NVA (ASX) Why Good Grades are Important

Originally posted by arkus: ↑

The TOMRA XRT 2.0 sorting machine can sort particles of up to 100mm at a rate of 1000 tph for one machine.

Navchabs sorting line is up for 80-90 percent of the time and has been running since 2016. The Navchab mine uses a cut off of 1.5, with particle size of 20-30mm at a sorting rate of 200 tph (tonnes per hour):

We have currently 0.3 grams per tonne, for 4.7 ,million OZ.

A TOMRA XRT 2.0 can sort 1000 tph with particle size of 100mm

Assuming the machine runs for 20 hours per day, it can sort 20,000 tpd.

@ 0.3 that is 190 oz per day, or 68000 oz per year (rough calculations)

So if Estelle had two TOMRA XRT 2.0 ore sorting machines, that would be 68000 (per machine) x 75% (recovery rate) x 2 machines = 102000 oz per year.

I still think this is a reasonable rate of initial production and we Probably better if the resource size comes down, becomes indicative and the grade goes up.

1 million 0Z at 0.5 grams per tonne would give an initial mine life of 10 years.

Using ore sorting to bring up the cutoff grade actually means that a lot more earth has to be moved:

518 million tonnes of earth for 0.15 g/t and a 4.7 moz resource

vs

57 million tonnes for cutoff of 0.45 g/t 1.1 moz resource

They are using the "idea" of the ore sorting tech to bring up the inferred resource, when the indicated and feasible could actually be a LOT lower.

I am struggling to work out if our resource has actually really grown at all, or if they have just found a way to bring the "possible" cutoff rate down, so to give themselves more options / cash / wealth. The low-grade resource has increased (1.5 cuttoff / 0.18 cutoff), whilst the resource at the upper grade is has actually come down / been diluted:

from 4.7 million upgrade

from maiden 2.5 million announcement:

@kduvey

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I honestly don't think we can speculate as to the economics of this project.

it is entirely going to be determined by how much gold there is, and that is still being understood to the detriment of the scoping study timelines.

no one wants to leave money on the table, and 10 year mine life vs 20, 30 or 50 year mine life will be a major determining factor.

if we can prove up the district rather than just Korbel alone, which is what we have at the moment, or Korbel and RPM, and potentiality a third prospect will be entirely different economics.

as will be if we can truck stuff in via a year round road vs flying it in. What about if we can (autonomous?) VTOL things like fuel and other things in via RotorX?

also, we need to consider how much money have, or us and our JV partner will have.

the final (but not really) consideration is the price of gold. At the point where it makes sense to process to a particular grade is entirely dependent of profitability. With POG expected to move back towards all time highs, are we really going to potentially throw away 0.1g or more per tonne? I don't think so.

I think we need to figure out how much gold we have, and the economics surrounding the project, until then it's harmless speculation.