An employee removing tellurium from a filter press at the Kennecott tellurium circuit. Courtesy of Rio Tinto

The tellurium circuit at Rio Tinto’s Kennecott mine will only produce about 20 tonnes of the critical mineral per year – a mere fraction of the roughly 200,000 tonnes of copper the Salt Lake City, Utah, mine pumps out annually. And the chemistry behind recovering tellurium from the metals-rich anode-slime waste material created by copper smelting is, according to Saskia Duyvesteyn, chief advisor of research and development for copper at Rio Tinto, “embarrassingly simple. It can happen in your kitchen.”