Yesterday we did one of our largest blast's of the year in one of the offshoot pits.
In our big pit, it was common to have blasts ranging from 250,000 - 500,000 Tonnes.
Because this pit is a lot smaller, so are the blast sizes.
In the posted video you will see 14,000 kgs of emulsion going off in a precisely timed detonation, designed for maximum fragmentation of the rock.
When the video changes over to slow motion, you will see what I mean by precise timing.
Notice those flashes?
Those are the caps detonating in a planned pattern. Sending a charge into the explosives inside that drill hole, row by row.
Each drill hole is done in a particular fashion depending on the type of blast your looking for.
For a typical bench blast like this, we use a pattern called a 5 x 2.5
Which is 5 drill holes, each centered 2.5 meters apart from one another.
If I was to design the blast so each hole blew at the same time, we would get what's called a "Frozen" blast.
That means that the rock had nowhere to go.
And rather than breaking the rock up into a manageable size, there would be chunks the size of your house left behind.
Do you see the way the blast is being directed?
In front of the blast pattern, you will see a void.
That void is there on purpose. Its what we call a "Blast Face."
All that rock is being blasted, row by row, into the direction of the void.
Avoiding a freeze, and giving the rock space for it to blast into.
Once the blast smoke clears, I bring my drone down into the blast area and get a good look at the fragmentation.
Everything here looks great!
We have what's called an invisible ore body.
Meaning, unlike gold, which you can see in rock, you cant see our ore with the naked eye.
The only way to really tell what our ore grade is, is by bringing drill hole samples to our assay lab.
Based on those assay results, we determine how much dilution (Low-Grade Ore) we can allow in the pattern.
Im not even joking when I say this.
But I have a video from our first blast in that pit, that shows a fox hanging around the blast pattern.
We have about 10 foxes that hang around people here looking for handouts.
Well, the boom goes off and you can see the fox running for his life as the rest of the pattern explodes.
No one knew he was on the pattern until we reviewed my footage.
Poor little guy.
The combined amount of tonnes of loose rock is actually over 40,000 tonnes.
Each drill hole goes down 11.2 meters
We take the top 10 meters of loose rock and leave the bottom 1.2 meters as a subgrade.
Having a subgrade ensures we will have a flat bench once all the loose rock is mucked.
It adds difficulty to the drillers job when their floor is up and down like a moonscape
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