** Shares of EcoGraf EGR.AX rise as much as 25% to A$0.475, their highest level since November 26
** Graphite explorer says it signs cooperation agreement with European Investment Bank for technical assistance in co's HFfree business
** Co's HFfree process upgrades graphite's carbon content, purifying it for industrial use in Critical Raw Minerals sector
** Stock up 5.4% YTD, including session's moves
(Reporting by Aamir Sheik Khalid in Bengaluru)
((Aamir.SheikKhalid@thomsonreuters.com))