StratMin Global Resources (LON:STGR), the Madagascar-based graphite producer, said March was its best month to date for sales and production from the Loharano mine.
Wet graphite volumes jumped to 528 tons last month, up from 360 tons in February.
StratMin sold 215 tons of graphite in March, up from 150 tons in February.
While the amount realised remained confidential under the firm’s off-take deal, it revealed prices received have increased as the grade has improved.
In its stock market announcement earlier, StratMin said its new mill has been installed and revealed limited test runs have been performed.
Its development is “ongoing” with the plant flow sheet near to reaching increased grades envisaged particularly in the smaller flakes, the company added.
Managing director Manoli Yannaghas said: "I am delighted to report a significant increase in both graphite production and sales during the month thereby making March StratMin's most successful month to date.
“These increases coupled with the new mill soon to become fully operational will see the company's efforts over the last two years come to fruition.
"The product quality has improved markedly over the quarter, much to the satisfaction of our customers.
“Further improvements to the process flow sheet are underway to increase grade and I expect these to have a positive effect during the next quarter."