Characteristics and Environmental Risk Analysis of Heavy Metal Leaching from Coal-based Solid Waste Under Different pH Values
Fly ash and coal gangue release different amounts of heavy metals when soaked in rainwater, which poses a threat to the ecological environment.Taking coal gangue and fly ash in Huaibei area as the research object,the physical and chemical properties of the samples were characterized by X-ray fluores-cence spectroscopy,X-ray diffraction and scanning electron microscopy.The leaching characteristics of arsenic (As),titanium (Ti),cobalt (Co)and cadmium (Cd)in fly ash and coal gangue were investigated by setting different initial pH indoor soaking experiments,and the potential risks of the leaching solution to the environment were analyzed.The results show that the fly ash is irregular spherical aggregation, and the coal gangue is layered accumulation.The two compounds are mainly SiO2 and Al2O3 ,and the mineral composition is mainly quartz.The network structure formed by high content of SiO2 can prevent harmful elements from leaching in the environment.The total leaching amount tends to be stable under long-term soaking and then increases slowly,but the dissolution trends are different.The pH value of the soaking solution significantly affected the release of heavy metal elements in fly ash and coal gangue.The maximum dissolution concentrations of As,Ti,Co and Cd in fly ash appeared at pH=3.00,which were 23.25、6.33、1.07 and 0.65μg/L,respectively.The leaching concentration of Co and Cd in coal gangue reached the maximum at pH=3.00,but the relationship between the leaching concentration of As and Ti and pH value was not obvious.In the process of stacking and utilization of coal gangue,As may cause great harm to the surrounding ecological environment after soaking by precipitation.The research results provides reference for the safe stacking and rational resource utilization of coal-based solid waste in Hua-ibei mining area.
万方数据
维普
