In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. Cement is made by heating limestone with small quantities of other materials to 1450 °C in a kiln, in a process known as calcination to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. The resulting substance is then ground to make "Portland Cement". Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The most common use for Portland cement is in the production of concrete. In response to a federal court ruling and data from industry, the U.S. Environmental Protection Agency (EPA) is proposing changes to its 2010 air standards for the Portland cement manufacturing industry. The proposal would continue the significant emission reductions from the 2010 standards while providing industry additional compliance flexibilities, including more time to implement the proposed updates by extending the compliance date for existing cement kilns from September 2013 to September 2015.
The proposed EPA amendments would adjust the way cement kilns continuously monitor particulate matter emissions, would adjust certain emissions limits and would extend the compliance deadline for existing kilns. EPA is making the proposed changes in response to a federal court decision and petitions for reconsideration.
Based on new technical information, EPA is proposing to make changes to the methods for particulate matter, along with changes to the particulate emission limits that would be necessary with the monitoring change. Kilns would still be required to continuously monitor these emissions under today’s proposed amendments, which are not expected to have a significant impact on reductions from the final rule.
The compliance date for existing kilns under the air toxics standard is extended by two years from September 2013 to September 2015. The agency believes additional compliance time is warranted to allow the cement industry to reassess its emission control strategies in light of the proposed changes to the particulate limits and monitoring methods.
The open clinker pile standards will be revised from the 2010 final rule by allowing facilities to choose from a list of work practices to control fugitive emissions. The work practices would apply to any open clinker piles, regardless of the quantity of clinker or the length of time that the clinker pile exists.
EPA’s amended air toxic standards will reduce air emissions of mercury, non-dioxin organic air toxics (measured as total hydrocarbons), hydrochloric acid and non-mercury toxic metals (measured as particulate matter) from both new and existing cement kilns.
For further information see Cement.
Cement Plant image via Wikipedia.