ORSU METALS CORPORATION -------------------------------------------------------------------------------------
As part of the ongoing Definitive Feasibility Study, Orsu is pleased to announce an increased Pit-Constrained Mineral Resource for its Karchiga Project comprising an Indicated Mineral Resource of 10.8Mt of combined sulphide and oxide mineralisation grading 1.73% Cu for 187,200t (412.7 Mlb) of contained Cu and an Inferred Mineral Resource of 0.02Mt of sulphide mineralisation grading 1.28% Cu for 300t (0.7 Mlb) of contained Cu
December 8, 2011
Orsu Metals Corporation (TSX:OSU, AIM:OSU ), the London-based precious and base metals exploration company, is pleased to announce an increased mineral resource estimate for its 94.75% owned Karchiga Volcanogenic Massive Sulphide ("VMS") copper project, northeast Kazakhstan (the "Karchiga Project"). The reported mineral resource estimate is constrained by an optimised open pit, has been reported according to Canadian Institute of Mining, Metallurgy and Petroleum Standards on Mineral Resources and Reserves (the "CIM Standards") and forms part of the ongoing Definitive Feasibility Study ("DFS") which is expected to be completed in January 2012.
The new pit-constrained mineral resource estimate (the "SRK December 2011 Mineral Resource Estimate") has been prepared by our lead DFS consultant SRK Consulting (UK) Limited, Cardiff, UK ("SRK") and relates to oxide and sulphide mineralisation in both the Central and North East lodes of the Karchiga deposit.
The new estimate reflects a 28% increase in the sulphide hosted Indicated Mineral Resource tonnage, and a 23% increase in the copper metal contained within this, compared to that reported by SRK in May of this year. This has been achieved not only through the upgrading of practically all previously reported Inferred Mineral Resources to the Indicated category, but also through the addition of 0.8 Mt of sulphide mineralisation in the North East which had not previously been delineated. The most significant difference, however, is the increase in the oxide Mineral Resource. Specifically SRK has reported a 137% increase in tonnage and a 109% increase in contained copper metal in comparison with Mineral Resource Estimates for oxide mineralisation completed by Wardell Armstrong International in March 2010 ("WAI 2010 Estimate"; see Company's press-release dated March 22, 2010).
Mineralisation at Karchiga occurs in a Central and a North East lode. The VMS style mineralisation in both lodes is hosted along the contacts between shallow dipping alternating amphibolite and quartz mica schist units. The two lodes have a strike length in excess of 1km and have been intersected down to depths of 200m below surface.
In the Central lode, the mineralisation is located within a series of shallow-dipping massive and disseminated sulphide bodies stacked at four stratigraphic levels and primarily consists of chalcopyrite-pyrrhotite and pyrite mineralisation. Above the sulphide mineralisation of the Central lode is a zone of oxide mineralisation (containing malachite, chrysocolla and native copper) which is separated from the sulphide mineralisation by a transition zone of secondary sulphides (comprising chalcocite, covellite and native copper) (see Company's press-release dated September 29, 2011).
In the North East lode, the mineralisation primarily consists of chalcopyrite-pyrrhotite and pyrite, with minor sphalerite, and is located within two subparallel shallow-dipping and moderately folded massive and disseminated sulphide lenses.
SRK December 2011 Mineral Resource Estimate
Table 1 presents the SRK December 2011 Mineral Resource Estimate which comprises an Indicated Mineral Resource of 10.8Mt of combined sulphide and oxide mineralisation with a mean grade of 1.73% Cu for 187,200t of contained Cu and Inferred Mineral Resources of 0.02Mt of sulphide mineralisation grading 1.28% Cu for 300t of contained Cu. These Mineral Resources have been constrained by two optimised pits and are reported at a cut-off grade of 0.3% copper for mineralisation considered to be amenable to flotation ("FL") and at a cut-off grade of 0.7% copper for mineralisation considered to be amenable to heap leaching ("HL").
As part of its work, SRK produced updated geological models for both the Central and North East lodes primarily based on a geological cut-off of 0.1% Cu and capped high grades where it considered this to be appropriate based on a statistical analysis of the available assay results.
SRK also remodeled the footwall of the oxide mineralisation and in addition to this has modeled a transition zone between the sulphide and oxide mineralisation based on an updated drillhole database and acid solubility data. Notwithstanding this, the resulting Mineral Resource Estimate has been reported using a 40% acid solubility threshold which assumes that material which has an acid solubility greater than 40% will be processed using heap leaching and that which has an acid solubility of less than 40% will be processed in the flotation concentrator.
A total of four domains have been modeled in the Central lode, and two in the North East lode. 3D wireframes were created from 2D sections which were spaced at a 25m interval in the Central and North East lodes. No more than 2m of waste was included in the 2D sections used to produce the 3D wireframes. SRK and Orsu previously interpreted four post-mineralisation faults which strike across the deposit but only one of these is now thought to have an effect on the mineralisation, offsetting it in the northern portion of the Central lode by some 120m. Further, the more recent drilling information does not suggest that the mineralisation is terminated by these faults as previously thought.
The grade interpolation was carried out on 2m downhole composited drillhole samples from within the 0.1% Cu grade wireframe. SRK used a block size of 25m (X) by 25m (Y) by 5m (Z). Cu, and Au grades were interpolated into the blocks using an Ordinary Kriging algorithm based upon the results of geostatistical modelling completed for the relevant sulphide and oxide data sets.
Specific gravity measurements were carried out for the different material types collected from Karchiga diamond drill core and an in-situ bulk density value assigned to the block model based on the relationship between grade and bulk density below the oxide mineralisation revealed by a regression analysis. Data from the 2008, 2010 and 2011 drilling has enabled separate density regression plots to be established for the sulphide mineralisation in the Central and North East lodes.
Table 2 shows the pit optimisation parameters that were used to define a pit outline which was then used to constrain the SRK December 2011 Estimates to material with reasonable prospects for economic extraction. The slope angle parameters are the result of the geotechnical study undertaken by SRK. The Mining, Processing, and Operating Cost and the NSR parameters have been derived based on on-going technical work as part of the DFS by SRK. A long term price of US$3.25/lb Cu was assumed based on market consensus forecasts, previously a price of US$3.00/lb Cu had been used by SRK in May 2011 and Micon's May 2010 PEA. Currently the Company is working towards completing its DFS and thereby reporting Mineral Reserves.
Quality Assurance / Quality Control
The reported Mineral Resource estimates are based on historical drilling performed in Soviet times as well as drilling undertaken by Orsu since 2007, including in-fill drilling completed in 2011 (see Company's press-releases dated September 1, 2011). Assays for the 2011 in-fill drilling programme have been completed for Cu, Zn, Pb, and Au in the laboratory of the Eastern Institute for Base Metals, based in Ust-Kamenogorsk, Eastern Kazakhstan, which is independent from Orsu and SRK. Standard, blank, and duplicate samples were inserted after approximately every twenty ordinary core samples. The ordinary half core samples have been taken from visually mineralised intervals and 5 m of visually unmineralised material below and above the mineralized intervals. The remaining half core samples are stored at the Orsu facility in Ust-Kamenogorsk, Kazakhstan. The SRK December 2011 Estimate used all data available at the end October 2011.
Comparison with Previous Estimates
Table 3 shows a comparison between the SRK December 2011 Mineral Resource Estimate and that previously completed by SRK in May 2011 for sulphide mineralisation ("SRK May 2011 Mineral Resource Estimate") and by Wardell Armstrong International for oxide mineralisation ("WAI 2010 Mineral Resource Estimate").
The reported results are part of the ongoing DFS for the Karchiga Project, the completion of which is expected in January 2011.
Dr Alexander Yakubchuk, COO and Director of Exploration of Orsu, commented: "We are very pleased with both the successful conversion of the previously reported inferred mineral resources to the indicated mineral resources and the additional growth of our sulphide mineral resource. In addition, a greater than expected growth of indicated mineral resources was achieved for both the tonnage of oxide mineralisation and its contained copper metal of 137% and 109%, respectively.
We are looking forward to completing a Mineral Reserve estimates for Karchiga as part of the DFS, with an expected life of mine in excess of eleven years."
ENDS
Full Release --------------------------------------------------------------------- For further information please contact:
Alexander Yakubchuk, COO, Orsu Metals Corporation Tel: +44 (0) 20 7518 3999
Ryan Gaffney / Andrew Chubb, Canaccord Genuity Limited Tel: +44 (0) 20 7050 6500
Vanguard Shareholder Solutions Tel: +1 604 608 0824 ir@vanguardsolutions.ca www.orsumetals.com |