The parties made binding offers last week for Minas de Aguas Tenidas, known as Matsa, Bloomberg reported, citing confidential sources.
Rumours had started to swirl around Singapore-based trader Trafigura selling out of copper assets earlier this year, as Mining Journal columnist Richard Wachman commented in March.
Trafigura had sold 50% of Matsa to the Abu Dhabi sovereign wealth fund Mubadala Investment Company in June 2015.
The joint venture partners had been looking to sell Matsa since the start of the year, the wire service said.
The Matsa joint venture has three underground mines, Aguas Teñidas, Magdalena and Sotiel, and produces about 500,000 tonnes annually in copper, zinc and lead concentrate.
Copper reached an all-time high above US$10,000/t in May and the price remains elevated, amid forecast dwindling supply and anticipated demand as part of the global energy transition.