“Lithium Australia continues its emphasis on developing novel solutions to lithium processing problems. Commercialization of the LieNA® process is an opportunity to improve the sustainability of the lithium-ion battery industry. We see an immediate application for it in Australia, which produces well over half the world’s lithium requirements and nearly all of the spodumene needed; however, significant quantities of the latter never make it into the process supply chain. The problem starts with the very nature of the mineral and the processes currently used to recover lithium from it. That problem may be solved with more efficient processing – and that remains our focus. LieNA® could help mitigate much of the waste in the lithium industry.”
Historically, lithium was mined from pegmatite deposits in North Carolina, Zimbabwe, Portugal, Brazil and China. With the advent of cheaper production of lithium from brines in South America (and to a lesser extent China) in the 1980s, hard-rock production in the above-mentioned countries dwindled. From the 1990s on, production of spodumene concentrate came to be dominated by the Greenbushes mine in Western Australia, a situation that persisted until the commissioning of new production in that state by the likes of Galaxy, Pilbara Minerals, Altura, Minres, Neometals, etc.
More recent developments in Western Australia (Wadgina, Pilgangora, Mt Marion, Bald Hill, Mt Cattlin and Earl Grey, as well as the expansion of Greenbushes) will result in considerable extra feed, as will new projects in Canada and southern Africa, but requirements are still likely to outstrip supply longer term.
Spodumene deposits mined to date have shown yields to commercial lithium concentrate of 50-70%, with some operations targeting optimised recoveries of 75%. But where is the rest reporting?
Lithium pegmatites are often characterised by complex mineralogy, with the lithium occurring in more than one mineral phase. Product specifications for commercial spodumene concentrates preclude other lithium mineral contaminants, meaning that lithium micas, petalite, amblygonite, eucryptite, etc. are rejected as tailings. Under some circumstances this can result in lithium losses as high as 30%. The situation is exacerbated by the requirement to meet quality specifications for commercially traded spodumene concentrates. Not only is liberation (to achieve chemical specifications) an issue but specified critical particle size for conventional ‘converter’ feed also reduces yield, the principal factor being acceptable sizing to feed counter-current rotary kilns.
Without radical departures from current processing technologies, lithium supply is most likely to be enhanced by greater exploitation of abundant sources, and of materials discarded during the processing of other resources. Ergo, the best targets are:
- waste generated during the processing of spodumene;
- the lithium micas found in pegmatites and greisen, and
- spent batteries.
The spodumene conversion dilemma
Given the ways in which spodumene mineral separation circuits perform, and how commercial concentrates are produced, most pegmatite orebodies produce only a low lithium yield. Partly, the issue revolves around the product specifications for spodumene converters in China (and soon Australia); these involve spodumene concentrates being fed into rotary kilns for the first stage of the lithium extraction process. The kilns convert α-spodumene (unreactive with sulphuric acid) to β-spodumene, from which the lithium is recovered by a sulphation bake and subsequent water leach. Lithium is extracted as a sulphate solution, which is purified prior to the manufacture of lithium carbonate or lithium hydroxide.
While such ‘conversion’ processes are well established they have a number of shortfalls: not only are they energy-intensive but feed rates are dependent on particle size (as gas flow is counter-current to the flow of concentrates being converted from α to β-spodumene). Such systems are best suited to relatively coarse feed material, but producers have to deal with the trade-offs of:
- concentrate purity, and
- product size specifications.
To date, trade in spodumene concentrates has been a ‘buyers’ market’, in which China dominates downstream conversion activities and the production of lithium chemicals. However, that is about to change as refining facilities in Australia (Tianqi, Albemarle, Minres and SQM/Kidman) come online. Although these companies will have greater flexibility in terms of product specifications, from a practical point of view refining will still entail commercial trade-offs in that much fine spodumene will be discharged to tailings.
Lithium Australia continues to work towards commercialization of its proprietary LieNA®
technology for the improved recovery of lithium from spodumene, the most common
hard-rock source of lithium for the production of critical battery chemicals. While the recovery rate of lithium from conventional spodumene beneficiation varies, it can be as low as 50% owing to the concentrate offtake specification constraints applied by the current generation of lithium chemical producers, all of which commence the process by roasting the concentrate. LieNA® (which, importantly, does not require a roasting stage) can recover lithium from the fine and contaminated spodumene that otherwise reports to waste or tailings streams during current concentration processes.
LieNA® consists of a caustic digestion process followed by acid leaching to recover the desired lithium chemical. Because no roasting is required, LieNA® is a more environmentally friendly solution to processing spodumene. Together, Lithium Australia and ANSTO (the Australian Nuclear Science and Technology Organisation) have completed extensive test work on the LieNA®
technology, with final recovery of lithium reported as greater than 85%.
With its ability to process fine and contaminated spodumene that would otherwise go to
waste, LieNA® has the potential to not only expand current hard-rock lithium resources, thereby reducing mining costs, but also enhance the sustainability of spodumene production and the subsequent manufacture of lithium chemicals.
As this is a standard patent, Lithium Australia now has long-term protection and control over the invention for up to 20 years.
Comment from Lithium Australia managing director Adrian Griffin
“Lithium Australia continues its emphasis on developing novel solutions to lithium processing problems. Commercialisation of the LieNA® process is an opportunity to improve the sustainability of the lithium-ion battery industry. We see an immediate application for it in Australia, which produces well over half the world’s lithium requirements and nearly all of the spodumene needed; however, significant quantities of the latter never make it into the process supply chain. The problem starts with the very nature of the mineral and the processes currently used to recover lithium from it. That problem may be solved with more efficient processing – and that remains our focus. LieNA® could help mitigate much of the waste in the lithium industry.”