Production of aluminum from its ores at aluminum smelters results in carbon dioxide CO2, carbon monoxide CO, sulfur dioxide SO2, and hydrogen fluoride HF gas emissions to the atmosphere.
Typically, the smelters have emission limit values (ELVs) for sulfur dioxide and hydrogen fluoride emissions. These emissions should be measured accurately, to ensure the smelter does not exceed its emission limit values.
In addition, several fluoride compounds may be produced during the process. These compounds include carbon tetrafluoride CF4, hexafluoroethane C2F6, sulfur hexafluoride SF6, and silicon tetrafluoride SiF4. These additional emission components are problematic, as they have high Global Warming Potential (GWP) values.
The GWP is a relative measure designed to demonstrate how much heat a greenhouse gas (GHG) traps in the atmosphere. Emission of one kilogram of carbon tetrafluoride into the atmosphere has the potential of heating the atmosphere as much as 7,000 kilograms of carbon dioxide over the next 100 years.