Control of Acid Generation from Pyrite Oxidation in a Highly Reactive Natural Waste: A Laboratory Case Study

Yan Zhou, Michael short, Jun Li, Russell Schumann, Roger St.C. Smart, Andrea Gerson, Gujie Qian

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5 Citations (Scopus)
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Laboratory kinetic leach column (KLC) tests were carried out to define the conditions required to control acid generation from a highly reactive, potentially acid-forming (PAF) iron ore waste rock. It was found that lime addition (0.1 wt % blended) plus either blending of silicates (25 wt % K-feldspar and 25 wt % chlorite), or addition of a non-acid forming (NAF) top cover containing about 10% dolomite (PAF:NAF = 5:1 wt %), when watered/flushed with lime-saturated water, greatly reduced acid generation as compared to the control KLC (PAF alone, watered/flushed with Milli-Q water), but did not result in circum-neutral pH as required for pyrite surface passivation and effective acid and metalliferous drainage (AMD) mitigation. In contrast, the combined use of these treatments—blended lime and silicates with an NAF cover and watering/flushing with limesaturated water—resulted in leachate pH of ≈12 (up to 24 weeks). Mass balance calculations for Ca 2+ and scanning electron microscopy (SEM) analyses suggest that calcite or gypsum may have formed in the NAF-amended KLCs and lime with added silicate KLC. Although the combined approach in the form trialled here may not be practical or cost-effective, control of a highly reactive natural PAF waste by pyrite surface passivation appears to be possible, and an improved treatment methodology (e.g., slightly increased lime blending without the need for further lime watering/flushing) could usefully be examined in the future.

Original languageEnglish
Article number89
Pages (from-to)1-10
Number of pages10
Issue number6
Publication statusPublished - Jun 2017
Externally publishedYes

Bibliographical note

'© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ('


  • at-source AMD remediation
  • kinetic leach column
  • NAF cover
  • pyrite surface passivation
  • reactive silicates
  • secondary minerals
  • Kinetic leach column
  • Reactive silicates
  • At-source AMD remediation
  • Secondary minerals
  • Pyrite surface passivation


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