Rio Tinto has started producing tellurium at its Kennecott copper operation in Utah, becoming one of only two US producers of the critical material used in advanced thin film photovoltaic solar panels.

Tellurium is mainly used together with cadmium in thin film solar cells.  The element also finds use in metallurgy (to improve machinability), electronics (including thermoelectric devices for cooling and energy generation), and a wide variety of minor applications.   Approximately 90% of the world’s tellurium resource is contained in copper ore and tellurium is recovered from by-product streams generated during copper refining (electrowinning).  A large number of countries have small-scale tellurium refining capacity, with the largest being Belgium and China.

Rio’s tellurium output helps bolster an emerging US supply chain.  Around 20tpy Te will be produced at the new US$2.9M circuit at Rio’s Kennecott refinery.  The material will be refined in North America by 5N Plus, a producer of specialty semiconductors and performance materials, under a commercial agreement between 5N Plus and Rio.  5N Plus will use some material to manufacture ultra-high purity semiconductor materials at its facility in St. George, Utah, to serve the security and medical imaging markets.  The majority, however, will be supplied to First Solar, the only US company among the world’s ten largest solar manufacturers, under an existing supply contract between 5N Plus and First Solar. 

First Solar, which produces cadmium telluride (CadTel) solar panels is expanding its US manufacturing capacity by 3.3 gigawatts (GW) annually, by building its third American manufacturing facility in Lake Township, Ohio. When fully operational, the new facility will scale the company’s Northwest Ohio footprint to a total annual capacity of 6 GW, which is believed to make it the largest fully vertically integrated solar manufacturing complex outside of China. 

The news follows last week’s announcement that Rio had produced the first batch of high purity scandium oxide at its commercial-scale demonstration plant in Canada, becoming the first North American producer of the critical material. While its scandium oxide output (once ramped up) gives Rio ~20% of global market capacity, its share of world tellurium capacity is more modest, likely around 3% of the global total.