Positive Initial Metallurgical Results From Stardust Project

VANCOUVER – NorthWest Copper Corp. reported positive results for initial metallurgical test work on its 100% owned Stardust copper-gold project in BC. Combined gravity and flotation produced copper recoveries from 94.2% to 98.6% and gold recoveries from 93.0% to 93.9%. Those tests produced copper in concentrate grades from 21.8% to 26.2%. These strong results further enhance the high-grade Stardust deposit.

Peter Bell, President & CEO, said, “These exciting positive results support the advancement of our combined Stardust and Kwanika project. High grades, strong recoveries and a simple flowsheet provide a foundation for the combination. We are finalizing an initial Stardust resource in the next several weeks which will help underpin our unique high-grade copper-gold project.”

Three composites were tested: low, medium, and high grade. Tests were conducted with the high-grade composite including gravity, flotation optimization, rougher kinetics and grind size, then batch cleaner tests. Finally, the low and medium grade composites were tested using parameters from the previous tests. These tests used a primary grind size of 150 microns with a 40 to 50 micron regrind, gravity and flotation.

Test work shows copper recovery had limited sensitivity to grind sizes between 75 and 150 microns. Gold showed much higher recoveries at 75 microns vs. 100 or 150 microns but the inclusion of a gravity circuit appears to remove the need for a finer primary grind. The inclusion of the gravity circuit allows for a relatively coarse primary grind size of 150 microns. Gravity recovered between 24% and 42% of the gold in the three tests.

All test work was completed by Base Metallurgical Laboratories Ltd. in Kamloops, BC. Composites received were crushed and split into 2kg test charges. Samples were analyzed prior to testing. A scoping level metallurgical study was undertaken to evaluate the flotation response of three composites prepared to represent a gradient of feed grades. Testing optimized conditions using the high-grade composite; a series of three rougher kinetic flotation tests evaluated the sensitivity of primary grind before optimizing the cleaner circuit with a further five tests. A single cleaner test was performed for each of the low grade and medium grade composites applying established conditions used for the high-grade composite.

The final flowsheet used for testing included gravity concentration of gold by Centrifugal Gold Concentration (CGC) using a laboratory Knelson, followed by cleaning using a Mozley Table at 150 microns. The combined Knelson and Mozley tails were advanced to 10 minutes of rougher flotation, the rougher concentrate was reground to a target of 40 to 50 microns and cleaned, requiring 2 to 3 stages of dilution cleaning.