Nighthawk's latest metallurgy continues to show strong gold recoveries for Colomac

Nighthawk Gold Corp. is pleased to provide an update of the latest heap leach testwork from ongoing preliminary metallurgical studies on the Colomac Gold Project ("Colomac"). Four (4) bulk drill core samples collected in 2018 were previously submitted for SAGDesign, gravity concentration, flotation, bottle roll cyanide leaching, and column heap leach testing. Standard metallurgical test results for those samples were reported earlier (see press release dated March 19, 2019) and are referenced in this release which covers the 2018 bottle roll and column heap leach testwork findings.

Dr. Michael Byron, President & CEO commented, "Metallurgical studies completed to-date have continued to show that Colomac rock performs exceptionally well in terms of its grind characteristics, gold recoveries, purity, and responsiveness to all standard gold recovery technologies. Although our ongoing heap leach bottle roll and column tests are still at a preliminary stage, results show a favourable response to the deposit's heap leach potential.

"Standard metallurgical testing on four Colomac 2019 samples is almost complete. Additional heap leach testwork is also underway, which will then give us a total of ten bottle roll and nine column leach tests and will shed considerable insight into the ongoing assessment of the deposit's heap leach and primary processing potential."

Testwork Highlights:

• Testing to-date has shown that Colomac rock is amenable to all standard gold recovery technologies including, flotation, gravity separation, and heap leaching. 

• Minimal variation in rock hardness is noted for all test samples indicating a relatively homogeneous host rock across both sills. 

• Utilising a combination of gravity and cyanide leach recovery processes, testing has shown that gold recoveries for all samples tested to-date when ground to a size of 80% passing 106 microns, range from 96.3% to 98.0%. 

• Current column leach tests on the four 2018 samples posted gold recoveries that varied from 54.9% to 69.7% and averaging 59.4% for the 206 day run, representing an average increase of 9.6% in recoveries when the leach time was extended for an additional 3 months (~100 additional days)(Table 2). 

• Current bottle roll leach tests on four samples (minus half (½) inch crushed material ran for 10 days) posted gold recoveries between 31.5% and 49.6% with an average gold recovery of 44.3%. Samples of lower-grade and higher-grade material collected in 2016 and 2017 returned recoveries of 81.8% and 57.5% respectively (see press release dated May 22, 2018). 

• Cyanide heap leach results show considerable variability between testing methods and grade of material processed but fall within an expected performance range for crushed material (recoveries between 31.5% up to 81.8% in all samples tested to-date).