Block cave ore reserves – are we reporting a reserve or potential inventory?

In a recent paper, Enthalpy Associate and Director at Stratavision Nat Burgio considered the question of whether current reserve reporting for block caving operations adequately considers the complexities and geotechnical challenges of mining in the modern context of stronger rock masses, at greater depths, and using taller extraction columns – particularly at conceptual and pre-feasibility levels when there are high levels of uncertainty. Acknowledging the significant and valuable advances in software modelling capability for prediction as well as back-analysis, he raises concern that reserves in the pre-production stage are optimistic. This is partly because in absence of studies and good information, estimators have to rely on assumptions and may not have applied a discounting factor for ore recovery that, for several key reasons, is incomplete. Given that risk assessments and investment decisions are underpinned by estimates of the ore reserve, Nat argues that each case in a range of plausible cases should have realistic and reasonable expectations with regard to ore recovery. Nat also highlighted the lack of guidelines for applying geotechnical modifying factors in caving operations, and called for improvements in consistency, completeness and transparency in reporting.

You can download the full paper here.

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