Waste Management Strategies Informed by Geochemical Risk

Okane conducted and interpreted the results of a drilling and geochemical testing program at several mine rock stockpiles (MRSs) at an an iron ore mine, assessing their potential for generating acid and metalliferous drainage (AMD).

Phase 1 testing produced acid load estimates for each MRS. Phase 2 testing refined the predicted acid load estimates by:

• Investigating the presence of existing or stored acidity and the potential reclassification of inferred sulfate acidity as non-acid generating.
• Assessing the relationship between sulfur grade and acid potential.
• Providing information about the effective buffering capacity of materials identified with positive acid neutralising capacity (ANC).
• Providing information on the mineralogy of secondary minerals formed due to oxidation processes and the potential for “coating” of sulfidic mineral surfaces.
• Providing information on laboratory static leaching potential to link with a regional environmental geochemical database.

A series of AMD estimation factors were developed from the Phase 2 testing program, increasing the accuracy of AMD loading estimations for the MRSs. These results assisted Okane and the client in designing effective waste placement strategies and MRS designs.