Mix Tricks: minimising the amount of waste mixing with ore

Challenge Statement

How can we maximise the amount of ore extracted while minimising the amount of waste picked up?

Background

The underground mining method at Cracow involves mining one section of the orebody out at a time. After a section is mined out, the empty void must be backfilled with waste material. When the next section is blasted and mined out there is inevitably some mixing of this ore and the backfilled waste. Minimising the amount of this dilution is critical to improving our results. One tonne of ore at an approximate grade of 5 g/t is worth $250, with 0 value on the waste that replaces it. It costs approximately $10/t to truck rock to the mill and another $35/t to process it for a net revenue of $205/t for ore and a net cost of $45/t for waste if it goes to the mill

Challenge

We want to minimise the amount of waste picked up while maximising the amount of ore extracted. Previous ideas have focused around some kind of barrier (mesh, concrete) at the interface before we backfill in order to stop the shedding of waste material into the next section to be mined.

Impact & Value

* Increased revenue by processing more ore and less waste.

* Reduced costs from trucking and processing waste