Rio Tinto starts Te production, signs deal with 5N Plus

UK-Australian mining firm Rio Tinto has started commercial production of critical metalloid tellurium at its Kennecott copper operation in Utah, and signed a supply deal with Canadian specialty material producer 5N Plus.

Rio Tinto is extracting the tellurium from by-product streams from copper refining operations at its Kennecott copper mine near Salt Lake, Utah. The company invested $2.9mn in building a circuit at the refinery capable of recovering 20 t/yr of tellurium. Construction was completed in less than a year.

The tellurium will be refined into metal and other compounds by 5N Plus under a commercial agreement between the two companies. The majority will be supplied to large US thin-film solar panel manufacturer First Solar under an existing supply contract with 5N Plus. 5N Plus will also use the tellurium to produce ultra high-purity semiconductor materials for medical imaging and defence applications at its plant in St George, Utah.

"We are proud to deliver a new domestic supply of tellurium to support the manufacturing of solar panels and other critical equipment here in the US. Around 90pc of the world's tellurium resource is contained in copper ore and no other metal has more critical mineral by-products than copper," Rio Tinto chief operating officer Clayton Walker said. "The Kennecott team is constantly looking for ways to extract new critical minerals to meet emerging demand for the clean energy transition," he added.

Initial production at Kennecott is small in terms of global supply, estimated at 600 t/yr by the US geological service, but reflects an increasing focus on critical minerals and regional supply chains.

Spot prices for tellurium metal have fallen recently on weaker demand in Europe, the US and Asia-Pacific. Argus prompt prices for 99.99pc metal were last assessed at $64-70/kg in-warehouse Rotterdam on 10 May.

By Caroline Messecar