Multiple EM Conductors To Be Tested
Diamond drilling of strong EM conductors identified from recent downhole EM (DHEM) surveys in MAD185, MAD192 and MAD193 is scheduled to begin within weeks
Western Australian nickel company St George Mining Limited (ASX: SGQ) is preparing to test a number of strong EM Conductors with a Diamond Drilling campaign at its flagship Mt Alexander Project, located in the north-eastern Goldfields.
DHEM surveys in drill holes MAD185, MAD192 and MAD193 have identified a total of 11 off-hole EM anomalies for follow-up testing.
A diamond drill rig is scheduled to arrive at site in late January 2021 to commence drilling of these exciting targets.
Each of MAD185, MAD192 and MAD193 intersected disseminated nickel-copper sulphides on the basal contact of the same mafic-ultramafic intrusive unit, a positive indication for the potential presence of massive nickel-copper sulphides along strike from these holes.
The first two targets to be drilled in 2021 will be the strongest of the off-hole conductors identified from the DHEM survey in each of MAD192 and MAD185.
Executive Chairman, John Prineas,said these two conductors, modelled with very high conductivity of 55,550 Siemens (MAD192) and 33,100 Siemens (MAD185) respectively, are outstanding targets for the discovery of new massive nickel-copper sulphide mineralisation. The conductors are located down-dip from the two drill holes and known massive sulphides, which is a favourable location for potential larger accumulations of mineralisation at depth.
An RC resource definition drilling programme has been designed for the Investigators and Cathedrals Prospects. An RC rig is expected to arrive at site in mid-February 2021 to commence the drill-out with more than 10,000m of drilling planned.
At Investigators, drilling will include the testing of at least 20 EM conductors (and potentially more) which have been largely identified from DHEM surveys completed in drill holes at Investigators. These conductors are located between or closely along strike from known nickel-copper sulphides intersected in previous drilling and are interpreted to indicate continuity of the known massive and semi-massive sulphides.
The large number of conductors suggests that a significant volume of nickel-copper sulphide mineralisation is likely to be identified by the drilling of the conductors.
The proposal for a starter mine operation at Mt Alexander envisages that mining will potentially commence at the Stricklands Prospect to be followed by mining at Investigators and Cathedrals. Each of these areas hosts high-grade nickel-copper-cobalt-PGE mineralisation that commences 30m from surface.
In 2020, resource definition drilling was completed at Stricklands to delineate a resource estimate for the shallow high-grade mineralisation discovered there. The drill-out focused only on the shallow mineralisation, between 30m to 100m below surface, and did not include a drill-out of deeper extensions – consistent with the concept of a starter mine that can be executed quickly and for a very low capital cost.
The resource estimate for Stricklands will be finalised once the metallurgical test work for Stricklands is completed. This will allow an accurate estimate of the amount of mineralisation that can be classified as economic ore and enable completion of pit optimisation work.
Meanwhile, XPS (Expert Process Solutions), based in Sudbury in Canada, has been mandated to complete detailed test work on the metallurgical performance of the Stricklands mineralisation and to develop a flowsheet for the potential mining and processing of the Stricklands ore.
Multiple metals – nickel, copper, cobalt and PGEs – are comprised in the ore, requiring a very comprehensive range of test work to best optimise the value that can be attained from the processing.
Interim results from the test work are very positive and indicate:
- The combined oxide and fresh composite is amenable to the production of separate nickel and copper concentrates from conventional flotation circuits
- Overall copper recoveries of 91% to 93%
- Overall nickel recoveries of 73% to 84%
- Talc up to 1% to 1.5%, which can be suppressed in the flotation process
The concept for mining at Stricklands envisages an open pit. Material that would be mined in this scenario includes partly oxidised mineralisation (both disseminated and massive) at the top of the deposit followed by fresh sulphide mineralisation (both disseminated and massive) below. This material would represent the Life of Mine (LOM) ore feed.
A master composite sample for metallurgical testing was prepared incorporating all mineralisation types. Test work results have shown that recoveries from the oxidised disseminated mineralisation are poor and therefore this small volume of material is unlikely to be classified as ore.
“2020 has been a difficult and odd year. Some businesses have been devastated by COVID-19 while others have flourished. Everyone has been required to make adjustments in order to survive in the new world environment,” Mr Prineas said.
“At St George, we have carefully managed our operations in compliance with COVID-19 regulations to protect the health and safety of our team and service providers.
“Notwithstanding the significant challenges faced by everyone, we have managed to achieve many important milestones in 2020.
“We commenced our deeper drill programme in June this year and completed multiple deep holes – the deepest to 850m. We confirmed the presence of fertile intrusive rocks at depth, giving confidence that the extensive shallow high-grade mineralisation already discovered could also occur at depth.
“We were further rewarded when downhole EM surveys in several deep holes lit up very powerful EM conductors. We have secured a diamond rig for January and look forward to starting 2021 with a new massive sulphide discovery.
“We believe our high-grade nickel-copper sulphides are amongst the best mineralisation discovered in Western Australia with a combination of high-grades of nickel, copper, cobalt and platinum group metals that is unmatched by other discoveries.
“Thorough metallurgical test work is required to develop a flowsheet that can maximise the value of all these metals in a potential mining and processing operation. Positive test work results have been delivered by work in Perth and Canada. The test work will be finalised next year, allowing for completion of a scoping study for a starter mine at Mt Alexander.
“The next year promises to be another exciting one as we continue to unlock the full value of our large, high- grade mineral system. On behalf of the Board of Directors, we thank our shareholders for their support in 2020 and look forward to sharing more success with you in 2021.”
