Sarytogan Graphite Ltd (ASX:SGA) is on track with its metallurgical test-work program to deliver spheroidized-graphite battery-testing results later this year on samples from the Sarytogan Graphite Deposit in central Kazakhstan.
This is when the results of current separation, spheroidization and further purification testing at laboratories in Australia and Germany will be concluded.
Testing coincides with pre-feasibility study (PFS) activities, including geotechnical and hydrogeological drilling on site. This work is progressing according to schedule for completion in 2024.
Bulk flotation concentrate
Following the breakthrough 99.87% carbon purity result last December, bulk flotation concentrate production was identified as the critical step to provide the feedstock for further purification and spheroidization.
READ: Sarytogan Graphite soars on achieving 99.87% graphite purity in metallurgical testing
The successful grinding and flotation steps for the project were first demonstrated by Australian laboratory Independent Metallurgical Operations Pty Ltd (IMO).
They were then replicated by German laboratory Pro-Graphite GmbH with guidance and advice from IMO. ProGraphite went on to achieve 99.87% carbon purity.
As IMO was unavailable for bulk flotation concentrate production earlier this year, this scope was awarded to a second German lab, UVR-FIA GmbH.
Sarytogan base case process flow and targeted products.
Like Pro-Graphite, UVR-FIA has required guidance and advice from IMO in the grinding and flotation methods for micro-crystalline graphite. This is continuing.
In the meantime, and to mitigate any impact to the overall project schedule, a second bulk flotation concentrate production run has been ordered with IMO at their first available time slot in the third quarter of 2023.
Removal of titanium
Titanium, present as the mineral rutile, has been identified as the main remaining diluent to be removed to achieve the standard 99.95% carbon purity for battery anodes.
Rutile has a specific gravity of 4.2, which is significantly heavier than graphite’s specific gravity of 2.3 g/cm3.
As such, gravity separation is expected to be successful in removing the titanium and other minor heavy metals.
IMO has identified the Falcon Ultra-Fine Classifier, a device commonly used in gravity separation of gold, as being most suitable to remove the titanium from the microcrystalline Sarytogan Graphite.
As soon as bulk flotation concentrate is available the gravity separation will be conducted by IMO.
The bulk flotation concentrate will then be sent to Pro-Graphite for chemical purification, spheroidization and battery testing, with battery testing results on schedule for the fourth quarter of 2023.
Alternative thermal purification
A PFS should consider several alternative options to select the best options to carry forward into further detailed engineering studies. As such, Sarytogan will also test the thermal purification flowsheet as a second option.
Thermal purification of graphite is a well-established process known to sublimate almost all diluents at temperatures of 2,000 to 3,000 degrees Celsius.
Typically, the carbon grades achieved far exceed battery specifications that may be suitable for additional advanced materials uses.
Proposals from two international laboratories have been received.
Small samples of Sarytogan graphite concentrates are being dispatched to one laboratory this week and larger quantities from the bulk flotation concentrates will be reserved for larger-scale thermal purification tests later this year.