What it is
Arsenic is a metalloid used in trace amounts in compound semiconductors (gallium arsenide), lead-acid battery grids, and specialised alloys.
Why it matters
It is largely a byproduct of copper and lead smelting. Supply tracks those host metals rather than its own demand.
Circular challenges
Whether arsenic re-enters the economy at end-of-life is mostly settled at the design stage. These are the recurring blockers.
Byproduct economics
Production cannot be ramped independently — it follows copper and lead output, so shortages cannot be fixed by mining more arsenic.
Toxicity blocks recovery
Health and environmental rules make recycling arsenic-containing waste expensive; most of it is stabilised and landfilled instead of recovered.
Embedded in chips
In GaAs wafers, arsenic is locked into the semiconductor lattice and is only recoverable through energy-intensive chemical processing.