Auric Mining Ltd (ASX:AWJ) has recorded “exceptional” preliminary test-work results on material from its Munda gold deposit near Kalgoorlie in WA.
A gravity separation activity, followed by leaching the gravity tails, managed to extract 96.57% of the ore’s gold by the 24-hour mark.
The test-work also demonstrated what’s considered an exceptionally fast leach rate, with 89.71% of gold leached in the first two hours.
All in all, the preliminary metallurgical test-work suggests that Munda’s gold mineralisation is ideally suited to conventional carbon-in-leach (CIL) processing techniques.
The results are in
Auric completed test-work on a composite sample from a single drill hole at Munda, which was completed in September last year as part of a 28-hole program.
The sample was taken at the same time as a metallurgical test-work program for the Jeffreys Find target, as announced earlier this month.
AWJ’s metallurgical program was designed and supervised by Upside Group Pty Ltd and took place at ALS Metallurgy’s Perth facility.
The principal findings were:
- Gravity separation and subsequent leaching of gravity tails yielded overall gold extraction of 96.57% by the 24-hour mark. Leach recovery was initially very rapid and did not improve after 24 hours;
- Gravity recovery was high, at 36.51%;
- Silver content in all samples is low, in line with what would be expected for the Munda deposit;
- The arsenic content is very low;
- Organic carbon concentrations are low, indicating that Munda does not have preg-robbing qualities;
- Sulphur concentrations are very low, which reiterates that Munda is not a refractory orebody; and
- Reagent consumption (such as cyanide, lime and oxygen) is low.
The Munda gold deposit carries a 4.48-million-tonne indicated and inferred gold resource, grading 1.38 g/t for 198,700 ounces.
Past, present, future
This isn’t the first time Munda ore has been subjected to test-work.
In 2006, Titan Resources completed a bottle roll test on seven Munda samples with a range of lithologies.
In all samples, gold recoveries after a 24-hour cyanide leach exceeded 92%, while five of the samples exceeded 96%.
Fast forward to today, and Auric says the fresh results support the earlier test-work and more comprehensively characterise Munda’s mineralisation in terms of conventional CIL processing.
The work is far from done: a test-work program that fully represents the Munda deposit — both spatially and lithologically — is required at a more advanced project stage.
The future program will include comminution test-work to establish grinding, but otherwise will follow a very similar flowsheet to the test-work described today