Lithium Australia NL (ASX:LIT) (FRA:3MW) (OTCMKTS:LMMFF) has been granted the US patent for its SiLeach extraction technology, which can produce a range of lithium chemicals, including lithium hydroxide, lithium carbonate and lithium phosphate.
The company received an ‘Issue Notification’ from the United States Patent and Trademark Office confirming the grant of patent (US 10,883,157 B2) for its application (US 16/076,643).
The patent now provides the company 17 years of legal protection in the US.
“Unlocking the value in clays and micas”
The granting of the US patent is timely given increased interest in the extraction of lithium from clays in North America and with the lithium ferrophosphate (LFP) sector the most rapidly expanding in the industry.
Lithium Australia managing director Adrian Griffin said: "[The] revolutionary SiLeach process unlocks the value in lithium-bearing clays and micas.
“The lithium and phosphorus required to manufacture LFP are both produced by SiLeach as a single lithium chemical.
“The use of lithium phosphate is the shortest route to the production of LFP batteries, which is advantageous from an environmental, social and governance perspective.”
SiLeach recovery process
SiLeach is a fluorine-assisted, acid-leach recovery process designed specifically for lithium mica minerals.
Although fluorite (naturally occurring calcium fluoride) is added to enhance the process, the micas themselves, during decomposition, release significant quantities of fluorine, since they may initially contain up to 8% or more fluorine as part of their makeup.
However, unlike other processes, the SiLeach flowsheet design contains specific fluorine removal and control steps, to optimise the handling of fluorine generated during the decomposition of the mica minerals.
Superior water balance is also a key attribute of the flowsheet, which can recover lithium from the dilute process liquors generated during the SiLeach process.
This approach eliminates much of the requirement for evaporation, which is a high capital and operating cost of competing systems.
Two generations of SiLeach pilot plants have been operated successfully at the ANSTO facility at Lucas Heights in New South Wales.
Reduced processing steps
SiLeach offers significant advantages over competing processes around the recovery of lithium from low-tenor solutions - which minimises the capital cost of evaporators and the high energy costs associated with evaporation.
Direct precipitation of lithium as a phosphate (and its subsequent refining) provides the potential for direct feed into the production of LFP cathode powders.
The company, through its 100%-owned subsidiary VSPC Ltd, has produced LFP from lithium phosphate generated via the SiLeach process with the LFP used to manufacture battery cells for testing.
Notably, the supply of lithium phosphate to LFP producers eliminates the requirement for lithium hydroxide or lithium carbonate in some of the LFP production processes, thereby shortening the supply chain.
Patent progresses in several jurisdictions
The company has also received a ‘Notice of Acceptance’ from IP Australia for the same application, with a grant of patent expected at the end of April 2021.
Once the patent is granted, SiLeach will have 20 years of legal protection in Australia.
Patent application PCT/AU2017/050104 (which details the first-generation SiLeach technology) has also been lodged in the following jurisdictions.
- Chile – ongoing examination;
- Europe – notification that the present claims considerable allowable;
- Brazil – ongoing examination; and
- Canada – request for accelerated examination filed.
Patent applications for process improvements
Patent application PCT/AU2019/050541 (which details the second-generation SiLeach patent application) is also progressing.
The company has received a written opinion from the International Searching Authority on the patentability of the application, confirming that the claims are novel and inventive.
The status of these applications are as follows:
- Australia – national phase entry has commenced;
- USA – filing of a request for national phase entry is imminent;
- Chile – preparation for filing national phase entry has commenced;
- Europe – preparation for filing national phase entry has commenced;
- Brazil – preparation for filing national phase entry has commenced; and
- Canada – request for national phase entry filed.