Study on effects of particle size on dissolution and release law of pollutants in gangue

In order to study the dissolution and release laws of different types of coal gangue contaminated components under different particle size conditions.In this study， four kinds of coal gangue in three coal mining areas of Shanxi Province and Liaoning Province were used as experimental materials.The pH， ORP， Ec， total hardness， Fe2+， Mn2+，pagenumber_ebook=183,pagenumber_book=178concentration of the four kinds of coal gangue leach liquids were analyzed by static immersion test under different particle size conditions and different leaching times.Combined with XRD and SEM， the mechanism of component dissolution interpretation of gangue pollution in different areas was clarified.The results showed that when the particle size is 0.18～0.25 mm， the pollutant quantity released by the four kinds of coal gangue reached a large value.The leaching solution of coal gangue from Haizhou open-pit mine is alkaline.The leaching solution of spontaneous coal gangue Leaching Solution in Gaode open-pit mine and original coal gangue from a coal mine in Shanxi Province was acidic.The total hardness andpagenumber_ebook=183,pagenumber_book=178concentration of spontaneous coal gangue Leaching Solution in Gaode open-pit mine are 589 mg/L and 529 mg/L respectively.The Fe2+ concentration of coal gangue Leaching Solution in Jincheng City is 10.79 mg/L.The Mn2+ concentration of coal gangue Leaching Solution in Haizhou open-pit mine is 1.97 mg/L.There are pores and small particles on the surface of coal gangue.Within 0～3 d of leaching， the pollutants are easily dissolved and released.Then， with time， the release level stabilized.The minerals including zeolite， pyrite， chlorite， kaolinite and magnetite are easy to dissolve， releasing pollutants into the water.The smaller the particle size of gangue， the easier the pollutant is to dissolve and release.It is recommended to keep the size of coal gangue larger than 0.18～0.25 mm during the construction of the mining area to reduce the release of pollution ions to the soil and groundwater during the process of accumulation and filling and reclamation.