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Session:

Plenary 5

Abstract No.:

O-047

Title:

Risk Analysis on Mining Planning and Reserves Assessment at a Brazilian Copper Mine.

Author(s):

C Diedrich, VALE (BR)
J F C L Costa, UFRGS - Federal University of Rio Grande do Sul (BR)
W F Paula, VALE (BR)

Abstract:

Mining industry continuously investigates proper reconciliation procedures and techniques for mapping possible risks in ore recovery and mining planning. A case study at a copper mine investigates the adequacy of using simulated grades for defining risky areas affecting mining planning and reserves. Conditional simulations were used to derive multiple copper grade models within a typical ore-body of the deposit and compared these models against the real production data (reconciliation). The comparison allowed a better understanding on grade variability and helped in defining a more consistent mining plan. The range of values derived from the simulations mapped areas of significant uncertainty affecting the pushback?s plan. Risk analyses were conducted by comparing the projected final pit limit and mining sequence against the simulated models of copper grade, assessing the operational impacts on key economical factors (mine net present value, discounted cash flow). Several final pit limits were generated for various simulated grade block models and compared to the previously pit planned using the ordinary kriging grade block model. The results highlighted possible risks associated with the operational pit limit. After, multiple alternatives for the operational mining sequence were investigated to adjust and minimize grade variations on the annual mining plan ensuring less risk on completion metal production goals. The results demonstrated the benefits of using risk analysis as a tool to preview and review the final pit limits and mining schedule helping to take better strategic decisions by the copper mine management.