School of Environment Science and Spatial Informatics, China University of Mining and Technology, 221116 Xuzhou, China.
State Key Laboratory for Geomechnics and Deep Underground Engineering, 221116 Xuzhou, China.
Int J Environ Res Public Health. 2018 Oct 21;15(10):2317. doi: 10.3390/ijerph15102317.
In China, coalmine wastes, such as gangues, are used for reclamation of mining subsided land. However, as waste rocks, gangues contain several trace metal elements, which could be released under natural weathering and hydrodynamic leaching effects and then migrate into the reclamed soil layer. However, it is very difficult to find adequate other backfill materials for substitution of gangues. In this paper, we present a novel method and case study to restrict the migration ability of trace metal elements in gangues by using another kind of coalmine solid waste-fly ashes from coal combustion. In this study, fly ashes were mixed with gangues in different mass proportions 1:0.2, 1:0.4, 1:0.6 and 1:0.8 as new designed backfill materials. Due to the help of fly ash, the occurrence states of studied trace metal elements were greatly changed, and their releasing and migration ability under hydrodynamic leaching effect were also significantly restricted. In this research seven trace metal elements in gangues Cu, Zn, Pb, Cd, Cr, Mn and Ni were studied by using soil column hydrodynamical leaching method and simulated precipitation for one year. The results show that under the driving of natural precipitation trace metal elements were generally transported deep inside the reconstructed land base, i.e., far away from soil layer and most of the trace metal elements were transformed into a bonded state, or combined in inert occurrence states, especially the residual state. With this method, the migration activities of tested trace metal elements were greatly restricted and the environmental potential risk could be significantly reduced.
在中国，煤矸石等煤矿废弃物被用于复垦采煤塌陷地。然而，作为废石，煤矸石含有几种痕量金属元素，这些元素可能会在自然风化和水动力浸出作用下释放出来，并迁移到复垦土壤层中。然而，很难找到足够的其他回填材料来替代煤矸石。本文提出了一种新的方法和案例研究，通过利用另一种来自煤燃烧的煤矿固体废物——粉煤灰来限制煤矸石中痕量金属元素的迁移能力。在这项研究中，粉煤灰与煤矸石以不同的质量比 1:0.2、1:0.4、1:0.6 和 1:0.8 混合作为新设计的回填材料。由于粉煤灰的帮助，研究中痕量金属元素的存在状态发生了很大变化，其在水动力浸出作用下的释放和迁移能力也受到了显著限制。在这项研究中，通过土壤柱水动力浸出法和模拟沉淀法，对煤矸石中的七种痕量金属元素 Cu、Zn、Pb、Cd、Cr、Mn 和 Ni 进行了研究，为期一年。结果表明，在自然降水的驱动下，痕量金属元素通常被运移到重构的地基深处，即远离土壤层，而且大部分痕量金属元素转化为结合态，或以惰性存在状态结合，特别是残余态。采用这种方法，可以大大限制测试痕量金属元素的迁移活动，显著降低环境潜在风险。
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