Liberty Gold Reports Weighted Average 79% Extraction in Bulk Sample Column Testing at Black Pine Project, Great Basin, USA

Liberty Gold Corp. is pleased to report results from Bulk Sample metallurgical testing on oxide material from its Black Pine Project in southeastern Idaho, providing support for a simple heap leach mining scenario. Gold extractions from six, 300 kilogram (“kg”), large-diameter column tests were rapid, and >80% of the leachable gold was extracted within 10 days, with final column leach gold extractions ranging up to 92.8%. 

Metallurgical test work included fine and coarse bottle rolls and column tests using material ranging up to 3 inch particle size. In total, 12 bottle rolls (six coarse mesh and six fine mesh) and six column tests were carried out on six bulk samples obtained from backhoe trenching of bedrock exposed on ramps in five historic pits and one drill target at Black Pine.

Results from the metallurgical test work demonstrate that oxide material from Black Pine responds well to column testing and will contribute to low capital and operating costs in the future.  The test work undertaken on the project has significantly mitigated the metallurgical risk related to the known mineralization. 

The work was supervised by independent consulting metallurgist Gary Simmons, formerly the Director of Metallurgy and Technology for Newmont Mining Corp. Mr. Simmons has managed or supervised a significant number of metallurgical testing programs on similar deposits throughout the Great Basin.  According to Mr. Simmons, “Data from metallurgical testing to date at Black Pine point to rapid leaching and relatively high gold extractions and suggest that a combination Run of Mine and coarse crush/agglomeration heap leaching may be the preferred process option at Black Pine.”

Table 1: Column Test and Bottle Roll Results, Liberty Gold Bulk Samples and Historical Data

In addition to the recently-complete bulk sample testing by Liberty Gold, the project benefits from metallurgical data generated in 1988 by Noranda Mining. Similar laboratory and processing methods were used, allowing for a direct comparison with the Liberty Gold program.  Noranda used eight samples derived from three bulk samples and five composites from drill core were used for the study.  The weighted average for Noranda fine bottle rolls was 84.1%, although this result was skewed by one 10.9 gram per tonne gold (“g/t Au”) sample.  The arithmetic mean was 79.9%.  The weighted average of 17 column tests at various feed sizes was 80.8%, similar to the results generated by the Liberty Gold program.

Metallurgical Program
Samples for this study were obtained through backhoe trenching of bedrock exposed on ramps in the five historic pit complexes at Black Pine, with one sample obtained from a drill road near the historic CD pit. 

For a map showing locations of drill holes used for metallurgical testing, please click here:
https://libertygold.ca/images/news/2020/June/BlackPineMetPRmap.pdf.

1000 kilogram bulk samples were sent to Kappes, Cassiday and Associates in Reno, Nevada for metallurgical testing, comprising bottle rolls, column testing and metallurgical characterization, including gold and silver assays, cyanide solubility, sulphur and carbon speciation, preg-rob analysis, ICP geochemical assays and whole rock analysis.

The Liberty Gold bulk samples were leached for 100 days in 300 mm (12 inch) diameter columns at low strength, 0.50 grams per litre of sodium cyanide (“NaCN”) solution. The A pit, BX Pit and Lower F Zone pit samples were agglomerated with up to 2.0 kg per tonne of cement due to elevated clay content. (Leaching time for the Noranda samples was up to 65 days, and two of the samples were agglomerated.)

Samples for bottle roll testing were milled/crushed respectively to 80% passing 200 mesh (75 microns) and 80% passing 10 mesh (1.7 mm) particle size.  The samples were rolled/agitated in bottles in a 1.0 grams per litre dilute cyanide solution for 72 hours (for 200 mesh) or 144 hours (for 10 mesh).

Liberty Gold bulk samples exhibited a range of extraction values, up to 92.8%, with rapid extraction in the first ten days of leaching.  The range in values and variability is consistent with that obtained by Noranda in a larger program in 1988.  The samples are now undergoing detailed mineralogical and gold deportment study to determine how the gold and gangue minerals are distributed in the rock, with particular attention to the I pit sample with reduced gold extraction at higher particle sizes.

ABOUT BLACK PINE

With its excellent jurisdiction, simple metallurgy and clear growth potential, Black Pine is one of the premium Carlin-style discoveries of the past decade.

Black Pine is located in the northern Great Basin, immediately adjacent to the Utah/Idaho border. It is a Carlin-style gold system, similar in many ways to the prolific deposits located along Nevada’s Carlin trend.  Like Newmont’s Long Canyon deposit, Black Pine represents a growing number of Carlin-style gold systems located off the main Carlin and Cortez trends in underexplored parts of the Great Basin.  The historic Black Pine Mine operated from 1992 to 1997, during a period of historically low gold prices, with 435,000 ounces of gold produced from five composite, shallow pits, at an average grade of 0.63 g/t Au.

A virtual site tour and 3D model of Black Pine property, including details about the geology and mineralization, is available on the homepage of the Company’s website, www.libertygold.ca.

ABOUT LIBERTY GOLD
Liberty Gold is focused on exploring the Great Basin of the United States, home to large-scale gold projects that are ideal for open-pit mining.  This region is one of the most prolific gold-producing regions in the world and stretches across Nevada and into Idaho and Utah.  We know the Great Basin and are driven to discover and advance big gold deposits that can be mined profitably in open-pit scenarios.  Our flagship projects are Black Pine in Idaho and Goldstrike in Utah, both past- producing open-pit mines, where previous operators only scratched the surface.

For more information, visit www.libertygold.ca or contact:
Susie Bell, Manager, Investor Relations
Phone: 604-632-4677 or Toll Free 1-877-632-4677
info@libertygold.ca