Bench scale tests on the brine from the project have yielded battery-grade (namely over 99.5%) lithium carbonate (Li2CO3).
READ THE BIG PICTURE: Millennial Lithium one to watch in emerging sector as it moves towards bankable feasibility at exciting Argentina project
That's significant because it means it can be used to make electric vehicle batteries.
The work was carried out by SGS Canada Inc, whose lab in Lakefield, Ontario received around 600 litres of brine.
"We are excited that the bench scale process test work recently completed by SGS has yielded very positive results with a lithium carbonate product purity of 99.92%," said president and CEO of the Vancouver-based firm Farhad Abasov.
"Typical lithium carbonate battery grade for EV batteries is approximately 99.5% Li2CO3, so we are very encouraged by these results that suggest the Pastos Grandes brine is amenable to industry standard processing and capable of producing a battery grade product.
"The bench scale testing has also provided an excellent framework for our pilot plant, which is currently in the final design phase, and provides a basis for the potential commercial plant design for the company's definitive feasibility study."
The final purification test work yielded a lithium carbonate product that was 99.92%, with low levels of magnesium (Mg), calcium (Ca), boron (B), sulphate (SO4) and iron (Fe), with no other detectable metals.
Millennial said as well as the promising purity of the lithium carbonate, it was also encouraging that metals and other impurities were very low to not detectable.
"Testing will continue at SGS to optimize the process, reduce impurities and improve recoveries and any positive achievements will be incorporated into the pilot plant design and tested on site at Pastos Grandes," it said.
Last week, the company updated on progress, noting the pilot processing plant was designed to produce three tonnes per month of lithium carbonate using concentrated brine from the pilot ponds on the salar.
Meanwhile, WorleyParsons Chile is progressing with the definitive feasibility study (DFS), which remains on schedule for completion in the second quarter of this year
Two drill rigs are now active on the Remsa license, a portion of the Pastos Grandes Project, which is testing the extension of the lithium-bearing brine acquirer, it added.
Additional geophysical surveys have also been used to determine the extension of the lithium-bearing brine to the west of the Remsa license.
And preliminary results from this survey show potential for additional brine further into the Remsa license portion at Pastos Grandes.
"A drill rig will be mobilized to collar PGMW19-21 on the western edge of the Remsa license and drilling will begin early in 2019," Millennial told investors.
Millennial Lithium Corp shares added 10 % in Toronto to stand at $1.43.
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