Removal of Cu, Ni, Zn, Cd and Pb in Artificial Acid Mine Drainage by Modified Oxygen Releasing Compounds

Abstract

The aim of the study is to investigate removal of Cu, Ni, Zn, Cd and Pb in acid mine drainage (AMD) using modified oxygen releasing compounds (MORCs) of which CaO2 is the main ingredient. When the MORCs are placed into AMDs, OH- will be released gently and continuously which can neutralize H+ and precipitate heavy metal ions as hydroxide/carbonates. Four types of artificial AMDs contained Cu, Ni, Zn, Cd and Pb ions with/without sulfate were prepared in the laboratory. The removal rates of the heavy metals were measured after adding MORCs to the artificial AMDs. The results showed that the removal rates of Cu, Ni, Zn, Cd and Pb in all 4 artificial AMDs, after 72 hours, are more than 97%, even to 100%. However, after 96 hours, Cu, Ni, Zn, Cd and Pb deposits can be re-dissolved by 16.4%, 11.2%, 7.0%, 5.0% and 4.8%, respectively, in the single-metal artificial AMDs; Pb and Cd deposits are more stable. Sulfate in the multi-metal artificial AMD hardly has effects on re-dissolution of the heavy metal deposits; and only Ni deposits in the single-metal AMD with sulfate and Cu deposits in the single-metal AMD without sulfate are re-dissolved significantly. It suggested that the MORCs should be an efficient material to remove Cu, Ni, Zn, Cd and Pb from AMDs after 72 hours than lime or limestone.