Trial Mining and Processing Update at Old Pirate
Perth, Oct 8, 2013 AEST (ABN Newswire) - ABM Resources NL (
ASX:ABU) ("ABM" or "The Company") presents an update on the Trial Mining and Processing at the Old Pirate High-Grade Gold Project in the Northern Territory of Australia.
Key Points:
- First gold delivered to Perth Mint.
- Plant feed (head grades) generally exceeding expectation.
- Tails grades indicating high rates of recovery (>90%) in-plant from gravity processing.
- Gold still building up in circuit.
- Trial Mining continues with new gold bearing veins identified at the Western Limb.
In-Plant Recoveries and Reconciliation at the Pilot Processing Facility
The Company recently received the first batches of plant-feed and tails-assay grades, which indicate excellent in-plant recoveries of over 90%. The Company remains pleased with the performance of the Knelson Concentrator, extracting both coarse and fine gold. The assay results from the first thirteen days of processing are outlined in the table below. The first three days utilised known low-grade material as part of plant commissioning.
Table 1. Plant Feed Grade vs Tails Assay Grade (Refer Appendix 2 for details).
---------------------------------------------------------------Date Plant Feed Grade Tails Assay Grade In-Plant Recovery (g/t Au) (g/t Au) (%)---------------------------------------------------------------07-Sep 5.06 0.46 90.90%08-Sep 4.59 0.39 91.49%11-Sep 3.38 0.46 86.39%12-Sep 22.97 0.68 97.04%13-Sep 6.54 1.04 84.10%15-Sep 6.52 0.76 88.42%16-Sep 32.30 0.80 97.52%17-Sep 18.88 0.75 96.05%19-Sep 12.35 0.77 93.81%20-Sep 20.65 0.63 96.95%21-Sep 26.45 0.49 98.15%22-Sep 21.83 1.11 94.91%23-Sep 8.26 0.81 90.25%----------------------------------------------------------------Totals / Averages 14.60 0.70 95.40%---------------------------------------------------------------
An on-site review of the Pilot Processing Plant recently undertaken by independent consultant metallurgist Adrian Hall (Metallurgy Matters Pty Ltd), confirmed there is substantial build-up of gold-incircuit (principally in the ball mill) which is considered normal in start-up. This gold will either make its way through the circuit in normal milling operations or will be recovered at the completion of the trial.
This build-up phase makes reconciliation unreliable at this early stage of the process. However, the plant is a closed circuit (with exception of tails), and, as verified by the consultant metallurgist, as long as the tails assay grades remain low the Company can be confident of good metallurgical recoveries throughout the plant and ultimately in reconciliation.
Perth Mint Refinery Consignment and Concentrate Upgrading
Last week the Company transported a batch of 13kg of upgraded gold concentrate to the Perth Mint with further consignments expected this week.
As expected, the free-gold bearing concentrate coming off the Gemini Table also contains iron oxides (Figure 1). The concentrate requires a combination of simple magnetic separation, which removes much of the iron oxide, and hydrochloric acid (HCl) wash, prior to refining into gold bars. As part of the trial processing, a 3kg test parcel of gold concentrate was first sent to the Perth Mint Refinery for trials on further concentrate upgrade methods prior to smelting. The Perth Mint Refinery successfully processed the gold from the concentrate using the methods noted above. The Company has also trialled acid wash successfully on site using dilute HCl and is also sourcing a small scale magnetic separator to further upgrade the concentrate on-site prior to smelting. The Perth Mint has agreed to take additional concentrate parcels (such as the 13kg parcel noted above) from the Company directly as part of the trial and the Company will receive full gold credits without penalty for this.
Throughput Rate
To date the Company has processed over 1500 tonnes of material. As part of the trial processing the Company has been experimenting with different configurations of pipes and pumps at the modular plant to balance water, recirculating load and slurry density and these tests ultimately impact on short-term throughput rates. In addition, a component failure in one of the crushing units (now rectified) resulted in reduced throughput for several days. The plant is now operating at nameplate operating capacity and processing between 100 and 150 tonnes per day (depending on maintenance and test schedules).
Trial Mining Continues
Trial Mining continues on the second bench of selected areas (refer to release dated 18/09/2013 for further details). Of particular geological note, the Company has for the first time started to see several quartz veins splaying off the footwall of the main vein on the Western Limb (Figure 3). At surface the Western Limb was observed as a relatively straight, single high-grade vein between 1m and 20cm wide.
However, in drilling the Western Limb commonly has multiple veins within zones averaging 3 to 5 metres wide with a maximum of 15 metres. The second bench of excavation at the Western Limb has revealed several splay structures and stock-work veins footwall to the main vein. Assays for these zones are pending. Visible gold has been observed and is encouraging for greater width along parts of the Western Limb.
For diagrams, figures and tables, please visit:
http://media.abnnewswire.net/media/en/docs/ASX-ABU-651797.pdf
About ABM Resources NL
ABM Resources (ASX:ABU) is developing several gold discoveries in the Central Desert region of the Northern Territory of Australia. The Company has a multi-tiered approach to exploration and development with a combination of high-grade production scenarios such as the Old Pirate High-Grade Gold Project, large scale discoveries such as Buccaneer, and regional exploration discoveries such as the Hyperion Gold Project. In addition, ABM is committed to regional exploration programs throughout its extensive holdings including the alliance with Independence Group NL at the regional Lake Mackay Project.
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