The test work has produced a conventional, 6% Li2O, low impurity concentrate with high recoveries.
Savannah said test work on drill core samples from the project's Grandao deposit had produced concentrates containing 6-6.5% Li2O, with corresponding lithium recoveries in excess of 80%.
The lithium concentrates also had low iron and impurity levels, making them suitable for conversion to lithium carbonate or lithium hydroxide to be used in lithium-ion batteries.
CEO David Archer said the test work results had been "encouraging as it continues to validate Mina do Barroso as a conventional lithium project in terms of the process flow-sheet and the product produced".
The next step in the metallurgical test work programme is to test the variability of the deposit, do further optimisation through locked cycle testing, and test the recovery of acceptable feldspar and quartz concentrates, which Savannah wants to produce as by-products for the regional ceramics industries.
Savannah said it was planning a bulk ore sampling programme to define the process flow sheet to a level suitable for final plant design and was also continuing test work on Mina do Barroso's other deposits, which Archer said would help refine the company's understanding of the produced material's behaviour.
The company is aiming for annual production from Mina do Barroso of 175,000 tonnes of spodumene concentrate at a grade of 6% Li2O, with the first five years to come from the Grandao deposit.
Savannah's shares edged up 1.78% on the news to 4.99p (US6.57c).