Cadmium
A toxic zinc by-product once dominated by batteries and pigments, now finding a second life in thin-film cadmium-telluride solar panels.
Tech & minor metals · No. 45
- India critical 2023
- HHI 2,044 · moderately concentrated
Zinc ores hold only about 0.03% cadmium, yet that trace now feeds thin-film solar panels as well as NiCd batteries.
Chart: Illustration: Cadmium
Where it comes from
Chart: Map of where it comes from
Nobody mines for cadmium. It stands in for zinc in sphalerite at about 0.03%, and zinc smelters strip it out while purifying their zinc solution.
Three things to know
- World cadmium sales in 2014 came to only about $43 million, a tiny market by metal standards.
- The leading US CdTe panel maker expected about 14 GW a year of domestic capacity once its fifth plant ramps up in 2026.
- The EU scores cadmium's supply risk at just 0.2, and only India's 2023 list calls it critical; the bigger issues are toxicity and surplus.
The journey
- 1 Zinc oreSphalerite with about 0.03% cadmium
- 2 SmeltingRoasted and leached at zinc smelters
- 3 PurificationCadmium stripped from zinc solution residues
- 4 RefiningCast as 99.95% metal
- 5 End usesNiCd batteries, CdTe panels, pigments, plating