Magnesium: Emissions
Coal versus hydro: a fourfold carbon gap
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 21.8 t CO2e per t range 5.3-21.8 (QSLM hydro-powered electrolysis 5.3 with credits; Israel electrolysis 14.0; Brazil silicothermic 10.1 with forest credits; China Pidgeon weighted average 21.8) · cradle-to-gate, Chinese Pidgeon weighted average, which is about 86% of world output Global emissions per year 22.0 Mt CO2e per year 2025 · intensity x production: 950 kt Chinese output x 21.8 t plus about 150 kt elsewhere x roughly 10-14 t (derived, indicative)Per t of primary magnesium ingot (cradle-to-gate). Intensity: International Magnesium Association carbon footprint study (Oct 2020), reported by Light Metal Age (2021). Global total: Derived from IMA 2020 and USGS MCS 2026.
Share of footprint by lifecycle phase
Extraction 2% Refining / processing 96% Movement 2%Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | small: dolomite quarrying and brine pumping, well under 1 t CO2e/t Mg (indicative) | 2% | diesel for quarrying, about 10 t of dolomite per t of Mg | Raw material is abundant and near surface; extraction is not the issue | Indicative estimate; IMA 2020 attributes almost all emissions to processing |
| Refining / processing | about 21 t CO2e/t Pidgeon: ferrosilicon about 50% (about 11 t), process CO2 from calcining dolomite about 4-5 t, coal or coke-oven gas for kilns and retorts most of the rest | 96% | ferrosilicon reductant made with coal power; CO2 released from dolomite; coal heating of steel retorts | Excluding ferrosilicon upstream emissions gives about 12.1 t (IMA). Calcination CO2 is stoichiometric: dolomite is about 48% CO2 by mass | IMA 2020 via Light Metal Age (2021); stoichiometry |
| Movement | about 0.1-0.3 t CO2e/t (indicative) | 2% | truck to Tianjin and container shipping to Europe or North America | Ingot is dense and compact, so freight is minor | Indicative, typical container freight factors (IMO GHG Study 2020) |
| Usage | no direct emissions; enabling: replacing steel or aluminium cuts vehicle weight and fuel or battery use | – | lightweighting in cars and aircraft; SF6 cover gas in casting | SF6 has a GWP of 23,500 (IPCC AR5), so casting shops that still use it can add large emissions; the IMA promotes SO2 and HFC alternatives | IPCC AR5; IMA |
| Recycling / end of life | remelting scrap uses a small fraction of primary energy (often cited as about 5%, indicative); 1 t of secondary Mg avoids most of the 21.8 t primary footprint | – | remelting of die-cast and new scrap; magnesium in aluminium alloy scrap recovered with the aluminium | EU end-of-life recycling input rate 13%; US secondary output 110 kt in 2025 (82 kt from new scrap) | EU CRM 2023; USGS MCS 2026; IMA (indicative) |
Other environmental impacts
Pidgeon plants in Shaanxi have caused local air pollution (dust, SO2) and were curbed under China's 2021 energy controls. Magnesite calcining for refractories releases about 1.1 t of process CO2 per t of MgO (stoichiometric).
Levers to cut emissions
- Switch from Pidgeon to electrolysis on low-carbon power: QSLM in Qinghai reports 5.3-8.5 t CO2e/t versus 21.8 t (IMA 2020)
- Decarbonise ferrosilicon, about half of Pidgeon emissions (IMA 2020)
- Replace coal with coke-oven gas or natural gas for retort heating, and add on-site solar as Turkey's Kar Madencilik has (IMA 2020)
- Raise scrap remelting and closed-loop die-casting returns (EU end-of-life input only 13%)
- Phase out SF6 cover gas in casting (GWP 23,500, IPCC AR5)
India
India makes no primary magnesium and imports ingot (5.5% of world HS 8104 imports by value in 2024), so its metal footprint is embedded in Chinese Pidgeon output at about 22 t CO2e/t. India mined 85 kt of magnesite in 2025; calcining it to magnesia for refractories releases about 1.1 t CO2 per t MgO from the rock itself.
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.