* API shareholders approve BHP offer
* Deal expected to close on March 23
TORONTO, March 18 (Reuters) - Athabasca Potash API.TO said on Thursday that its shareholders had voted in favor of global mining giant BHP Billiton's (BHP.AX) (BLT.L) C$341 million ($338 million) cash takeover offer.
In January, BHP offered to buy the potash exploration company for C$8.35 a share, in a bid to expand its asset base in the potash-rich Canadian province of Saskatchewan.
The two companies expect the deal to close by March 23.
Athabasca's Burr project in Saskatchewan is adjacent to BHP's own Jansen project, the junior potash player also owns a number of exploration properties in the vicinity. (Reporting by Euan Rocha; Editing by Derek Caney)