FA/SAR 0.11 28.33 0.0000 HAFA/SAR 0.11 12.81 0.0000
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