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Beck, P. (2003). CL:AIRE – Providing support for remediation research. Land Contam. Reclam., 11(2), 99–104.
Abstract: CL:AIRE (Contaminated Land: Applications in Real Environments) is a public-private partnership which was established in 1999 to encourage the demonstration of remediation research and technologies on contaminated sites throughout the UK. Project proposals are submitted to CL:AIRE and reviewed and approved by the CL:AIRE Technology & Research Group. CL:AIRE provides independent verification of its projects and plays a crucial role in the dissemination of project information. During the course of the project, progress is reported through the newsletter, CL:AIRE view, which is mailed free of charge to a database of more than 4500 stakeholders with an interest in contaminated land. Progress is also tracked on the CL:AIRE website at www.claire.co.uk. On completion of the project, a project report is published and a one page summary fact sheet is prepared. The fact sheet is distributed to our database subscribers and posted on the website. The project is also presented at the CL:AIRE Annual Project Conference. In addition, aspects of the research which have practical application will be published as CL:AIRE Research Bulletins. Acid mine waters discharging from abandoned mines represent a significant environmental problem in many parts of the UK. Considerable research has been carried out to understand the geochemical process involved, and the knowledge has been used to manage groundwater discharge through physical/chemical treatment and constructed wetlands. CL:AIRE supports the development of a national site for wetland research managed by the University of Newcastle and will encourage collaborative research projects to be submitted through CL:AIRE. CL:AIRE is currently supporting two projects which demonstrate remediation of acid mine drainage and is disseminating the results of this and other research to improve confidence in the use of these techniques.
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Benner, S. G., Blowes, D. W., & Ptacek, C. J. (1997). A full-scale porous reactive wall for prevention of acid mine drainage. Ground Water Monitoring and Remediation, 17(4), 99–107.
Abstract: The generation and release of acidic drainage containing high concentrations of dissolved metals from decommissioned mine wastes is an environmental problem of international scale. A potential solution to many acid drainage problem is the installation of permeable reactive walls into aquifers affected by drainage water derived from mine waste materials. A permeable reactive wall installed into an aquifer impacted by low-quality mine drainage waters was installed in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The reactive mixture, containing organic matter, was designed to promote bacterially mediated sulfate reduction and subsequent metal sulfide precipitation. The reactive wall is installed to an average depth of 12 feet (3.6 m) and is 49 feet (15 m) long perpendicular to ground water flow. The wall thickness (flow path length) is 13 feet (4 m). Initial results, collected nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. Comparing water entering the wall to treated water existing the wall, sulfate concentrations decrease from 2400 to 4600 mg/L to 200 to 3600 mg/L; Fe concentration decrease from 250 to 1300 mg/L to 1.0 to 40 mg/L, pH increases from 5.8 to 7.0; and alkalinity (as CaCO<inf>3</inf>) increases from 0 to 50 mg/L to 600 to 2000 mg/L. The reactive wall has effectively removed the capacity of the ground water to generate acidity on discharge to the surface. Calculations based on comparison to previously run laboratory column experiments indicate that the reactive wall has potential to remain effective for at least 15 years.
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Bennett, J. W., Timms, G. P., & Ritchie, A. I. M. (1999). The effectiveness of the covers on waste rock dumps at Rum Jungle and the impact in the long term. Mining into the next century : environmental opportunities and challenges Proceedings of the 24th annual environmental workshop Townsville October, , 379–388.
Abstract: Covers are widely used as a means of controlling pollutant generation from sulfidic waste piles. To date, there has been little data available to test the effectiveness of such covers. Monitoring of two waste rock dumps at Rum Jungle over more than fifteen years has provided the opportunity to assess cover effectiveness in the medium term. For the first 9 years the infiltration rate through the cover on Whites dump was less than the design figure of 5 per cent of rainfall. In subsequent years, however, the rate has increased to between 5 and 10 per cent. In the first six years the infiltration rate through the cover on Intermediate dump was also less than 5 per cent. Unfortunately, further measurements had to be abandoned due to equipment malfunction in this dump. Oxygen and temperature profiles measured below the cover have been used to estimate the overall oxidation rate in the two dumps. This is between 30 and 50 per cent of the oxidation rate prior to installation of the cover. The effect these results have on pollutant loads in drainage in the long term depends on the nature of the control mechanisms in the system. If pollutant concentrations in drainage are determined by secondary mineralisation within the dumps then pollutant loads in the long term will be essentially proportional to any further increase in the infiltration rate. If the pollutant loads in drainage are largely determined by the overall oxidation rates then we can expect the pollutant loads from the two dumps to increase in the long term to a level about one third to one half of that prior to rehabilitation. In this context, 'long term' means about 40 years after installation of the cover system. Given the implications this work has for the use of soil covers, the following additional studies should be undertaken: A measurement program to quantify the pollution loads from Intermediate and Whites waste rock dumps. A program of computation, backed by acquisition of mineralogical data on the wastes, to address the question of controls on concentration and load in effluent from the two dumps. A program to determine the reason for the deteriorating performance of the covers at Rum Jungle.
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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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Coulton, R., Bullen, C., & Hallett, C. (2003). The design and optimisation of active mine water treatment plants. Land Contam. Reclam., 11(2), 273–280.
Abstract: This paper provides a 'state of the art' overview of active mine water treatment. The paper discusses the process and reagent selection options commonly available to the designer of an active mine water treatment plant. Comparisons are made between each of these options, based on technical and financial criteria. The various different treatment technologies available are reviewed and comparisons made between conventional precipitation (using hydroxides, sulphides and carbonates), high density sludge processes and super-saturation precipitation. The selection of reagents (quick lime, slaked lime, sodium hydroxide, sodium carbonate, magnesium hydroxide, and proprietary chemicals) is considered and a comparison made on the basis of reagent cost, ease of use, final effluent quality and sludge settling criteria. The choice of oxidising agent (air, pure oxygen, peroxide, etc.) for conversion of ferrous to ferric iron is also considered. Whole life costs comparisons (capital, operational and decommissioning) are made between conventional hydroxide precipitation and the high density sludge process, based on the actual treatment requirements for four different mine waters.
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