Air pollution control and noise emissions
Besides having to address the issues of dust and noise, HeidelbergCement also faces a major challenge in terms of air pollutant emissions at the cement business line. Whereas dust and noise are generated during various phases of the production process, nitrogen oxides, sulphur oxides, heavy metals, dioxins and furans are produced only during kiln operation. These pollutants are regularly monitored and measured.
State-of-the-art filtering technologies, innovative procedures and process-integrated environmental protection measures have enabled us to substantially reduce the impact our activities have on people and nature. SO2 emissions have declined by 18% since 2008, for example. Our goal is to further reduce these emissions. Considerable investment in this effort will continue to be necessary in the cement business line. To this end, we have already installed a scrubber for SO2 reduction at our Brevik cement plant in Norway, and we have also invested extensively in new technologies in North America that will reduce the emissions of mercury, dust and NOX.
Emissions and how they come into existence
Dust is produced when materials are quarried, loaded and transported. It also forms as a result of grinding and burning activities during the cement production process. The dedusting of exhaust air at our cement production facilities is carried out using state-of-the-art electric and bag filters. In 2009 and 2010, we were able to significantly reduce emissions per ton of clinker. Cement kiln dust (CKD) is reincorporated into our production processes to the greatest extent possible.
Nitrogen oxides (NOx) are formed during the clinker production process because of the associated high temperature of 2,000 °C. We are continually optimizsing the operation of our kilns in order to reduce NOx emissions and we also utilizse reduction technologies such as the selective non-catalytic reduction process (SNCR).
Sulphur oxides (SO2) can also form as a result of the clinker burning process. The base substance here is the sulphur contained in the raw material, most of which gets incorporated in the clinker. Sulphide sulphur compounds in the raw material can lead to increased SO2 emission levels. Since 2008, we have succeeded in reducing these emissions by 18%.
Heavy metals are present in both raw materials and fuels. Most of these heavy metals get incorporated in the clinker; the lion’s share of volatile heavy metals and their compounds are separated along with kiln dust in dedusting systems. We also regularly measure mercury emissions at our plants.
Dioxins and furans are destroyed by long exposure to high temperatures and a surplus of oxygen in the cement kilns. In order to prevent the re-formation of dioxins in exhaust gas, our facilities are designed to ensure that kiln exhaust gases rapidly cool down to a temperature below the critical zone.
Noise arises in quarries, gravel pits and industrial facilities that employ heavy equipment, machines and means of transport. Our noise reduction measures start with the design of our facilities. Raw material extraction in particular leads to vibrations whose impact we reduce through specialised (blasting) technologies.