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Berg, G. J., & Arthur, B. (1999). Proposed mine water treatment in Wisconsin. In D. Goldsack, N. Belzile, P. Yearwood, & G. J. Hall (Eds.), Sudbury '99; mining and the environment II; Conference proceedings. Sudbury: Sudbury Environmental.
Abstract: Water quality standards are driving wastewater effluent limits to ultra-low levels in the nanogram/L range. Standards are proposed that require discharges to match background water quality. The new ultra-low level standards require cautious sampling techniques, super clean laboratory methods and more advanced treatment technologies. This paper follows a case history through water quality standards for ultra-low metals, laboratory selection, and the design of a wastewater treatment system that can meet the water quality standards which are required to permit a proposed copper and zinc mine in Northern Wisconsin. A high degree of care must be taken when sampling for ultra-low level metals. Both surface water and treated effluent samples present new challenges. Sampling methods used must assure that there are no unwanted contaminants being introduced to the samples. The selection of a laboratory is as critical as the construction of a state of the art wastewater treatment system. Treatment methods such as lime and sulfide precipitation have had a high degree of success, but they do have limitations. Given today's ultra-low standards, it is necessary to assess the ability of reverse osmosis, deionization, and evaporation to provide the high level of treatment required.
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Benzaazoua, M., & Bussiere, B. (1999). Desulphurization of tailings with low neutralizing potential; kinetic study and flotation modeling. In D. Goldsack, N. Belzile, P. Yearwood, & G. Hall (Eds.), Sudbury '99; Mining and the environment II; conference proceedings.
Abstract: Environmental desulphurization is an attractive alternative for acid generating tailings management as demonstrated during the last few years. In fact, such process placed at the end of the primary treatment circuit allows to reduce greatly the amount of problematic tailings by concentrating the sulphidic fraction. Moreover, the desulphurized tailings (non-acid generating) have the geotechnical and environmental properties for being used as fine material in a cover with capillary barrier effects. To produce desulphurized tailings, non selective froth flotation is the most adapted method as shown in many previous works. Desulphurization level is fixed by tailings sulphur content (or sulphide content) and neutralization potential NP. The final residue should have enough NP to compensate for his acid generating potential AP. In this paper, the authors present the results of laboratory tests conducted in Denver cells for studying the sulphide flotation kinetics of four mine tailings which are characterized by a weak neutralization potential (under 37 kg CaCO (sub 3) /t). Tailings 1, 2, 3 and 4 contain respectively 5.27, 10, 4.25 and 16.9 sulphur Wt. %. Tailings 1 and 2 are cyanide free and are well floated at pH around 11 by using amyl xanthate as collector. Collector dosage was optimized for these tailings and the results show that Tailing 2 need more collector. However, Tailings 3 and 4, which come from a gold cyanidation process, could not provide good sulphide recovery with xanthate collector because of the pyrite depression. To overcome this problem, amine acetate was used successfully but induces important entrainment. The consumption of this collector was also optimized. The results of kinetic tests and collector dosage were combined and modeled to establish relationships which allow to estimate the desulphurization performances.
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Aube, B. C., & Zinck, J. M. (1999). Comparison of AMD treatment processes and their impact on sludge characteristics.
Abstract: Lime neutralisation for the treatment of acid mine drainage is one of the oldest water pollution control techniques practised by the mineral industry. Several advances have been made in the process in the last thirty years, particularly with respect to discharge concentrations and sludge density. However, the impact of different treatment processes on metal leachability and sludge handling properties has not been investigated. A study of treatment sludges sampled from various water treatment plants has shown that substantial differences can be related to the treatment process and raw water composition. This study suggests that sludge densities, excess alkalinity, long-term compaction properties, metal leachability, crystallinity and cost efficiency can be affected by the neutralisation process and specific process parameters. The study also showed that the sludge density and dewatering ability is not positively correlated with particle size as previously suggested in numerous studies. The treatment process comparisons include sludge samples from basic lime treatment, the conventional High Density Sludge (HDS) Process, and the Geco HDS Process.
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