Metallurgical Testwork

Following receipt of the very favourable results of the initial RC drilling, a preliminary metallurgical testwork programme was undertaken. Two representative composite samples, with estimated grades of 9.75 g/t Au and 8.81 g/t Au were submitted Wardell Armstrong Ltd’s testing laboratory in the UK. The results of this testwork programme can be found here. Testwork included head assays, whole ore bottle roll cyanide leach tests, gravity separation tests, and cyanidation leaching of the gravity products.

Results of the testwork are summarised below:

  • Gold recoveries of 97.4% and 97.9%, and silver recoveries of 85.2% and 87.9% (after 48 hours), from the whole ore bottle roll cyanide leach tests
  • Gold recoveries to >100 micron gravity concentrate: 56.4% and 62.2%, from the gravity separation tests
  • Cumulative gold recoveries of 96.0% and 96.7%, and cumulative silver recoveries of 85.1% and 91.3% (after 48 hours), from leach testing of the gravity concentrate and tails products

Gold extraction vs. leach residence time, whole ore bottle roll leach tests

The excellent recoveries of both gold and silver from the 2 tested composite samples are very encouraging, and suggest that the Semna mineralisation is metallurgically simple, and is readily amenable to both conventional CIL and gravity separation plus secondary leaching processing routes.