Cadmium: Emissions
Why cadmium's footprint mirrors zinc smelting
Why cadmium's footprint mirrors zinc smelting What this tab covers The greenhouse-gas footprint of the commodity at a global level, split by lifecycle phase: extraction (or farming), refining and processing, movement, usage, and recycling or end of life. Intensities are per unit of product; the global total combines intensity with world output. Also covers other environmental impacts and the main levers to cut emissions. Emission intensity 3.50 t CO2e per t range about 2.5-6, higher where zinc is smelted on coal power · cradle-to-gate, allocation within zinc smelting. Cadmium ($3.90/kg) and zinc ($2.87/kg) prices were close in 2025, so mass and economic allocation give similar values near zinc's own footprint. Derived, indicative Global emissions per year 0.08 Mt CO2e per year 2025 · about 3.5 t CO2e/t x 23,000 t (derived, indicative)Per t of refined cadmium (99.95%), cradle-to-gate. Intensity: Derived from zinc footprint (IZA, indicative) and USGS MCS 2026 / World Bank 2025 prices. Global total: Derived from USGS MCS 2026.
Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | allocated share of zinc mining and concentration | – | diesel haulage, grinding electricity | Cadmium follows zinc into sphalerite concentrate | USGS MCS 2026 (qualitative) |
| Refining / processing | largest share: roasting, leaching and zinc electrowinning (allocated), then cadmium cementation with zinc dust and electrolytic or distillation refining | – | electricity for zinc electrowinning | Chinese and Korean smelting on fossil grids raises the figure | USGS MCS 2026 (qualitative) |
| Movement | small | – | zinc concentrate shipping, then small lots of cadmium | Concentrate freight is allocated with zinc | Qualitative |
| Usage | no direct emissions; CdTe modules produce power at about 8-16 g CO2e/kWh | – | solar generation, batteries | Enabling: CdTe solar displaces fossil generation | Fthenakis & Leccisi 2021, Progress in Photovoltaics |
| Recycling / end of life | EU end-of-life recycling input rate 30%; about 20% of world supply was recycled in 2008 | – | industrial NiCd battery recycling, electric-arc-furnace dust, CdTe panels | Recycling also keeps a toxic metal out of landfill | EU CRM 2023; USGS Circular 1365 (2010) |
Other environmental impacts
Cadmium is a toxic heavy metal. Historic zinc smelting caused soil and rice contamination (Itai-itai disease in Japan), and uncontrolled e-waste and battery disposal remain risks. Smelters that cannot sell cadmium must store it as hazardous waste.
Levers to cut emissions
- Decarbonise zinc smelting power, which sets most of cadmium's footprint
- Refine and sell cadmium rather than store residues, keeping it in controlled use
- Expand NiCd and CdTe recycling (EU rate already 30%)
- Tight emission controls at smelters to limit cadmium release to air and water
India
Hindustan Zinc's smelters at Chanderiya, Debari and Dariba produce cadmium with 827 kt of zinc (FY2025) but publish no cadmium tonnage; their partly captive coal power makes Indian zinc, and so cadmium, more carbon-intensive than the world average (indicative).
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.