Mishra Dhatu Nigam Ltd(Midhani Ltd), a special grade metal making Defence PSU Thursday said its partner NMDC Ltd is expected to complete the due diligence for pickingup minority stake in a tungsten mine located in Vietnam. NMDC and Midhani signedanMOU in October2016to explore suitable Tungsten assets in India and abroad for investment as well as development of technologies for converting tungsten ore to Ammonium Para Tungstate.