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Altus Strategies announces preliminary testwork results

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Global Mining Review,

Altus Strategies Plc has announced the results of preliminary metallurgical testwork undertaken on composite samples of fresh rock collected from core drilling at the FT Prospect of its Tabakorole gold project located in southern Mali. Exploration activities at Tabakorole are being funded by Marvel Gold Ltd (under its joint venture (JV) with Altus.


  • Initial metallurgical testwork on fresh rock samples completed at Tabakorole, southern Mali.
  • Bottle roll tests on core samples from diamond drilling (DD) at the FT Prospect indicate:
    • A straightforward, clean and non-refractory ore with low reagent consumption.
    • High gold recoveries of 92.7% to 96.6% for grind sizes (P80) of 150 to 75 microns.
  • Project hosts a mineral deposit for which a mineral resource estimate (MRE) has been generated (see news release dated 30 September 2020), comprising:
    • 16 600 000 t at 1.2 g/t Au for 620 000 oz in the inferred category.
    • 7 300 000 t at 1.2 g/t Au for 290 000 oz in the indicated category.
  • 43% of the current MRE is situated within 100 m of surface.
  • MRE is in accordance with the JORC Code, an acceptable foreign code for the purposes of NI 43-101.
  • 6300 m resource expansion reverse circulation (RC) drilling programme is underway.
  • Marvel has earned a 51% interest in the project and paid Altus US$200 000 in cash.
  • Marvel has commenced JV stage-3 to earn an aggregate 70% by expending US$3 million.
  • Altus holds a 2.5% net smelter return (NSR) gold production royalty on Tabakorole.

Steven Poulton, Chief Executive of Altus, commented: "The results of the preliminary metallurgical testwork on fresh rock from drill core at the FT prospect of the Tabakorole project are excellent. Non-refractory mineralisation with high gold recoveries highlights the potential for a simple, industry standard gold processing flow sheet. Future metallurgical testwork is expected to include potential optimisations of grind size and residence times.

"Our ASX-listed JV partner Marvel Gold has now completed the stage-2 commitments of the JV, including payment of US$200 000 to Altus and earned a 51% interest in the project. Marvel has already commenced stage-3 of the JV at Tabakorole, which includes the current 6300 m RC resource expansion drill programme.

"Tabakorole currently hosts a significant gold resource which is open along strike in both directions, and at depth. The project is emerging as a significant west African gold deposit and these metallurgical testwork results represent a significant step in advancing the project. We look forward to updating shareholders once the final results from the current drilling programme are received."

Tabakorole metallurgical testwork

A total of four composite samples were collected from four diamond drillholes completed by Marvel in mid-2020. The composites were made from the coarse split of diamond drilling samples based on the drillhole locations within the Tabakorole deposit and the head grade assay of the original samples. The composites targeted the current MRE grade of 1.2 g/t Au and ranged from 1.1 to 1.9 g/t Au. All samples were taken in fresh rock as this material represents approximately 90% of the Tabakorole MRE. Initial bottle roll testing is the industry standard first-step to determine gold recoveries from cyanide leaching.

Sample head analysis included duplicate gold assays along with a 26 element inductively coupled plasma mass spectrometry (ICP) scan. Composites were crushed to produce three size fractions (75 µm, 106 µm and 150 µm) before subjecting the samples to cyanide leaching with sampling undertaken at 12, 24 and 48 hours. Cyanide levels and pH were controlled, and consumption measured.

Results from the bottle roll testing show high recoveries from all samples, with low cyanide and lime consumption. Average leach recoveries were 92.7%, 94.8% and 96.6% for the four samples at the three grind sizes. The high recoveries indicate that the gold is likely to be recoverable via a simple carbon-in-leach process flow sheet, with no indications of refractory gold.

Sampling at 12, 24 and 48 hours indicate the leach kinetics are fast, with an average of over 90% recovery achieved in 12 hours at the finer grind. Future metallurgical testing is expected to look at comminution testwork and reagent concentrations with the aim of optimising the extraction process to aid in future plant design.

Multi-element assaying of the four samples returned generally low levels of deleterious elements including organic carbon, arsenic, cadmium, mercury and lead. Importantly there was no apparent correlation between arsenic content and gold recovery, indicating that the two phases most likely represent distinct mineralising events.

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