DevEx’s metallurgical testing has found that the clay-hosted rare earths mineralisation at its Kennedy project in Queensland are indeed of the much sought after ionic adsorption type.

Leach test work by the Australian Nuclear Science and Technology Organisation (ANSTO) demonstrated rapid recoveries by desorption of REE in the first 30 minutes using an ammonium sulphate (AMSUL) solution in weak acidic conditions (pH4).

Adding further interest, this was achieved with very low acid consumption and very low dissolution of gangue (waste) elements such as iron, calcium and aluminium.

This is hugely significant for DevEx Resources (ASX:DEV) as while there have been many clay-hosted REE discoveries in Australia, actual ionic adsorption deposits are much rarer.

IAC deposits typically have much lower processing costs that offset their lower grades compared to hard rock REE deposits as well as hosting significant quantities of valuable magnet REEs such as terbium and dysprosium that are used to manufacture permanent magnets used in electric vehicles and wind turbines.

The later point is also true at the Kennedy project with final 1m composite assay results from wide-spaced reconnaissance drilling returning results such as 2m grading 1,639 parts per million (ppm) total rare earth oxides (TREO) (22MGRAB008), 2m at 1,607ppm TREO (22MGRAB003) and 1m at 2,391ppm TREO (22MGRAB004) with all including the high-value REE’s of praseodymium, neodymium, dysprosium and terbium.

Drilling and metallurgical test work

Rotary airblast drilling at the Kennedy project was designed to test the target regolith for elevated REEs in surficial clays at very broad spacings of 800m to 1,300m apart.

All holes tested to a vertical depth of 15m remained in clay dominated unconsolidated sediments and intersected significant TREO grades from surface, with widths ranging from 2-4 metres in thickness.

DevEx noted that while the assays suggest consistency of TREO grades between the drill-holes, the distances between each hole remain very broad and a variability in thickness may occur.

To help address this, the company plans to carry out infill drilling this month.

Further drilling will also be carried out over the much broader project area over the coming months as the full extent of the target regolith remains untested.

Meanwhile the leach testing resulted in recoveries of 38% praseodymium, 40% neodymium, 29% dysprosium and 31% terbium in just 30 minutes using the pH4 solution.

These increased to 49% praseodymium, 51% neodymium, 44% dysprosium and 47% terbium when left for 24 hours while a slightly stronger pH3 solution achieved recoveries in between the two in 30 minutes.




This article was developed in collaboration with DevEx Resources, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.