The Efemçukuru underground mine in western Turkey is an intermediate sulfidation, epithermal gold deposit. The bulk of the mineral resources and all of the mineral reserves lie within the Kestanebeleni (KB) vein system. This system comprises four spatially-distinct mineralised zones: the south ore shoot (SOS), the middle ore shoot (MOS), the north ore shoot (NOS) and the KB north-west ore shoot. Production currently occurs only in the SOS, MOS and NOS zones. The gold mineralisation is very fine grained and occurs as free grains in quartz and carbonate, and as inclusions in sulfide minerals. Gold is recovered as part of a sulfide concentrate by flotation methods. Though hosted in the KB vein, the gold mineralisation is not evenly distributed within the veins. Definition of its occurrence is totally dependent on diamond drilling.
Diamond drilling at Efemçukuru is
done with its own equipment and staff, all managed by the mine geology group.
The process over the mine’s six year production history incorporates continual
improvement with an innovative approach by focusing on the following:
- drill team organisation
- career development and training
- product research and effective equipment management
- cost reduction
- planning and scheduling of development for drill stations.
Over 40 000 metres of mostly BQ size core are drilled annually by three drill rigs at a cost approaching US$35/m.
The planning and execution of the drilling pattern depends on the configuration of the ore shoot and the planned mining method. Ore extraction is mainly by drift and fill mining augmented by about 15 per cent longhole stoping. The drilling of a specific area is scheduled to be finished 3 to 8 months prior to mining. This scheduling is sufficient for short-term grade model updates and any needed changes to the planned development or stope sequencing prior to planned production from the stope area.
Arslan, N and Ozkayhan, M, 2017. Diamond drilling at
Efemçukuru gold mine, Turkey – a case study on the benefits of timely and
cost-effective drilling to short-term planning, in Proceedings Tenth
International Mining Geology Conference 2017, pp 285–290 (The Australasian
Institute of Mining and Metallurgy: Melbourne).