Timberline Announces Positive Metallurgical Test Results From Its Talapoosa Gold Project - Seite 2

Saturated permeability was measured in laboratory testing on each coarse fraction under load pressures simulating 200 feet of leach pad height. Compared to the rate of leachate solution to be applied on the heap leach pad as proposed in the PEA, these permeability test results indicate that, on average, the heap leach pad would maintain acceptable levels of permeability at more than 20 times the anticipated application rate of the leachate solution. Based on these results we have concluded that permeability of the heap leach pad for the coarse material is very good.

Column Leach Testing

Two column leach tests of agglomerated coarse material are on-going. To-date, cumulative gold and silver extracted in the leachate solution indicates that recovery trends closely parallel those generated in previous column tests by Gunpoint upon which recoveries were predicted in the PEA (Figure 1). Based on positive recovery slopes and the previous leach trends, it is anticipated that gold recoveries will match or exceed the PEA estimates of 65% for the BCHW zone and 59% for the BCFW zone. The column tests will continue until recovery curves flatten. Silver recoveries also parallel previous trends.

Figure 1. Interim Gold Leach Rate Profiles, Column Leach Tests of Agglomerated BCFW and BCHW Coarse (+75um) Material

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A separate column test of agglomerated fine material is currently leaching and demonstrates accelerated leaching of gold through the initial 10 days (Figure 2). The recovery of gold is estimated to be approximately 80% for gold and 55% for silver, based on extracted solution and head grades.

Figure 2. Interim Gold Leach Rate Profiles, Column Leach Tests of Agglomerated Composite of BCFW and BCHW Fine (-75um) Material

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Bucket Leach Testing

In addition to the on-going column tests on the coarse and fine material, bucket leach tests have been completed on the fine fraction of the combined BCHW and BCFW material to test potential vat leaching of gold and silver.

Final gold and silver leach results after 7 weeks of testing indicate recovery of approximately 82% of the gold and 60% of the silver in the BCHW fine material and approximately 68% of the gold and 66% of the silver in the BCFW fine material (Figure 3). Most of the recovery occurs within the initial 48 hours of leaching.