‘Clever science’ is at play in a collaboration between OD6 Metals Ltd (ASX:OD6) and the Australian Nuclear Science Organisation (ANSTO), which has welcomed positive results from continued metallurgical testing of rare earths from the Splinter Rock Project in WA.
The company hopes to enhance the extraction and processing techniques at four key prospects at the project.
TREO grades increased
Testing focused on the effects of removing coarse material (greater than 75um) from samples, which enhanced total rare earth oxide (TREO) grades by as much as 224%, with an average improvement of 157%.
Additionally, the removal process significantly reduced hydrochloric acid (HCl) consumption by up to 79%, averaging a 35% decrease across tests. Such a reduction could markedly improve the economic viability of the project.
Further detailed testing revealed that finer fractions, under 75um, contain 80% to 90% of TREO and magnet rare earth oxides (MREO), while constituting a smaller portion of the original sample mass.
The process also demonstrated a potential for further optimisation of screening sizes to maximise rare earth recovery and minimise acid use.
About the testing
The testing regime included 13 phase-one samples from various clays across different locations and depths at Splinter Rock.
These were subjected to ANSTO’s standard diagnostic leach tests to better understand the geo-metallurgical variability in acid consumption and recovery across the site’s diverse regolith types.
OD6 Metals has designed a simplified processing map, central to which is a site-based chlor-alkali facility to produce hydrochloric acid and sodium hydroxide from high-purity sodium chloride.
This facility is crucial for the leaching process of rare earth elements and the subsequent precipitation of a mixed rare earth product.
The results from this testing phase will inform further developments in phases two and three, which include additional screening and bottle roll tests.
They will also potentially be incorporated into the mineral resource estimate, providing a clearer view of the project’s scale and feasibility.
Clever science, solid engineering
Managing director Brett Hazelden said: “These latest results demonstrate that a significant increase in TREO grades can be achieved by removing coarse material greater than 75um.
“Leaching of the finer faction material has the corresponding benefit of consuming an average of 35% less acid as a total of product processed.
“This provides a potential benefit to the overall cost profile of any future operation by reducing the amount of material that needs to be leached with acid by approximately 40%. Additional screening size optimisation will occur in future phases of work providing the potential for further improvements.”
Non-executive chair Darren Holden added: “OD6 has demonstrated that the application of clever science and solid engineering is the key to the future development of clay REE in Australia.
“We have already proven, with drilling, that OD6 has some of the best thickness and grades of clay REE in Australia.
"This work will be applied to our ongoing geometallurgical exploration programs – where we are steadfastly prioritising the ‘best of the best’ zones within our vast thick clay basins – as well as to metallurgical programs and ultimately our economic studies.”