19 April 2017
TORONTO, ONTARIO--(Marketwired - April 19, 2017) - Nighthawk Gold Corp. ("Nighthawk") (TSX VENTURE:NHK) is pleased to announce encouraging preliminary results from its ongoing metallurgical test work program on the Colomac Gold project. Testing was completed at Bureau Veritas in Richmond, BC, and audited by Starkey & Associates Inc. in Oakville, Ontario. Three drill core bulk samples from various portions of the Colomac gold deposit were assayed and tested for grindability using the SAGDesign methodology. A master composite was then amalgamated from the bulk samples and used for additional metallurgical testing. Initial results indicate that gold recoveries of up to 96.5% may be achieved and the rock is amenable to all standard gold recovery technologies. This represents a significant increase in recovery over the historic production results of 88.1% (1994 to 1997). Additional testwork is expected to yield further optimization and confirmation of these results.
Highlights include:
• Variation in rock hardness of the three bulk samples was minimal indicating that the material is relatively homogeneous;
• The master composite sample, having a head grade of 1.81 grams per tonne gold measured by fire assay, generated favourable recoveries for all process options, including heap leaching, flotation, and gravity separation;
• Gold extraction by flotation ranged from 94.1% - 95.5% with maximum recoveries achieved at a feed size F80of 151 microns;
• Cyanide heap leaching of minus 12,700 micron material reported up to 81.8% gold recoveries, perhaps an option for lower grade material which would otherwise be considered waste;
• Cyanidation of ground rock increased gold recovery significantly up to 96.5%.
"Results from this initial metallurgical testing have significantly exceeded our expectations in comparison to Colomac's known historical recoveries", commented Nighthawk President & CEO, Dr. Michael Byron. "In particular, Colomac material shows excellent grind characteristics, exceptional gold recoveries and responsiveness to all standard gold recovery technologies, comparing favourably to similar projects in North America. It's also important to note that the rock is exceptionally clean as no deleterious materials were detected that could otherwise adversely affect processing, or impact the environment. We are very pleased with the initial results, and expect the final testwork to confirm these findings".