Optimal Dig-Line of Reblocked Conditional Simulation

An Optimum Dig-Line plot of reblocked conditional simulation is automatically inserted beneath a reblocked data loader after Simulation Generation.

The Optimum Dig-Line component is used to determine which blocks should be milled, and which should be treated as waste. The classification of each block is calculated based on the premise that a loss can be made in one of the following ways:

• The true block grade is above economic cut-off and the block is dumped.
• The true block grade is below economic cut-off and the block is milled.

Supervisor does not assume a symmetric loss function, where the cost to dump ore is equal to the cost of milling waste. Instead, Supervisor uses risk aversion and resource preservation factors to determine whether each block is economic to treat as ore.

A threshold value is computed for each block, based on the range of grades in the simulation set (each considered equally likely), and the user-specified risk aversion and resource preservation factors. For each block, the threshold is compared to the probability that its grade exceeds the cut-off. Where the probability exceeds the threshold, the block is accepted. With all else being equal, a higher risk aversion and/or lower resource preservation produces a higher threshold value for each block, and therefore results in fewer blocks being selected.

The threshold probability is calculated as follows: