According to Mining News Pro - All the major copper producers are plagued by aging mines and falling grades, but Rio’s Kennecott operations in Utah have become a real headache for the company.

Rio blames the sharp fourth-quarter output drop of 9% to 138.7kt on the mine and says higher grades will only be accessed by the end of 2020, resulting from the first phase of its south wall pushback project.

In December, Rio announced it is spending $1.5 billion to expand Kennecott to extend the life of the more-than 100-year-old open-pit mine near Salt Lake City from 2026 through to 2032. Kennecott accounts for nearly a fifth of US copper production.

Rio upped its spending on exploration by 28% to $624m last year, mainly on the back of work done at its Resolution copper project in Arizona, partly owned by BHP.