RE: RNS29 Apr 2025 07:13
Gold Processing and Refining
As a continuation of the evaluation of the Waste Tip, further sampling of the -20mm screened ore has been undertaken. The sampling focused on material derived from Trenches 2 and 4, with samples processed through the recently modified gravity recovery plant. Initial sampling of Trenches 2 and 4 in May 2024 returned average head grades of 0 g/t and 5.33 g/t respectively (see the Alba RNS of 15 May 2024). This resampling was as much a test of the reconfigured plant layout as verification of the original trench sampling. Concentrate samples were submitted to an independent laboratory for assay, with the balance of the concentrates submitted to the Company's usual refiners to recover the total gold content.
All concentrate samples assayed by ALS returned gold grades for both trenches with a low of 0.6 g/t, a maximum of 23.9 g/t and an average of 7.9 g/t. The back-calculated head grade of the assays averaged 0.22 g/t. However, as before, the gold grades from the laboratory assays significantly understated the actual gold content in the samples. The results from the refinery showed an average concentrate grade of 450.6 g/t across both trenches, equating to an average head grade of 9.2 g/t (2.0 g/t for Trench 2 and 19.9 g/t for Trench 4).
The grade variability is a reflection of the irregularity of the gold distribution on the Waste Tip. However, the increased grades in general when compared to the May 2024 results in respect of material from the same trenches is also considered to be a consequence of the recent pilot plant process flow modifications made by Alba.
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