The company continues to adjust and trial various rates of throughput and slurry density to achieve optimal recoveries and maximise sustainable throughput at the processing plant.
Throughput is currently maintained at a steady rate of 15 tonnes of material per hour after the coarse gold jig was bypassed to simplify the circuit though it noted that this is not thought to materially affect recoveries due to the outstanding performance and capacity of the Knelson Concentrator, which is recovering both the fine and coarse gold.
It added that while it did not have an on-site laboratory and is waiting on assays of the tails to assess the overall recovery, panning of tailings samples has revealed negligible amounts of gold compared to the gold being captured in the Knelson Concentrator and seen across the Gemini Table.
High-grade, gold-bearing concentrate is being securely stored on site in preparation for campaign smelting. Test smelting of concentrate has been carried out to assess how much upgrading is required for a smelt product and the gold separated well from the slag in the furnace.
ABM has completed mining the first bench (1 metre to 1.5 metres depth), extracting over 5,000 tonnes of material, and is now carrying out second bench mining, which is completed over the Golden Hind area.
The company is intentionally mining the system slowly to allow time for geological mapping and sampling. The geological information collected is a very important part of the trial process and will be used to design the mine for Stage Two.
Detailed grade-control sampling has been completed for the top of the second bench of the Trial Mine areas.
This has in general, reconciled with previous surface work and is within the bounds expected from the resource estimation work.
There is evidence that high-grade zones within individual veins are plunging to the south as per the resource model. Several veins have revealed good `blow-outs' where the vein width increases over a short-strike length to increase overall tonnes per vertical metre.
Trialling of Different Assay Techniques
ABM is also trialling different assay techniques to help better analyse the coarse gold and has used the more expensive leach-well process on every twentieth sample greater than 1 gram per tonne gold to compare against its standard fire assay.
Of the 35 samples re-assayed using leach-well analysis a total of 24 samples (68%) showed a higher result from leach-well versus fire assay.
The higher grade samples (>80g/t) in particular show a marked increase in grade when leach-well assaying is conducted.
This implies that fire assayed samples used in the resource estimation may have under-called the grade. This work is ongoing and further tests are being carried out.
ABM's Stage One trial mining is being conducted under the exploration licence and involves the extraction and processing of up to 10,000 tonnes of gold-bearing material.
This takes the place of a Feasibility Study though with the advantage of providing more robust data, as well as producing saleable gold.
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