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Inhibition of sulfide oxidation

Published: 23 September 2014

Non-ferrous mining (eg copper, lead, and zinc) produces large quantities of sulfide-enriched mine waste. When subjected to oxygen and water, the sulfides weather; Often resulting in a leachate characterized by a low pH and high concentrations of sulfate, metals and metalloids, more commonly known as acid rock drainage (ARD). Today in Sweden, the most common way of treatment for ARD, is through active treatment, requiring large amounts of lime, resulting in an iron and sulfate-rich sludge with high content of trace elements in need of further Treatment. Finding ways of preventing sulfide oxidation during operation is crucial from an economical and environmental point of view.

An innovative, relatively new method is inhibition which prevents sulfide oxidation through precipitation of secondary minerals on the sulfide surface thus resulting in a decrease of acid production, metals, metalloids and sulfate in leachate.

By-products and industrial remnants such as cement kiln dust, steel slag, lime kiln dust and fly ash are investigated for their potential to prevent/inhibit sulfide oxidation in waste rock.

Ongoing tests in small-scale laboratory test cells containing industrial remnants and sulfidic waste rock show remarkable results indicating the successfulness of reducing the oxidation in laboratory scale, however, further research is needed to explain geochemical processes occurring and how the method would work on a larger scale. Identification of formed secondary minerals and their stability along with trace element enrichment is crucial in evaluating the respective by-product and industrial remnant’s suitability for this application.

Overall objectives:

  • Prevent sulfide oxidation in waste rock and the subsequent generation of acid metalliferous drainage during operation by inhibition and/or stabilization technologies.

Specific objectives:

  • Evaluation of inhibition and/or stabilization technologies useful from economic, environmental and technical perspectives.
  • Recommendation of suitable residues for specific techniques of inhibition/ stabilization purposes for non-oxidized waste rock