Risk Analysis in Short-Term and Medium-Term Mine Planning

July 7, 2021

The planning and sequence of exploration of an area in an underground environment consists of evaluating mineral reserves and scheduling of their exploration. Geomechanical and economic parameters are accounted for in mining reserves evaluations and the risk or uncertainty associated with the reserves should take into account the uncertainty associated with these parameters, as in the quantification of resources. The aim of this work was to present a methodology in which the most important parameters - mining recovery, metal prices, zinc head grades - are considered random variables with probability distribution inferred from experimental data. For this purpose, 181 monthly zinc price observations of the last 15 years were analysed and, applying the Holt exponential smoothing method, the price forecast for the next 3 months was obtained, with MAPE equal to 9.66%. The cumulative distribution of 17 mining recovery observations was adjusted to an exponential equation whose determination coefficient (R2) was 96.9%. Finally, a sample of 49 observations of zinc head grades was analysed, from which it was inferred that the sample came from a normal distribution with parameters mean equal to 7.6% and standard deviation equal to 0.795%. The set of probability distributions was simulated and co-simulated using the Monte Carlo method. Knowing that mines generate NSRs around 50% for zinc, a probability distribution of mineral reserves was obtained, with cut-off value above 5.3%, and probability distribution of NSR, which can be quantified as risk over the 3 months of the mining plan in the short-medium term.

Authors in the community:

• 

  T

  Tchipato Amade Karimo

  ist179662

Supervisors of this institution:

• 

  A

  Amílcar de Oliveira Soares

  ist12180

civil-engineering - Civil engineering

por - Portuguese

Instituto Superior Técnico