African Copper Plc

African Copper Plc

October 18, 2006 02:00 ET

African Copper Plc: Resource Estimates for Dukwe Project Show Significant Tonnages Available for Extended Mine Life

Clear Indications of Viability of Processing Oxide and Supergene Ore through Proposed Dukwe Concentrator Open Pit option being optimised and evaluated within existing timetable to production

LONDON, UNITED KINGDOM--(CCNMatthews - Oct. 18, 2006) - African Copper Plc (TSX:ACU)(AIM:ACU)(BSE:AFRICAN COPPER) -

  • Final results have been received from RSG Global Consulting ("RSG") for the resource estimate at the Dukwe Project in Botswana.
  • Final results have also been received from a parallel resource estimate completed by Caracle Creek International Consulting ("CCIC").
  • The two estimates report similar amounts of global contained copper. Differences in the tonnages and grades reported for each class of mineralization result from differing methodologies employed in the two independent estimates.
  • RSG reports an estimated indicated mineral resource of 32.85 million tonnes grading 1.61% copper and an estimated inferred mineral resource of 14.39 million tonnes at 1.38% copper in both cases using a 0.8% cut-off.
  • CCIC reports an estimated indicated mineral resource of 40.75 million tonnes grading 1.41% copper and an estimated inferred mineral resource of 9.48 million tonnes at 1.35% copper. In each case for this estimate, estimated mineral resources represent a mineralized envelope based on a 0.25% copper cut-off.
  • Both estimates are SAMREC, JORC and NI43-101 compliant.
  • Recent metallurgical testing has shown the viability of producing marketable oxide concentrate within the Dukwe concentrator
  • The Company is proceeding immediately with open pit optimization studies for early exploitation of oxide and supergene zones - results expected early November 2006
  • An extensive drilling programme in oxide and supergene zones has been completed - a revised resource expected early December 2006
  • African Copper Plc ("African Copper" or the "Company") is pleased to announce the results of comprehensive mineral resource estimates completed by independent consultants RSG Global Consulting ("RSG") and Caracle Creek International Consulting ("CCIC"). The two consulting groups used identical databases and geological interpretations as a starting point, but used differing methodologies to arrive at their final estimates. The delivery of this resource estimate is within the scope and timing of the development plan for establishing production from Dukwe on schedule early in 2008. African Copper is proceeding immediately with open pit optimization studies and expects to be able to present mining schedules in early November. The mining of the oxide and supergene portions of the deposit by open pit methods reduces the mining risk in the project, and allows the Company to confidently produce at design capacity throughout the critical start-up phase of the project. Surface works have started at the Dukwe site with the establishment of a functioning EPCM camp, access road, power line engineering, water field access and pipeline route. Construction activities will accelerate over the next two months. The coarse-grained semi-massive to disseminated nature of the sulphide mineralization at Dukwe has the potential to lead to estimation errors. The use of two globally recognized independent consultants with differing methodologies has added confidence in allowing the Company to finalize the resource base available to support an extended mine life at Dukwe. The RSG estimate utilized 5 metre composite samples to assign grades to 10m x 30m x 30m block sizes. Ordinary kriging was applied to determine a global estimate, and uniform conditioning was applied to the resultant block model to assign values to the geological wireframes. Subcells to a minimum of 5m x 10m x 10m were used. RSG utilized soft boundaries between "oxide", "supergene" and "sulphide" mineralization styles which produced a continuous estimate across the three types. The CCIC estimate utilized 1 metre composite samples to assign grades to 10 m x 30m x 15 m block sizes. Ordinary kriging was applied individually to each mineralized domain as well as the surrounding poorly mineralized breccia. Mineralized domains define zones of improved mineralization, based on a 0.25% copper cut-off as a guideline. In order to improve on local tonnage estimates CCIC used subcells to a minimum of 1m x 5m x 5m. CCIC utilized hard boundaries between geological wireframes and between "oxide", "supergene" and "sulphide" mineralization styles. A comparison of the two estimates is shown in the following table.
                               CCIC Estimate               RSG Estimate
                                  1 m composite,              5 m composite,
                                 10m x 30m x 15m            10 m x 30m x 30m
                                 block size with             block size with
                                     subcells to                 subcells to
                                  1 m x 5m x 5m,              5m x 10m x 5m,
                         ordinary kriging, 0.25%     Uniform Conditioning of
                   cut-off mineralized envelope;      Ordinary Kriging, 0.8%
                               effective date of     cut-off; effective date
                           estimate:30 Sept 2006      of estimate:9 Oct 2006
    Indicated             tonnes  % Cu Contained      tonnes  % Cu Contained
     resources                            Cu (t)                      Cu (t)
    Oxide              1,380,613  1.66    22,899   2,840,000  1.77    50,268
    Supergene          4,456,594  2.11    93,949   5,770,000  1.89   109,053
    Sulphide          34,913,804  1.31   456,111  24,240,000  1.53   370,872
     Total Indicated  40,751,010  1.41   572,960  32,850,000  1.61   530,193
    Inferred resources    tonnes  % Cu                tonnes   % Cu
    Oxide                715,129  1.44    10,274      20,000   1.16      232
    Supergene            260,956  1.78     4,632     270,000   1.29    3,483
    Sulphide           8,507,751  1.33   113,390  14,100,000   1.38  194,580
     Total Inferred    9,483,836  1.35   128,297  14,390,000   1.38  198,295
    Note: CCIC and RSG are both independent consulting firms commissioned by African Copper. The RSG estimate was prepared under the supervision of Ken Lomberg B.Sc.(Hons) B.Com. Pr.Sci.Nat, an employee of RSG and a "Qualified Person" for the purposes of National Instrument 43-101 in Canada. The CCIC estimate was prepared under the supervision of Desmond Subramani Bsc.(Hons), Pr. Sci. Nat., an employee of CCIC and a "Qualified Person" for the purposes of National Instrument 43-101 in Canada. Both estimates have been completed to SAMREC, JORC and National Instrument 43-101 definitions and standards. The database for these calculations was assembled by RSG, who managed all aspects of data collection and verification between June 2005 and Aug 2006 during a 38,000 metre diamond drilling campaign. Historic data that has been incorporated into the database has been verified by a twin hole programme that was supervised by RSG. Samples of half core (0.5m to 1.5m intervals) for the current drill holes were cut and placed into sealed bags on the Dukwe site under the direct supervision of RSG. These were transported weekly by commercial carrier to Johannesburg. All sample preparation and analyses were completed at ALS Chemex laboratories in Johannesburg (ISO 17025 accredited and independent of African Copper and RSG). Copper assays are completed using standard preparation of crushing to 70% less than 2 mm followed by splitting and pulverizing to 85% less than 75 micron. Analyses were generally completed utilizing 27 element four-acid ICP-AES in addition to a four-acid ore-grade element digestion followed by ICP-AES. Any over-limit analyses were reanalyzed using an ore-grade four-acid digestion with AA or ICP-AES finish. QA/QC procedures included the submission by RSG of systematic duplicates, blanks and both low-grade and high-grade standard samples within the sample batches submitted to ALS Chemex. Control samples comprise 20% of all samples submitted. Referee analysis for the entire Dukwe dataset has been supervised by RSG and completed at Genalysis Laboratories in Perth Australia. The results of the RSG QA/QC programme for copper analyses have been reviewed by RSG, by CCIC and by Joseph Hamilton, P.Geo, and Chief Operating Officer of the Company. RSG provided a verified database, including geological interpretations, to CCIC to facilitate the CCIC resource estimate. CCIC did not conduct a site visit. Major assumptions used during the resource estimates are shown in the table above. The amount of material that can be converted to reserve categories must await the finalization of open pit designs, in the case of oxide and supergene material, and of the results of underground trial mining, in the case of sulphide material. Historical estimates reported similar amounts of contained copper (Additional information with respect to the Dukwe project is contained in a technical report prepared by A.C.A Howe International Limited dated March 30, 2006 and entitled "Technical Report on the Dukwe Copper Project and Matsitama Prospecting Licences, Botswana Africa". This technical report can be reviewed via the SEDAR website at The technical reports prepared in conjunction with the Resource Estimates presented in the table above will be available on the SEDAR website shortly. Metallurgical Update Recent metallurgical testing has shown that it is possible to create a marketable oxide concentrate within the Dukwe concentrator. African Copper is currently optimizing the flowsheet for the processing of oxide mineralization. Previous plans to commence mining only supergene material from underground were based on an assumption that the oxide flotation could not be optimized. This assumption is now challenged, and the Company believes that the oxide portions of the deposit represent a recoverable and profitable portion of the overall Dukwe mineralization. Oxide and Supergene Grade Estimation Recent twin hole drilling suggests that the oxide and supergene grades have been underestimated during historic drilling (see press release dated 21 September 2006). The above Resource Estimates used historic grades in the determination of the oxide and supergene grades. The Company believes that the grades shown in the above Resource Estimates may be understated. An extensive drilling programme to improve the grade estimate of the oxide and supergene zones has been completed with 150 metre deep vertical holes placed on a 20 metre grid over the Bushman and Mapanipani areas of the deposit. Results of this programme should be available in early December, and the Company expects to restate the oxide and supergene estimates before year-end. Sulphide Grade Estimation The 38,000 metre drill programme completed over the past year on the sulphide portions of the deposit has improved the confidence of the tonnage and grade estimate in the deeper portion of the deposit. The semi-massive to disseminated nature of mineralization within the breccia-hosted Dukwe deposit leads the Company to believe that a bulk mining method will likely be the most suitable for extraction of the sulphide material. The Resource Estimates set out in the table above (the "Resource Estimates") use relatively large block sizes which have the effect of increasing the tonnes and decreasing the grade when compared to using smaller block sizes suitable for the planning of selective mining activities. The Company believes that the tonnage and grade reported in the Resource Estimates can realistically be extracted in an underground mining scenario. Sulphide Treatment The host rock which contains the copper mineralization is predominantly coarse grained quartz + calcite +/- graphite with chalcopyrite. The Company has completed preliminary testing of dense media separation ("DMS") methods which may allow a pre-concentration of copper prior to milling and flotation. The results to date are sufficiently encouraging that the Company believes a bulk mining method could be utilized. These mining methods result in high tonnages at lower grades, but the Company believes that a pre-concentration step would allow concentrate production to remain steady with little increase to operating costs and no modification to the mill or concentrator flowsheet. Further testing of DMS technology and centrifugal separation techniques will be completed over the next few months. African Copper is a tri-listed (AIM, TSX, Botswana Stock Exchange) international exploration and development company. The Company is planning to develop its first copper mine at the Dukwe Project and commence production in 2008. The Company's other interests are the 4,000 sq km Matsitama exploration concession adjacent to Dukwe, which contains two known copper deposits and numerous base metal exploration targets. African Copper has approximately 130 million shares outstanding. Mr. Joseph Hamilton, P.Geo., and Chief Operating Officer of African Copper, is a "qualified person" as defined in Canada by National Instrument 43-101. This press release has been prepared under Mr. Hamilton's supervision. This document contains or refers to forward-looking information, including statements regarding the estimation of mineral resources, exploration results, exploration and mine development plans, timing of commencement of operations and estimates of market conditions, and is based on current expectations that involve a number of business risks and uncertainties. Factors that could cause actual results to differ materially from any forward-looking statement include, but are not limited to, failure to convert estimated mineral resources to reserves, the grade and recovery of ore which is mined varying from estimates, capital and operating costs varying significantly from estimates, delays in obtaining or failures to obtain required governmental, environmental or other project approvals, political risks arising from operating in Africa, uncertainties relating to the availability and costs of financing needed in the future, changes in equity markets, inflation, changes in exchange rates, fluctuations in commodity prices, delays in the development of projects and the other risks involved in the mineral exploration and development industry. Forward-looking statements are subject to significant risks and uncertainties, and other factors that could cause actual results to differ materially from expected results. Readers should not place undue reliance on forward-looking statements. These forward-looking statements are made as of the date hereof and the Company assumes no responsibility to update them or revise them to reflect new events or circumstances other than as required by law. The mineral resource figures for the Dukwe project disclosed in the table above are estimates and no assurances can be given that the indicated levels of copper 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 resource estimates disclosed in this press release are well established, by their nature resource estimates are imprecise and depend, to a certain extent, upon statistical inferences which may ultimately prove unreliable. If such estimates are inaccurate or are reduced in the future, this could have a material adverse impact on the Company. 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. Further information about our properties, to download a copy of our Annual Report or any technical report or to access our Press Release Archive please visit or our website at

    Contact Information

    • African Copper Plc
      David Jones / Joseph Hamilton
      +44 (0)20 7321 3721
      Numis Securities Limited (NOMAD)
      John Harrison / James Black
      +44 (0)20 7776 1590
      Parkgreen Communications
      Justine Howarth / Ana Ribeiro
      +44 (0)20 7493 3713