Far East Gold (ASX: FEG) has begun a revised scoping study for its Wonogiri copper-gold project in Indonesia’s south central Java region, as survey work continues at Woyla. The company has engaged Mining One Consultants to update former owner Augur Resources’ scoping study that was prepared in 2016. As part of this, Mining One has begun metallurgical test work on porphyry and epithermal drill core samples, and will reassess the study based on current commodity prices, and an optimal processing flow sheet. The previous scoping study was based on a 2016 gold price of US$1,350 per ounce and copper attracting US$5,500 per tonne. Far East noted Mining One had already provided it with a pit optimisation study for Wonogiri, which included a high-level open-pit and underground mining scenario for the Randu Kuning deposit.
Initial metallurgical results
The metallurgical test work is looking at gold and copper samples of Wonogiri porphyry ore, which has head grades ranging from 0.8-1.7 grams per tonne gold and 0.11-0.21% copper. Epithermal samples are also being analysed for optimal recoveries with head grades ranging from 0.58-10g/t gold and 6-8.5g/t silver. Initial porphyry metallurgical results have achieved 35-51% gold recoveries using simple gravity. A further 83-85% of the gold in the gravity tailings can be recovered using conventional carbon-in-lead processing. To-date, overall gold recoveries ranged from 90-91%, with associated silver recoveries of around 65%. Under the test work program, Far East is investigating reducing cyanide usage and potentially regenerating cyanide to further minimise consumption.
Potential to grow resources
Augur previously developed a JORC 2012 resource for Wonogiri’s Randu Kuning deposit, which contains 1.15 million ounces of gold equivalent. This comprises 996,000oz of gold and 190 million pounds of copper. Far East noted that the potential to grow these resources is indicated by previous drilling where an extensional hole intercepted 37m at 1.77g/t gold and 0.23% copper from 458m, with mineralisation remaining open at depth.
Woyla copper-gold project
In parallel with the updated scoping study at Wonogiri, Far East is advancing its Woyla copper-gold project in Indonesia’s Aceh region. The project covers 24,260 hectares and Far East is increasing its 51% stake to 80% by completing a feasibility study and delivering a maiden JORC resource. Exploration at Woyla is underway with an induced polarisation (IP) survey crew mobilised to the project site last month. The survey is being carried out as part of a collaboration with the Indonesian Government’s Ministry of Energy and Mineral Resources. Initial survey work has been completed at the Anak Perk North section of the Anak Perak prospect, and will begin at the Anak Perak Main Zone section of the prospect later this week. Far East is anticipating survey results early next month. The rationale behind the survey is to further Far East’s understanding of the 4.7km epithermal vein system identified at the project, where rock chip sampling has uncovered up to 119g/t gold and 361g/t silver. Results from the survey along with the historical mapping, sampling and trenching will be used to pinpoint targets for the maiden drill program at Woyla.