First Quantum Minerals Ltd., the owner of Africa’s biggest copper mine, is drawing preliminary takeover interest from global miners after losing half its value over the past five years, people with knowledge of the matter said.

Vancouver-based First Quantum, which has a market capitalization of $7.7 billion, is working with defense advisers to examine its options, according to the people. It hasn’t yet received any formal takeover offers, the people said, asking not to be identified because the information is private.

Shares rose 15 per cent in trading Thursday before closing in Toronto at $11.16 a piece, up about 10 per cent on the day.

First Quantum controls the open-pit Kansanshi mine in Zambia, which has 340,000 metric tons of annual copper production capacity. The company has been at loggerheads with the the government of the southern African country over issues from royalty increases to the planned introduction of a sales tax.

It also owns other assets around the world including the Sentinel copper operation in Zambia, Las Cruces in Spain and the Ravensthorpe nickel mine in Western Australia. First Quantum also started ramping up production at the giant Cobre Panama copper development project in the central American country earlier this year.

No final decisions have been made, and there’s no certainty the deliberations will lead to any transaction, the people said. Representatives for First Quantum didn’t respond to requests for comment.

Copper, used in everything from automobiles to plumbing pipes, has dropped in five of the past six months as trade-war fears heat up and demand appears to be slowing in top-user China. Still, the metal’s long-term prospects are seen as strong amid under-investment in new mine supply and surging usage in electric vehicles.

--With assistance from Steven Frank