Abstract:
In order to explore the release law and characteristics of heavy metals in natural coal gangue under the action of rainwater leaching and leaching, the natural coal gangue was characterized by scanning electron microscope (SEM) analysis technology to observe the microscopic characteristics of the natural coal gangue before and after leaching. The chemical composition and changes of coal gangue before and after leaching were determined by XRD technology. Through the continuous static soaking and dynamic leaching experiments of simulated precipitation, the coal gangue was investigated under different solid-liquid ratio, particle size, pH and soil medium conditions. The release law and characteristics of heavy metal elements. The results show that: ①SEM and XRD analysis results show that the surface of natural coal gangue has a layered structure with high smoothness. The difference in the content of each mineral phase is small, and the coal gangue has high stability in the process of natural rainfall leaching. ②The simulated continuous static immersion test shows that the leaching content of As and Mn is higher, and the release rate is As>Cd> Cu≈Ni>Mn>Cr>Zn>Pb, the cumulative release of As has a higher risk of adversely affecting the surrounding soil environment and groundwater, and the leaching of Cu has two stages: rapid release and stable release; Zn, Pb, and Cd belong to the later stage Release elements; Cr and As belong to indirect release elements; Mn belongs to fast release elements; Ni belongs to slow release elements. The cumulative release is significantly higher, and the cumulative release of As and Cr under neutral conditions is higher than that of acidity; after the introduction of the soil medium, the cumulative release of Cr and As is significantly reduced, indicating that these two heavy metal elements show state of accumulation in the soil.