Stawell Gold Mines (SGM) is an underground mining operation located in Victoria, Australia. The mining method employed is long hole retreat stoping, utilising up and downholes and artificial concrete pillars. Stawell is currently mining the Golden Gift and Magdala orebodies.
Access to the Magdala and Golden Gift deposits is via 6.0 m wide by 5.5 m high declines developed at a gradient of one in eight to one in seven from the surface to a depth of 1500 m, with a planned depth of 1650 m. From the declines, cross cutting drives are developed to intersect the orebodies. Orebodies in the Gift system are discrete lodes which are generally mined from a bottom up centre retreat to minimise geotechnical stresses.
Ore development fronts are currently located between 1000 m and 1500 m below surface, with all ore being hauled to the surface using a fleet of 60 tonne underground trucks. With the use of conventional pyrotechnic long period (LP) delays, broken rock of combined ore and waste is thrown 10 m from the face and the materials hauled to the surface. The majority of the mullock from development is consumed in the underground as backfill.
With the use of Orica Mining Services eDev™ Electronic Blasting System for Tunnelling, the waste is thrown up to 40 m from the face, while majority of the ore is left 5 – 10 m from the face, effectively segregating ore and waste. This enables significant recovery of gold values with minimal loss and significantly reduced dilution. By using this technique in ore drives with a 30:70 waste to ore ratio, SGM is able to haul 24 000 tonnes less mullock to the surface annually. Resue mining is applied to narrow vein headings and gives a 40 per cent grade increase at the faces as well as increasing the economic footprint of development. This will also contribute to an improved grade profile for the year from 3.98 – 4.16 g/t Au and allow extra capacity for ore haulage from stoping and for milling.
This paper describes the application
and the successful blast outcomes achieved using the eDev™ Electronic Blasting
Systems for resue mining at SGM. Results to date, since commencement in March
2010, have been achieving significant benefits in terms of ore grade as
confirmed by geologists grab sample grades. Face advance have also shown
improvement with better breakage of perimeter holes giving improved face
profile. These benefits are delivering increased productivity and safety
performance when compared to other resue firing techniques.
Hamilton, C and
Degay Jr, B, 2011. Resue mining
with eDev™ electronic detonators at Stawell gold mines, in Proceedings 11th AusIMM Underground Operators’
pp 73-80 (The Australasian Institute of Mining and Metallurgy: