Enhanced Heavy Metal Mobilization from Unsaturated Mine Tailings.
Trans SME 1991 288:1801-1805
The dissolution of metals from various metal-nonmetal mine tailings has been studied through column leach tests at U.S. Bureau of Mines laboratories. Metal mobilization in unsaturated columns was consistently greater than metal dissolution in water-saturated columns. Leachate ph was also frequently lower when a leachant was passed through columns but showed a mixed residence-time dependence. On the other hand, metal and sulfate ion concentrations in the leachate increased with dry-cycle residence time. Results suggest that acid formation through atmospheric oxidation of pyrite may compete with non-acid-forming oxidation of other metal sulfides. The two processes lead to decreased ph and increased metal mobilization, respectively. Leach tests using sodium lauryl sulfate indicated that microbial activity was not a factor in these studies.
Trans. SME, V. 288, 1991, PP. 1801-1805