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The Cement Manufacturing Process and Enviromental Performance

U.S. cement companies are dedicated to producing a superior product while continuously challenging manufacturing policies and procedures to improve energy efficiency and minimize emissions.

Four Steps to Produce Cement
Portland cement manufacturing is a four-step process:

1. Most raw materials, including limestone and other native materials, such as sand, shale, iron ore and clay, come from quarries, usually located near the cement manufacturing plant.
2. The materials are carefully analyzed, combined and blended, and then ground for further processing.
3. The materials are heated in an industrial furnace, called a kiln, which reaches temperatures of 3,400 degrees Fahrenheit (1,870 degrees Centigrade). The heat causes the materials to turn into a new marble-sized substance called clinker. The kiln is fueled by powdered coal, powdered petroleum coke, natural gas, oil, or recycled materials burned for energy recovery.
4. Red-hot clinker is cooled and ground with small amounts of gypsum and limestone. The end-result is a fine gray-colored powder called portland cement. This cement is so fine that one pound of cement powder contains 150 billion grains.
   

Environmental Performance Measures
The U.S. cement industry has adopted voluntary reduction targets for key environmental performance measures. PCA member companies have adopted these four goals:

• Carbon Dioxide—Reduce carbon dioxide emissions by 10 percent (from a 1990 baseline) per ton of cementitious product produced or sold by 2020.
  
• Cement Kiln Dust—Reduce the disposal of cement kiln dust by 60 percent (from a 1990 baseline) per ton of clinker produced by 2020.
  
• Environmental Management Systems—At least 40 percent of U.S. cement plants will implement an auditable and verifiable environmental management system by 2006, 75 percent by 2010, and 90 percent by 2020.
  
• Energy Efficiency—Improve energy efficiency by 20 percent (from a 1990 baseline) as measured by total Btu per unit of cementitious product by 2020.
  
  

More information Online:
2008 Report on Sustainable Manufacturing
Virtual Tour of Cement Plant
Cement and Concrete Basics
Canadian Cement Industry Sustainability Report

Related Topics:
PCA Sustainable Manufacturing Report

ConcreteThinker

Track Record of Sustainability

Cement and Concrete Reference Guide