Nordstrom D K, Alpers C N
United States Geological Survey, 3215 Marine Street, Boulder, CO 80303-1066, USA.
Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):3455-62. doi: 10.1073/pnas.96.7.3455.
The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as -3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter. Copious quantities of soluble metal sulfate salts such as melanterite, chalcanthite, coquimbite, rhomboclase, voltaite, copiapite, and halotrichite have been identified, and some of these are forming from negative-pH mine waters. Geochemical calculations show that, under a mine-plugging remediation scenario, these salts would dissolve and the resultant 600,000-m3 mine pool would have a pH of 1 or less and contain several grams of dissolved metals per liter, much like the current portal effluent water. In the absence of plugging or other at-source control, current weathering rates indicate that the portal effluent will continue for approximately 3, 000 years. Other remedial actions have greatly reduced metal loads into downstream drainages and the Sacramento River, primarily by capturing the major acidic discharges and routing them to a lime neutralization plant. Incorporation of geochemical modeling and mineralogical expertise into the decision-making process for remediation can save time, save money, and reduce the likelihood of deleterious consequences.
铁山铜矿床的里士满矿含有一些有史以来报告过的酸性最强的矿井水。测得的pH值低至-3.6，金属总浓度高达200克/升，硫酸盐浓度高达760克/升。已鉴定出大量可溶性金属硫酸盐，如铁矾、胆矾、水绿矾、斜方绿矾、水铜矾、叶绿矾和水镁矾，其中一些是由负pH值的矿井水形成的。地球化学计算表明，在封堵矿井的修复方案下，这些盐会溶解，形成的60万立方米矿坑积水的pH值将在1或更低，每升含有几克溶解金属，这与当前的井口排水情况非常相似。如果不进行封堵或其他源头控制，根据目前的风化速率，井口排水将持续约3000年。其他补救措施主要是通过捕获主要的酸性排放物并将其输送到石灰中和厂，大大减少了进入下游排水系统和萨克拉门托河的金属负荷。将地球化学建模和矿物学专业知识纳入修复决策过程可以节省时间、节省资金，并减少产生有害后果的可能性。
