Selwyn Resources Announces Improved Metallurgy for XY Central High-Grade Mineralization
VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 06/14/10 -- Selwyn Resources Ltd. (TSX VENTURE: SWN) is pleased to provide an update to investors on the projected zinc-lead metallurgical performance at the Selwyn Project. The recent testwork continues to indicate that there is good predictability of metal recovery and concentrate quality. In particular, the high-grade nature of the Selwyn zinc concentrates and their low iron content are attractive to zinc smelters.
In June 2009, Selwyn engaged G&T Metallurgical Services Ltd. ('G&T') based in Kamloops, British Columbia to assess the metallurgical performance of higher grade mineralization from the XY Central zone and develop a process flow sheet. This work was under the direction of Peter Taggart, P. Eng., Selwyn's Independent Qualified Person for metallurgical and process testwork, who has also reviewed the content of this news release. The latest G&T testwork confirms their previous testwork program in 2007 that demonstrated good metal recoveries to high-grade saleable zinc and lead concentrates (see December 4, 2007 News Release). G&T's 2010 testwork results will be incorporated into Wardrop Engineering Inc.'s ('Wardrop') ongoing bankable feasibility study (see January 5, 2010 News Release).
G&T KM2427 Program Metallurgical Results
G&T's 2010 testwork utilized a 6.6 tonne sample of XY Central mineralized material from which a composite was extracted grading 10.1% zinc and 4.02% lead. The program recommended a conventional flow sheet and a primary grind to 40 microns (80% passing). Based on the G&T testwork results, it is projected that, under operational conditions, 85% of the zinc is recoverable to a 55% zinc concentrate with low iron content; and 69% recovery of lead to a lead concentrate grading 60% (see table).
No secondary metals or minor elements of the zinc or lead concentrates are expected to attract smelter penalties, with the possible exception of a modest silica penalty in the zinc concentrates. The silica content of the zinc concentrates varies depending on grade of zinc in the concentrates - higher zinc grade corresponds with lower silica content. The concentrates contain measurable quantities of potentially valuable minor metals such as gallium, germanium and cadmium, but the grades are expected to be variable and no smelter payment is anticipated at this point in time.
G&T 2010 vs G&T 2007 Comparison
The following table, comparing the metallurgical performance results of the G&T 2007 and 2010 programs, illustrates the improved zinc and lead recoveries. The 2007 (KM1948) results are from locked cycle tests of three composite samples (low, medium and high-grade composites). The 2010 locked cycle test results are taken directly from the most recent G&T Report.
The predicted metallurgical performance is based on concentrate grade/metal recovery curves, minus a 2% downward adjustment to metal recoveries under lab conditions to allow for actual process plant operating conditions.
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Feed Lead Zinc
Grade Concentrate Concentrate
Primary ----------------------------------
Grind Pb Pb Zn Zn
P80 Pb Zn Grade Rec. Grade Rec.
micro- ----------------------------------
Report/Test # Sample meter % Pb % Zn % Pb % % Zn %
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G&T 2007
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KM1948 #87, #89 Low Grade 37 1.55 5.58 62.8 57.5 55.0 80.0
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KM1948 #83,#86, #95 Low Grade 66 1.54 5.41 68.2 53.7 56.7 71.4
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KM1948 #88, #90, Low Grade 92 1.51 5.73 64.5 58.3 50.8 70.7
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KM1948 #92 Medium Grade 65 3.04 7.87 54.1 67.0 55.6 68.6
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KM1948 #93 High Grade 77 4.01 9.94 49.5 62.6 54.0 75.5
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G&T 2010
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KM2427 #55, #63 HG Composite 39 4.0 10.0 60.8 70.0 55.5 84.0
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KM2427 #56, #64 HG Composite 39 4.2 10.2 56.2 84.0 56.2 84.0
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KM2427 #67 HG Composite 61 4.1 10.8 64.1 68.0 50.8 91.0
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Predicted from
Testwork 40 4.0 10.0 60.0 69.0 55.0 85.0
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The 2010 results demonstrate improvement in projected zinc and lead metal recoveries whilst maintaining concentrate grades. As with prior studies, the results demonstrate a recovery curve that is remarkably flat at higher zinc concentrate grades. This is interpreted to be the result of the very low iron content of the mineralization that results in the clean separation of the sulphide minerals through fine grinding in regrind circuit, thereby allowing the preparation of high-grade products with minimal loss of recovery.
Additional Process Testwork and Preliminary Flowsheet
Additional refinement testwork is planned for 2010 to assess the metallurgical characteristics of the Selwyn mineralization at the Don zone and to determine detailed 'grindability' properties for SAG mill sizing purposes. A continuing program of testwork will also evaluate the variability of the metallurgy within the proposed initial mining areas as additional core becomes available.
Subject to G&T recommended grind size and the additional testwork, the process flow-sheet is contemplated to be a three-stage grinding circuit consisting of SAG, ball and vertimills, and differential flotation of concentrates with the standard pre-float and rougher/cleaner flotation stages and rougher concentrate regrinding. This flow sheet will generate high-grade saleable zinc and lead concentrates with good metallurgical recoveries.
Future Process Opportunities
Although none of the current work for metallurgy focused on Dense Media Separation ('DMS'), DMS is considered a future opportunity to upgrade lower grade ores prior to entering the primary mill circuit, by rejecting lower density fractions of mill feed that contain little zinc-lead mineralization. Prior work in the 1970s by previous owners US Steel, and more recently by SGS Lakefield and G&T, confirmed that the grade of typical Selwyn run-of-mine mineralization can be increased by up to 50% meaning greater metal throughput (see January 17, 2007 News Release). The grade enhancement is offset by some metal losses to DMS rejects, modest additional operating costs, plus incremental capital costs of the DMS equipment and associated plant modifications. Consideration will be made by Wardrop in the process building design layout of the mill for a possible inclusion of a DMS circuit should it be considered attractive for future process upgrade. Such an upgrade would be focussed on managing excessive mining dilution associated with mining lower grade material adjacent to the planned higher grade mining areas.
The Selwyn Project represents one of the largest undeveloped resources of zinc and lead in the World and is located in the politically attractive jurisdiction of the Yukon. It is therefore both a unique opportunity and a strategic asset with the potential to provide a long term, secure supply of zinc and lead to the Pacific Margin markets.
This press release contains forward-looking statements concerning the metallurgical performance of Selwyn Project mineralization. These forward- looking statements are based on assumptions and judgments of Qualified Persons and management regarding future events or results that may prove to be inaccurate as a result of technical and other risk factors beyond Selwyn's control. As a result, actual results may differ materially from the expected results.
Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
Contacts:
Selwyn Resources Ltd.
Dr. Harlan Meade
President and CEO
(604) 801-7240 or Toll-free: 1-888-989-9188
Selwyn Resources Ltd.
Jasmin TamDoo
Manager of Investor Communications
(604) 801-7240 or Toll-free: 1-888-989-9188
(604) 689-8355 (FAX)
info@selwynresources.com
www.selwynresources.com