Equinox Minerals is to make an offer to acquire Lundin Mining for about C$4.8bn (US$4.9bn) in cash and shares.
Equinox has proposed the acquisition of all of the outstanding common shares of Lundin for a total consideration value of C$8.10 (US$8.32) a share.
According to Equinox, the merger will generate a higher copper production profile over the next six years compared with the profile of the proposed Lundin-Inmet merger, delivering about 500,000t of incremental copper over the period.
The combined firm would provide significant geographic and copper production diversity, including five substantial producing operations by mid 2012.
Equinox is currently constructing the Jabal Sayid project in Saudi Arabia and operates the Lumwana mine in Zambia.
Lundin's assets include the Tenke Fungurume copper mine in Congo, Neves-Corvo in Portugal and Zinkgruvan in Sweden.