Historically the Yukon is most famous for the Klondike gold rush, but it was also the site of another major mineral discovery in 1918 that touched off its own stampede. This was the mighty silver deposit found in the Keno Hill Silver District, a discovery that would produce more paydirt than the Klondike and would eventually put the Yukon on the map for its silver too!
While those days have come and gone, the silver has not, nor has interest in the Keno Hill District for that matter, and that’s why companies like Alexco Resource Corp. are back in earnest to once again make the Yukon a world leader in the production of silver.
From its Bellekeno silver mine about 330 km north of Whitehorse, Alexco will soon bring back the glory days of the early 1900s by going into production this year with a mine containing more than 11,870,000 ounces of contained silver.
Knowing the silver is there is one thing, getting it out is another and that’s why Alexco’s team has spent thousands of hours and millions of dollars determining how much is there, where it’s located and what’s the safest and most economical way of extracting the silver from this historic site.
Since starting work at Keno in 2006, Alexco has driven in excess of 1100 m of new underground development, rehabilitated approximately 1500 m of existing development, drilled more than 350 diamond drill holes district-wide, totaling about 59,700 m on multiple targets (Historical and New Exploration targets), has flown 2,016 line km of airborne geophysics and has completed approximately 35,000 historical documents into a 300 gigabyte digital database/library of geological information.
In other words, they’ve done their homework and are now ready to “go for the silver.”
Because of the historical status of the Keno Hill District, permitting and other approvals were somewhat straightforward but Alexco still had to provide authorities with detailed reports on the historical Bellenko workings to enable an extensive underground resource drilling program as well as rehabilitate the historic infrastructure, re-establish mine ventilation and provide secondary escape.
As can be imagined, incorporating ancient workings into a new mine concept,
with new technologies, required extensive geotechnical study and assessment of ground conditions in the resource body to enable Alexco engineers to develop a strategy for ground control management.
The new mine will be ‘trackless’ because mining will be carried out using predominantly cut-and-fill mining methods augmented with some minor shrink stoping to optimize high-grade mineralization extraction and reduce dilution.
Mined-out stopes will be backfilled with a cemented blend of development waste rock and the pyritic component of dry filtered tailings backhauled from the process plant.
Milling and milling operations will be carried out year-round at a base-plan production rate of 250 tonnes per day.
Processing will utilize a standard lead and zinc differential flotation process incorporating dry stack tailings technology, with the processing plant carrying a design capacity of 408 tonnes per day. Average LOM recoveries are estimated to be 95.8% silver, 96.9% lead and 88.4% zinc to produce approximately 42,043 dry tonnes of lead/silver concentrate and 29,293 dry tonnes of zinc/ silver concentrate over the LOM.
Accounting for mining dilution and recovery, a total of 321,941 tonnes containing an estimated 871 g/t silver, 9.5% lead and 5.6% zinc on a payable metal basis are included in the LOM mining plan. The mining plan is based entirely on indicated resources. LOM metal production to concentrate is estimated to be approximately 8.6 million ounces of silver, 65.2 million pounds lead and 35.2 million pounds zinc.
Approximately 83,000 tonnes of zinc rich inferred resources in the mine’s lower East zone are not included in the mine plan, but represent a potential opportunity to expand the minable resource base depending upon definition drilling and future zinc prices.
Additionally, based on structural and stratigraphic studies combined with the extensive drilling carried out at the Bellenko deposit, a number of resource and exploration targets have been identified in areas within and immediately adjacent to the existing minable resource.
As stated at the outset, the Keno Hill Silver District put the Yukon on the map once and Alexco Resource Corp is determined to put it back there again because there’s still “silver in them, thar hills” and plenty of it!
Total construction and development capital to achieve commercial production is estimated to be C$41.6 million, including a contingency factor of approximately 16%.
PHOTO BY RICHARD HARTMEIER