how many ounces, page-2

“How many ounces will test produce.
my est =3000 @10g ???”

I think we might be able to expect head grades of around 15g/t (roughly 20% higher than jorc uncut grade) if they take representative samples across the entire deposit. I explained below how I arrived at that based on the reduced mining widths (less dilution) being achieved in trial mining.
15g/t on 10,000t would yield 4,500oz assuming 95% recovery. That would return $6.8mill to the bank balance at A$1500 gold. They may instead take larger samples from more important areas such as GH, WL and the central OP area and less from the less important lower grade areas like Old Glory. If they do so then we might see more than 4,500oz recovered, especially if GH makes up a higher proportion of trial mined ore.


What head grades might be expected from reduced mining widths during commercial mining?
The uncut resource grade is 11.96g/t. IMO the uncut grade is going to be the better estimate. There is too much very high grade gold in this system for a top cut to be used for the purpose it was intended -to cut out infrequent, non representative high grades from a resource estimate. With OP, very high grades are typical so it is pointless to cut them. They will be there during production and they are representative of the deposit.
The 12g/t was estimated after diluting narrower veins out to at 1m. Less dilution is now being achieved suggesting diluted head grades on narrower veins will be higher than estimated for the resource. Based on that 12g/t is likely to be exceeded assuming the resource estimated grade was accurate. A previous announcement stated that mining widths well below 1m were being achieved.
A hypothetical 40cm wide vein at 30g/t within the vein diluted out to 1m would give a mined head grade of 12g/t.
If dilution is reduced to 0.8m mining width then the head grade would come in at 15g/t which is a 25% higher head grade (compared to diluting to 1m mining width).
If diluted to 0.7ms (typical of what appears is being achieved through trial mining), the head grade will be 17.1g/t or a 43% increase in head grade.
If diluted to only 0.6ms width, the head grade will be 20g/t or a 67% increase in head grade.
Darren said in today’s interview that mining widths were being achieved down to as low as 0.5m. On any veins less than 0.5ms wide with that reduction in mining width you would expect a 100% increase in head grade compared to a 1m mining width. These improvements in head grade only apply to veins narrower than the mining widths where there is dilution factored in on their grade estimates. Any vein averaging greater than 1m wide would see no improvement in mined grade over what was earlier estimated allowing for 1m minimum mining widths.
Going with the mid point at around 0.7m mining width; on any veins less than 0.7ms wide we can expect a 43% increase in head grade on those veins when they are mined allowing for diluted grade.
If 50% of the resource is made up of veins less than 0.7ms wide then a rough estimate would be that we could expect average head grade of the entire resource to be 21.5% higher than what was estimated to a dilution to 1m min mining width. 21.5% on top of 12g/t would be 14.6g/t.
While reducing mining dilution increases head grade it does not increase the contained gold. However the benefits are two fold. First the processing costs are reduced as less material is processed for the same gold output so profit margins per oz increase. More importantly, with the same size plant you would get (in the above example) 21.5% more gold production per year which translates to 21.5% higher revenue and much better than 21.5% higher profit each year (greater revenue with lower processing costs and same fixed costs such as admin and exploration). A 21% increase in revenue on a smaller throughput rate during stage 2 at 150ktpa (where fixed costs are a greater proportion of total cost), could lead to a 50% increase in net profit. On a 300ktpa operation where admin and exploration are a smaller proportion of total costs, a 21.5% increase in revenue might lead to a 30% increase in profits.
This just shows a range of possibilities. Actual improvement of mined head grade, annual revenue and profits (compared to what would have been expected for 1m minimum mining widths) will depend on average mining width achieved on narrow veins across the entire resource and on what proportion of the resource is made up of these narrow veins. This is only meant to be a look at the possibilities not a forecast.