The dissolution of metals from various metal-mine tailings has been studied through a series of batch tests of submerged tailings at U.S. Bureau of Mines laboratories. Samples included basic sulfidic tailings, acidic sulfidic tailings, and nonsulfidic oxidized tailings. Initial concentrations of metals in the slurry depended on the nature and amount of specific minerals in the waste. The tests indicated that changes in metal concentrations in supernatant liquids were influenced by percentage of oxygen saturation (aeration), solid-liquid contact time, ratio of contact surface area to liquid volume, amount of nonsubmerged (exposed) tailings, ph, and constituents in replacement leaching water. During the first few months, observed metal concentrations were consistently higher in aerated, reactive sulfide tailings; however, as solid-liquid contact time increased, metal concentrations tended to resemble those from unaerated systems. Metal concentrations in acidic tailings, whether neutralized or not, increased as solid-liquid contact time increased. The effects of these factors on metal dissolution from submerged tailings and their implications for tailings management are examined.
Proceeds 2nd Int'l. Conf. Abatement of Acidic Drainage, Quebec, Canada, V. 2, PP. 139-155