The January 2011 report as part of the annual Mineral Commodity Summaries, produced by the US Geological Survey (USGS) has recently been released. The report consists of summative statistical data on the nature of the cement industry in the US, and shows a continued trend of low construction spending levels.
Domestic production and use
In 2010, about 61 million t of Portland cement and 1.8 million t of masonry cement were produced at 102 plants in 36 US states. Cement also was produced at two plants in Puerto Rico. Overall production was the lowest since 1982 and reflected continued plant closures and indefinite inactivation. Although the rate of decline abated significantly, sales volumes in 2010 were the lowest in 27 years and were nearly 59 million t (45%) below the record level of 2005. The overall value of sales was about US$6.5 billion. Most of the cement was used to make concrete, worth at least US$35 billion. About 73% of cement sales went to ready-mixed concrete producers, 12% to concrete product manufacturers, 10% to contractors (mainly road paving), 2% to building materials dealers, and 3% to other users. In descending order, Texas, California, Missouri, Pennsylvania, Alabama, and Michigan were the six leading cement-producing states and accounted for about 50% of US production.
Events, trends, and issues
Construction spending levels remained low because of the combined effects of the ongoing depressed housing market, high numbers of housing foreclosures, reduced tax revenues to the states, credit tightening, and high levels of unemployment. In the construction sectors requiring significant amounts of concrete (hence cement), stimulus spending had little impact in 2009 and through the first half of 2010. Cement production began to pick up modestly after the first quarter in 2010 but still registered a decline for the year. The spate of announced plant closures and inactivation begun in 2008 abated somewhat in 2010, although it was uncertain if some of the still idle plants would ever reopen. From 2008 through 2010, at least six plants were closed permanently, another plant permanently shut its only kiln, and nine plants were placed into indefinite idle status. Many multiple kiln plants reduced the number of kilns in operation, and plants overall inactive kilns temporarily for slow sales and extended the periods of maintenance downtime on the kilns. One new plant was expected to open toward the end of 2010.
The manufacture of clinker for cement releases a great deal of carbon dioxide, and plant-level reporting of these emissions to the US Environmental Protection Agency (EPA) became mandatory in 2010. Carbon dioxide reduction strategies by the cement industry largely aim at reducing emissions per t of cement product rather than by overall plant. These strategies include installation of more fuel efficient kiln technologies, partial substitution of noncarbonated sources of calcium oxide in the kiln raw materials, and partial substitution of supplementary cementitious materials (SCM), such as pozzolans, for Portland cement in the finished cement products and in concrete. As SCM do not require the energy-intensive clinker manufacturing (kiln) phase of cement production, their use, or the use of inert additives or extenders, reduces the unit monetary and environmental costs of the cement component of concrete. Research was ongoing toward developing cements that require less energy to manufacture than Portland cement, and/or that utilise more benign raw materials.
A new emissions limitation protocol for cement plants was finalised in 2010 by the EPA after initial release in 2009 and revisions in the interim. The protocol would significantly lower the acceptable emissions levels of mercury and certain other pollutants. It was unclear how many plants would be able to comply with the new limits; the mercury limits were further expected to make it difficult for cement plants to continue to burn flyash as a raw material for clinker manufacture.
To view a PDF version of the report with statistical data please visit the USGS website, http://minerals.usgs.gov/minerals/pubs/commodity/cement/
Read the article online at: https://www.worldcement.com/the-americas/18032011/us_geological_survey_releases_its_annual_report_on_the_us_cement_industry-/