90% Gold Recoveries from Metallurgical Tests - Dona Maria
Perth, Oct 19, 2015 AEST (ABN Newswire) - Crusader Resources Limited (
ASX:CAS) has received very encouraging results from the first metallurgical testwork program over Dona Maria - the high-grade gold prospect recently highlighted in the Juruena Gold Project maiden JORC compliant mineral resource estimate (ASX Announcement - 29 September 2015).
Highlights
- Metallurgical testwork at Dona Maria prospect recovers +90% gold in standard leaching tests
- Various tests including leaching and leaching plus gravity at different grind sizes and leach times, recover between 85.4% and 91.0% gold (39.7% and 47.6% Ag)
- A head grade of 31.2 g/t gold of the composite sample, composed of recent drill cuttings, is indicative of the high grades observed at Dona Maria
- Negligible copper associated with mineralisation, (unlike adjacent Crentes prospect)
- Additional tests to refine and potentially improve the results are now being proposed
Dona Maria is a high-grade prospect with geometry suited to potential exploitation by underground mining. Dona Maria's recently announced inferred mineral resource estimate of 196kt at 11.8 g/t Au for 76,087oz of gold (using a 60 g/t top-cut) is the subject of a current conceptual study into potential development.
The Juruena Project (> 400km2 of contiguous tenements, 100% Crusader owned) is located in Central Brazil on the southern fringe of the Amazon basin. Situated on the western end of the prospective Juruena-Alta Floresta gold belt (estimated to have produced ~7Moz Au), Juruena has been worked extensively by artisanal miners (garimpeiros) since the 1980s, producing an estimated 500koz of gold.
As noted above, Crusader recently announced a maiden resource for three prospects at Juruena, including Dona Maria, Querosene and Crentes. Metallurgical sampling from Querosene was recently announced (see ASX release 1 July 2015) and the results mirror the results reported over Dona Maria today.
At Dona Maria, a 15kg composite sample was collected from mineralised sections of the recent RC and diamond drilling program and dispatched to the independent metallurgical testing laboratory- Testwork Desenvolvimento de Processo Ltda. (Testwork) in Belo Horizonte. Testwork crushed, mixed and selected sub-samples for testing and then performed a series of leaching, grinding and physical property tests on the samples. It is noted that the high head grade of 31.2 g/t Au will be further investigated via additional planned tests. Assaying of the various concentrates, tails and composites was performed at SGS labs in Belo Horizonte.
Commenting on the results, Crusader's Managing Director Rob Smakman said; "These are really impressive first pass results and indicate that Dona Maria ore should be easily treatable in a standard leach plant. We note the similarities to the metallurgical characteristics we have at Querosene and are therefore confident that the same process flow sheet will be suitable for both the prospects- which are only 1km apart. The results today are a key part of the conceptual design we continue to work towards and should enhance the overall project."
Results indicate that using cyanide leaching alone, recoveries of 85-87% are possible, with moderate consumption of cyanide (See Section 1 of Table 1 in link below). Additional leaching time (from 24 to 32 hours residency) did not significantly increase the recovery. It should be noted that the high-grade tail (between 4.5-4.7 g/t Au) will be the subject of additional testing in order to minimise the gold sent to tailings.
The overall gold recovery results are improved when the samples were subjected to gravity separation first and the rejects leached in cyanide for up to 32 hours (Section 2 of Table 1, in link below). The grade of the tails were also reduced using the combined beneficiation however the inclusion of a gravity circuit will be the subject of a trade-off study to ensure the additional gold recovery is worthwhile.
Additional testwork is now being planned and will include multiple samples from different areas of the project (with various head-grades), inclusion of a pre-lime step (to increase recovery and decrease Cyanide consumption), the addition of carbon to the leaching process and the addition of oxygen to the leaching process in order to study the effect on recoveries.
To view tables and figures, please visit:
http://media.abnnewswire.net/media/en/docs/ASX-CAS-737757.pdf
About Crusader Resources Limited
Crusader Resources Limited (ASX:CAS) is a minerals company focussed on the identification, acquisition, development and operation of projects in Brazil. Crusader believes that Brazil is a vastly underexplored country with high potential for the discovery of world class mineral deposits. The company has already acquired a diverse portfolio of projects including gold, iron ore, tin, tungsten and uranium and continues to utilise its strong networks in Brazil to identify new opportunities.
Crusader is characterised by a tight corporate structure and features an experienced board of directors who are strongly focussed on the success of the company.
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