Lithium Australia targets sustainability with processing technology

With the future of lithium looking bright Lithium Australia has set out to play a key role in creating a sustainable industry that will capitalise on this momentum.

The Perth-based company is developing a hydrometallurgical process, known as Sileach, that will enhance the recovery of lithium from hard rock, one of the two key sources of lithium chemicals.

Prior to 1990 much of the world’s lithium was sourced from hard rock. That was until the other key lithium source, brine, took over as predominantly South American companies achieved production at much lower operating costs.

A resurgence in hard rock lithium production in recent years has seen it once again eclipse brine as the world’s primary source, with capital requirements now much lower and because it can be efficiently brought to the market to react to demand.

However, a drawback of hard rock production is that a large amount of lithium finishes up in the waste stream as the costs required to extract the metal from low-grade concentrates are currently too high.

To change this situation, and unlock new opportunities for the sector, Lithium Australia has been developing the potential of Sileach through extensive testing with ANSTO Minerals (a division of the Australian Nuclear Science and Technology Organisation) at Lucas Heights, on the outskirts of Sydney.

Unlike traditional processing technology, Sileach processes lithium concentrates at atmospheric pressure, using significantly less energy by removing the need for roasting. The process is also capable of delivering high recoveries and crucial by-product credits.

Global potential

Lithium Australia’s managing director Adrian Griffin said the Sileach technology was showing the potential to revolutionise the global lithium industry by reducing processing costs and providing an opportunity for previously uneconomic deposits to enter the marketplace.

“Today, there is a large amount of lithium discharged in waste streams,” Griffin told Australian Mining.

“We looked at the waste streams that contain low-grade concentrates that can’t be processed with existing technology because it is too expensive to produce lithium chemicals out of. We also looked at waste streams that contain other minerals that with conventional technologies can’t compete on the production cost curve.

“If you can create a process that is more efficient and under some circumstances produces a by-product credit then you have the potential of dropping the operating costs for hard rock deposits to the same levels as brine deposits.”

Griffin said the key drivers of the Sileach™ process would be to reduce exposure to mining costs (as in many cases the material is contained in waste, with mining already paid for), a low energy footprint and valuable by-product credits.

Importantly, the Sileach process is being developed to enable mining companies to release value from lithium silicate deposits that have been quarantined due to sub-economic grades.

Due to the lower projected operating costs, Sileach has also shown it could transform low-grade spodumene occurrences into viable ore as it isn’t as sensitive to feed grade.

This would mean lower cut-off grades may be used for resource calculations, existing resources can be expanded without the requirement for further drilling, and that an increase in recovery of metal inventories is possible.

As the lithium chemicals are precipitated from solution in the Sileach process, all impurities in lithium silicate feed can be rejected during the production of lithium chemicals.

Spodumene, and other silicates in which impurity concentrations would otherwise be uneconomic, would be considered a viable process feed with Sileach.

The road to commercialisation

Lithium Australia took major steps towards commercialisation of Sileach in 2016.

The company completed a pilot testing program with ANSTO Minerals in October. The testing was supported by the Australian Government, which provided a grant to advance the process for the recovery of metals, such as lithium from silicate minerals.

The Sileach testing with ANSTO involved a pilot plant, consisting of leaching and impurity removal circuits, and feed of ore from Lepidolite Hill in Western Australia. About 650 kilograms of ore was processed at an average throughput of six kilograms per hour.

Extraction of lithium in the Sileach process exceeded 95 per cent in the leach circuit, validating both the overall extraction and accelerated rate of extraction achieved in a laboratory test program.

The next step in Sileach testing, which commenced in December, is processing low-grade spodumene concentrates from Pilbara Minerals’ Pilgangoora project, where Lithium Australia has formed a strategic partnership.

Griffin said the testing would focus on lower-grade materials that would not otherwise be recovered at commercially viable costs.

“The commercialisation agreement with Pilbara Minerals is very critical arrangement for us,” Griffin explained.

“The agreement has a number of commercialisation hurdles, commencing with lab testing, for which we have achieved a successful outcome. The next hurdle is pilot testing at ANSTO Minerals which we have already commenced.”

“We would then commit to a large-scale pilot plant with an output of about 2500 tonnes per annum lithium carbonate. If we can demonstrate that we can produce lithium chemicals on a commercial basis from that plant the two parties will enter into a 50-50 joint venture to process mineral concentrates from Pilgangoora.”

A sustainable future

Griffin believes Sileach, if commercialised, would provide a ‘very timely’ technology capable of delivering new opportunities for the lithium sector, which is currently experiencing substantial growth.

However, he said the company’s main goal was to commercialise Sileach so it could help guide the industry towards becoming more sustainable, both in Australia and internationally.

“That means stopping lower grade material from going into tailings dams – if companies have off-spec product then we don’t want them throwing it away,” Griffin said.

“We have got to provide the industry at-large with a more efficient way of doing things and provide them with the ability to capitalise on by-product credits. Even when you roast and leach you are throwing away something that is a valuable resource.

“Why not turn the residues into chemicals instead?”

Internationally, the company also has a Sileach processing agreement with pending ASX float, Canada’s MetalsTech, which owns several lithium exploration properties in Quebec.

It also has a technology development agreements with Toronto-listed Alix Resources, Lithium Australia’s JV partner in the Electra project in Mexico.

Lithium Australia plans to continue to advance these arrangements, as well as its locally-based agreements, throughout 2017.