43-101 2008 Technical Report On The La Fortuna Project, Durango ...
43-101 2008 Technical Report On The La Fortuna Project, Durango ...
43-101 2008 Technical Report On The La Fortuna Project, Durango ...
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Mineral reserves for this study were reported using a 0.15g/tonne Au operating cut-off grade. Blocks<br />
within the optimum pit with grades less than 0.15g/tonne Au would have to be mined, but would be<br />
considered as waste.<br />
14.2.5.1 Reserve Cut-off Grades<br />
<strong>The</strong>re are several different types of cut-off grades. During the pit design process when one is determining<br />
whether a block will be mined and processed, an operational cut-off grade is used. This is the grade at<br />
which revenue exceeds mining and processing costs. For the base case, $625 gold price scenario, the<br />
operational cut-off grade was 0.22 grams Au per tonne.<br />
<strong>On</strong>ce the pit limit has been decided, it follows that everything within the pit must be mined. In other<br />
words, mining costs are sunk and the decision shifts to whether a mined block will be sent to the mill or to<br />
the waste pile. <strong>The</strong> processing cut-off grade is the grade at which revenue exceeds only the processing<br />
costs. For the base case, $625 gold price scenario, the processing cut-off grade was 0.15 grams per tonne.<br />
<strong>The</strong> following tables are the undiluted reserves results of the pit optimization based on various gold prices:<br />
Undiluted Reserves at $550 per Ounce Gold<br />
Overburden Tonnes 12,100,000<br />
Oxide Below 0.15 g/tonne* 11,100,000<br />
Subtotal, Waste Rock 23,200,000<br />
In-Pit Proven and Probable Reserves<br />
In-Pit Inferred Resources<br />
Cut-off Tonnes Average Cut-off Tonnes Average<br />
Grade Above Grade Grade Above Grade<br />
(g/tonne) Cut-off (g/tonne) Ounces (g/tonne) Cut-off (g/tonne) Ounces<br />
0.15 40,000,000 0.53 680,000 0.15 35,000 0.32 400<br />
Undiluted Reserves at $575 per Ounce Gold<br />
Overburden Tonnes 12,800,000<br />
Oxide Below 0.15 g/tonne* 11,800,000<br />
Subtotal, Waste Rock 24,600,000<br />
In-Pit Proven and Probable Reserves<br />
In-Pit Inferred Resources<br />
Cut-off Tonnes Average Cut-off Tonnes Average<br />
Grade Above Grade Grade Above Grade<br />
(g/tonne) Cut-off (g/tonne) Ounces (g/tonne) Cut-off (g/tonne) Ounces<br />
0.15 42,400,000 0.52 707,000 0.15 41,000 0.32 400<br />
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