Alford East Copper-Gold ISR Project, South Australia
The directors of Thor Mining Plc (“Thor”) (AIM, ASX: THR, OTCQB: THORF) are pleased to advise the results from our initial pump test for preliminary hydrogeological assessment at the Alford East Copper-Gold Project, SA.
Project highlights:
- Initial aquifer pump test successfully completed.
- Copper-gold mineralisation at the test site is saturated below the water table; essential for ISR production.
- Groundwater salinity reports in the range of 15,000 – 55,000 milligrams per litre total dissolved solids (mg/L TDS). This is classed as saline and precludes agricultural or potable use.
- Ground water is alkaline with pH – 8.1. This is ideal for trial lixiviant glycine.
- Short term pumping tests demonstrated consistent water flows suitable for ISR production.
- The host rock is permeable.
- This work is all co-funded by the SA Government Accelerated Discovery Grant (ADI) of A$300,000, as announced on 20 May 2021.
Nicole Galloway Warland, Managing Director of Thor Mining, commented:
“Pump testing of our initial water bore has shown favourable water characterisation and permeability for potential In Situ copper-gold recovery at our Alford East Project. This is positive news as we progress the project towards ISR assessment and development of an environmentally, low carbon emission alternative to conventional open cut and underground mining.”
A copy of the Tenement and Prospect Location Plan may be viewed via the following link:
https://cms.thormining.com/sites/thormining/media/maps/20-005-1d-yorke-pen-jv.jpg
Alford East Project Background
The Alford East Copper-Gold Project is located on EL6529, where Thor is earning up to an 80% interest from unlisted Australian explorer Spencer Metals Pty Ltd, covering portions of EL6255 and EL6529 (ASX: THR Announcement 23 November 2020).
The Alford East Project covers the northern extension of the Alford Copper Belt, located on the Yorke Peninsula, SA. The Alford Copper Belt is a semi coherent zone of copper-gold oxide mineralisation, within a structurally controlled, north-south corridor consisting of deeply kaolinised and oxidised troughs within metamorphic units on the edge of the Tickera Granite, Gawler Craton, SA.
Utilising historic drill hole information, Thor completed an inferred Mineral Resource Estimate (MRE) (ASX: THR Announcement 27 January 2021):
- 125.6Mt @ 0.14% Cu containing 177,000t of contained copper
- 71, 500oz of contained gold
Based on the nature on the oxide mineralisation, the deposit is considered amenable to In Situ Recovery (ISR) techniques. For further information on ISR please refer to Thor’s website via this link for an informative video: www.youtube.com/watch?v=eG_1ZGD0WIw
Table A: Alford East Mineral Resource Estimate as at 22 January 2021, with AR-5 extending towards AE-8 domains the focus of the recently completed drilling program.
Note: MRE reported on oxide material only, at a cut-off grade of 0.05% copper, which is consistent with the assumed In Situ Recovery technique.
Hydrogeology
As part of the ‘proof of concept’ for In Situ Recovery of copper and gold at Alford East Project, recently completed diamond drillhole 21AED001 was developed into a water bore. The aim of this work was to establish baseline hydrogeological conditions of the rock hosting the Alford East copper and gold mineralisation. This included measuring:
- ground water levels,
- ground water quality (chemical composition)
- hydraulic conductivity (permeability)
- and collecting water samples for use in hydrometallurgical test work
The program comprised the installation of an investigation well ( 6430-2702) into the Alford East mineralised zone, and a subsequent aquifer (pumping) test.
Table B: Collar Position of 21AED001 – Water Bore
Coordinates are in GDA94, MGA Z53 using DGPS position
21AED001 was selected based on its central position within AE-5 MRE domain (Figure 2 and Figure 3) and its broad copper-gold intercepts including (21AED001 previously reported THR:ASX Announcement 31 August 2021):
- 108.2m @ 0.17% Cu and 0.1g/t Au from 6.2m including,
- 59.9m @ 0.31% Cu from 21.9m and
- 32.9m @ 0.4% Cu and 0.31g/t Au from 81.5m
21AED001 was developed into a 4-inch water bore by GMP Drilling Pty Ltd with B & T Lehmann Drilling Pty Ltd carry out the pump testing operation under the direction and supervision of consultants, Groundwater Science. Water samples were analysed by Eurofins Environment Testing in Victoria, with water levels and hydraulic conductivity measurements conducted by Groundwater Science. Groundwater sampling was undertaken in accordance with EPA Guidelines (2019).
Key Findings:
· The copper-gold mineralisation at the test site is saturated below the water table. The water table elevation is approximately 38 m Australian Height Datum (AHD). At the test site, this equates to a depth to water of 12 m below ground surface. For ISR, the mineralised zone needs to be saturated for lixiviant fluids to flow through.
· Groundwater salinity within 20km of site reports in the range of 15,000 – 55,000 milligrams per Litre total dissolved solids (mg/L TDS), with onsite investigation reporting 19,000mg/L. This is classified as saline and precludes agricultural or potable use. The beneficial use category of this high salinity water as defined in the South Australian Environmental Agency (EPA) water quality policy (2015) and the Australian and New Zealand Guidelines for Fresh and Marine Water Quality ANZECC Guidelines (2020) for industrial use only, not suitable for irrigation or livestock (Table C).
· Ground water is alkaline with pH – 8.1, this is ideal for the trial lixiviant, glycine. Glycine is a naturally occurring amino acid, and an environmentally friendly reagent in an alkaline carrier.
· Groundwater is found within the weathered zone (saprolite) of the basement rock, rather than in discrete fractures.
· The rock hosting the copper and gold mineralisation is moderately permeable.
· Short-term test pumping calculated an aquifer transmissivity (T) of 2 to 3 m2/day. The resultant concomitant bulk hydraulic conductivity is approximately 0.14 m/day. In an ISR setting, wells with 18 m long screens can be expected to yield around 0.5 L/s. This assumes transmissivity values consistent with results from recent test pumping. This is very positive for ISR production.
A copy of the Alford East Project AE-5 domain showing drillhole location plan including 21AED001-Waterbore may be viewed via the following link:
https://cms.thormining.com/sites/thormining/media/Maps/ae-5-location-plan.jpg
A copy of the Alford East Project Cross section 6,256,360mN looking NNE, showing 21AED001 (Water Bore), 21AED003 and 21AED005 may be viewed via the following link
https://www.thormining.com/sites/thormining/media/banners/section_waterbore1.jpg
Table C: Salinity Classification
( https://www.epa.sa.gov.au/environmental_info/water_quality/advice-and-assistance )
Next Step
1) Future aquifer pump testing and tracer tests in trial well array, to be designed and carried out in conjunction with next resource drilling program.
2) A seasonal monitoring program comprising quarterly water level monitoring and groundwater quality sampling to be implemented.
3) Preliminary hydrometallurgical studies by Mining and Process Solutions (MPS) on potential glycine lixiviants for copper and gold recovery are underway with results anticipated November.
This work is all co-funded by the SA Government Accelerated Discovery Grant (ADI) of A$300,000.
Elements: Cu=Copper, Au = Gold, Ag=Silver, Mo=Molybdenum, Co=Cobalt, Se= Selenium, Bi=Bismuth, Ba=Barium and Te=Tellurium
Ends –
For further information on the Company, please visit www.thormining.com or contact the following:
Thor Mining PLC
Nicole Galloway Warland, Managing Director
Ray Ridge, CFO / Company Secretary
Tel: +61 (8) 7324 1935
Tel: +61 (8) 7324 1935
