Gascoyne Resource’s Dalgaranga Gold mine reduces ore loss: Adding A$151,522 of value in one blast

Commodity Ore Grade Geology Powder Factor Location
Gold Low Narrow-vein Low – Medium

4.0 – 7.0

Australia
Dalgaranga is a low-grade open pit gold mine owned by Gascoyne Resources Limited. Located in the Dalgaranga Greenstone Belt within the Murchison gold mining region of WA, approximately 600km north west of Perth by road.  The Dalgaranga Project has a Proved and Probable Reserve of 16.9Mt @ 0.9 g/t for 501,800 oz Au (ASX release 3rd October 2019).

Challenges

BVI poly-pipe was not accurately accounting for blast movement due to highly complex and narrow veined nature of the ore body

• Significant gold bearing material sent to waste dump (ore loss) and waste being put through the mill (dilution)
• Blast Vector Indicators (BVI’s) were both underestimating blast movement at the surface and providing no information for blast movement at depth
• Lack of visual distinction between ore and waste meant that this couldn’t be corrected in the field during ore block mark up

Solution

The BMT system allowed Dalgaranga to accurately translate pre to post blast dig lines as a result of blast movement

• Blast movement monitors (BMMs) are installed in monitoring holes throughout the shot
• installation and detection as per site standard operating procedures
• BMM Explorer software calculates new dig lines for each flitch, and areas of ore loss and dilution that would have occurred without monitoring

Results

In one blast alone, Dalgaranga recovered an additional 2,874 t of ore valued at AUD $151,522 that otherwise would have been sent to the waste pile had blast movement not been accounted for.

• Measured horizontal movement ranged from 1.7-10.3
• Measured vertical movement of up to 3m
• Reduction in dilution of over 25%
• Recovered an additional 2,874 t of ore valued at AUD $151,522

Blast Movement Ore Loss per Blast Dilution
Avg Grade Ore Loss Value Dilution Value
%, gm/t, Tonne % AUD Tonne % AUD
0.8 2,874 t 19 % 151,522 3,823 t 25 % 40,136
Total Ore Recovered $151,522

Stated assumptions
– Grade of Waste material < 0.2 g/t
– Gold price = AUD$2150/oz
– Density of rock = 2.2 t/m3
– Average grade = 0.8 g/t
– Mill Recovery = 88%

Top Flitch

Bottom Flitch

* Numbers are rounded
** Avg grade of ore bodies 0.8g/t
*** Calculated at a metal price of AUD $2150/oz

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