Rio Tinto to produce tellurium in the US
To recover critical solar energy mineral from Utah refinery Metal Tech News – March 10, 2021
Last updated 3/16/2021 at 5:54pm
With solar panel production driving up the demand for tellurium, Rio Tinto plans to recover roughly 20 metric tons of this critical mineral per year from its Kennecott copper mine near Salt Lake City, Utah.
One of the rarest stable elements on the periodic table, tellurium is almost always recovered as a byproduct of refining other metals it is associated with.
"Most rocks contain an average of about 3 parts per billion tellurium, making it rarer than the rare earth elements and eight times less abundant than gold," the United States Geological Survey wrote in a 2015 report on tellurium. "Grains of native tellurium appear in rocks as a brittle, silvery-white material, but tellurium more commonly occurs in telluride minerals that include varied quantities of gold, silver, or platinum."
Roughly 500 metric tons of tellurium is produced globally per year as a byproduct of refining copper concentrates, with roughly 60% being produced in China.
Traditionally, the small amounts of tellurium produced globally has been used as an additive to improve the strength and pliability of steel, copper, and lead alloys. This has changed with the advent of the cadmium telluride (CdTe) thin-film solar panels, which account for roughly 40% of global tellurium consumption last year.
Rio Tinto is investing $2.9 million to set up a plant that will recover tellurium as a byproduct of smelting copper at Kennecott, extracting about 20 metric tons of this valuable mineral per year from the waste streams at its Utah smelter.
"With abundant natural resources, Utah is ideally positioned to help supply the critical minerals essential to maintain American manufacturing competitiveness," said Utah Gov. Spencer Cox. "Rio Tinto's smelter at Kennecott is one of only two that is capable of producing copper and other critical minerals. The new tellurium plant is another valuable contribution to critical mineral independence and energy security in the U.S."
In addition to accounting for nearly 20% of U.S. copper production, Kennecott's smelting process also recovers gold, silver, lead carbonate, platinum, palladium, and selenium. With the addition of the molybdenum recovered from Rio Tinto's Copperton concentrator, nine products are currently recovered from Kennecott ore.
"The minerals and metals we produce are essential to accelerate the transition to renewable energy," said Rio Tinto Kennecott Managing Director Gaby Poirier. "Adding tellurium to our product portfolio provides customers in North America with a secure and reliable source of tellurium produced at the highest environmental and labor standards with renewable energy."
Rio Tinto expects to add tellurium to the list of metals recovered from Kennecott before the end of this year, creating a new North American supply chain for this critical mineral.
Rio Tinto is a partner with the U.S. Department of Energy's Critical Materials Institute and works closely with CMI experts to discover further ways to economically recover critical mineral byproducts such as rhenium, tellurium, and lithium.
The company is also investing in new facilities to extract battery-grade lithium from waste rock at its Boron, California mine site and high-quality scandium oxide from waste streams at its metallurgical complex in Quebec, Canada.
"Rio Tinto is committed to using innovation to reduce waste in our production process and extract as much value as possible from the material that we mine and process," said Poirier.