Acid Mine Drainage Risk Assessment Utilising Drill - Hole Data and Geological Modelling Tools

For an Australian iron ore operation in the Pilbara region of Western Australia, an acid and metalliferous drainage (AMD) study has considered available drill-hole data (chemical assays and geological logging information) combined with mine planning information to conduct a high level assessment of the potential for AMD from mined waste storage facilities and within the pit void.

Geological modelling tools (Vulcan, Leapfrog) were used to generate 3D visualisations of the distribution of sulfur (a key parameter indicative of AMD risk) within the mined volume. The final sulfur model was aligned with the existing block model to aid future mine planning. Small volumes representing sulfur - bearing ‘hot - spots’ were identified and pit void maps were generated to determine the location of these hot spots on exposed pit walls. Simila rly, volumetric quantities of sulfur-bearing material that would report to waste rock dumps and ore stockpiles were estimated.

Outcomes from the assessment were used to focus ongoing geochemical characterisation activities, and can be used as a basis for scoping calculations to predict the possible quality of drainage waters from mined waste storage facilities and pit walls. This paper describes the overall assessment approach and summarises outcomes from the AMD risk assessment.