Thanks to the combined efforts of an active ASX-listed junior and a tertiary education institution, Western Australia may soon become a leading producer of the critical mineral rubidium.
Perth-based Everest Metals Corporation (EMC) is confident it is developing one of the world’s highest grade rubidium mineralised systems at its Mt Edon hard rock target in WA’s Mid-West.
Aside from upping its exploration stake, earlier this year the company entered into a research agreement with Edith Cowan University’s Mineral Recovery Research Centre (MRRC) to help determine how to treat the deposit’s ore through direct extraction.
In the first half of July, the junior announced it had completed the first phase of its resource drilling program, which comprised 14 RC holes (1,266 metres) and assayed pegmatite intersections.
As a result, the company now expects to deliver Mt Edon’s maiden JORC-compliant mineral resource by the end of August.
Meanwhile, in late July, EMC announced the first stage of its collaboration with the MRRC involved a small-scale laboratory demonstration of all the processing steps in the recovery of the critical mineral.
The direct rubidium extraction (DRE) test work and studies utilise advanced processes such as ion exchange.
Due to the increasing need for sustainable and environmentally friendly extraction processes, these studies aim to develop a state-of-the-art technique that maximises the recovery of rubidium and mica.
By selecting suitable cations (a positively charged ion) and optimising cost-effective operating conditions, this approach leverages cutting-edge and innovative methodologies and industry best practices to ensure a sustainable and profitable extraction process.
The circuit encompasses purification and refining, ultimately leading to the conversion into a final product such as rubidium salt, metal and, potentially, mica.
As part of this study, a critical assessment of the feasibility work and possible enhancements of the DRE will be conducted, thus allowing EMC and Edith Cowan to jointly apply for the Co-operative Research Centre’s projects grants, and the Australian Research Council’s Linkage Program, to scale up the process technology.
Two extraction methods (non-destructive and destructive) were used to extract rubidium and lithium.
Various test work was conducted by the MRRC with results demonstrating acceptable levels of both elements in the leach liquor.
During process development, special attention was given to both potential by-products and industrial minerals such as quartz, mica and feldspar that may be recovered during mineral concentration, leaching and purification.
In the non-destructive method, the structure of muscovite remained unchanged. Two sets of acidic and non-acidic experiments were performed, and X-ray diffraction analysis was conducted on the samples before and after the tests to explore the structure of the solid powder.
Meanwhile, in the non-acidic tests, low acid concentrations of the sample were prepared to enhance rubidium extraction.
In this stage of the project, multiple tests were performed and most of the experiments were repeated two or more times.
Inductively coupled plasma mass spectrometry was used for assay analysis.
EMC said five different chemical compounds were utilised in this set of tests. Some of these chemicals were used only during the non-acidic experiments.
Since this set of experiments was conducted without acid, the impact of the time of chemicals reacting with the sample and temperature was also investigated for the sake of optimisation.
During the tests, all chemical compounds were used with different concentrations of acids whilst maintaining a similar methodology.
The effect of different concentrations of acid and various temperature ranges were then examined. The results indicated that with the application of acid, the maximum achievable rubidium extraction was about 41 per cent.
Furthermore, unwanted cations showed different behaviours while using various chemicals as their extraction depended on the presence of various ions within the solution.
In most cases, lithium ions were extracted in a low quantity that was manageable.
Moreover, in the destructive method, the muscovite structure has deteriorated to gain the maximum extraction of rubidium.
Different acid types and concentrations were utilised in this phase.
Several tests were also conducted in this stage and the repeatability of the results was checked to attempt to achieve the same results again.
The maximum rubidium extraction achieved in this stage demonstrated repeatability within a range of 75 plus 10 per cent.
“The laboratory test work underpins the commencement of an assessment of a variety of global critical mineral processing grants available as development funding for next phase pilot plant scale up,” EMC’s executive chairman and chief executive Mark Caruso said.
Rubidium is a critical raw material for various high-tech applications, including the development of new energy conversion and fibre optic communications.
About 80 per cent of it is used in the research and development of these fields.
Other key applications include defence and military (night vision imaging, special glass, radiation detectors, photoelectric tubes, radio-electronic tubes, military infrared signal lights, aerospace (ion propulsion engines and atomic clocks) and medical items (such as sedatives, tranquilisers and medications for treating epilepsy as well as synthetic alkaline solvents.
It is also used in special glass, industrial catalysts (like ammonia and sulphuric acid synthesis, hydrogenation, oxidation, and polymerisation reactions) and electronic devices (photovoltaic cells, photoemission tubes, television cameras and photomultiplier tubes).
Researchers have also recently proposed the use of rubidium for chemical storage within hydrogen batteries, expanding the potential market for this critical mineral.
Rubidium and caesium and their hydrides present both opportunities and challenges.
Global production of the two elements is significantly lower than that of other alkali metals, while the cost is substantially higher than lithium, sodium or potassium.
Due to the gradual depletion of caesium resources, and the continued demand of these industries, a replacement is required, with rubidium being a suitable candidate.
The downstream application fields of rubidium salts are rapidly growing, enhancing EMC’s market advantage in this sector.
As a result, rubidium has been listed as one of the 35 critical minerals by several countries around the globe.
According to the US Geological Survey, global resources are relatively scarce, with most resources containing limited content.
With the increasing interest in rubidium resources in recent years, several granite-hosted deposits/resources in leucogranite pluton have been discovered in China.
Most of them, however, are very low grade, ranging between 0.12 and 0.15 per cent.
Several market factors support growth in demand for rubidium and underpin the current price of around US$1,200 per kilogram.
Among these, there is significant global demand for newer and faster electronic products due to the rapid pace of innovation, technological advancement and research and development activities in the electronics industry.
North America holds a significant share of the rubidium market in terms of both market share and revenue. But, similar to most critical minerals, China maintains control of the market.
Commodity analysts believe if more rubidium was produced, the market could grow rapidly. Therefore, supply constraints outweigh the lack of demand.
