Further Considerations of Gold Production from Tailings
Previously, I estimated that the historical tailings discharge of Tailing Pond #2 from the Pine Cove Mill contained about 30,000 ounces of gold .
I have reviewed and see no reason to change that number.
The NR that contained tailings statistics provided sampling grades of 8 cores from the Pine Cove mill tailings discharge and an amalgamated sample of 11.4 grams per ton from the Aggregates wash plant.
The average grade of these 9 core samples is 5.8 grams per ton but with large variance from near zero to 1 ounce per ton.
Maritime planned further sampling but that info has yet to be released.
Setting that aside, the question remains as to how many tons of tailings are these gold fines contained.
The simplest way that I can arrive at this estimate is that, at the average grade availabe ..5.8 grams per ton..those 30,000 ounces would be contained in 160,000 tons of sedimentary discharge ( 30,000 ounces ** 31 grams / 5.8 grams ).
Being 6 times heavier than granite, I presme that most of the tailings gold fines would be at the bottom of the 1 meter sediment slury.
The grades provided might just be those , meaning that above this bottom zone , the gold content was very low .
It could be that by hydraulic dredging , only this bottom layer was selectively removed for storage on site at the Pine cove mill.
Ignoring that possibility, the Pine cove mill has a 1300 tpd milling capacity which means that it will take about 120 days to process the full tailings slurry ( 160,000 tons / 1300 tpd ) .
So about 4 months or so .
What is very interesting is that being already ground fines , its quite possible that gold recovery of 98 % could be achieved by just floatation.....see extract of mett NR below.
"The mineralization responds well to conventional flotation using potassium amyl xanthate and methyl isobutyl carbinol reagents, with over-95-per-cent gold recovery to a concentrate in only four minutes of laboratory rougher flotation time, and over 98 per cent by the conclusion of the test, with a mass pull of approximately 15 per cent. "
This means very little energy costs to mill these gold fines from Tailings ..and excellent recoveries .
Now, I only have access to early tailings grades and subsequent sampling may have significantly changed that .
But , as currently documented , we have a very significant tailings resource to keep the Pine Cove mill , including whatever can be scrounged from stockpiles.
Divide by 2 to be conservative , it amounts to about 15,000 ounces of low cash costs gold resources , most already ground to small sizes needing no further size reduction by the ball mills and quickly recoverable by just floatation .
AIMHO
GLTA