典型前驱体材料金属物质浸出行为研究

Leaching of metals from typical solid wastes used as precursor materials

通过水平振荡法的静态浸出实验和室内小型填充柱法的动态浸出实验,探究废弃物材料赤泥、矿渣以及偏高岭土中金属物质(Al、Fe、Ti、Ni、Pb、Mn和Cu)在不同时间和pH条件下的浸出和迁移行为。结果表明,在pH=3和振荡8 h的条件下,3种材料的静态浸出量达到最大值:赤泥中Al和Fe高达19.63,2.84 mg/L;矿渣Al、Mn、Fe和Ti元素含量分别高达25.64,20.75,4.78,7.05 mg/L;偏高岭土Al元素含量达到25.37 mg/L;其它元素如Cd元素浸出浓度较低,而Ni和Pb未检出。动态浸出实验表明,3种材料浸出行为相似,在0.33 mL/min的流速条件下,约8~10 h后浸出浓度达到最高值后缓慢降低或趋于稳定,Al为主要浸出物。在24 h淋滤时间内,浸出液中pH值较稳定,而电导率则迅速降低,并趋于稳定。研究结果可为该类物质的循环利用和环境风险评估提供数据参考。

The leaching and transport of selected metals(Al,Fe,Ti,Ni,Pb,Mn and Cu)in precursor materials based on wastes(red mud and slag)and metakaolin under different leaching time and pH conditions were investigated by static leaching experiments with horizontal oscillations and dynamic leaching experiments with small columns.Results show that the maximum leaching amount of metals from the three studied materials were obtained at the conditions of pH=3 and 8 h of oscillation.The Al and Fe contents leached from the red mud were as high as 19.63 and 2.84 mg/L;the contents of Al,Mn,Fe,and Ti leached from slag were 25.64,20.75,4.78 and 7.05 mg/L,respectively,and the content of Al from metakaolin was 25.37 mg/L.Other elements such as Cd showed lower leached concentration,while Ni and Pb were not detected.In column experiments,three selected materials showed similar shapes for their leaching curves.Under the flow rate of 0.33 mL/min,the leaching concentration reached the maximum after around 8~10 h irrigation then slowly decreased or became stable,and Al was the main leaching substance that could be detected.During 24 h irrigation,pH values in the leachate were keeping relatively stable and the conductivities decreased quickly and then were gradually stale.The findings of this study can provide information for the recycling of similar wastes and the environmental risk assessment.