Testing shows promise for Bornite cobalt
North of 60 Mining News – March 8, 2019
Last updated 9/25/2020 at 2:17pm
Trilogy Metals Inc. March 5 reported promising results from additional copper and cobalt metallurgical results for the Bornite project in the Ambler mining district of Northwest Alaska.
According to a 2016 calculation, the Bornite project hosts roughly 6.4 billion pounds of copper and 77 million lb of cobalt. These metal quantities, however, are expected to rise when an update resource calculation currently underway is complete.
Nine samples from drilling over the past two years, representing a wide range of grades from both the open-pit and underground portions of the Bornite deposit, were analyzed in the latest round of metallurgical testing for Bornite.
In addition to furthering the analysis on the recovery of copper into a saleable concentrate, this metallurgical work investigated the potential for recovering cobalt in a second concentrate.
Using traditional grinding and flotation processes, this testing recovered an average of 89.7 percent of the copper in the nine samples into a copper concentrates that contained an average of 27.6 percent copper.
Most of the cobalt in the Bornite deposit in attached to the pyrite found there. This cobalt-rich pyrite is largely discharged as tailings after the copper is recovered.
In order to produce a cobalt-rich concentrate, an additional flotation stage was added to recover pyrite from the copper flotation tailings. This pyrite concentrate was subsequently cleaned to produce a pyrite concentrate.
This added step to the recovery process demonstrates that roughly 60 percent of the contained cobalt can by recovered into pyrite concentrate containing 700 to 4,500 grams per metric ton cobalt.
"These initial metallurgical test results continue to demonstrate that conventional processing technology is expected to produce a clean, very high-quality, copper concentrate over a wide range of typical open-pit and underground copper grades," said Trilogy Metals President and CEO Rick Van Nieuwenhuyse. "I also note that we are very pleased with the first pass cobalt results which show that the Bornite project could recover between 50 and 70 percent of the contained cobalt to a high-quality pyrite concentrate."
Trilogy said it intends to carry out further optimization work on the copper recoveries and is planning the next stage of work to determine the optimal method to recover cobalt from the pyrite concentrate.
"The next steps include finding out if the cobalt concentrate can be further processed into a saleable product," Van Nieuwenhuyse added.