Variation characteristics and cause of mine water quality in Malan coal mine

Quality characteristics of mine water and mineral compositions of sediments at different time from the Malan coal mines, Shanxi Province, China were investigated. The results show that water quality types of all mine water samples were SO₄-Ca, and mine water samples had high concentrations of sulfate and iron. With mining of the upper coal seam, pH increased and Eh value, SO₄^2-, Fe, Mn and Zn ions concentrations of mine water samples decreased. Mine water samples in three sampling sites showed the same change patterns and the most significant changes of mine water quality happened in No.1 northern inclined shaft. Mineral composition and crystalline degree of sediments are controlled by water quality index and velocity of mine water. The minerals of sediment in No.1 northern inclined shaft have changed form schwertmannite to goethite in twice sampling. There were no changes of mineral constituents in other two sediment sampling sites, which were composed of goethite.