Andromeda Metals Ltd (ASX:ADN) is higher after defining zones of high-grade halloysite-kaolin within the Bright White domain at Hammerhead prospect on the Eyre Peninsula in South Australia, highlighting a potential construction product application.
The area of Bright White kaolin has been defined with a minimum thickness of 10 metres extending over an area of 2.4 kilometres by 0.5 kilometres, setting the path for a mineral resource estimate to be prepared once the final XRD analyses have been received.
Samples from the high-grade halloysite zone at Hammerhead are giving excellent results in concrete application testing.
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Hammerhead drill hole ISO Brightness composite assays.
Andromeda has now received complete ISO Brightness and XRF results for all samples submitted from two aircore drilling programs undertaken in December 2019 and May 2020.
To date, XRD results have been received from 48 drill holes with results from a final batch of samples collected from a further 14 drill holes outstanding.
Andromeda’s XRD testing, which is undertaken by CSIRO, is used to quantify the percentage of kaolinite and halloysite in samples.
Construction product application
Previous published research work has shown that pure halloysite gives some interesting performance benefits when used in concrete mix designs.
The company has been investigating opportunities in various construction industry applications by testing the naturally occurring halloysite-kaolin hybrid material from the Great White Kaolin Deposit and the Hammerhead Prospect to establish the optimum combination of the two minerals.
Positive results from preliminary investigations have led to a comprehensive study being undertaken in several commercially significant concrete mix designs and mine backfill compounds.
This work is ongoing, but results from concrete trials performed after 28 days already show clear performance gains when using the right halloysite-kaolin additive.
Benefits for civil projects
Early results indicate that when adding 1 kilogram of the product to 1-metre of concrete, an approximate 12% improvement in strength can be achieved after 48 hours, which increases to around 15% after 14 days.
The gain is proportional to additional levels with a 4-kilogram addition giving nearly 30MPa after seven days, whereas the concrete control was 8MPa lower at 22MPa.
This early strength gain presents a potentially huge benefit for civil projects in reducing project wait times and has prospective benefits for underground mining backfill applications where the speed of curing to design strength is critical in stope scheduling.
A bulk sample of two tonnes has been collected from Hammerhead for future test-work.
Samples of product from the Great White Deposit are also showing excellent test results for mine backfill applications.
In addition to Great White deposit and Hammerhead, additional high-quality halloysite-kaolin prospects occur extensively across the Great White Kaolin Project area making this a region of global significance for the mineral with the potential of supporting a considerable long-life mining operation, should final feasibility studies determine the project to be economically viable.