Selenium

A copper-refining by-product that decolourises glass, boosts manganese electrolysis and feeds crops and livestock; supply follows copper, not selenium demand.

Tech & minor metals · No. 42

• India critical 2023
• HHI 2,280 · moderately concentrated

Selenium decolourises glass, helps make manganese and feeds farm animals, yet its supply hinges on copper refining, not selenium demand.

Chart: Illustration: Selenium

Where it comes from

Chart: Map of where it comes from

Selenium travels with copper from mine to smelter, then settles in anode slimes during electrorefining, beside tellurium and precious metals. World output reached 4,237 t in 2024.

Three things to know

1. More than 80% of all selenium ever produced has come from anode slimes in copper refineries.
2. Metallurgy, mainly electrolytic manganese, used about 40% of world selenium in 2025, ahead of agriculture and glass at 20% each.
3. China made 53% of refined selenium in 2025, after its copper anode capacity more than doubled in a decade.

The journey

1. 1 Copper oreCopper sulphides carry trace selenium
2. 2 AnodesConcentrate smelted into copper anodes
3. 3 Anode slimesSelenium settles during electrorefining
4. 4 RefiningSlimes treated to 99.5% selenium
5. 5 ProductsPowder, shot, dioxide and compounds
6. 6 End usesGlass, manganese, feed, fertiliser, CIGS cells

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