Passivation of pyrite for reduced rates of acid and metalliferous drainage using readily available mineralogic and organic carbon resources: A laboratory mine waste study

Rong Fan, Gujie Qian, Michael D. Short, Russell C. Schumann, Stephane Brienne, Roger St C. Smart, Andrea R. Gerson

Research output: Contribution to journalArticlepeer-review

Abstract

Acid and metalliferous drainage (AMD) is a major environmental issue resulting largely from exposure to weathering of mine wastes containing pyrite (FeS2). At-source strategies to reduce the rate of formation of AMD have potential to be more cost-effective and sustainable than post-generation downstream treatments. The objective of this study was to examine the efficacy of geochemical and microbial treatments for at-source control through pyrite surface passivation. Six kinetic leach columns (KLCs), using a mine waste containing 3.8 wt% pyrite, were subjected to various treatments: 1) untreated, 2) blended calcite, and applications of 3) calcite-saturated water, 4) lime-saturated water followed by calcite-saturated water, 5) biosolids extract water (providing a source of organic carbon to promote microbial growth) and 6) biosolids extract in calcite-saturated water. The untreated KLC leachate pH was on average 5.7 for the first 12 weeks, followed by a gradual decrease to pH 4.5 at week 52. This slow pH decrease is attributed to neutralisation released upon Mg-siderite dissolution. The leachate pH from all treated KLCs was near-neutral at the end of the tests. Pyrite was surface-passivated and leaching supressed by all treatments except for calcite-saturated water. Leaching of Mn and Zn from the untreated waste identified the potential for adverse environmental impact. No evidence was found for surface passivation of Zn- or Mn-containing minerals in the treated KLCs. Blended calcite addition and lime-saturated water followed by calcite-saturated water were most effective at reducing release of Zn and Mn, likely due to precipitation as hydroxides/carbonates.

Original languageEnglish
Article number131330
Number of pages10
JournalChemosphere
Volume285
DOIs
Publication statusPublished - Dec 2021

Keywords

  • Acid drainage
  • Geochemical remediation
  • Metalliferous drainage
  • Microbial remediation
  • Pyrite passivation

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