GAM claims Talison's expansion of lithium mining and processing at Greenbushes threatens to sterilise and waste tantalum resources.
It receives tantalum extracted by Talison during the mining of lithium-bearing spodumene and wants the expansion carried out in a way that allows similar extraction.
GAM has scored two recent legal victories in the dispute. The court granted an injunction restraining Talison from pursuing a separate expert determination outside of the action related to GAM's direct mine plan and dismissed applications from Talison-related companies to set aside the subpoenas lodged by GAM seeking access to documents.
Massachusetts-based GAM chief executive Andrew O'Donovan said the company acknowledged the significant benefit of lithium production for the WA economy and supported its development.
"However, contractually the expansion of Talison's lithium production cannot be at the expense of GAM's rights to its tantalum and all other minerals at Greenbushes," he said.
"The nature of the ore body at Greenbushes is such that the proposed expansion of lithium mining and processing in its current form will irreparably sterilise tantalum owned by GAM.
"The mining agreement between our two companies, which moderates this trade-off between lithium and the other mineral rights, is being ignored by Talison." 'We remain confident in our legal position'
A Talison spokesman said it looked forward to a final resolution to the legal action started in July last year.
"We remain confident in our legal position and in the meantime are getting on with the job of expanding the Greenbushes lithium operation, creating hundreds of new jobs and building on the success of this significant contributor to the WA economy," he said.
Talison, which acquired the Greenbushes mine from the Sons of Gwalia administrators in 2007, already supplies about a third of the world's lithium. It is building a new facility, Chemical Grade Plant 2 (CGP2), to double production to 1.34 million tonnes a year.
Talison is weighing up longer-term plans to double that again with two additional processing plants, a new crusher, bigger tailings dam and upgraded power supply.
Talison declined to comment on potential delays as a result of the court action. It said CGP2 remained on track for completion in the second quarter of 2019.
Tianqi, which owns 51 per cent of Talison, is spending more than $700 million on a lithium hydroxide plant at Kwinana south of Perth, with construction well advanced.
Albemarle is pushing ahead with its plans for the staged development of a similar plant that could have capacity to produce 100,000 tonnes a year by 2025, at Kemerton in WA.
GAM has secondary processing facilities at Greenbushes and ships tantalum to its downstream production plants in Pennsylvania and Japan.
Mr O'Donovan said it was increasing near-term production in response to growing demand for tantalum capacitors and other products in the electronics, aerospace, automotive and chemical processing industries.
It has capacity to produce about 1 million pounds of tantalum pentoxide from Greenbushes.
"Over a decade ago, WA was the largest single source of tantalum raw material in the world and GAM's plans involving tantalum production from Greenbushes and other sources will once again place WA at the centre of global tantalum supply," Mr O'Donovan said.
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