The directors of Thor Mining Plc (“Thor”) (AIM, ASX: THR) are pleased to advise additional positive results from the initial hydrogeological drilling program at the Kapunda ISR (Insitu Recovery) copper project carried out by EnviroCopper Limited.
EnviroCopper Limited ( www.envirocopper.com.au ), via subsidiary Environmental Copper Recovery Pty Ltd, holds an agreement to earn, in two stages, up to 75% of the rights over metals which may be recovered via in-situ recovery (“ISR”) contained in the Kapunda deposit, from Australian listed company, Terramin Australia Limited (“Terramin” ASX: “TZN”). Thor hold a 25% interest in EnviroCopper Limited with rights to increase that interest to 30%.
· The hydrogeological testing program was successful, with the tracer test showing fluid movement from well to well in a relatively short time period, providing potential for cost saving through reducing the number of wells for optimum production.
· Laboratory assays confirm previously reported portable XRF results along with some elevated gold levels.
· Groundwater is acidic (pH 3.8 – 4.0) with naturally elevated copper levels, indicating potentially lower expected pre-conditioning operating costs, and demonstrating that the copper is highly soluble.
· Laboratory testing to date shows several lixiviant systems suit the natural low pH environment, minimising likely impact on environment & microorganisms.
· Initial laboratory scale metal recovery tests – Ion Exchange, Electro Winning and Cementation all produce copper.
Mick Billing, Executive Chairman of Thor Mining, commented:
” Very solid progress being made by EnviroCopper at the Kapunda copper ISR project, continuing to confirm the potential for production of copper using ISR, against a background of rising copper prices”.
“There is a very busy schedule of activities during the second half of calendar 2020 with potential to add significant inv estor value via gold focussed drilling, and more field test activities to further demonstrate the potential for economic ISR production at Kapunda.”
“Some zones within the Kapunda deposit have previously been reported to host highly promising gold values, including 95metres @ 3.06g/t, ( www.asx.com.au/asxpdf/20190403/pdf/4440hfmqpsl83y.pdf ) and we look forward to the drill program to confirm and extend these.”
Three holes were drilled south of the Kapunda mine site. Their purpose was to establish an array of wells for
• Pump testing to determine aquifer properties,
• Tracer testing to determine fracture connectivity between wells.
The drilling comprised one pilot hole (KPFRT01) to determine the geology, ore distribution, depth to water table and permeable water yielding zones and then two additional bores were drilled and cased as test production bores (KPFRT02 and KPFRT 03) located approximately 10m apart. Hole KPFRT01 was geophysically logged to provide additional downhole information on fracture density and orientations.
Drill chip samples from these holes were analysed using portable XRF on site, ( www.thormining.com/sites/thormining/media/pdf/asx-announcements/20191127-preliminary-drilling-results-at-kapunda-project.pdf ) then sent to NATA accredited laboratories for chemical assays to confirm copper concentrations with table B containing a summary of the results. Copper values were higher than expected for the area, as it is off the existing mine site and gold assays confirmed the presence of gold in the system.
Pump Test (KPFRT02 and KPFRT 03)
Pumping was undertaken using a 24-volt diaphragm pump. Groundwater was discharged to a 1m³ bulk container and the water level rise in the container was used to monitor flow rate.
Pumping continued for 480 minutes with the flow rate holding constant for most of the test.
Drawdown was measured manually and by data-logger in the pumped well (KPFRT03) and in the observation well (KPFRT02) located 15 metres away.
Tracer Test (KPFRT02 and KPFRT 03)
A tracer test was undertaken with the aim of determining the connectivity of fractures between the two test production bores. The test comprised injection of a sodium bromide tracer into one well KPFRT03 and simultaneous extraction of groundwater from KPFRT02 . Samples were taken every 15 minutes and a selection of samples were analysed for bromide concentration. Breakthrough of the bromide tracer occurs at approximately 150 minutes. There was incomplete tracer recovery in the 8-hour period the test was run.
This tracer testing showed that the longer screened intervals and increased distances apart may yield more satisfactory results than small scale, focused extraction by small diameter well patterns. This could contribute to potentially lower capital costs with a smaller number of wells required.
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