The brief

Analyst view

• Building Project Crucible, a $7.4B smelter in Clarksville, Tennessee, to make 13 metal products from 2029.
• Backed by a $1.4B US Department of War investment and up to $210M in CHIPS Act funds from Commerce.
• Onsan refinery capacity: 650,000 t of zinc and 420,000 t of lead a year.

Technical approach

As reported

Smelting

One site, many metals

Zinc, lead and copper circuits are linked, so residue from one feeds the next and trace metals in the ore are captured instead of dumped.

By-products

Rare metals from common ore

Indium, germanium, gallium, antimony and bismuth occur in tiny amounts in zinc and lead ore; recovering them needs dedicated refining steps.

Acid

Sulfur into sulfuric acid

Sulfur released when roasting ore is captured as sulfuric acid, including an ultra-pure grade used to clean chips in semiconductor fabs.

Replication

Copying Onsan abroad

The Tennessee plant is designed on the Onsan model at a smaller scale, reusing a proven layout instead of inventing a new process.

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