Indium: Emissions
Why zinc smelting sets indium's carbon footprint
Why zinc smelting sets indium's carbon footprint 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 102 t CO2e per t range not published; allocation within zinc smelting dominates · cradle-to-gate, 2008 supply mix, economic allocation from zinc smelting Global emissions per year 0.11 Mt CO2e per year 2025 · 102 t x about 1,100 t refinery output (derived, indicative)Per t of refined indium metal, cradle-to-gate. Intensity: Nuss & Eckelman 2014, PLoS ONE (ecoinvent 2.2 data, economic allocation, 2008 supply mix; value read from Fig. 2, indicative). Global total: Derived from Nuss & Eckelman 2014 and USGS MCS 2026.
Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | small allocated share of zinc mining | – | zinc ore at under 1 to 100 ppm indium | Not paid for at most mines | USGS MCS 2026 (qualitative) |
| Refining / processing | dominant: allocated zinc smelting burden, residue leaching, solvent extraction, cementation and electrorefining | – | zinc smelter electricity and fuel; reagents | Nuss & Eckelman find purification (including zinc smelting) contributes more than final refining | Nuss & Eckelman 2014 |
| Movement | negligible per tonne | – | small ingot lots by air or container | Not material | Qualitative |
| Usage | no direct emissions; target making and sputtering waste much indium (planar targets use only about 30% of their material, indicative) | – | display and touchscreen manufacture | Low sputtering yield means much indium cycles through recycling | Industry practice (indicative) |
| Recycling / end of life | ITO target and chamber scrap recycled at scale in Japan and Korea; end-of-life recycling input rate about 1% (EU) | – | spent targets, chamber scrap; little recovery from scrapped screens | Recycled indium avoids the zinc smelting allocation | USGS MCS 2026; EU CRM 2023 |
Other environmental impacts
Indium compounds (especially ITO dust) are linked to lung disease in workers, so target making and recycling need dust control; host zinc smelting produces jarosite and other residues.
Levers to cut emissions
- Rotary sputtering targets with higher material use than planar targets
- Recover indium from end-of-life displays (now about 1%)
- Recover indium at zinc smelters on low-carbon power (Korea, Canada, Europe)
- Thinner ITO layers or substitutes such as silver nanowires in touch panels
India
India has no indium refining and imports all it needs, so its footprint is embedded in imported metal and in imported displays, which are the main use.
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.