Challenger Exploration (ASX: CEL) announced that high-grade gold recoveries of 91-94% were reported from Phase 1 metallurgical testing at Hualilan Gold Project in the San Juan province in the Argentine Republic.
The company said that the initial metallurgical testing of the skarn mineralisation demonstrated excellent gold and silver recoveries via simple gravity separation followed by single stage sulphide flotation generating gold recoveries of 91-94% and silver recoveries of 84-86%. CEL said that the Phase 1 program would be followed by Phase 2 Comminution and Cleaner Flotation testing.
CEL said that the results of the Phase 1 program represent a significant increase in overall combined gravity and flotation recoveries compared to the historical testing which indicated recoveries of 80% for gold and silver.
The company said that this initial round of metallurgical testing confirms that gravity and flotation recovery of gold/base metal concentrates, which is a low risk and industry-standard process, provides a clear path to evaluate commercialisation with excellent recoveries plus base metal credits.
Phase 1 metallurgical testing
The company had recently commenced Phase 1 metallurgical testwork program comprising first pass gravity and rougher flotation testing at the Hualilan project. Phase 1 was designed to determine the recovery of gold that is amenable to gravity separation while the rougher tests determine the relative rate of float recovery of the sulphide minerals. The initial metallurgical testwork from the high-grade skarn mineralisation was undertaken at SGS Canada Inc in Lakefield Ontario.
The testwork was conducted on a 147 kg bulk sample collected by the drilling and sampling of 3/4 core from four dedicated metallurgical holes, with additional material provided by a further 2 holes from which 1/4 core was provided. The holes were located at Main Manto, Cerro Norte (GNDD003, GMDD-039, and GMDD-043), Sentazon (GMDD-0040), and the Magnata Manto (GNDD018 and GMDD-041).
CEL noted that the program of metallurgical testing was designed prior to the discovery of the intrusive hosted mineralisation as a significant target at the Hualilan project. The company said that the bulk sample of the intrusive hosted mineralisation is currently being prepared for metallurgical testing.
Excellent Au and Ag recoveries
The company announced that the testing comprised an initial test that demonstrated excellent recoveries into a bulk rougher concentrate (F1); a series of rougher flotation tests designed to produce a Cu/Pb and a Zn rougher concentrate (F2-F4); and a final bulk sulphide float (F5).
CEL said that high gravity gold recoveries were achieved in all tests with gravity recovery averaging 42.4% and ranging from 32% to 49%. Importantly, fine grinding was not required with best recoveries using a P80 = 86-106 micron grind.
The overall recoveries and grades of the five tests (on the basis of combining the gravity and rougher concentrates into a single product) are shown below.
Simple flotation testing
CEL said that simple flotation testing producing a simple bulk rougher and a bulk sulphide concentrate returned excellent recoveries of 91-94% (gold) and 84-86% (silver) at a P80 of 100-106 micron grind. The concentrate grades of 40-43 g/t (gold), 90-120 g/t (silver), and 11% (zinc) are expected to be improved with cleaning.
The company said that the recoveries are significantly better than both the historical recoveries and the Company’s initial expectations.
Rougher flotation tests
Challenger said that the rougher flotation tests designed to produce a separate Cu/Pb concentrate followed by a Zn rougher concentrate demonstrated the recovery of significant base metal credits. The best result produced recoveries of 89% (gold), 84% (silver), 79% (zinc), 79% (lead) at a grind size of P80 of 86 microns.
CEL said that rougher flotation tests indicate the potential to recover significant base metal credits via gravity followed by a simple two stage float produced high quality gravity and Cu/Pb rougher concentrates grading 442 g/t and 232 g/t gold respectively and a separate Zn rougher concentrate containing 73% of the zinc. The company noted that the potential to efficiently recover base metals can significantly improve economics with zinc accounting for 10 % of the value of the high-grade skarn mineralisation
Phase 2 program planned
The company announced that Phase 2 of the metallurgical test program would be undertaken after the completion of Phase 1 metallurgical testing on the intrusion-hosted mineralisation.
CEL said that Phase 2 would involve Comminution Testing including Bond Ball Mill Grindability and Bond Abrasion tests and Cleaner Flotation and Cleaner Variability testing. Phase 2 will also include additional rougher flotation testing utilising different reagent regimes designed to further improve the recoveries into the rougher Cu/Pb and Zn concentrates.
The company said that this will be followed by a series of cleaning tests to separate the Cu/Pb rougher concentrate into separate copper and lead concentrates and cleaning tests to upgrade the zinc/gold rougher concentrate.
CEL Managing Director, Mr. Kris Knauer, said: “The initial results from Phase 1 metallurgical are a significant uplift on what was achieved historically and I am delighted with gold recoveries of over 91% from a process consisting of gravity recovery followed by a single sulphide float. This is about as simple as metallurgy gets providing us with the ability to evaluate commercialisation via an option which traditionally requires far less capital expenditure than the alternatives.
The ability to recover significant base metal credits while maintaining high gold and silver recoveries, again via simple gravity recovery followed by flotation, is also an excellent outcome. This can significantly improve economics with zinc accounting for 10 % of the value of the high-grade skarn mineralisation. The high gold grades in these rougher concentrates will make them extremely sought after and we expect cleaning tests will be able to further improve their quality.
We look forward to updating the market on further metallurgical testing over the coming months.”
*Image Source: Challenger Exploration Ltd