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Younger, P. L. (2000). Holistic remedial strategies for short- and long-term water pollution from abandoned mines. Transactions of the Institution of Mining and Metallurgy Section a-Mining Technology, 109, A210–A218.
Abstract: Where mining proceeds below the water-table-as it has extensively in Britain and elsewhere-water ingress is not only a hindrance during mineral extraction but also a potential liability after abandonment. This is because the cessation of dewatering that commonly follows mine closure leads to a rise in the water-table and associated, often rapid, changes in the chemical regime of the subsurface. Studies over the past two decades have provided insights into the nature and time-scales of these changes and provide a basis for rational planning of mine-water management during and after mine abandonment. The same insights into mine-water chemistry provide hints for the efficient remediation of pollution (typically due to Fe, Mn and Al and, in some cases, Zn, Cd, Pb and other metals). Intensive treatment (by chemical dosing with enhanced sedimentation or alternative processes, such as sulphidization or reverse osmosis) is often necessary only during the first few years following complete flooding of mine voids. Passive treatment (by the use of gravity-flow geochemical reactors and wetlands) may be both more cost-effective and ecologically more responsible in the long term. By the end of 1999 a total of 28 passive systems had been installed at United Kingdom mine sites, including examples of system types currently unique to the United Kingdom. Early performance data for all the systems are summarized and shown to demonstrate the efficacy of passive treatment when appropriately applied.
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Zinck, J. M., & Aube, B. C. (2000). Optimization of lime treatment processes. CIM Bull., 93(1043), 98–105.
Abstract: Lime neutralization technology is widely used in Canada for the treatment of acid mine drainage and other acidic effluents. In many locations, improvements to the lime neutralization process are necessary to achieve a maximum level of sludge densification and stability. Conventional lime neutralization technology effectively removes dissolved metals to below regulated limits. However, the metal hydroxide and gypsum sludge generated is voluminous and often contains less than 5% solids. Despite recent improvements in the lime neutralization technology, each year, more than 6 700 000 m3 of sludge are generated by treatment facilities operated by the Canadian mining industry. Because lime neutralization is still seen as the best available approach for some sites, sludge production and stability are expected to remain as issues in the near future. Several treatment parameters significantly impact operating costs, effluent quality, sludge production and the geochemical stability of the sludge. Studies conducted both at CANMET and NTC have shown that through minor modifications to the treatment process, plant operators can experience a reduction in operating costs, volume of sludge generated, metal release to the environment and liability. This paper discusses how modifications in plant operation and design can reduce treatment costs and liability associated with lime treatment.
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Zou, L. H. (2000). Sulfide precipitation flotation for treatment of acidic mine waste water. Transactions of Nonferrous Metals Society of China, 10, 106–109.
Abstract: Sulfide precipitation flotation of copper-iron-bearing acidic waste water from a large copper mine and the stimulated waste water were studied. The pH of the waste water was 2.2, with 130 mg/L Cu2+ and 500 mg/L Fe3+ (Fe2+). Results show that, when Na2S was added as precipitating agent, sodium butylxanthate as collector and at pH 2.0, the removal of copper could be as high as 99.7 % and the residual copper decreased to 0.2 mg/L, however, almost no iron was removed. When the floated solution was neutralized to pH = 8.0, more than 98 % iron was precipitated and the residual iron was less than 10 mg/L. In experiment on actual mine effluents, after the use of precipitate flotation technology to recover copper and pH neutralization to precipitate iron, the treated waste water does meet the emission standards for sewage and valuable floating copper graded 37.12%. The chemical calculation and mechanism of solution were also presented.
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