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By Shane Lasley
Mining News 

Bornite cobalt resource weighs in at 77M lb

Adds to 6.4B lb of copper at growing Northwest Alaska deposit


Last updated 6/15/2018 at 4:09am

Trilogy Metals' Bornite copper cobalt deposit Northwest Alaska

Trilogy Metals Inc.

The historic headframe rises above the exploration camp at Bornite, where historical and recent drilling has outlined a growing deposit in Northwest Alaska with roughly 6.4 billion pounds of copper and 77 million lb of cobalt.

The Bornite deposit at Trilogy Metal Inc.'s Upper Kobuk Mineral Projects in Northwest Alaska contains 77 million pounds of cobalt, according to a maiden resource estimate published by the company on June 5.

This significant cobalt resource, among the largest in North America, is a by-product to the roughly 6.4 billion lb of copper that has been outlined so far at this world-class deposit in the Ambler Mining District.

Trilogy Metals anticipates that a US$10 million exploration program currently underway at Bornite will significantly increase the pounds of both of these increasingly important energy metals.

"(W)e expect to continue to grow both the copper and the cobalt resources with an 8,000- to 10,000-meter drill program of in-fill and resource expansion drilling about to get underway during the summer field program in Alaska," said Trilogy Metal President and CEO Rick Van Nieuwenhuyse.

Cobalt resource

Like the current copper resource for Bornite, Trilogy utilized assay data from holes it drilled between 2011 and 2013 and re-sampled historical holes drilled by Kennecott in the 1960s and 1970s.

A 2016 resource calculation for Bornite used a 0.5 percent copper cut-off grade for the near-surface portion of the deposit being considered for open-pit mining and a 1.5 percent cut-off for the deeper, higher grade mineralization.

The Bornite open-pit contains 40.5 million metric tons of indicated resource averaging 1.02 percent (913 million lb) copper; and 84.1 million metric tons of inferred resource averaging 0.95 percent (1.77 billion lb) copper.

The underground portion contains 57.8 million metric tons of inferred resource averaging 2.89 percent (3.68 billion lb) copper.

Likewise, the cobalt resource for Bornite was calculated for proposed open-pit and underground mining.

The Bornite open-pit is now estimated to contain 124.6 million metric tons of inferred resource grading 0.017 percent (45 million lb) cobalt.

The underground section is estimated another 57.8 million metric tons grading 0.025 percent (32 million lb) cobalt.

Combined, Bornite is estimated to host 182.4 million metric tons of inferred resource averaging 0.019 percent (77 million lb) cobalt.

"We are very pleased to report an initial 77 million lb cobalt resource for our Bornite project," said Van Nieuwenhuyse.

Results from Trilogy's on-going metallurgical studies indicate that roughly 80 to 90 percent of the cobalt occurs as cobaltiferous pyrite, which preferentially reports to the tailings after the copper is extracted.

"This is great because forming a pyrite concentrate from the copper tails should be relatively straight forward using flotation or dense media separation," said Van Nieuwenhuyse. "In the next few months we will complete flotation test work to concentrate cobalt into a pyrite-rich product that can be considered for further upgrading and recovery of cobalt metal at the Bornite site."

More cobalt, copper

The 77 million pounds of cobalt in inferred resources, places at Bornite reported below is one of the largest cobalt resources in North America.

For comparison, Fortune Minerals Ltd.'s NICO project in Northwest Territories hosts 33.1 million metric tons of proven and probable reserves averaging 0.11 percent (82.3 million lb) cobalt in a deposit that also hosts gold, bismuth and copper.

"Based on market comparable we believe cobalt adds significant value for our shareholders," said Van Nieuwenhuyse.

The shareholder value is expected to get a further boost when large expansions of the Bornite deposit are brought into the copper and cobalt resources.

A US$10 million drill program carried out last year demonstrated that the underground portion of Bornite covers a 1,500- by 2,500-meter area beyond the previously defined resource. All holes drilled to the target depth in this expansion area tapped copper and cobalt mineralization, indicating a significant increase in both metals the next time a resource is calculated.

The holes, however, are too widely spaced to calculate a resource for the copper and cobalt in this expansion area.

The wide spacing of the holes was largely due to the fact that South32 Ltd., a coal and base metals miner spun out of BHP Billiton, was more interested in gaining an understanding of the extent of the Bornite mineralization than calculating the resource there.

Early last year, South32 cut a US$150 million deal with Trilogy to earn up to a 50 percent joint venture interest in the Upper Kobuk Mineral Projects.

To keep this option open on UKMP, South32 agreed to invest US$10 million a year on the project over a three-year span, funds that have been spent so far on expanding Bornite.

This year's US$10 million program is expected to include at least 8,000 meters of drilling to in-fill and expand upon the area outlined during 2017.

"We look forward to reporting an updated copper and cobalt resource, along with results of further metallurgical test work, once the work has been completed," Van Nieuwenhuyse said.

Critical cobalt

Due to growing demand, lack of domestic mines and unreliable overseas supply, the United States Geological Survey has listed cobalt as one of the 35 minerals critical to the U.S.

In its annual report, Mineral Commodity Summaries 2018, the United States Geological Survey forecasts that the rechargeable battery sector is expected to drive the demand of cobalt higher and faster than the mining sector will bring new supplies of the battery metal to market.

The U.S. currently relies on overseas sources for 75 percent of its current needs, a dependence that is further complicated by the fact that the Democratic Republic of Congo (DRC) supplies more than half of the world's mined cobalt.

Bornite cobalt exploration drill map Ambler Mining District Alaska

Trilogy Metals Inc.

"With the market interest in finding cobalt resources outside of the Congo – where child labor and worker exploitation have been highlighted by Amnesty International and others as problematic for the auto and electric battery industries, defining a large, North American cobalt resource has become a priority for the company," the Trilogy CEO added.

For more information on cobalt and where it can be found in Alaska, read Critical Minerals Alaska – Cobalt, published in North of 60 Mining News on May 25.

Editor's Note: This article was corrected to read "The Bornite open-pit contains 40.5 million metric tons of indicated resource averaging 1.02 percent (913 million lb) copper" at 8:15 am (Alaska time) June 8, 2018.

Author Bio

Shane Lasley, Publisher

Over his more than 11 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.

Email: [email protected]
Phone: (907) 726-1095


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