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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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Gusek, J. J. (2005). Design challenges for large scale sulfate reducing bioreactors. Contaminated Soils, Sediments and Water: Science in the Real World, Vol 9, 9, 33–44.
Abstract: The first large-scale (1,200 gpm capacity), sulfate-reducing; bioreactor (SRBR) was constructed in 1996 to treat water from an underground lead mine in Missouri. Other large-scale SRBR systems have been built elsewhere since then. This technology holds much promise for economically treating heavy metals and has progressed steadily from the laboratory to industrial applications. Scale-up challenges include: designing for seasonal temperature variations, minimizing short circuits, changes in metal loading rate s, storm water impacts, and resistance to vandalism. However, the biggest challenge may be designing for the progressive biological degradation of the organic substrate and its effects on the hydraulics of the SRBR cells.
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Guay, R. (1999). Effect of flooding of oxidized mine tailings on T-ferrooxidans and T-thiooxidans survival and acid mine drainage production: a 4 year restoration-environmental follow-up. Biohydrometallurgy and the Environment toward the Mining of the 21st Century, Pt B 1999, 9, 635–643.
Abstract: A pilot-scale study on the effect of flooding unoxidized and oxidized Cu/Zn tailings demonstrated the technical feasability of this technology to remediate a mining site where over 3 million tons of tailings were impounded. Full-scale flooding of the tailing pond with free running water was undertaken after the construction of an impervious dam; approximately 2 million m(3) of surface water at pH 7,4 completely covered the tailings after 16 months. The minimal water column over the tailings was established at 1,20 m and reached 4,5 m, depending on the site topography. Water and tailings samples were collected from 9 different locations from the surface of the man-made lake using a specially designed borer and were analyzed for pH, conductivity, iron- and sulfur-oxidizing bacteria activity and numbers as well as the sulfate reducing bacteria (SRB) population. We showed that over a four year period of flooding, the overall population of iron-oxidizers decreased considerably; their numbers drastically fell from 1 x 10(6) to 1 x 10(2) active cells per g of oxidized tailings while the SRBs increased from 10(1) to 10(5)/g. The pH of the influent, the reservoir and the effluent water remained fairly constant between 6,9 up to 7,4 over the entire period. During this time, interstitial water pH increased from 2,9 to 4,3 in flooded tailings where lime could not be incorporated in the first 20 cm of tailings; elsewhere, the pH of the tailings suspensions remained fairly constant around neutral values (pH 7,0). Dissolved oxygen was measured at fixed intervals and remained also constant between 6 and 7.5 mg/L while water temperatures fluctuated below freezing point to +20C respectively in winter and summer season.
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Boonstra, J. (1999). Biological treatment of acid mine drainage. Biohydrometallurgy and the Environment toward the Mining of the 21st Century, Pt B 1999, 9, 559–567.
Abstract: In this paper experience obtained with THIOPAQ technology treating Acid Mine Drainage is described. THIOPAQ Technology involves biological sulfate reduction technology and the removal of heavy metals as metal sulfide precipitates. The technology was developed by the PAQUES company, who have realised over 350 high rate biological treatment plants world wide. 5 plants specially designed for sulfate reduction are successfully operated on a continuous base (1998 status).
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Burt, R. A., & Caruccio, F. T. (1986). The effect of limestone treatments on the rate of acid generation from pyritic mine gangue. Environmental geochemistry and health, 8, 8.
Abstract: Surface water enters the Haile Gold Mine, Lancaster County, South Carolina by means of a small stream and is ponded behind a dam and in an abandoned pit. This water is affected by acidic drainage. In spite of the large exposures of potentially acid producing pyritic rock, the flux of acid to the water is relatively low. Nevertheless, the resulting pH values of the mine water are low (around 3.5) due to negligible buffering capacity. In view of the observed low release of acidity, the potential for acid drainage abatement by limestone ameliorants appears feasible. This study investigated the effects of limestone treatment on acid generation rates of the Haile mine pyritic rocks through a series of leaching experiments. Below a critical alkalinity threshold value, solutions of dissolved limestone were found consistently to accelerate the rate of pyrite oxidation by varying degrees. The oxidation rates were further accelerated by admixing solid limestone with the pyritic rock. However, after a period of about a month, the pyrite oxidation rate of the admixed samples declined to a level lower than that of untreated pyrite. Leachates produced by the pyrite and limestone mixtures contained little if any iron. Further, in the mixtures, an alteration of the pyrite surface was apparent. The observed behaviour of the treated pyrite appears to be related to the immersion of the pyrite grains within a high alkalinity/high pH environment. The high pH increases the rate of oxidation of ferrous iron which results in a higher concentration of ferric iron at the pyrite surface. This, in turn, increases the rate of pyrite oxidation. Above a threshold alkalinity value, the precipitation of hydrous iron oxides at the pyrite surface eventually outpaces acid generation and coats the pyrite surface, retarding the rate of pyrite oxidation.
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