RE: Havieron August 202428 Aug 2024 10:25
My repost
“3mt mining plan by stoping
Each stope is 30x30x50=45,000m cubed
3 specific gravity = 135,000 ton
3mt divided by 135k =22 stopes required
There are around 10 stopes that can be worked on one level, therefore at least 3 levels need to be worked on in the first year.
Paste backfilling and curing needs to be completed before the in between stopes can be worked on.
More levels therefore are needed lower down to be opened up for stoping.
After about the sixth level there are less stopes per level so the pace of opening up more levels lower down quickens.
Introducing a hoist for the top 600m could be 2 years away before commissioned therefore will be too late for the top levels so the hoist needs to go lower maybe lower than the original mining plan to say 1200m of ore.
3mt extraction = 8,219 t per day
This is 17 days to empty one stope
A 40t truck can carry around 27ton when a 30% bulking factor is taken into account, so therefore 304 truck loads per day are required.
To get 6mt per year by truck would need 610 loads per day and need at least 45 stopes per year.
That’s nearly half way down the ore body and the next year down to the bottom of the ore body.
Decline to get to 750m depth of ore ( the original plan depth) @1:7 @6m per day = 880 days or 2.5 years.
That doesn’t include the infrastructure drives to the stopes.
In conclusion in my opinion 3mt is a maximum limit on the Decline trucking and of the original mine plan.
6mt is not an option on this shaped ore body with stoping and a hoist would not help in this instance.
However the FS is looking to optimise the current plan.
My thoughts on this is to take in more high grade pods in the top levels this will increase the life of mine but keeping it at 3mt.
Introduce bigger stopes reducing the number required for each year.
Allows time for the Decline to be completed and installation of a hoist for subsequent SLC operations under the slope of the Dyke ( the footwall)”