acid mine drainage

Topics: PH, Environmental issues with mining, Acid mine drainage Pages: 18 (4634 words) Published: September 23, 2013
Hydrometallurgy 104 (2010) 459–464

Contents lists available at ScienceDirect

j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / h yd r o m e t

Biokinetic test for the characterisation of AMD generation potential of sulfide mineral wastes
A.H. Hesketh a,b, J.L Broadhurst b, C.G Bryan a, R.P van Hille a, S.T.L. Harrison a,b,⁎ a

Centre for Bioprocess Engineering Research, Department of Chemical Engineering, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa Minerals-to-Metals Research Initiative, Department of Chemical Engineering, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa

a r t i c l e

i n f o

Available online 17 June 2010
Acid mine drainage
Prediction test
Sulfide tailings

a b s t r a c t
Acid mine drainage (AMD) is formed by the microbially catalysed oxidation of sulfide minerals on exposure to moisture and air. It results in the ongoing contamination of water streams with acidity, sulfate and metal ions in solution, limiting subsequent use of the water without its remediation. AMD prevention is a key requirement for meeting mine closure standards and AMD prediction plays an integral role in waste management and AMD prevention. However, both the static and kinetic tests used currently have shortfalls, including only providing a worst case scenario, providing limited kinetic data, particularly with respect to microbial catalysis or requiring an excessive time frame for the provision of useful data. In this study, we review biological tests reported to predict AMD generation potential and propose an extension to these tests in the form of a biokinetic test. The proposed test provides information on the potential and likelihood of acidification upon microbial colonisation as well as the relative kinetics of the acid-consuming and acidproducing reactions. This provides more meaningful data than static tests, within a reasonable timeframe. Experiments performed to evaluate the biokinetic test, using copper sulfide flotation tailings, show results consistent with those of traditional static tests. However, these also provide additional kinetic information that could help to inform management strategies.

© 2010 Elsevier B.V. All rights reserved.

1. Introduction
Acid mine drainage (AMD) from sulfide tailings deposits, waste rock, disused mine sites and spent materials is one of the biggest environmental challenges in the minerals processing industry. Typically, AMD has been addressed in an “end of pipe” approach. This has focused on deposition techniques to increase chemical and physical stability, which reduce AMD formation from the waste materials, or on approaches to treating AMD, or both. The long-term impacts of current AMD management practices are not well understood, and their implementation as well as the implementation of remediation strategies is costly and difficult. Previous research has shown that integrated waste management techniques can reduce the long-term potential for AMD generation, thereby reducing, rather than delaying the risk of AMD generation (Hesketh et al., 2010; Benzaazoua et al., 2008). Legislation is developing to place the burden of responsibility of waste dumping onto mining companies in perpetuity. This, and the growing awareness for the need to design towards a sustainable process industry, has necessitated a change in process

⁎ Corresponding author. Centre for Bioprocess Engineering Research, Department of Chemical Engineering, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa. Fax: + 27 21 650 5501.

E-mail address: (S.T.L. Harrison).
0304-386X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.hydromet.2010.01.015

thinking to enable these risks to be monitored carefully to facilitate long-term risk assessment. AMD prediction plays an important role in planning for mine waste disposal. Typically,...
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