Strike threat looms at BHP's Escondida and Spence copper mines in Chile

The 205 workers run the company's Integrated Operations Centre which manages pits and cathode and concentrator plants in the north of the country from the Chilean capital Santiago.

Contract talks started at the end of March and the union received what the company described as a final offer over the weekend to voted on this week.

Jessica Orellana, the union president, said workers' demands and their critical role in the productive chain had been overlooked. "We are raising awareness among our people to vote in support of the strike, hopefully 100% of them will," she said.

The threat of a strike impacting operations of Spence and Escondida - the world's largest copper mine - comes at a time of record high prices for the red metal and tight supply in the concentrate market amid surging demand as the world economy recovers from COVID-19 slumps and investments into green energy sectors ramp up.

Should workers vote in favour of a strike, local law stipulates the two parties must still undergo a period of government-led mediation for five to 10 days.

BHP could use a legal loophole to replace striking workers since they are covered by mine service contracts.

Orellana said they were hoping that other BHP workers would decline to step into their shoes. "It would involve them performing other functions that do not pertain to their roles," she said.

BHP did not immediately respond to a request for comment.

Escondida produced 1.19-million tonnes in 2020, while Spence produced 146 700 t of Chile's total 5.7-million tonnes.