Venus Metals along with their joint venture partner Rox Resources has had major success with its metallurgical test work recently conducted on the Youanmi Deeps Resource in WA. Test work completed last month delivered substantial improvement in gold extraction for Youanmi Deeps with new test work improving extraction to 95.6 per cent.
The improvement in recoveries is a substantial increase from the historical production by Gold Mines of Australia in the 1990s, which averaged 86.8 per cent gold recovery.
The metallurgical work was overseen by Orway Mineral Consultants and draws on new methodologies not previously utilised at Youanmi. Como Engineers have been engaged to complete scoping level process plant design and costing work which also commenced last month.
The test work forms part of development studies currently underway into potential future production at the Youanmi gold project which is a joint venture between Venus Metals and Rox Resources. The first part of the study is tasked with identifying processing pathways to optimise gold recovery prior to progressing to more extensive and detailed feasibility study level metallurgical test work.
The September 2021 test work results included two composite samples taken from 30 individual diamond drill core intervals of historical drilling comprising of mainly half and quarter NQ drilling core. It included 14 sections from the upper part of the Hangingwall Lode domain, and 16 sections from the upper part of the Main Lode domain. The Main Lode and Hangingwall Lode domains combined represent over 30 per cent of the entire Deeps Mineral Resource.
The success in achieving gold recovery results of 95.6 per cent came from the use of a pressure oxide leach process. The joint venture partners did also note that this early-stage test work is highly relevant to the Youanmi Deeps Resource which comprises just over half the total resource of 1.7 million ounces.
Managing Director Rox Resources, Alex Passmore said: “Preliminary metallurgical test work indicates a 10% increase on historical gold recoveries by utilising a pressure oxidation leach process (i.e. POX). Furthermore, we look forward to results of (scoping level) process plant design and costing later this year being undertaken by Como Engineers who have a long track record of success for both design and development of similar sized gold processing facilities in WA with a variety of flowsheet designs.”
Rox also commissioned a petrographic study to determine the gold speciation, grain size and mode of occurrence as well as to generally characterise the mineralogical composition of the ore across the deposit. Results showed visible gold was observed in all 11 samples submitted. Gold particles sizes range from 2 microns to a huge 150 microns. At least three gold species were observed, including low-silver gold, which is most abundant, along with high-silver gold and antimony rich gold. Most gold particles seem to occur on the pyrite grain boundaries and not within the grains, which is important as the gold particles are more likely to be free milling.
The company says the test work has established a well-understood pathway to very high gold recoveries - something which was not achieved by the former owners in the 1990s. Further test work is now planned in combination with the costing studies to determine the optimal and most economical feasible process solution, exploring various other suitable processes.
Future work is planned to include a wider range of underground resource domains from diamond drill core and will be included in the next resource update.
The Youanmi Gold Project is located 480 kilometres north-east of Perth and 400km inland and to the east of Geraldton. The historic Youanmi Gold Mine is located near the centre of the project tenement package and has historic production of 667,000 ounces of gold grading 5.42 grams per tonnes gold from open pit between 1987–1993 and underground operations. The operation was closed in 1997 when the gold price was hovering at a mere $400 per ounce with the last parcel of ore mined underground at 14.6 g/t gold grade.
Venus and Rox resources are re-exploring the area under multiple joint ventures and their tenure stretches over more than 350 square kilometres of the gold and base-metal rich stratigraphy. The effective use of new modern exploration techniques across the Youanmi terrane has given rise to a rash of new discoveries including the high-grade Penny West Deeps gold deposit, the Grace gold prospect adjacent to the Youanmi mill, the Junction and Link targets within the historical open pit mining area and the Currans Well discoveries just to the north of Penny West.
This improvement in exploration coupled with the advanced processing methods bodes well for what could potentially be buckets more gold now able to be extracted from the area.
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By Matt Birney
