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Minerals 2017, 7(3), 42; https://doi.org/10.3390/min7030042

Strategies for Reduced Acid and Metalliferous Drainage by Pyrite Surface Passivation

1
Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, MLK 26, Mawson Lakes, SA 5095, Australia
2
Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
3
Levay and Co. Environmental Services, Mawson Lakes, SA 5095, Australia
4
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, China
5
Blue Minerals Consultancy, Middleton, SA 5213, Australia
*
Authors to whom correspondence should be addressed.
Academic Editor: Liliana Lefticariu
Received: 16 December 2016 / Revised: 13 March 2017 / Accepted: 14 March 2017 / Published: 17 March 2017
(This article belongs to the Special Issue Biogeochemistry of Acid Mine Drainage)
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Abstract

Acid and metalliferous drainage (AMD) is broadly accepted to be a major global environmental problem facing the mining industry, requiring expensive management and mitigation. A series of laboratory-scale kinetic leach column (KLC) experiments, using both synthetic and natural mine wastes, were carried out to test the efficacy of our pyrite passivation strategy (developed from previous research) for robust and sustainable AMD management. For the synthetic waste KLC tests, initial treatment with lime-saturated water was found to be of paramount importance for maintaining long-term circum-neutral pH, favourable for the formation and preservation of the pyrite surface passivating layer and reduced acid generation rate. Following the initial lime-saturated water treatment, minimal additional alkalinity (calcite-saturated water) was required to maintain circum-neutral pH for the maintenance of pyrite surface passivation. KLC tests examining natural potentially acid forming (PAF) waste, with much greater peak acidity than that of the synthetic waste, blended with lime (≈2 wt %) with and without natural non-acid-forming (NAF) waste covers, were carried out. The addition of lime and use of NAF covers maintained circum-neutral leachate pH up to 24 weeks. During this time, the net acidity generated was found to be significantly reduced by the overlying NAF cover. If the reduced rate of acidity production from the natural PAF waste is sustained, the addition of smaller (more economically-feasible) amounts of lime, together with application of NAF wastes as covers, could be trialled as a potential cost-effective AMD mitigation strategy. View Full-Text
Keywords: acid and metalliferous drainage control; kinetic leach columns; pyrite surface passivation; reactive natural mine waste; reduced acid generation acid and metalliferous drainage control; kinetic leach columns; pyrite surface passivation; reactive natural mine waste; reduced acid generation
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Qian, G.; Schumann, R.C.; Li, J.; Short, M.D.; Fan, R.; Li, Y.; Kawashima, N.; Zhou, Y.; Smart, R.S.C.; Gerson, A.R. Strategies for Reduced Acid and Metalliferous Drainage by Pyrite Surface Passivation. Minerals 2017, 7, 42.

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