Having found a way to remove the selenium contaminant that plagues the Wolverine polymetallic deposit in the southeastern Yukon,
The Vancouver-based company intends to raise $2-3 million this summer for Wolverine, followed by $10-15 million in the fall in order to advance Finlayson through to the final feasibility stage.
The Finlayson project centres on the proposed joint development of the recently acquired Kudz Ze Kayah base and precious metals deposit and the 60%-owned Wolverine deposit.
In March, Expatriate made a move to consolidate the Finlayson Lake district by acquiring from
Expatriate offered the Cominco assets for inclusion in the Wolverine joint venture. However, Atna declined to participate after commissioning Kilborn Engineering Pacific to carry out an independent third-party review of the economics of the Finlayson project, including capital estimates, operating costs and metallurgy. Atna’s based its decision on what it considered to be significant requirements for capital investment, as well as considerable technical risks. Atna’s 40% interest in the Wolverine deposit was unaffected by this decision.
The joint venture intends to spend $1 million at Wolverine this year in preparation for going underground in 2001. This year’s program includes metallurgical work, underground mine planning and infill drilling to provide additional data for geotechnical purposes and reserve estimation.
Expatriate now holds a direct interest in 8,700 mineral claims covering 1,740 sq. km in the Finlayson district. The company currently has $1.2 million in cash, with 21.2 million shares outstanding, or 30.5 million fully diluted.
Discovered in 1994 by Cominco, the Kudz Ze Kayah deposit contains an indicated resource, minable by open-pit methods, of 11.3 million tonnes grading 5.9% zinc, 0.9% copper and 1.5% lead, plus 1.3 grams gold and 133 grams silver per tonne, at a stripping ratio of about 6.7-to-1. Selenium averages about 0.03%.
The project site lies above the tree line at a 1,400-metre elevation in the extreme northeastern ranges of the Pelly Mountains, 110 km southeast of Ross River and 20 km southwest of Finlayson Lake.
Kudz Ze Kayah is a tabular body and appears to contain several lenses of mineralization that are collectively up to 22.5 metres thick. The deposit dips moderately to the north near its subcrop and becomes flatter dipping at depth. Only the upper part of the deposit is in the proposed open pit.
Even though several widely spaced holes limit the deposit at depth and along strike, Expatriate believes there is potential for the discovery of additional lenses in areas adjacent to the main deposit. Cominco found a small near-surface zone of mineralization southwest of Kudz Ze Kayah that appears truncated by a fault.
In 1998, Cominco discovered the smaller GP4F deposit while drill-testing a geophysical target 5 km southeast of Kudz Ze Kayah. Seven holes have defined an inferred resource of 6.4% zinc, 0.1% copper and 3.1% lead, plus 2 grams gold and 90 grams silver. Compared with the grades of Kudz Ze Kayah and Wolverine, the GP4F resource is anomalously low in copper and enriched in lead, suggesting that this massive sulphide lens represents more distal mineralization.
GP4F has a significantly lower selenium content and appears to be in a lower stratigraphic sequence of quartz and feldspar porphyritic felsic volcanic rocks — factors which, according to Expatriate, enhance the potential of this emerging volcanogenic massive sulphide (VMS) district.
On hold
Cominco had advanced the Kudz Ze Kayah project to the stage where it had successfully negotiated a socio-economic agreement with Ross River Kaska Dena first nations, as well access road surface rights, and acquired a water licence for development of a proposed 3,000-tonne-per-day open-pit operation. However, an economic analysis in 1998 induced Cominco to place the project on hold pending an improvement in zinc prices.
Expatriate believes that economies of scale — in particular, the consolidation of known mineral resources in the district — improves the potential of Kudz Ze Kayah.
Wolverine, a classic VMS deposit hosted in felsic volcanic and argillaceous sedimentary rocks, was discovered in 1995, 25 km southeast of Kudz Ze Kayah, by 60-40 partners Westmin Resources and Atna. Based on 68 holes drilled to the end of 1997, Wolverine contains an indicated resource of 6.2 million tonnes grading 12.66% zinc, 1.33% copper and 1.55% lead, plus 1.76 grams gold and 371 grams silver. Selenium averages 0.1%. The massive sulphides occur in two tabular, semi-continuous lenses averaging 5.1 metres thick. The Wolverine and Lynx zones are partly defined and remain open for expansion downdip along the 800-metre-long boundary of the adjoining WOL claims, which Expatriate has acquired from Cominco.
Development plans for the Wolverine deposit were stalled after metallurgical studies indicated high levels of selenium in the metal concentrates. Selenium creates problems during the smelting and refining process owing to the difficulty in separating it from the metal and sulphur products. High selenium concentrates are generally penalized by smelters or else avoided altogether.
Boliden purchase
In early 1998, Westmin was purchased by
Extensive studies of the selenium issue during the past 18 months have enabled the joint venture to arrive at two possible solutions. By co-milling the Wolverine ore with that of Kudz Ze Kayah, a “somewhat more salable” concentrate averaging 0.05% can be produced, says Brad Marchant, vice-president of mining and development for Expatriate.
Expatriate envisions an open-pit mine at Kudz Ze Kayah operating at 3,000 tonnes per day and an underground mine at Wolverine producing 1,250 tonnes per day. The two mine operations would provide a combined ore feed of 4,250 tonnes per day to a single metallurgical plant at the Kudz Ze Kayah site, providing for a mine life of 13 years.
Based on locked cycle flotation tests, performed under the direction of Morris Beattie using composite drill samples from both Wolverine and Kudz Ze Kayah, the combined operation could produce, on a yearly basis, 201,700 tonnes of zinc concentrate averaging 55% zinc and 40,300 tonnes of copper concentrate rich in precious metals averaging 25% copper. Recoveries to final concentrate average about 91% for zinc, 81% for copper and 64% for lead; overall recovery for silver and gold are 85% and 73%, respectively.
Roasting
The second alternative involves treating the zinc concentrate on-site using a roasting facility to produce a clean zinc oxide product virtually free of selenium. Tests by RPC in Fredericton, N.B., show that 96% of the selenium can be removed by a single-stage roast, with a weight loss of 19%. The zinc concentrate grade was increased to 65.5% in the oxide product.
Concurrent with the metallurgical work, Expatriate has initiated discussions to determine potential buyers of the zinc and copper concentrates. Responses from smelters in Asia and North America indicate that the copper concentrate is acceptable without any pre-treatment, owing to its high precious metal content. However, the concentrate does contain elements that could potentially carry smelter penalties; these include arsenic, antimony and selenium. Expatriate is investigating the benefits of pre-treating the copper concentrate using a conventional bio-leach process in order to reduce the penalty payments.
Marketing inquiries also indicate that the zinc concentrate could be sold to smelters without additional secondary treatment on site. The prefeasibility study, to be completed late this year, will compare the cost benefits of on-site roasting to those of shipping the zinc concentrate directly to the smelter for treatment.
Samples of zinc sulphide, zinc oxide and copper sulphide concentrates have been sent to smelters in Asia, Europe and Canada in advance of more definitive discussions.
Early projections for capital costs for the Finlayson project total $268 million, including $61 million for a roaster. Fluor Daniel Wright has completed a draft study on the roaster alternative, which shows that, for an additional $22 million price tag, the roaster has the potential to produce 9 MW of electrical power from a conventional steam plant.
$3.4m planned
A $3.4-million exploration program (including the $1-million Wolverine joint venture budget) is planned for this season. Expatriate intends to add an additional 7 million tonnes to the project’s development plan, or five years of production. Approximately 4 million tonnes will be achieved as a result of converting a portion of the resource that sits outside the proposed Kudz Ze Kayah open pit into underground reserves. Additional drilling will target the deeper resource for underground mine planning.
The remaining resources required to meet this objective are dependent on whether Expatriate is successful in delineating extensions to existing deposits and new discoveries.
Expatriate is drill-testing the downdip extension of the Wolverine’s Lynx zone — on the WOL claims, which it picked up from Cominco. Based on the thickness and copper zoning of the Lynx zone, which showed a north-northwest trend, the company stepped out with its first hole, 100 metres of previous hole 96-64, and hit 7.4 metres of true thickness grading 13.56% zinc, 0.68% copper and 1.16% lead, plus 0.59 gram gold and 152 grams silver, starting at a depth of 426 metres down-hole. Hole 96-64, which was drilled close to the WOL property boundary, had intersected a true thickness of 4.2 metres grading 11.19% zinc, 9.82% copper and 0.78% lead, plus 0.95 gram gold and 399 grams silver. Expatriate is targeting a further 100 metres downdip with hole 2.
Goal Net
A second rig on the wholly owned Goal Net property, 15 km southwest of Wolverine and 7 km southeast of the GP4F deposit, is testing a lead-zinc soil anomaly that coincides with a flat-lying induced-polarization (IP) geophysical anomaly. Samples of leached sub-crop have yielded assays of up to 0.6 gram gold, 32 grams silver and 4.55% lead. Six priority targets have been identified.
A ground geophysical survey is under way on Expatriate’s Red Line property, in preparation for follow-up drilling. Another prime target is the Sable zone, discovered by the Wolverine joint venture in 1997, 1.6 km southeast of the Wolverine deposit on the southeastern end of the property, abutting Expatriate’s Puck property. Two drill holes, 100 metres apart, intersected narrow intervals of high-grade massive sulphides with strong chlorite alteration in the footwall. The Sable hole nearest to the property boundary intersected 0.6 metre grading 13.3% zinc, 0.8% copper and 0.8% lead, plus 1.9 grams gold and 416 grams silver. The nearest stratigraphic hole on the Puck claims is 240 metres to the southeast. Expatriate believes follow-up drilling is warranted on both sides of the claim boundary.
Drilling will also test the lateral extent of the GP4F deposit. Further evaluation of the database for the mineral claims acquired from Cominco is expected to confirm additional drill targets for testing in the latter part of the field season. Cominco has defined several geophysical anomalies 2.5 km northwest of the Wolverine deposit, along the favourable Wolverine horizon.
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