“To extend the lifespan of one mine past its prime, Arizona’s Carlota Mine, its owner, KGHM Polska Miedz S.A., has recently recruited a group of unconventional miners. They arrived by the millions, transported in barrel-sized containers from a laboratory in Colorado.

These miners are specialized microbes, acid-loving microorganisms that liberate copper from ore by digesting surrounding iron and sulfur compounds. Endolith, a Denver-based startup that supplies the microbes to KGHM, will continue to grow them in bioreactors onsite. From there, the microbes are channeled into a sprinkler system to mix with sulfuric acid. That liquid then drips into vast heaps of crushed rocks — some as large as 10 sports stadiums — setting off a series of biochemical reactions in a process known as bioleaching to release copper.

If all goes as planned, Endolith’s microbial miners will help squeeze more copper out of the heaps and reduce the use of sulfuric acid at a time when the war in Iran has sent the feedstock’s price sky-high.”

From Bloomberg.