浸泡淋滤作用下煤矸石重金属元素的释放规律及特征研究
Study on the Release Law and Characteristics of Heavy Metals in Coal Gangue under the Action of Soaking and Leaching
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摘要: 为探究天然煤矸石在雨水浸泡淋滤作用下重金属元素的释放规律及特征,通过扫描电镜(SEM)分析技术对天然煤矸石进行表征以观察其淋滤前后的微观形貌特点,通过X射线衍射仪(XRD)技术测定煤矸石的淋滤前后的化学成分组成及变化情况. 通过模拟降水连续静态浸泡与动态淋滤实验,考察在不同固液比、粒径、pH、土壤介质条件下煤矸石中重金属元素的释放规律与特性. 结果表明:①SEM和XRD分析结果表明,天然煤矸石表面呈层状结构,光滑度较高,淋滤后的煤矸石表面凹凸结构较多,淋滤前后煤矸石中各矿物相含量差异较小,煤矸石在自然降雨淋滤过程中具有较高的稳定性. ②模拟连续静态浸泡试验表明,As、Mn的浸出含量较高,释放率依次为As>Cd>Cu≈Ni>Mn>Cr>Zn>Pb,As的累积释放对周边土壤环境及地下水产生不利影响的风险较高,Cu的浸出存在快速释放和稳定释放两个阶段;Zn、Pb、Cd属于后期释放型元素;Cr、As属于间接性释放型元素;Mn属于快速释放型元素;Ni属于缓慢释放型元素. ③连续动态淋滤试验验表明,pH为3时,Mn、Cu、Zn、Ni的累积释放量明显较高,As、Cr在中性条件下累积释放量高于酸性;引入土壤介质这一因素后,Cr、As的累积释放量明显减少,表明了这两种重金属元素都呈现出在土壤中积累的状态.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.
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Key words:
- gangue /
- heavy metals /
- release law /
- leaching /
- Influencing factors
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