HighGold (TSX-V:HIGH, OTCQX:HGGOF) Mining Inc has announced positive metallurgical test results for the Johnson Tract (JT) polymetallic gold project in southcentral Alaska.
The project hosts the high-grade polymetallic (Au-Zn-Cu-Pb-Ag) JT Deposit with a 0.75 million ounces (Moz) gold equivalent (AuEq) indicated resource at 10.9 grams per ton (g/t) AuEq and a 0.13Moz AuEq inferred resource at 7.1 g/t AuEq. An updated and expanded mineral resource estimate for the JT Deposit is expected to be delivered before the end of the second quarter of 2022.
"We are very pleased with these metallurgical results, which demonstrate excellent metal recoveries to high-quality concentrate products," HighGold Mining president and CEO Darwin Green said in a statement. "Metallurgy is critically important to understanding the potential economics of a mineral project and these new results, which corroborate and enhance decades-old historic data, are an important step in de-risking the JT Project and laying the foundation for future engineering and economic studies.”
READ: HighGold Mining unveils plans for US$9M exploration program at Johnson Tract project, Alaska
“In addition to producing gold-enriched base metal concentrates that are highly attractive for the global smelting market, the program was also successful in producing a saleable high-grade gold concentrate. The ability to produce a separate gold (pyrite) concentrate provides processing optionality with the added environmental benefit of generating tails that contain very low-sulphide content," added Green.
The company said the polymetallic JT deposit exhibits an excellent response using conventional metallurgical techniques. Locked cycle flotation tests yielded very high-quality copper, zinc, lead and gold concentrates produced at a coarse primary grind with very good metal recoveries, low impurities and negligible penalty elements.
Highlights include:
- Gold recovery of 97.2% combined total of payable gold to concentrates and leaching of tails
- Zinc recovery of 92.3% to a concentrate grading 52.6% zinc
- Copper recovery of 84.5% to a concentrate grading 30.6% copper
- Lead recovery of 72.4% to a concentrate grading 62.1% lead
- Gold pyrite concentrate grading 64.3 g/t gold
The metallurgical test program was completed by Blue Coast Research Ltd, a leading metallurgical testing and consulting firm based in British Columbia, and the testwork was completed on a master composite sample prepared from approximately 180 kg of one-half sawn HQ drill core from two dedicated holes, JT21-125 and JT21-134, drilled into the JT Deposit mineral resource in 2021. The master composite has a head grade of 11.85 g/t gold, 6.2 g/t silver, 0.52% copper, 5.13% zinc, and 1.27% lead.
The program included mineralogical analysis, comminution testwork, flotation optimization testwork, locked cycle testwork, cyanidation of rougher tails and cleaner concentrates for global gold recovery, and follow-up mineralogical analysis of concentrates and tailings for deleterious elements.
Mineralogical analysis of the master composite showed that primary sulphide minerals are sphalerite, pyrite, chalcopyrite and galena. Pyrite, sphalerite and chalcopyrite all show very good liberation, with galena showing moderate liberation.
All concentrates met target grades for the metal of interest and recoveries were overall very good. Gold concentration is at payable levels for all concentrate products, including the zinc concentrate, with a majority reporting to the copper, lead and pyrite concentrates where pay-ability is highest. Low levels of deleterious elements and impurities were detected in the final concentrates and no penalties are expected for any of the concentrate products based on current smelter contract standards.
Estimated total payable gold recovery is 97.2%. For the purpose of calculating total payable gold recovery, it is assumed that the gold concentrate will be sold (not leached) and all final tails products (Au Rougher tails plus Zn and Au cleaner tails) will be combined and leached together at 81% recovery.
Additional metallurgical test work is ongoing to assess JT Deposit variability including the evaluation of other mineralization styles such as the footwall copper zone.
Summer exploration program planned
The company recently announced plans for a US$9 million summer exploration program for the project, including a minimum of 13,000 meters of diamond drilling with two drill rigs, geological mapping, prospecting and geochemical sampling programs, airborne drone-magnetic surveying, the commissioning of a new onsite sample preparation facility to reduce assay turnaround times, and preliminary engineering and baseline studies. One-third of the planned drilling will focus on infill and step-out drilling on the JT Deposit, while the remaining two-thirds will follow up on the new high-grade DC Prospect Discovery
The Johnson Tract project is located near tidewater, 125 miles southwest of Anchorage in Alaska. The 21,000-acre property includes the high-grade JT Deposit and at least nine other mineral prospects over a 12-kilometer strike length.
The JT Deposit hosts an Indicated Resource of 2.14 million tons (Mt) grading 10.93 g/t AuEq comprised of 6.07 g/t Au, 5.8 g/t Ag, 0.57% Cu, 0.80% Pb and 5.85% Zn. The Inferred Resource of 0.58 Mt grading 7.16 g/t AuEq is comprised of 2.05 g/t Au, 8.7 g/t Ag, 0.54% Cu, 0.33% Pb, and 6.67% Zn. Prior to HighGold Mining, the project was last explored in the mid-1990s by a mid-tier mining company that evaluated direct shipping material from Johnson to the Premier Mill near Stewart, British Columbia.
HighGold is a mineral exploration company focused on high-grade gold projects located in North America. Its flagship asset is the high-grade Johnson Tract Gold (Zn-Cu) Project located in Southcentral Alaska, USA.
Contact the author at jon.hopkins@proactiveinvestors.com