Leftist Gabriel Boric favours a more active role for the state and higher royalties, while extreme-right José Antonio Kast wants more private investment in state-owned Codelco and changes to mining property law.

Sierra Gorda will be South32’s second-largest deal since it listed in 2015 and will add 70,000 to 80,000 tonnes of copper to its portfolio.

US-based researchers are looking into the possibility of producing hydrogen fuel from hydrogen sulphide, also known as sewer gas.