Crowflight’s Bucko Lake Project

The newest nickel mine in Manitoba is operated not by a global giant, but by tiny Crowflight Minerals Inc. The determination of the Toronto junior was responsible for developing a successful producer despite turmoil in the ownership of Canadian nickel assets and a global economic meltdown.

The C$110 million that Crowflight raised for the Bucko Lake underground mine and mill near the town of Wabowden has created a producer with this year’s projected cash costs of only US$4.80 to $5.25/lb and over 118 million lb of nickel in the ground.

Those are enviable numbers for a small producer in the Thompson Nickel Belt. Up to now the only player in the region has been Inco (now Vale Inco) with its mines and smelter in Thompson. The area did not go unnoticed by Canada’s other major nickel miner, Falconbridge (now Xstrata Nickel), but sometimes a project needs a nimble junior to get it off the ground, and that is exactly what Crowflight has done.

Crowflight was granted an option on Falconbridge’s Bucko claims in June 2004. The agreement was that Crowflight could earn 50% of the property by spending $25 million over five years during which time a bankable feasibility study would be completed. Crowflight secured a 100% interest in the property in July 2007, and moved the project forward to begin production in February 2009.

In 2004 when Crowflight took its option at Bucko Lake, there was a 12-year-old historical estimate that put the Bucko reserve block at 2.5 million tonnes grading 2.2% Ni and 0.2% Cu within a global resource of 19.0 million tonnes grading 1.0% Ni. Extensive exploration and drilling of the Bucko deposit over the last four years, put the NI-43-101-compliant estimate at 3.7 million tonnes grading 1.45% Ni in the proven and probable reserves category (1.25% Ni cutoff) plus measured and indicated resource of 2.8 million tonnes grading 1.53% Ni (1.0% Ni cutoff).

And what happened to the other 19.0 million tonnes described earlier as a “global” resource? It has become inferred resources in several other occurrences. Together the inferred resources already total more than 30.0 million tonnes.

Crowflight COO Paul Keller told CMJ he joined the Bucko Lake project in February 2005, a time when the previous exploration shaft was capped. He’s been in on the ground floor as it was rehabilitated and all the development work done. Preproduction costs ran $25 million for the underground work and $70 million for surface work and facilities.

Keller said that the company’s current licence allows the mining of 1.8 million tonnes at 1.9% Ni, but reserves total 2.4 million tonnes at 1.8% Ni. The deposit is open at depth and in the Hinge zone. Consequently, the project that currently has a seven-year life has “great potential for a longer life,” he added.

To extend the life of the mine, Crowflight may in the future boost tonnage and recover lower grade ore (1.4% to 1.5% Ni).

The Bucko Lake mine

The mining method chosen for the Bucko Lake mine is longhole open stoping with sublevel access on 30-metre intervals. Maximum stope dimension will be 20 metres wide by 20 metres long. Stopes will run parallel to each other and be mined along strike from the hanging wall to the footwall. Backfill will consist of development waste and cemented hydraulic fill delivered by drill holes and piping located along the ramp. The daily mining rate is 1,000 tonnes of ore plus 500 tonnes of waste.

There is a 340-metre shaft providing access to the active mining areas between the 450 and 500 levels and between the 1000 and 800 levels. The shaft has three compartments rigged with a skip, cage-under-skip, and a manway. There is a 2.4-metre-diameter Nordberg hoist installed. A ventilation raise connects the 1000 level to the surface; two, 200-hp fans have been installed to circulate fresh air. The 15% ramp is being extended to the 1900 level to access the lower portion of the orebody.

Underground mining is carried out under contract by Dumas Contracting of Timmins, Ont., using 20-tonne trucks, 4.5- m load-haul-dumpers, a pair of two-boom jumbos and Cubex longhole drills.

Commercial production was declared on June 10, 2009, from stopes between the 1000 and 900 levels, beginning in the South zone, then the North zone. Next year development will be carried out on levels above 1000, and the ramp will be extended.

The Bucko Lake mill

To fast track construction of the Bucko Lake concentrator, Crowflight bought a used mill building, explained Keller. The mill has a capacity of 1,500 t/d, but is being run at only 1,000 t/d to produce 100 tonnes of 20% Ni and 2% Cu concentrate daily.

The mill has a conventional sulphide flotation flowsheet. Run-of-mine ore is crushed to 125 mm in a 800 by 800-mm jaw crusher, and then to 12.5 mm in a 1.5- metre cone crusher ahead of the fine ore bin. The fine ore is conveyed to a 2.7 by 3.6 metre rod mill. Slurry from the rod mill is further reduced in a 3.6 by 4.9 metre ball mill. Ball mill discharge is cycloned and the overflow sized to 80% passing -100 mesh is piped to the flotation circuit. Cyclone underflow returns to the ball mill.

At the head of the flotation circuit are two 1.8-m-wide by 3.7-m-high preconditioning tanks. Slurry from the second of these feeds a rougher circuit. This is followed by three stages of cleaning in five 1.4 m primary cells, three 1.4 m secondary cells and two 4.6 m tertiary cells.

The tailings product from the scavenger cells is combined with the primary cleaner tailings and pumped to either the tailings dam or the backfill plant. The tertiary cleaner concentrate, the final product, is pumped to the concentrate thickener and filter section for dewatering. Dewatering includes a 5-metre-diameter thickener followed by a Larox filter.

Dried concentrate containing approximately 8% moisture is shipped by truck to Winnipeg and then by rail to Xstrata Nickel’s smelter in Sudbury, Ont. Production for 2009 will be 144,000 tonnes of concentrate containing approximately 4.1 million pounds of payable metal.

Tailings are being stored temporarily on surface, but ultimately Crowflight would like to dispose of them under the waters of Bucko Lake. If permission is not forthcoming from the federal government, the company will apply to the province for an extension of its temporary tailings permit.

Positive outcome

“The Bucko Lake mine has reached commercial production,” Keller said, “and it will have a positive cash flow by the end of the year.”

That gives the project a bright future, no doubt about it. With production costs this year in the roughly US$5.00-range, Crowflight is on track to take advantage of increasing strength in the nickel market as prices rise to US$8.00/lb and above.