Orsu Metals Corporation
AIM : OSU
TSX : OSU

Orsu Metals Corporation

April 28, 2011 07:03 ET

Orsu Metals Corporation Announces Positive Metallurgical Test Work Results for the Karchiga Project

As part of ongoing Definitive Feasibility Study, Orsu announces positive results of the final metallurgical test work for its Karchiga Project in Eastern Kazakhstan. The test work indicates that the composite ore material from the two lodes should produce a 27.9% Cu concentrate, with 95.76% recovery, and the ores from the North East and Central lodes should produce a 21.6% and 24.15% Cu concentrate, with 91.59% and 96.2% recoveries, respectively.

LONDON, UNITED KINGDOM--(Marketwire - April 28, 2011) - Orsu Metals Corporation ("Orsu" or the "Company") (TSX:OSU)(AIM:OSU), the London-based precious and base metals exploration and development company, is pleased to announce the results of the final metallurgical test work, which was carried out by the Eastern Research Institute for Base Metals ("VNIITsvetMet") based in Ust-Kamenogorsk, Kazakhstan as part of ongoing Definitive Feasibility Study ("DFS"). All test work was conducted under the direction of Orsu personnel and our lead consultant SRK Consulting (UK) Limited, Cardiff, UK ("SRK").

The metallurgical test work was conducted on 1.5 tonnes of metallurgical samples, selected from the drill core of metallurgical holes drilled in late 2010 as part of the DFS in both the Central and North East lodes of the deposit. Test results indicate an amenability to produce marketable copper concentrates (see technical report entitled "Preliminary Assessment of The Karchiga Copper Project, East Kazakhstan Region, Kazakhstan", dated May 25, 2010). The recent testwork is the most representative study to date, which was focussed on:

  • Improvement of copper grade in concentrate without loss of copper recovery and improved zinc rejection in the ores from the Central and North East lodes and their composite samples ("Froth Flotation");

  • Development of a copper heap leaching process to potentially treat the oxide ores and transitional secondary sulphide components of the Central lode ("Heap Leaching").

Froth Flotation

A testwork programme, staged in three phases, was performed on a composite sample of sulphide ores from both the Central and North East lodes, mixed in the proportion of 40% to 60%, respectively (the "Main Composite").

During Phase 1, various grinds, reagents and flow sheets were tested. During Phase 2, combinations of the Phase 1 tests with improved parameters were examined. Phase 3 tests were finally comprised of variability testing of the optimised process on spatial diversity of the lodes plus locked cycle testing on composite samples, individually representing the massive and disseminated ores from the Central and North East lodes (the "Central and North East Composites", respectively).

For the Main Composite, reduced quantities of the flotation collectors (Butyl Xanthate and Aerofloat) and the Na2S (Sodium Sulphide) modifier, coupled with extended flotation times in rougher, scavenging and cleaning sections of the flow sheet, gave the desired improvements in the copper concentrate grade. The result for the locked cycle test performed on the Main Composite is given in the Table 1 in comparison with the result from locked cycle test, performed by VNIITsvetMet in 2009 on a similar composite sample.

Table 1 – Locked cycle tests for Main Composite
Test%% Cu Grade% Zn Grade% Cu% Zn
YearMassininRecoveryRecovery
ConcentrateConcentrate
200910.1119.903.3291.0583.84
20118.8627.905.0095.7681.54

Table 1 shows a significantly improved copper recovery into concentrate from 91.05% to 95.76%, achieved during the Phase 3 test work programme. At the same time, the copper grade of the concentrate produced from the Main Composite has increased from 19.9% Cu to 27.9% Cu, whereas the overall mass recovery into the concentrate has been lowered from 10.11% to 8.86%, which will ultimately translate to reduced transportation costs.

The zinc recovery has been lowered from 83.84% to 81.54% while the zinc grade in the concentrate has increased, partly due to the higher zinc head grade, still remaining at an acceptable level of 5% Zn. The greater flotation selectivity, achieved in this round of testwork, affords the opportunity to operate at a lower concentrate grade of, for instance, 25% Cu, which would result in an increase in the copper recovery and a decrease in the zinc grade in the concentrate.

In addition, the gold grade in the Main Composite concentrate was 1.57 g/t Au, with 50.44% recovery.

Table 2 shows results from locked cycle tests performed on the samples, representing the Central and North East Composites of the two individual lodes and respective potential pits of the Karchiga deposit. The Central Composite is a blend of 15% massive and 85% disseminated ores, whereas the North East Composite is a blend of 25% massive and 75% disseminated ores.

Table 2 - Locked cycle test for the Central and North East Composites
Lode%
Mass
of
Ore
%
Cu
Grade
in
Concentrate
%
Zn
Grade
in
Concentrate
g/t
Au
in
Concentrate
%
Cu
Recovery
%
Zn
Recovery
%
Au
Recovery
Central10.3424.151.280.3496.2073.9728.18
North East9.9821.607.201.6591.5986.9354.95

The results for the Central Composite are on a par with those of the Main Composite in terms of copper and zinc grades. The gold grade in the Central Composite concentrate is 0.34 g/t Au.

In the North East Composite, however, the copper grade in concentrate is 21.6%, with the gold grade of 1.65 g/t Au. The level of zinc in the concentrate was higher than expected. This is thought to be related to a build up of frother in the locked cycle test, leading to poor selectivity between the copper and zinc sulphides. This might be simple to rectify. For instance, the ore from the Central pit may be processed alone in the Year 1. A blend of ores from the Central and North East pits may then be processed during Years 2 to 6, and this may be followed by just over 4 years of further processing of ore from the North East pit only. Optimization for mine planning and milling will be undertaken as part of the DFS to determine the best way to blend and treat these ores.

Variability testing using the optimised flotation process has been performed on nine different samples from different locations in the deposit or their composite make up. The variability test results did not highlight any major behavioural deviation in metallurgical response from that of the standard composite in terms of recovery and grade.

Heap Leaching

The Central lode of the Karchiga deposit has an indicated resource of the oxide ore in the amount of 0.923Mt (at 0.5% Cu cutoff) grading 1.39% Cu and containing 12,868 t Cu (see technical report entitled "Updated Report on the Karchiga Property held by Orsu Metals Corporation, Kazakhstan" and dated March 22, 2010). Three acid leach columns were loaded with a blend of oxide and transitional secondary sulphide from the Central pit area and subsequently irrigated with a weak acid solution. Of the three columns, one, which contained added bacteria and which was aerated at the base, significantly outperformed the other two columns. This result was not unexpected and serves to demonstrate the efficiency of bacterial leaching for this type of ore. After 100 days, this column had achieved 68% Cu recovery, which corresponds very closely to 100% of the total material that was available in the sample for leaching.

The reported results of the metallurgical test work are part of the ongoing DFS. Completion of DFS is expected in September 2011.

Dr Sergey V Kurzin, Executive Chairman of Orsu commented: "The sulphide ore flotation tests demonstrate a possibility to achieve a significantly higher copper grade in concentrate and copper recoveries into concentrate from the Karchiga ores than indicated in the May 2010 Scoping Study. They show a marked improvement over all previous test work. These positive results will allow progressing further a detailed engineering design of the ongoing Definitive Feasibility Study. In addition, the positive results of the leaching test work of oxide and transitional ores demonstrate an additional potential economic benefit for the Karchiga Project, which is likely to be realized from the cash flow generated during mining and production of copper from the sulphide ores."

NOTE TO EDITOR:

  1. The technical report related to the Scoping Study referred to in this press release entitled "Preliminary Assessment of The Karchiga Copper Project, East Kazakhstan Region, Kazakhstan", dated May 25, 2010 and prepared by L S Carroll, MIMMM CGeol FGS, G Harris, MAusIMM, Ì L Owen, CGeol EurGeol FGS, J Steedman, MAusIMM and D Ò Wells, MIMMM CEng of Micon International Co. Limited is available under the Company's profile on SEDAR (www.sedar.com).

  2. The indicated mineral resource estimates (March 22, 2010) referred to in this press release are contained in the technical report entitled "Updated Report on the Karchiga Property held by Orsu Metals Corporation, Kazakhstan", dated March 22, 2010 and prepared by Ì L Owen and L S Carroll of Wardell Armstrong International Limited, which is available under the Company's profile on SEDAR (www.sedar.com).

FORWARD-LOOKING INFORMATION

This press release contains forward-looking information which is not comprised of historical facts. Forward-looking information involves risks, uncertainties and other factors that could cause actual events, results, performance and opportunities to differ materially from those expressed or implied by such forward-looking information. Forward-looking information contained (or referred to) in this press release includes, but may not be limited to: statements relating to mineral resource estimates; the Company's expectations with respect to updating and upgrading current mineral resource estimates and the possible increase in tonnage; the timing for the completion of an updated NI 43-101 compliant resource estimate; and the timing of the Company's receipt of results from and timely completion of the ongoing Definitive Feasibility Study.

Factors that could cause actual results to differ materially from those described in such forward-looking information include, but are not limited to, risks normally incidental to exploration and development of mineral properties, uncertainties in the interpretation of drill and test results, the possibility that future exploration, development and/or mining results will not be consistent with expectations (including the possibility that gold may not be able to be economically recoverable from the North East lode), uncertainty of mineral resources estimates, the Company's inability to obtain, maintain, renew and/or extend required licences, permits, authorizations and/or approvals from the appropriate regulatory authorities and other risks relating to the regulatory framework in Kazakhstan, adverse changes in the political environment in Kazakhstan and the laws governing the Company, its subsidiaries and their respective business activities, adverse changes in commodities prices, as well as certain other risks set out in the Company's public documents, including its annual information form dated March 24, 2010, filed under the Company's profile on SEDAR at www.sedar.com.

The forward-looking information in this press release reflects the current expectations, assumptions and/or beliefs of the Company based on information currently available to the Company. In connection with the forward-looking information contained in this press release, the Company has made assumptions about: the Company's business, the economy and the mineral exploration industry in general; the Company's ability to raise any required additional financing, as needed; the regulatory framework in Kazakhstan with respect to, among other things, the Company's ability to obtain, maintain, renew and/or extend required permits, licences, authorizations and/or approvals from the appropriate regulatory authorities; the political environment in Kazakhstan; and the Company's ability to continue to obtain qualified staff and equipment in a timely and cost-efficient manner to meet the Company's demand. The Company has also assumed that no unusual geological or technical problems occur, plant and equipment work as anticipated and no significant events occur outside of the Company's normal course of business. Although the Company believes that the assumptions inherent in the forward-looking information are reasonable, forward-looking information is not a guarantee of future performance and accordingly undue reliance should not be put on such information due to the inherent uncertainty therein.

The mineral resource figures contained and/or referred to in this press release are estimates only and no assurances can be given that the indicated levels of minerals will be produced. Such estimates are expressions of judgment based on knowledge, mining experience, analysis of drilling results and industry practices. Valid estimates made at a given time may significantly change when new information becomes available. While the Company believes that the mineral resource estimates contained and referenced herein are well established, by their nature, mineral resource estimates are imprecise and depend, to a certain extent, upon statistical inferences which may ultimately prove unreliable. If such mineral resource estimates are inaccurate or are reduced in the future, this could have a material adverse impact on the Company. Due to the uncertainty that may be attached to inferred mineral resources, it cannot be assumed that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource as a result of continued exploration. Inferred mineral resources are estimated on limited information not sufficient to verify geological and grade continuity or to allow technical and economic parameters to be applied. Inferred mineral resources are too speculative geologically to have economic considerations applied to them to enable them to be categorized as mineral reserves. Mineral resources are not mineral reserves and do not have demonstrated economic viability. There is no certainty that mineral resources can be upgraded to mineral reserves through continued exploration.

Any forward-looking information speaks only as of the date on which it is made and, except as may be required by applicable securities laws, the Company disclaims any intent or obligation to update any forward-looking information, whether as a result of new information, future events or results or otherwise.

Contact Information

  • Orsu Metals Corporation
    Ray Oates
    Technical Director
    +44 (0) 20 7518 3999
    www.orsumetals.com

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