Antofagasta's wholly-owned investment company subsidiary has agreed to acquire the rest of Duluth Metals, the miner's joint venture partner in Twin Metals Minnesota.The FTSE 100 company, which currently holds 14.2m shares in Duluth, will pay C$0.45 per Duluth share, equal to a total consideration of C$96m.As part of the agreement, Antofagasta will fund the liquidity requirements of Duluth until the close of the deal.Antofagasta's chief Diego Hernandez remarked: "The acquisition of Duluth provides Antofagasta with a long-term option to develop a large poly-metallic resource in a stable and proven mining region."We believe that the Duluth Complex is an attractive deposit and upon closing of the offer we will commence the process of re-evaluating the project's design while also continuing with the permitting activities."The offer price represents a premium of around 49% to the 90-day volume-weighted average price of Duluth shares for the period ended 31 October.Twin Metals Minnesota is currently developing a copper-nickel-cobalt-platinum-palladium-gold-silver project in the Duluth Complex in north-eastern Minnesota, US.The deal will take Antofagasta's stake in the venture to 100%.