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OPERATIONS UPDATE: BRONZEWING & LEONORA Emerging Perth-based gold production company Navigator Resources Limited (ASX: NAV) is pleased to provide the following operations update from its Bronzewing and Leonora Gold Projects (BGP & LGP). Highlights * Bronzewing mill operating at budgeted 2.0Mtpa throughput rate * Current Bronzewing plant recovery at approximately 90% * Bronzewing mill feed now predominantly ROM ore from open pits * Bronzewing RC grade control drilling predicting 8-15% more ounces than ore reserve * Plant throughput rate increase initiatives being pursued * Leonora T2 ore parcel reinforces positive grade reconciliation performance of Bruno supergene ore * Leonora T3 ore treatment underway * Surplus Bruno supergene ore being road hauled to Bronzewing * Leonora development analysis to include prospective, standalone, low capital, low operating cost treatment of Cardinia supergene ore BRONZEWING GOLD PROJECT NAV announced on 9 April 2010 that it had commissioned the Bronzewing processing plant on low grade ore and subsequently announced on 22 April 2010 that it had poured its first gold. Since that time the Company has been increasing mill throughput and progressively substituting low grade ore with run-of-mine (ROM) ore generated from open pit mining. The Company is providing this update on progress as it moves towards its target of 100,000oz per annum of gold production. Daily mill throughput has progressively increased to a sustained annualised production level of 2.0Mtpa as demonstrated in Figure 1 below. The temporary interruption to the increasing throughput trend on 6/7 May 2010 occurred due to a short mill shutdown, which was extended by a faulty electrical circuit breaker causing a delay in the mill restart. Mill recovery is now averaging just under 90% although this is expected to increase to 92% with the achievement of full scale ROM ore presentation from the open pits and a steady state, consistent feed blend occurring. Recovery has increased, as demonstrated in Figure 2, as higher grade ore has been substituted into the mill feed. Average monthly mill production of 167,000 tonnes of ore is required to achieve the forecasted annual rate of 2.0Mtpa. Actual mill throughput achieved for May 2010 was 148,000 tonnes, which concurs with the Company"s internal ramp up prediction for May of 150,000 tonnes processed. As noted above and demonstrated in Figure 1, daily mill production is now running at the planned annualised rate. NAV previously advised in its presentation to the Sydney Resources Round-up on 11 May 2010 that open pit mining in "Central Pit will provide more than 50% of the mill ore feed by the end of May 2010" and that "Success Pit ore production to blend with Central Pit ore" was "scheduled by June 2010". The Company is pleased to report that actual ore mined from Central Pit during May 2010 totalled 110,000 tonnes, amounting to 73% of the required monthly mill feed. Ore mining has also commenced at Success Pit and processing of this higher grade ore will commence in early June 2010. The daily trend of contained gold presented to the mill since commissioning is shown in Figure 3 below. The rising trend is a reflection of the increasing daily mill throughput rate and the systematic replacement of low grade ore with higher grade ROM ore generated from Central Pit. The Company has now concluded two substantial programs of RC grade control drilling and has modelled the assay data utilising the widely accepted, industry standard software MP3. Overall indications are that when compared to the mining reserve ore blocks, MP3 is predicting 8-15% more ounces of gold, but that there are more ore tonnes at a slightly lower grade. See Table 1 below for a summary of the results of the two grade control programs. It is too early to report on reconciliation of modelled/predicted ore tonnes compared to the mill performance due to inadequate mill history to draw meaningful comparisons. NAV expects to be able to report in more detail on the performance of mining reserve versus grade control versus reconciled mill performance in the June 2010 Quarterly Report. In the meantime, NAV has implemented two new initiatives. A specialist consulting mine geologist has been engaged to work with the Bronzewing geological team to further enhance the modelling process against what is predicted in the reserve and what is mined. In addition, the Company is targeting technical initiatives aimed at increasing processing plant throughput to above budgeted levels as well as enhancing overall mill performance. These initiatives are being driven by the operations management group with support from an independent metallurgist who has undertaken a comprehensive metallurgical audit. To the end of May 2010, an estimated 6,400oz of recovered gold has been produced with approximately 4,000oz of gold being poured (awaiting final refinery outturns from the largest pour to date on 1 June 2010). The difference is the gold in circuit. NAV is pleased to confirm its previous market advice of 13,000oz of gold to be produced in the June 2010 quarter. LEONORA GOLD PROJECT Open pit mining at the Leonora Gold Project to complete the 75,000 tonne trial is coming to an end. This trial has been a great success for NAV, as explained below. Mining in the Mert 2 hardrock pit is now complete and mining in the Bruno supergene pit will conclude in the coming week. Mining conditions in the Bruno supergene open pit have been better than expected. Free dig excavation from surface to full design pit depth of 32.5 metres has been confirmed. Anticipated difficult haul truck trafficking conditions have not occurred. Mining unit costs and productivity projections have been confirmed so that there is now a high level of confidence in modelling future mining key performance inputs. As previously advised, the first parcel of ore processed at St Barbara Limited"s (ASX: SBM) Leonora mill (T1) consisted exclusively of Bruno supergene ore. As expected, the damp clay did present some materials handling problems in SBM"s plant, which is designed to treat predominantly hardrock ore, however the Bruno supergene ore demonstrated a substantial grade uplift effect of some +60% and very high plant recovery. T1 summary results were as follows: During May, the second ore parcel (T2) was processed. T2 consisted of a blend of Bruno supergene ore and Mert 2 low grade hardrock ore. Blending the hardrock ore with Bruno ore saw the achievement of significantly higher mill throughput rates (T2: 120tph compared to T1: 83tph). T2 ore parcel results are summarised in Table 3 below. Importantly, the positive grade trend for the Bruno supergene ore observed in T1 continued for T2. Geostatistical modelling of the Bruno supergene ore included the application of a 15g/t Au top cut to previous drill assays. That is, assays higher than 15g/t were reduced to 15g/t Au. The cut and uncut Bruno Pit mining inventory estimates are summarised in Table 4 below. Indications from actual mill trials (T1 and T2) are that the grade of the Bruno supergene ore more closely approximates the uncut mining reserve grade than the estimate in which a 15g/t Au top cut is applied. NAV is pleased to advise that the third parcel of Leonora ore (T3) consisting of a mix of Bruno supergene and higher grade Mert 2 ore commenced on 1 June 2010. Results of T3 will be announced upon completion. Encouraged by the processing and grade performance results of the Bruno supergene ore, NAV decided to continue mining ore from Bruno Pit beyond the requirement for the 75,000 tonne ore trial (40,000 tonnes of Bruno ore and 35,000 tonnes of Mert 2 ore). In generating the initial 40,000 tonnes of Bruno ore, NAV removed the bulk of the waste material contained within the pit design so that the remaining ore within the pit design could be mined with a low waste:ore strip ratio of 1.7:1.0. Mining of the Bruno open pit to final depth of 32.5 metres to generate a total of more than 90,000 tonnes of ore will conclude in the coming week. NAV has evaluated the cost of transporting and processing Bruno ore that is surplus to the 75,000 tonne ore trial commitment with SBM, as well as determining the likely timeframe for SBM to process the surplus ore. The combined cost of road haulage and mill processing at Bronzewing compares favourably with the cost structure for treating at SBM"s plant in Leonora. Therefore the decision was made to mine the additional ore for transport to Bronzewing for processing. NAV commenced the road haulage of some 400-500 tonnes per day of Bruno ore to Bronzewing on 7 May 2010. Dozer shaping at waste dumps is occurring to enable NAV to close out the trial mining regulatory requirements. At Bruno, this work also includes topsoil spreading and crossripping ready for seeding. Based upon the results of the Leonora trial ore mining and processing to date, NAV will now begin assessing its options for developing Leonora into its second producing gold mine. In addition to the project configuration as defined in the Pre-Feasibility Study (PFS) (results released in March 2009) where Cardinia supergene ore would be blended with more competent Mertondale ore, NAV will assess the viability of a staged development at Leonora. It is not yet clear whether the grade uplift effect observed to date with Bruno Pit supergene ore applies across the wider Cardinia supergene system. NAV will however evaluate whether a low capital, low unit cost, purpose built processing facility to exclusively treat Cardinia ore is a sensible alternative to the higher capital, centralised processing facility contemplated in the Leonora PFS. In the event that the grade uplift effect experienced to date is demonstrated to apply across the wider Cardinia supergene system, NAV believes that a low capital, circa 500,000tpa processing facility could produce 30,000-40,000oz of gold per annum at a unit cash operating cost at or below A$600 per ounce, with an initial mine life of approximately four years. The Company looks forward to reporting further progress as more information becomes available. Managing Director NAVIGATOR RESOURCES LIMITED For Further Information: Please direct any queries, or requests for further information, to: David Hatch Email: navigator@navigatorresources.com.au |