In addition to carbon dioxide (CO2), a certain number of other substances are released into the air from cement kiln stacks: dust, nitrogen oxides (NOX) and sulphur dioxides (SO2). Mineral dusts are emitted at the kiln stack, and their composition is very close to that of the non-harmful raw materials processed in the cement kiln. Dust may also be released during the handling, transportation and storage of raw materials, clinker and cement. NOX are formed by the oxidation of nitrogen compounds in the fuel and by nitrogen in the combustion air at the high temperatures required to manufacture clinker. They can be controlled through the application of appropriate combustion techniques. SO2 is generated from raw materials or fuels containing sulphur that is not trapped in the process.
To reduce these emissions, Italcementi Group dedicates a substantial part of its industrial investments to replacing electrostatic with bag filters and choosing appropriate combustion techniques and fuel mixes.
By the end of 2010, the Group has committed to reduce its total emissions at the kiln main stacks down to 130 g/t clinker for dust, 1,760 g/t clinker for NOX and 570 g/t clinker for SO2, an 11%, 30% and 56% reduction respectively, compared to 2004 reported emission factors.
Atmospheric emissions can be monitored using either Continuous Emission Monitors (CEMs) at kiln stacks or periodic analyses carried out by certified laboratories. By the end of 2010, the Group aims at having over 90% of its kilns equipped with CEMs for measuring SO2, NOX and dust emissions at kiln stacks.