ABSTRACT

The seasonal change of the precipitates from the acid coal mine drainages is remarkable in the Taebaek coal field in the middle eastern part of the Korean peninsula. The mineral precipitates in the creeks show various colors such as brownish yellow, white, and reddish brown, depending on the chemical conditions of stream waters. The brownish yellow precipitate consist maily of schwertmannite, the white one of poorly crystalline Al-sulfate, and the reddish brown one of ferrihydrite. Neutralization of acid mine drainage took place by mixing with unpolluted waters and/or buffering by dissolution of carbonate or aluminosilicates. The main factors leading to the seasonal change of precipitates are precipitation of hydroxide mineral, water mixing from adjacent unpolluted branch streams, and water-rock interaction.