The information gained from drilling helps mine geologists estimate the amount of gold within the ore bodies and is used to generate underground designs to extract that ore. At Fosterville Gold Mine, drilling geologists work specifically with underground diamond drill rigs.
Before drilling begins Geologists decide where to drill, how many holes are necessary, how long the holes will be, what the target is, and what the best location is to drill from.
Once drilling has begun, down hole surveys are taken regularly, which allows geologists to track the hole. Geologists work closely with drillers to manipulate drilling techniques and vary equipment to reach the desired spacing between drill holes.
Once drilling is completed, geologists log the drill core. If the hole contains important structures, mineralisation or gold, these areas are sampled by logging geologists.
Samples are sent to a local laboratory to determine how much gold the rock contains. When results are returned, they are subjected to quality control. If the results pass all tests, they are reported and utilised to build resource and reserve models. Engineers then use these to evaluate the validity of mining.
This starts by creating an access portal at the surface and a main decline. Once the decline has reached the desired depth, horizontal tunnels are then developed in order to reach the ore body.
A jumbo drill, a Load Haul Dump machine (also known as a “bogger”), haul truck and shotcrete machine are used to bore out the face and lengthen the tunnel.
Fosterville Gold Mine is trialling a battery electric loader with a vision to move to a battery powered fleet in the future.
The void that is created is called a stope. The ore is then removed using the remote control Load Haul Dump machine or bogger, and placed into ore trucks. The trucks bring the ore to the surface and tip it on the stockpile in readiness for processing.