Approach to using ore only block model in Pit Optimisation

Philip van vuuren 6 years ago in Mining updated by oenesterov 6 years ago 1

I would like to make sure of the correct approach to using a ore only block model in Pit Optimisation:

I have a regular block model 5X5X5 of the ore.

I have a dtm of the surface.

I have a ore wireframe

I have assigned the ore wireframe to the block model to obtain the block factor i.e. portion of the ore block within the wireframe.

I have adjusted the grade in the block to account for the portion of ore in the block i.e. I have multiplied grade by the block factor for example the grade is 1.2 g/t, BF is 0.5 the adjusted grade is 0.6 g/t.

I then use the adjusted grade in the Pit Optimisation

Is this the approach correct?

Has any one compared using this technique with going the whole route of creating a block that consists of ore and waste and has block factors?

Or is there any other technique out there such as sub-blocking the block model into the wireframe and assigning grades to the sub-blocking?

This is correct. Two notes:

1. If you use regularised model and dilute it with BF, then mining dilution is likely to be 0, assuming that 5x5x5 is your SMU

2. If you model has some blocks or their portions above the topo surface, you should calculate and use second BF for the material that is above/below topo. The second BF should not be used for dilution though, but you can multiply it with one of the coordinates (X or Z, for example) to reduce the tonnage.