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Flash Joule Heating Shows Potential To Revolutionise Lithium Extraction From Ore

MTM Critical Metals Limited (MTM) advises that initial Flash Joule Heating (FJH) tests show a 92 % reduction in calcination time of spodumene concentrate from a lithium mine over conventional processing in a rotary kiln.

Simplified flowsheet for Lithium production from hardrock spodumene ore source. FJH target area shown. Image Credit: MTM Critical Metals Limited

The objective of this study is to determine whether lithium extraction from the mineral spodumene can be made more efficient, addressing the significant energy demands of current industrial processes. Due to the refractory nature of spodumene, conventional recovery processes are very energy-intensive and involve the use of rotary kilns operating at high temperatures for extended periods. Calcination, which is essential for rendering spodumene amenable to acid leaching, is the most energy and CO2-intensive step in producing battery-grade lithium, accounting for over 50 % of the energy consumption and carbon emissions released (Fig. 1 & 3).

MTM Chairman, Mr John Hannaford said: “FJH has the potential to revolutionise lithium refining by significantly enhancing or even eliminating the calcination step, which is crucial for making the mineral spodumene amenable to leaching. FJH treatment of spodumene concentrate rendered the material unrefractory in a fraction of the time required by conventional kiln calcination. While these results are preliminary and unoptimized, they present an exciting path forward for FJH to revolutionise how lithium is extracted in the future.

“Refractory mineral processing presents a formidable challenge and financial burden for the current mining industry and these promising initial tests open the door for MTM to target other critical metals, such as rare earths & niobium. The opportunity to develop an energy efficient carbon reduced process open the door to the 2 onshoring of lithium processing in key markets globally and ex-China. The Company has already begun commercial discussions with several leading industrial firms in this sector, and further updates will follow in due course”.

Spodumene Processing

Spodumene, the world's largest source of lithium, is highly refractory in its natural α-monoclinic form, resisting acid leaching. The conventional method to make it leachable involves calcination at over 1000°C for up to three hours in a rotary kiln, converting it to the more acid-soluble β-tetragonal form (Salakjani et al., 2016). This industry-standard process, developed over 70 years ago, consumes large amounts of fossil fuels and results in significant CO2 emissions, as current kiln technology relies on natural gas or diesel and is thermally inefficient.

Preliminary results indicate that FJH can transform α-spodumene to β-spodumene after only a short pulse (minutes timeframe) of ‘flashing’ mimicking what takes 2-3 hours at high temperatures in a conventional calcination kiln (Salakjani et al. 2016). The 'flashed' material may also demonstrate enhanced downstream leaching properties compared to the conventional "calcination-sulfation-roasting" (CSR) method. Ongoing tests are being prepared to explore this further.

FJH technology offers a disruptive means of improving the process by which lithium is currently refined and the initial unoptimized tests are very encouraging. Applying energy directly to the material with FJH is conceptually more thermodynamically efficient than conventional kiln calcination, which requires heating not only the spodumene concentrate but also the kiln internals and surrounding air. The prolonged heating process of rotary kilns further increases heat dissipation and thermal losses (Boateng 2015, pp. 243-244).

Test Work Method and Results

Samples of spodumene concentrate (~6 % w/w Li2O content) were tested utilising the Company’s FJH prototype unit in Houston, Texas. Test samples were ‘flashed’ and assessed pre and post-flashing using semi-quantitative XRD to determine the extent of conversion of refractory α-spodumene to β. Flashing was undertaken for a variable time frame to achieve a set energy density which at this stage is unoptimized.

Results from these tests are shown in Table 1 below.

Table 1. Test results showing the positive effect on spodumene mineral conversion using FJH technology. Source: MTM Critical Metals Limited

Sample ID “Conventional” Kiln Process used in industry1 FJH Test J1-H2001 FJH Test J2-H1001 FJH Test J3-H1001
α-β spodumene conversion (%) 90 % 74 % 41 % 58 %
Reaction time (minutes) 120-180 14 12 54
Time saving vs Industry Standard (%) N/A 88-92 % 90-93 % 55-70 %


Notes to Table 1:

  • Results are preliminary only. There remains significant scope for further optimisation and refinement.
  • The concentrate contains approximately 6 % Li2O by mass, typical of spodumene mines.
  • The measurement of alpha (α) and beta (β) spodumene in the concentrate and flash residue is based on semi-quantitative XRD analysis.

Further Metallurgical Test Work

MTM, in conjunction with KnightHawk Engineering, Texas, will continue to test spodumene samples, using the data to help refine and improve the technology. MTM has also engaged with a commercial metallurgical laboratory to assess and quantify the effects of the FJH treatment on the downstream leaching of the concentrate, with objective of showing that FJH offers a benefit over the conventional calcination and acid baking process used for lithium extraction.

Further Studies – Can Lithium be Recovered From Spodumene Waste Tailings?

Future studies will explore the potential of FJH technology to extract lithium from spodumene waste tailings. In a traditional spodumene concentrator plant, fine ore particles (sub ~20 microns) are typically discarded to tailings because conventional processing methods cannot recover them, and they are also problematic in terms of material handling within the downstream calcination and roasting kilns.

This waste stream can comprise up to 20 % of the ore by mass, signifying a substantial loss of valuable metal. If the lithium in this material could be recovered by using FJH technology, this could have significant commercial implications for operating spodumene mines, where vast quantities of tailings have accumulated since production began.

Strategic Collaborations & Partnerships

MTM is in discussion with top-tier industrial firms in both the US and Australia. Additionally, the Company is exploring complementary technologies with Rice University and engaging with leading research institutions in the US and Australia to accelerate our development efforts.

Flash Joule Heating

FJH is an advanced processing and recycling technology being developed to extract critical metals including REE, titanium, nickel, cobalt and lithium from waste material including lithium-ion batteries, e-waste, coal fly ash produced by coal-fired power stations or bauxite residue derived from alumina refining.

The FJH technology is an electro-thermal process that involves the rapid and intense heating of material to both directly recover critical metals and make materials more amenable to metal recovery through conventional acid leaching methods.

MTM has recently executed a global licence agreement over the FJH technology patents with Rice University (see MTM ASX announcement dated 31 May 2024).

This announcement has been authorised for release by the Board of Directors.


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