Hi spid81 happy to debate this...
Strip Ratio
High strip ratio along with higher cut off grade reduce capex cost...Separate your mining level cost to mill level cost...Keep in mind at mining level the operation is a daily cost while Mill level is an upfront cost....Start up Capex of plant.
Quality is a consideration in strip ratio.If a deposit contains low grade quality ore more of it must be mined in order to achieve a return on investment. A higher grade deposit can support a higher strip ratio. There is an inverse relationship between deposit grade and strip ratio. The higher the grade inversely reduces plant capex and ROM of mine.
The higher the grade inversely reduces plant capex and ROM of mine
Walkabout Resource
raised there strip/ratio level from 2:1 of previous DFS now to 4.4:1 over life of mine...At the same time they increased the cut off grade...There is little point raising strip ratio if you can not increase the cut off...10% TGC below this is now considered to be waste material of no value...
4.4 plus 1 Tons of material are moved for 1 ton of concentrate...Importantly the concentrate of value is all greater than 10% TGC...We have 24 year life of mine with 17.9% TGC average
Previously with out the high grade extension from surface our strip ratio was 2:1 while cut off was lower...
Increase the strip ratio increase the cut off and only process higher grade material...
The rest is treated as reserves....
Why would they do this....?
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Only Walkabout Resource can do this which may explain why some posters have failed to grasp the
select mill feed strategy...
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While other projects have lower strip ratio they also have a low uneconomical cut off....IMO
From my previous Strip ratio post mining level activity varied from $13-25 dollars per ton of material moved...To max this out an 7:1.1 would only cost $200 per ton of feed concentrate at a grade of greater than 10% TGC....
Where it matters is capex of plant...
Thru put and high feed grade advantage....
Project A
1000 tons x 5 % TGC with LOM 2:1 strip ratio and cut off at 2 % TGC and LOM at 3.3% TGC
with recovery at 90% yield...29.7 tons
Mining level cost $75 (3 x 25)
Project B
1000 tons x 20% TGC /LOM 4.4:1 strip ratio and cut off at 10 % TGC /LOM at 17.9% TGC
with recovery at 90% yield...161 tons
Mining level cost $135 (5.4 x 25)
Scale this up and it is there for all to see the intrinsic value of high strip/ratio higher cut off advantage projects....We treat grades of 10% TGC as waste not ore which is expensive to process...projects to date have not secured funding with capex to high...
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Our project starts in high grade with only 10 meters of over burden for life of mine at an 8 % cut off...
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Croc
(20min delay)